Merge remote-tracking branch 'upstream/master' into route_response

BUILD

@@ -319,8 +319,9 @@ grpc_cc_library(
     deps = [
         "grpc_common",
         "grpc_lb_policy_cds",
+        "grpc_lb_policy_eds",
         "grpc_lb_policy_grpclb",
-        "grpc_lb_policy_xds",
+        "grpc_lb_policy_lrs",
         "grpc_lb_policy_xds_routing",
         "grpc_resolver_xds",
     ],
@@ -338,9 +339,10 @@ grpc_cc_library(
     deps = [
         "grpc_common",
         "grpc_lb_policy_cds_secure",
+        "grpc_lb_policy_eds_secure",
         "grpc_lb_policy_grpclb_secure",
+        "grpc_lb_policy_lrs_secure",
         "grpc_lb_policy_xds_routing",
-        "grpc_lb_policy_xds_secure",
         "grpc_resolver_xds_secure",
         "grpc_secure",
         "grpc_transport_chttp2_client_secure",
@@ -1025,7 +1027,9 @@ grpc_cc_library(
         "grpc_deadline_filter",
         "grpc_client_authority_filter",
         "grpc_lb_policy_pick_first",
+        "grpc_lb_policy_priority",
         "grpc_lb_policy_round_robin",
+        "grpc_lb_policy_weighted_target",
         "grpc_client_idle_filter",
         "grpc_max_age_filter",
         "grpc_message_size_filter",
@@ -1359,41 +1363,75 @@ grpc_cc_library(
 )
 
 grpc_cc_library(
-    name = "grpc_lb_policy_xds",
+    name = "grpc_lb_policy_cds",
     srcs = [
-        "src/core/ext/filters/client_channel/lb_policy/xds/xds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/cds.cc",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+        "grpc_xds_client",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc_lb_policy_cds_secure",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/cds.cc",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+        "grpc_xds_client_secure",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc_lb_policy_eds",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/xds/eds.cc",
     ],
     hdrs = [
         "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
     ],
+    external_deps = [
+        "absl/strings",
+    ],
     language = "c++",
     deps = [
         "grpc_base",
         "grpc_client_channel",
+        "grpc_lb_address_filtering",
         "grpc_xds_client",
     ],
 )
 
 grpc_cc_library(
-    name = "grpc_lb_policy_xds_secure",
+    name = "grpc_lb_policy_eds_secure",
     srcs = [
-        "src/core/ext/filters/client_channel/lb_policy/xds/xds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/eds.cc",
     ],
     hdrs = [
         "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
     ],
+    external_deps = [
+        "absl/strings",
+    ],
     language = "c++",
     deps = [
         "grpc_base",
         "grpc_client_channel",
+        "grpc_lb_address_filtering",
         "grpc_xds_client_secure",
     ],
 )
 
 grpc_cc_library(
-    name = "grpc_lb_policy_cds",
+    name = "grpc_lb_policy_lrs",
     srcs = [
-        "src/core/ext/filters/client_channel/lb_policy/xds/cds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc",
     ],
     language = "c++",
     deps = [
@@ -1404,9 +1442,9 @@ grpc_cc_library(
 )
 
 grpc_cc_library(
-    name = "grpc_lb_policy_cds_secure",
+    name = "grpc_lb_policy_lrs_secure",
     srcs = [
-        "src/core/ext/filters/client_channel/lb_policy/xds/cds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc",
     ],
     language = "c++",
     deps = [
@@ -1420,6 +1458,24 @@ grpc_cc_library(
     name = "grpc_lb_policy_xds_routing",
     srcs = [
         "src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc",
+        ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc_lb_address_filtering",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/address_filtering.cc",
+    ],
+    hdrs = [
+        "src/core/ext/filters/client_channel/lb_policy/address_filtering.h",
+    ],
+    external_deps = [
+        "absl/strings",
     ],
     language = "c++",
     deps = [
@@ -1466,6 +1522,35 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "grpc_lb_policy_priority",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/priority/priority.cc",
+    ],
+    external_deps = [
+        "absl/strings",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+        "grpc_lb_address_filtering",
+    ],
+)
+
+grpc_cc_library(
+    name = "grpc_lb_policy_weighted_target",
+    srcs = [
+        "src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc",
+    ],
+    language = "c++",
+    deps = [
+        "grpc_base",
+        "grpc_client_channel",
+        "grpc_lb_address_filtering",
+    ],
+)
+
 grpc_cc_library(
     name = "lb_server_load_reporting_filter",
     srcs = [

BUILD.gn

@@ -223,6 +223,8 @@ config("grpc_config") {
         "src/core/ext/filters/client_channel/http_proxy.h",
         "src/core/ext/filters/client_channel/lb_policy.cc",
         "src/core/ext/filters/client_channel/lb_policy.h",
+        "src/core/ext/filters/client_channel/lb_policy/address_filtering.cc",
+        "src/core/ext/filters/client_channel/lb_policy/address_filtering.h",
         "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc",
         "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc",
@@ -238,10 +240,13 @@ config("grpc_config") {
         "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc",
         "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h",
         "src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc",
+        "src/core/ext/filters/client_channel/lb_policy/priority/priority.cc",
         "src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc",
         "src/core/ext/filters/client_channel/lb_policy/subchannel_list.h",
+        "src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc",
         "src/core/ext/filters/client_channel/lb_policy/xds/cds.cc",
-        "src/core/ext/filters/client_channel/lb_policy/xds/xds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/eds.cc",
+        "src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc",
         "src/core/ext/filters/client_channel/lb_policy/xds/xds.h",
         "src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc",
         "src/core/ext/filters/client_channel/lb_policy_factory.h",
@@ -963,6 +968,7 @@ config("grpc_config") {
         ":address_sorting",
         ":upb",
         ":absl/types:optional",
+        ":absl/strings:strings",
         ":absl/container:inlined_vector",
         "//third_party/cares",
         ":address_sorting",

CMakeLists.txt

@@ -457,7 +457,6 @@ if(gRPC_BUILD_TESTS)
   add_dependencies(buildtests_c compression_test)
   add_dependencies(buildtests_c concurrent_connectivity_test)
   add_dependencies(buildtests_c connection_refused_test)
-  add_dependencies(buildtests_c control_plane_credentials_test)
   add_dependencies(buildtests_c cpu_test)
   add_dependencies(buildtests_c dns_resolver_connectivity_using_ares_resolver_test)
   add_dependencies(buildtests_c dns_resolver_connectivity_using_native_resolver_test)
@@ -1316,6 +1315,7 @@ add_library(grpc
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
+  src/core/ext/filters/client_channel/lb_policy/address_filtering.cc
   src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
@@ -1324,9 +1324,12 @@ add_library(grpc
   src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
   src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
+  src/core/ext/filters/client_channel/lb_policy/priority/priority.cc
   src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
+  src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc
   src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
-  src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/eds.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc
   src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc
   src/core/ext/filters/client_channel/lb_policy_registry.cc
   src/core/ext/filters/client_channel/local_subchannel_pool.cc
@@ -1745,6 +1748,7 @@ target_link_libraries(grpc
   address_sorting
   upb
   absl::optional
+  absl::strings
   absl::inlined_vector
 )
 if(_gRPC_PLATFORM_IOS OR _gRPC_PLATFORM_MAC)
@@ -1971,6 +1975,7 @@ add_library(grpc_unsecure
   src/core/ext/filters/client_channel/http_connect_handshaker.cc
   src/core/ext/filters/client_channel/http_proxy.cc
   src/core/ext/filters/client_channel/lb_policy.cc
+  src/core/ext/filters/client_channel/lb_policy/address_filtering.cc
   src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
@@ -1979,10 +1984,17 @@ add_library(grpc_unsecure
   src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
   src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
+  src/core/ext/filters/client_channel/lb_policy/priority/priority.cc
   src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
+  src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc
   src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
+<<<<<<< HEAD
   src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
   src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc
+=======
+  src/core/ext/filters/client_channel/lb_policy/xds/eds.cc
+  src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc
+>>>>>>> upstream/master
   src/core/ext/filters/client_channel/lb_policy_registry.cc
   src/core/ext/filters/client_channel/local_subchannel_pool.cc
   src/core/ext/filters/client_channel/parse_address.cc
@@ -2324,6 +2336,7 @@ target_link_libraries(grpc_unsecure
   address_sorting
   upb
   absl::optional
+  absl::strings
   absl::inlined_vector
 )
 if(_gRPC_PLATFORM_IOS OR _gRPC_PLATFORM_MAC)
@@ -4827,40 +4840,6 @@ target_link_libraries(connection_refused_test
 )
 
 
-endif()
-if(gRPC_BUILD_TESTS)
-
-add_executable(control_plane_credentials_test
-  test/core/end2end/cq_verifier.cc
-  test/core/end2end/data/client_certs.cc
-  test/core/end2end/data/server1_cert.cc
-  test/core/end2end/data/server1_key.cc
-  test/core/end2end/data/test_root_cert.cc
-  test/core/security/control_plane_credentials_test.cc
-)
-
-target_include_directories(control_plane_credentials_test
-  PRIVATE
-    ${CMAKE_CURRENT_SOURCE_DIR}
-    ${CMAKE_CURRENT_SOURCE_DIR}/include
-    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
-    ${_gRPC_SSL_INCLUDE_DIR}
-    ${_gRPC_UPB_GENERATED_DIR}
-    ${_gRPC_UPB_GRPC_GENERATED_DIR}
-    ${_gRPC_UPB_INCLUDE_DIR}
-    ${_gRPC_ZLIB_INCLUDE_DIR}
-)
-
-target_link_libraries(control_plane_credentials_test
-  ${_gRPC_ALLTARGETS_LIBRARIES}
-  grpc_test_util
-  grpc
-  gpr
-  address_sorting
-  upb
-)
-
-
 endif()
 if(gRPC_BUILD_TESTS)
 

Makefile

@@ -1047,7 +1047,6 @@ completion_queue_threading_test: $(BINDIR)/$(CONFIG)/completion_queue_threading_
 compression_test: $(BINDIR)/$(CONFIG)/compression_test
 concurrent_connectivity_test: $(BINDIR)/$(CONFIG)/concurrent_connectivity_test
 connection_refused_test: $(BINDIR)/$(CONFIG)/connection_refused_test
-control_plane_credentials_test: $(BINDIR)/$(CONFIG)/control_plane_credentials_test
 cpu_test: $(BINDIR)/$(CONFIG)/cpu_test
 dns_resolver_connectivity_using_ares_resolver_test: $(BINDIR)/$(CONFIG)/dns_resolver_connectivity_using_ares_resolver_test
 dns_resolver_connectivity_using_native_resolver_test: $(BINDIR)/$(CONFIG)/dns_resolver_connectivity_using_native_resolver_test
@@ -1424,7 +1423,6 @@ buildtests_c: privatelibs_c \
   $(BINDIR)/$(CONFIG)/compression_test \
   $(BINDIR)/$(CONFIG)/concurrent_connectivity_test \
   $(BINDIR)/$(CONFIG)/connection_refused_test \
-  $(BINDIR)/$(CONFIG)/control_plane_credentials_test \
   $(BINDIR)/$(CONFIG)/cpu_test \
   $(BINDIR)/$(CONFIG)/dns_resolver_connectivity_using_ares_resolver_test \
   $(BINDIR)/$(CONFIG)/dns_resolver_connectivity_using_native_resolver_test \
@@ -1916,16 +1914,12 @@ test_c: buildtests_c
 	$(Q) $(BINDIR)/$(CONFIG)/cmdline_test || ( echo test cmdline_test failed ; exit 1 )
 	$(E) "[RUN]     Testing combiner_test"
 	$(Q) $(BINDIR)/$(CONFIG)/combiner_test || ( echo test combiner_test failed ; exit 1 )
-	$(E) "[RUN]     Testing completion_queue_threading_test"
-	$(Q) $(BINDIR)/$(CONFIG)/completion_queue_threading_test || ( echo test completion_queue_threading_test failed ; exit 1 )
 	$(E) "[RUN]     Testing compression_test"
 	$(Q) $(BINDIR)/$(CONFIG)/compression_test || ( echo test compression_test failed ; exit 1 )
 	$(E) "[RUN]     Testing concurrent_connectivity_test"
 	$(Q) $(BINDIR)/$(CONFIG)/concurrent_connectivity_test || ( echo test concurrent_connectivity_test failed ; exit 1 )
 	$(E) "[RUN]     Testing connection_refused_test"
 	$(Q) $(BINDIR)/$(CONFIG)/connection_refused_test || ( echo test connection_refused_test failed ; exit 1 )
-	$(E) "[RUN]     Testing control_plane_credentials_test"
-	$(Q) $(BINDIR)/$(CONFIG)/control_plane_credentials_test || ( echo test control_plane_credentials_test failed ; exit 1 )
 	$(E) "[RUN]     Testing cpu_test"
 	$(Q) $(BINDIR)/$(CONFIG)/cpu_test || ( echo test cpu_test failed ; exit 1 )
 	$(E) "[RUN]     Testing dns_resolver_connectivity_using_ares_resolver_test"
@@ -2210,8 +2204,6 @@ test_cxx: buildtests_cxx
 	$(Q) $(BINDIR)/$(CONFIG)/cli_call_test || ( echo test cli_call_test failed ; exit 1 )
 	$(E) "[RUN]     Testing client_callback_end2end_test"
 	$(Q) $(BINDIR)/$(CONFIG)/client_callback_end2end_test || ( echo test client_callback_end2end_test failed ; exit 1 )
-	$(E) "[RUN]     Testing client_channel_stress_test"
-	$(Q) $(BINDIR)/$(CONFIG)/client_channel_stress_test || ( echo test client_channel_stress_test failed ; exit 1 )
 	$(E) "[RUN]     Testing client_interceptors_end2end_test"
 	$(Q) $(BINDIR)/$(CONFIG)/client_interceptors_end2end_test || ( echo test client_interceptors_end2end_test failed ; exit 1 )
 	$(E) "[RUN]     Testing codegen_test_full"
@@ -3646,6 +3638,7 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
+    src/core/ext/filters/client_channel/lb_policy/address_filtering.cc \
     src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc \
@@ -3654,9 +3647,12 @@ LIBGRPC_SRC = \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
+    src/core/ext/filters/client_channel/lb_policy/priority/priority.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
+    src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-    src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc \
     src/core/ext/filters/client_channel/lb_policy_registry.cc \
     src/core/ext/filters/client_channel/local_subchannel_pool.cc \
@@ -4276,6 +4272,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
+    src/core/ext/filters/client_channel/lb_policy/address_filtering.cc \
     src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc \
@@ -4284,9 +4281,12 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
+    src/core/ext/filters/client_channel/lb_policy/priority/priority.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
+    src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-    src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc \
     src/core/ext/filters/client_channel/lb_policy_registry.cc \
     src/core/ext/filters/client_channel/local_subchannel_pool.cc \
@@ -7844,53 +7844,6 @@ endif
 endif
 
 
-CONTROL_PLANE_CREDENTIALS_TEST_SRC = \
-    test/core/end2end/cq_verifier.cc \
-    test/core/end2end/data/client_certs.cc \
-    test/core/end2end/data/server1_cert.cc \
-    test/core/end2end/data/server1_key.cc \
-    test/core/end2end/data/test_root_cert.cc \
-    test/core/security/control_plane_credentials_test.cc \
-
-CONTROL_PLANE_CREDENTIALS_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(CONTROL_PLANE_CREDENTIALS_TEST_SRC))))
-ifeq ($(NO_SECURE),true)
-
-# You can't build secure targets if you don't have OpenSSL.
-
-$(BINDIR)/$(CONFIG)/control_plane_credentials_test: openssl_dep_error
-
-else
-
-
-
-$(BINDIR)/$(CONFIG)/control_plane_credentials_test: $(CONTROL_PLANE_CREDENTIALS_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-	$(E) "[LD]      Linking $@"
-	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LDXX) $(LDFLAGS) $(CONTROL_PLANE_CREDENTIALS_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/control_plane_credentials_test
-
-endif
-
-$(OBJDIR)/$(CONFIG)/test/core/end2end/cq_verifier.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-
-$(OBJDIR)/$(CONFIG)/test/core/end2end/data/client_certs.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-
-$(OBJDIR)/$(CONFIG)/test/core/end2end/data/server1_cert.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-
-$(OBJDIR)/$(CONFIG)/test/core/end2end/data/server1_key.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-
-$(OBJDIR)/$(CONFIG)/test/core/end2end/data/test_root_cert.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-
-$(OBJDIR)/$(CONFIG)/test/core/security/control_plane_credentials_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LIBDIR)/$(CONFIG)/libaddress_sorting.a $(LIBDIR)/$(CONFIG)/libupb.a
-
-deps_control_plane_credentials_test: $(CONTROL_PLANE_CREDENTIALS_TEST_OBJS:.o=.dep)
-
-ifneq ($(NO_SECURE),true)
-ifneq ($(NO_DEPS),true)
--include $(CONTROL_PLANE_CREDENTIALS_TEST_OBJS:.o=.dep)
-endif
-endif
-
-
 CPU_TEST_SRC = \
     test/core/gpr/cpu_test.cc \
 

build_autogenerated.yaml

@@ -382,6 +382,7 @@ libs:
   - src/core/ext/filters/client_channel/http_connect_handshaker.h
   - src/core/ext/filters/client_channel/http_proxy.h
   - src/core/ext/filters/client_channel/lb_policy.h
+  - src/core/ext/filters/client_channel/lb_policy/address_filtering.h
   - src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h
@@ -740,6 +741,7 @@ libs:
   - src/core/ext/filters/client_channel/http_connect_handshaker.cc
   - src/core/ext/filters/client_channel/http_proxy.cc
   - src/core/ext/filters/client_channel/lb_policy.cc
+  - src/core/ext/filters/client_channel/lb_policy/address_filtering.cc
   - src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
@@ -748,9 +750,12 @@ libs:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
   - src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
+  - src/core/ext/filters/client_channel/lb_policy/priority/priority.cc
   - src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
+  - src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
-  - src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/eds.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc
   - src/core/ext/filters/client_channel/lb_policy_registry.cc
   - src/core/ext/filters/client_channel/local_subchannel_pool.cc
@@ -1133,6 +1138,7 @@ libs:
   - address_sorting
   - upb
   - absl/types:optional
+  - absl/strings:strings
   - absl/container:inlined_vector
   baselib: true
   dll: true
@@ -1279,6 +1285,7 @@ libs:
   - src/core/ext/filters/client_channel/http_connect_handshaker.h
   - src/core/ext/filters/client_channel/http_proxy.h
   - src/core/ext/filters/client_channel/lb_policy.h
+  - src/core/ext/filters/client_channel/lb_policy/address_filtering.h
   - src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h
@@ -1572,6 +1579,7 @@ libs:
   - src/core/ext/filters/client_channel/http_connect_handshaker.cc
   - src/core/ext/filters/client_channel/http_proxy.cc
   - src/core/ext/filters/client_channel/lb_policy.cc
+  - src/core/ext/filters/client_channel/lb_policy/address_filtering.cc
   - src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
@@ -1580,10 +1588,17 @@ libs:
   - src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
   - src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
   - src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
+  - src/core/ext/filters/client_channel/lb_policy/priority/priority.cc
   - src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
+  - src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
+<<<<<<< HEAD
   - src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
   - src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc
+=======
+  - src/core/ext/filters/client_channel/lb_policy/xds/eds.cc
+  - src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc
+>>>>>>> upstream/master
   - src/core/ext/filters/client_channel/lb_policy_registry.cc
   - src/core/ext/filters/client_channel/local_subchannel_pool.cc
   - src/core/ext/filters/client_channel/parse_address.cc
@@ -1890,6 +1905,7 @@ libs:
   - address_sorting
   - upb
   - absl/types:optional
+  - absl/strings:strings
   - absl/container:inlined_vector
   baselib: true
   dll: true
@@ -3096,6 +3112,7 @@ targets:
   - mac
 - name: completion_queue_threading_test
   build: test
+  run: false
   language: c
   headers: []
   src:
@@ -3145,25 +3162,6 @@ targets:
   - gpr
   - address_sorting
   - upb
-- name: control_plane_credentials_test
-  build: test
-  language: c
-  headers:
-  - test/core/end2end/cq_verifier.h
-  - test/core/end2end/data/ssl_test_data.h
-  src:
-  - test/core/end2end/cq_verifier.cc
-  - test/core/end2end/data/client_certs.cc
-  - test/core/end2end/data/server1_cert.cc
-  - test/core/end2end/data/server1_key.cc
-  - test/core/end2end/data/test_root_cert.cc
-  - test/core/security/control_plane_credentials_test.cc
-  deps:
-  - grpc_test_util
-  - grpc
-  - gpr
-  - address_sorting
-  - upb
 - name: cpu_test
   build: test
   language: c
@@ -5519,6 +5517,7 @@ targets:
 - name: client_channel_stress_test
   gtest: true
   build: test
+  run: false
   language: c++
   headers:
   - test/cpp/end2end/test_service_impl.h

config.m4

@@ -50,6 +50,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/http_connect_handshaker.cc \
     src/core/ext/filters/client_channel/http_proxy.cc \
     src/core/ext/filters/client_channel/lb_policy.cc \
+    src/core/ext/filters/client_channel/lb_policy/address_filtering.cc \
     src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc \
@@ -58,9 +59,12 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc \
     src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
     src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
+    src/core/ext/filters/client_channel/lb_policy/priority/priority.cc \
     src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
+    src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-    src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
+    src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc \
     src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc \
     src/core/ext/filters/client_channel/lb_policy_registry.cc \
     src/core/ext/filters/client_channel/local_subchannel_pool.cc \
@@ -822,7 +826,9 @@ if test "$PHP_GRPC" != "no"; then
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/grpclb)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/pick_first)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/priority)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/round_robin)
+  PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/weighted_target)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/lb_policy/xds)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/dns)
   PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/dns/c_ares)

config.w32

@@ -19,6 +19,7 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\http_connect_handshaker.cc " +
     "src\\core\\ext\\filters\\client_channel\\http_proxy.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\address_filtering.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\child_policy_handler.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\client_load_reporting_filter.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\grpclb.cc " +
@@ -27,9 +28,12 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\grpclb_client_stats.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb\\load_balancer_api.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\pick_first\\pick_first.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\priority\\priority.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\round_robin\\round_robin.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\weighted_target\\weighted_target.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\cds.cc " +
-    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\eds.cc " +
+    "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\lrs.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy\\xds\\xds_routing.cc " +
     "src\\core\\ext\\filters\\client_channel\\lb_policy_registry.cc " +
     "src\\core\\ext\\filters\\client_channel\\local_subchannel_pool.cc " +
@@ -822,7 +826,9 @@ if (PHP_GRPC != "no") {
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\grpclb");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\pick_first");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\priority");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\round_robin");
+  FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\weighted_target");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\lb_policy\\xds");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\resolver");
   FSO.CreateFolder(base_dir+"\\ext\\grpc\\src\\core\\ext\\filters\\client_channel\\resolver\\dns");

doc/environment_variables.md

@@ -57,6 +57,7 @@ some configuration as environment variables that can be set.
   - compression - traces compression operations
   - connectivity_state - traces connectivity state changes to channels
   - cronet - traces state in the cronet transport engine
+  - eds_lb - traces eds LB policy
   - executor - traces grpc's internal thread pool ('the executor')
   - glb - traces the grpclb load balancer
   - handshaker - traces handshaking state
@@ -66,12 +67,14 @@ some configuration as environment variables that can be set.
   - http1 - traces HTTP/1.x operations performed by gRPC
   - inproc - traces the in-process transport
   - flowctl - traces http2 flow control
+  - lrs_lb - traces lrs LB policy
   - op_failure - traces error information when failure is pushed onto a
     completion queue
   - pick_first - traces the pick first load balancing policy
   - plugin_credentials - traces plugin credentials
   - pollable_refcount - traces reference counting of 'pollable' objects (only 
     in DEBUG)
+  - priority_lb - traces priority LB policy
   - resource_quota - trace resource quota objects internals
   - round_robin - traces the round_robin load balancing policy
   - queue_pluck
@@ -84,8 +87,8 @@ some configuration as environment variables that can be set.
   - transport_security - traces metadata about secure channel establishment
   - tcp - traces bytes in and out of a channel
   - tsi - traces tsi transport security
+  - weighted_target_lb - traces weighted_target LB policy
   - xds_client - traces xds client
-  - xds_lb - traces xds LB policy
   - xds_resolver - traces xds resolver
 
   The following tracers will only run in binaries built in DEBUG mode. This is

gRPC-C++.podspec

@@ -233,6 +233,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/http_connect_handshaker.h',
                       'src/core/ext/filters/client_channel/http_proxy.h',
                       'src/core/ext/filters/client_channel/lb_policy.h',
+                      'src/core/ext/filters/client_channel/lb_policy/address_filtering.h',
                       'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',
@@ -683,6 +684,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/http_connect_handshaker.h',
                               'src/core/ext/filters/client_channel/http_proxy.h',
                               'src/core/ext/filters/client_channel/lb_policy.h',
+                              'src/core/ext/filters/client_channel/lb_policy/address_filtering.h',
                               'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',

gRPC-Core.podspec

@@ -206,6 +206,8 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/http_proxy.h',
                       'src/core/ext/filters/client_channel/lb_policy.cc',
                       'src/core/ext/filters/client_channel/lb_policy.h',
+                      'src/core/ext/filters/client_channel/lb_policy/address_filtering.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/address_filtering.h',
                       'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc',
                       'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc',
@@ -221,10 +223,13 @@ Pod::Spec.new do |s|
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc',
                       'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
                       'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/priority/priority.cc',
                       'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
                       'src/core/ext/filters/client_channel/lb_policy/subchannel_list.h',
+                      'src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc',
                       'src/core/ext/filters/client_channel/lb_policy/xds/cds.cc',
-                      'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/eds.cc',
+                      'src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc',
                       'src/core/ext/filters/client_channel/lb_policy/xds/xds.h',
                       'src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc',
                       'src/core/ext/filters/client_channel/lb_policy_factory.h',
@@ -1033,6 +1038,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/filters/client_channel/http_connect_handshaker.h',
                               'src/core/ext/filters/client_channel/http_proxy.h',
                               'src/core/ext/filters/client_channel/lb_policy.h',
+                              'src/core/ext/filters/client_channel/lb_policy/address_filtering.h',
                               'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h',
                               'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',

grpc.gemspec

@@ -128,6 +128,8 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/http_proxy.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/address_filtering.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/address_filtering.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc )
@@ -143,10 +145,13 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/priority/priority.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/subchannel_list.h )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/cds.cc )
-  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/eds.cc )
+  s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds.h )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc )
   s.files += %w( src/core/ext/filters/client_channel/lb_policy_factory.h )

grpc.gyp

@@ -426,6 +426,7 @@
         'address_sorting',
         'upb',
         'absl/types:optional',
+        'absl/strings:strings',
         'absl/container:inlined_vector',
       ],
       'sources': [
@@ -442,6 +443,7 @@
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
         'src/core/ext/filters/client_channel/http_proxy.cc',
         'src/core/ext/filters/client_channel/lb_policy.cc',
+        'src/core/ext/filters/client_channel/lb_policy/address_filtering.cc',
         'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc',
@@ -450,9 +452,12 @@
         'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc',
         'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
+        'src/core/ext/filters/client_channel/lb_policy/priority/priority.cc',
         'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
+        'src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/cds.cc',
-        'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/eds.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc',
         'src/core/ext/filters/client_channel/lb_policy_registry.cc',
         'src/core/ext/filters/client_channel/local_subchannel_pool.cc',
@@ -917,6 +922,7 @@
         'address_sorting',
         'upb',
         'absl/types:optional',
+        'absl/strings:strings',
         'absl/container:inlined_vector',
       ],
       'sources': [
@@ -933,6 +939,7 @@
         'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
         'src/core/ext/filters/client_channel/http_proxy.cc',
         'src/core/ext/filters/client_channel/lb_policy.cc',
+        'src/core/ext/filters/client_channel/lb_policy/address_filtering.cc',
         'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc',
@@ -941,9 +948,12 @@
         'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc',
         'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc',
         'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
+        'src/core/ext/filters/client_channel/lb_policy/priority/priority.cc',
         'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
+        'src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/cds.cc',
-        'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/eds.cc',
+        'src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc',
         'src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc',
         'src/core/ext/filters/client_channel/lb_policy_registry.cc',
         'src/core/ext/filters/client_channel/local_subchannel_pool.cc',

include/grpc/impl/codegen/grpc_types.h

@@ -348,18 +348,11 @@ typedef struct {
    balancer before using fallback backend addresses from the resolver.
    If 0, enter fallback mode immediately. Default value is 10000. */
 #define GRPC_ARG_XDS_FALLBACK_TIMEOUT_MS "grpc.xds_fallback_timeout_ms"
-/* Time in milliseconds to wait before a locality is deleted after it's removed
-   from the received EDS update. If 0, delete the locality immediately. Default
-   value is 15 minutes. */
-#define GRPC_ARG_LOCALITY_RETENTION_INTERVAL_MS \
-  "grpc.xds_locality_retention_interval_ms"
-/* Timeout in milliseconds to wait for the localities of a specific priority to
-   complete their initial connection attempt before xDS fails over to the next
-   priority. Specifically, the connection attempt of a priority is considered
-   completed when any locality of that priority is ready or all the localities
-   of that priority fail to connect. If 0, failover happens immediately. Default
-   value is 10 seconds. */
-#define GRPC_ARG_XDS_FAILOVER_TIMEOUT_MS "grpc.xds_failover_timeout_ms"
+/* Timeout in milliseconds to wait for the child of a specific priority to
+   complete its initial connection attempt before the priority LB policy fails
+   over to the next priority. Default value is 10 seconds. */
+#define GRPC_ARG_PRIORITY_FAILOVER_TIMEOUT_MS \
+  "grpc.priority_failover_timeout_ms"
 /* Timeout in milliseconds to wait for a resource to be returned from
  * the xds server before assuming that it does not exist.
  * The default is 15 seconds. */

include/grpcpp/impl/codegen/client_callback_impl.h

@@ -267,8 +267,12 @@ class ClientBidiReactor {
   /// StartWritesDone that indicates that there will be no more write ops.
   /// The number of RemoveHold calls must match the total number of AddHold
   /// calls plus the number of holds added by AddMultipleHolds.
+  /// The argument to AddMultipleHolds must be positive.
   void AddHold() { AddMultipleHolds(1); }
-  void AddMultipleHolds(int holds) { stream_->AddHold(holds); }
+  void AddMultipleHolds(int holds) {
+    GPR_CODEGEN_DEBUG_ASSERT(holds > 0);
+    stream_->AddHold(holds);
+  }
   void RemoveHold() { stream_->RemoveHold(); }
 
   /// Notifies the application that all operations associated with this RPC
@@ -331,7 +335,10 @@ class ClientReadReactor {
   void StartRead(Response* resp) { reader_->Read(resp); }
 
   void AddHold() { AddMultipleHolds(1); }
-  void AddMultipleHolds(int holds) { reader_->AddHold(holds); }
+  void AddMultipleHolds(int holds) {
+    GPR_CODEGEN_DEBUG_ASSERT(holds > 0);
+    reader_->AddHold(holds);
+  }
   void RemoveHold() { reader_->RemoveHold(); }
 
   virtual void OnDone(const ::grpc::Status& /*s*/) {}
@@ -364,7 +371,10 @@ class ClientWriteReactor {
   void StartWritesDone() { writer_->WritesDone(); }
 
   void AddHold() { AddMultipleHolds(1); }
-  void AddMultipleHolds(int holds) { writer_->AddHold(holds); }
+  void AddMultipleHolds(int holds) {
+    GPR_CODEGEN_DEBUG_ASSERT(holds > 0);
+    writer_->AddHold(holds);
+  }
   void RemoveHold() { writer_->RemoveHold(); }
 
   virtual void OnDone(const ::grpc::Status& /*s*/) {}

package.xml

@@ -108,6 +108,8 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/http_proxy.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/address_filtering.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/address_filtering.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc" role="src" />
@@ -123,10 +125,13 @@
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/priority/priority.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/subchannel_list.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/cds.cc" role="src" />
-    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/eds.cc" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc" role="src" />
     <file baseinstalldir="/" name="src/core/ext/filters/client_channel/lb_policy_factory.h" role="src" />

src/core/ext/filters/client_channel/client_channel.cc

@@ -2264,10 +2264,32 @@ void CallData::FreeCachedSendOpDataForCompletedBatch(
 void CallData::RecvTrailingMetadataReadyForLoadBalancingPolicy(
     void* arg, grpc_error* error) {
   CallData* calld = static_cast<CallData*>(arg);
+  // Set error if call did not succeed.
+  grpc_error* error_for_lb = GRPC_ERROR_NONE;
+  if (error != GRPC_ERROR_NONE) {
+    error_for_lb = error;
+  } else {
+    const auto& fields = calld->recv_trailing_metadata_->idx.named;
+    GPR_ASSERT(fields.grpc_status != nullptr);
+    grpc_status_code status =
+        grpc_get_status_code_from_metadata(fields.grpc_status->md);
+    std::string msg;
+    if (status != GRPC_STATUS_OK) {
+      error_for_lb = grpc_error_set_int(
+          GRPC_ERROR_CREATE_FROM_STATIC_STRING("call failed"),
+          GRPC_ERROR_INT_GRPC_STATUS, status);
+      if (fields.grpc_message != nullptr) {
+        error_for_lb = grpc_error_set_str(
+            error_for_lb, GRPC_ERROR_STR_GRPC_MESSAGE,
+            grpc_slice_ref_internal(GRPC_MDVALUE(fields.grpc_message->md)));
+      }
+    }
+  }
   // Invoke callback to LB policy.
   Metadata trailing_metadata(calld, calld->recv_trailing_metadata_);
-  calld->lb_recv_trailing_metadata_ready_(error, &trailing_metadata,
+  calld->lb_recv_trailing_metadata_ready_(error_for_lb, &trailing_metadata,
                                           &calld->lb_call_state_);
+  if (error == GRPC_ERROR_NONE) GRPC_ERROR_UNREF(error_for_lb);
   // Chain to original callback.
   Closure::Run(DEBUG_LOCATION, calld->original_recv_trailing_metadata_ready_,
                GRPC_ERROR_REF(error));

src/core/ext/filters/client_channel/lb_policy/address_filtering.cc

@@ -0,0 +1,83 @@
+//
+// Copyright 2020 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/address_filtering.h"
+
+#include "src/core/lib/channel/channel_args.h"
+
+#define GRPC_ARG_HIERARCHICAL_PATH "grpc.internal.address.hierarchical_path"
+
+namespace grpc_core {
+
+namespace {
+
+void* HierarchicalPathCopy(void* p) {
+  std::vector<std::string>* path = static_cast<std::vector<std::string>*>(p);
+  return static_cast<void*>(new std::vector<std::string>(*path));
+}
+
+void HierarchicalPathDestroy(void* p) {
+  std::vector<std::string>* path = static_cast<std::vector<std::string>*>(p);
+  delete path;
+}
+
+int HierarchicalPathCompare(void* p1, void* p2) {
+  std::vector<std::string>* path1 = static_cast<std::vector<std::string>*>(p1);
+  std::vector<std::string>* path2 = static_cast<std::vector<std::string>*>(p2);
+  for (size_t i = 0; i < path1->size(); ++i) {
+    if (path2->size() == i) return 1;
+    int r = (*path1)[i].compare((*path2)[i]);
+    if (r != 0) return r;
+  }
+  if (path2->size() > path1->size()) return -1;
+  return 0;
+}
+
+const grpc_arg_pointer_vtable hierarchical_path_arg_vtable = {
+    HierarchicalPathCopy, HierarchicalPathDestroy, HierarchicalPathCompare};
+
+}  // namespace
+
+grpc_arg MakeHierarchicalPathArg(const std::vector<std::string>& path) {
+  return grpc_channel_arg_pointer_create(
+      const_cast<char*>(GRPC_ARG_HIERARCHICAL_PATH),
+      const_cast<std::vector<std::string>*>(&path),
+      &hierarchical_path_arg_vtable);
+}
+
+HierarchicalAddressMap MakeHierarchicalAddressMap(
+    const ServerAddressList& addresses) {
+  HierarchicalAddressMap result;
+  for (const ServerAddress& address : addresses) {
+    auto* path = grpc_channel_args_find_pointer<std::vector<std::string>>(
+        address.args(), GRPC_ARG_HIERARCHICAL_PATH);
+    if (path == nullptr || path->empty()) continue;
+    auto it = path->begin();
+    ServerAddressList& target_list = result[*it];
+    ++it;
+    std::vector<std::string> remaining_path(it, path->end());
+    const char* name_to_remove = GRPC_ARG_HIERARCHICAL_PATH;
+    grpc_arg new_arg = MakeHierarchicalPathArg(remaining_path);
+    grpc_channel_args* new_args = grpc_channel_args_copy_and_add_and_remove(
+        address.args(), &name_to_remove, 1, &new_arg, 1);
+    target_list.emplace_back(address.address(), new_args);
+  }
+  return result;
+}
+
+}  // namespace grpc_core

src/core/ext/filters/client_channel/lb_policy/address_filtering.h

@@ -0,0 +1,99 @@
+//
+// Copyright 2020 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_ADDRESS_FILTERING_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_ADDRESS_FILTERING_H
+
+#include <grpc/support/port_platform.h>
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+
+#include "src/core/ext/filters/client_channel/server_address.h"
+
+// The resolver returns a flat list of addresses.  When a hierarchy of
+// LB policies is in use, each leaf of the hierarchy will need a
+// different subset of those addresses.  This library provides a
+// mechanism for determining which address is passed to which leaf
+// policy.
+//
+// Each address will have an associated path that indicates which child
+// it should be sent to at each level of the hierarchy to wind up at the
+// right leaf policy.  Each LB policy will look at the first element of
+// the path of each address to determine which child to send the address
+// to.  It will then remove that first element when passing the address
+// down to its child.
+//
+// For example, consider the following LB policy hierarchy:
+//
+// - priority
+//   - child0 (weighted_target)
+//     - localityA (round_robin)
+//     - localityB (round_robin)
+//   - child1 (weighted_target)
+//     - localityC (round_robin)
+//     - localityD (round_robin)
+//
+// Now consider the following addresses:
+// - 10.0.0.1:80 path=["child0", "localityA"]
+// - 10.0.0.2:80 path=["child0", "localityB"]
+// - 10.0.0.3:80 path=["child1", "localityC"]
+// - 10.0.0.4:80 path=["child1", "localityD"]
+//
+// The priority policy will split this up into two lists, one for each
+// of its children:
+// - child0:
+//   - 10.0.0.1:80 path=["localityA"]
+//   - 10.0.0.2:80 path=["localityB"]
+// - child1:
+//   - 10.0.0.3:80 path=["localityC"]
+//   - 10.0.0.4:80 path=["localityD"]
+//
+// The weighted_target policy for child0 will split its list up into two
+// lists, one for each of its children:
+// - localityA:
+//   - 10.0.0.1:80 path=[]
+// - localityB:
+//   - 10.0.0.2:80 path=[]
+//
+// Similarly, the weighted_target policy for child1 will split its list
+// up into two lists, one for each of its children:
+// - localityC:
+//   - 10.0.0.3:80 path=[]
+// - localityD:
+//   - 10.0.0.4:80 path=[]
+
+namespace grpc_core {
+
+// Constructs a channel arg containing the hierarchical path
+// to be associated with an address.
+grpc_arg MakeHierarchicalPathArg(const std::vector<std::string>& path);
+
+// A map from the next path element to the addresses that fall under
+// that path element.
+using HierarchicalAddressMap = std::map<std::string, ServerAddressList>;
+
+// Splits up the addresses into a separate list for each child.
+HierarchicalAddressMap MakeHierarchicalAddressMap(
+    const ServerAddressList& addresses);
+
+}  // namespace grpc_core
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_ADDRESS_FILTERING_H \
+        */

src/core/ext/filters/client_channel/lb_policy/priority/priority.cc

@@ -0,0 +1,875 @@
+//
+// Copyright 2018 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <grpc/support/port_platform.h>
+
+#include <inttypes.h>
+#include <limits.h>
+
+#include "absl/strings/str_cat.h"
+
+#include <grpc/grpc.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy.h"
+#include "src/core/ext/filters/client_channel/lb_policy/address_filtering.h"
+#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/timer.h"
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_priority_trace(false, "priority_lb");
+
+namespace {
+
+constexpr char kPriority[] = "priority_experimental";
+
+// How long we keep a child around for after it is no longer being used
+// (either because it has been removed from the config or because we
+// have switched to a higher-priority child).
+constexpr int kChildRetentionIntervalMs = 15 * 60 * 1000;
+
+// Default for how long we wait for a newly created child to get connected
+// before starting to attempt the next priority.  Overridable via channel arg.
+constexpr int kDefaultChildFailoverTimeoutMs = 10000;
+
+// Config for priority LB policy.
+class PriorityLbConfig : public LoadBalancingPolicy::Config {
+ public:
+  PriorityLbConfig(
+      std::map<std::string, RefCountedPtr<LoadBalancingPolicy::Config>>
+          children,
+      std::vector<std::string> priorities)
+      : children_(std::move(children)), priorities_(std::move(priorities)) {}
+
+  const char* name() const override { return kPriority; }
+
+  const std::map<std::string, RefCountedPtr<LoadBalancingPolicy::Config>>&
+  children() const {
+    return children_;
+  }
+  const std::vector<std::string>& priorities() const { return priorities_; }
+
+ private:
+  const std::map<std::string, RefCountedPtr<LoadBalancingPolicy::Config>>
+      children_;
+  const std::vector<std::string> priorities_;
+};
+
+// priority LB policy.
+class PriorityLb : public LoadBalancingPolicy {
+ public:
+  explicit PriorityLb(Args args);
+
+  const char* name() const override { return kPriority; }
+
+  void UpdateLocked(UpdateArgs args) override;
+  void ExitIdleLocked() override;
+  void ResetBackoffLocked() override;
+
+ private:
+  // Each ChildPriority holds a ref to the PriorityLb.
+  class ChildPriority : public InternallyRefCounted<ChildPriority> {
+   public:
+    ChildPriority(RefCountedPtr<PriorityLb> priority_policy, std::string name);
+
+    ~ChildPriority() {
+      priority_policy_.reset(DEBUG_LOCATION, "ChildPriority");
+    }
+
+    const std::string& name() const { return name_; }
+
+    void UpdateLocked(RefCountedPtr<LoadBalancingPolicy::Config> config);
+    void ExitIdleLocked();
+    void ResetBackoffLocked();
+    void DeactivateLocked();
+    void MaybeReactivateLocked();
+    void MaybeCancelFailoverTimerLocked();
+
+    void Orphan() override;
+
+    std::unique_ptr<SubchannelPicker> GetPicker() {
+      return absl::make_unique<RefCountedPickerWrapper>(picker_wrapper_);
+    }
+
+    grpc_connectivity_state connectivity_state() const {
+      return connectivity_state_;
+    }
+    bool failover_timer_callback_pending() const {
+      return failover_timer_callback_pending_;
+    }
+
+   private:
+    // A simple wrapper for ref-counting a picker from the child policy.
+    class RefCountedPicker : public RefCounted<RefCountedPicker> {
+     public:
+      explicit RefCountedPicker(std::unique_ptr<SubchannelPicker> picker)
+          : picker_(std::move(picker)) {}
+      PickResult Pick(PickArgs args) { return picker_->Pick(args); }
+
+     private:
+      std::unique_ptr<SubchannelPicker> picker_;
+    };
+
+    // A non-ref-counted wrapper for RefCountedPicker.
+    class RefCountedPickerWrapper : public SubchannelPicker {
+     public:
+      explicit RefCountedPickerWrapper(RefCountedPtr<RefCountedPicker> picker)
+          : picker_(std::move(picker)) {}
+      PickResult Pick(PickArgs args) override { return picker_->Pick(args); }
+
+     private:
+      RefCountedPtr<RefCountedPicker> picker_;
+    };
+
+    class Helper : public ChannelControlHelper {
+     public:
+      explicit Helper(RefCountedPtr<ChildPriority> priority)
+          : priority_(std::move(priority)) {}
+
+      ~Helper() { priority_.reset(DEBUG_LOCATION, "Helper"); }
+
+      RefCountedPtr<SubchannelInterface> CreateSubchannel(
+          const grpc_channel_args& args) override;
+      void UpdateState(grpc_connectivity_state state,
+                       std::unique_ptr<SubchannelPicker> picker) override;
+      void RequestReresolution() override;
+      void AddTraceEvent(TraceSeverity severity, StringView message) override;
+
+     private:
+      RefCountedPtr<ChildPriority> priority_;
+    };
+
+    // Methods for dealing with the child policy.
+    OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
+        const grpc_channel_args* args);
+
+    void OnConnectivityStateUpdateLocked(
+        grpc_connectivity_state state,
+        std::unique_ptr<SubchannelPicker> picker);
+
+    void StartFailoverTimerLocked();
+
+    static void OnFailoverTimer(void* arg, grpc_error* error);
+    static void OnFailoverTimerLocked(void* arg, grpc_error* error);
+    static void OnDeactivationTimer(void* arg, grpc_error* error);
+    static void OnDeactivationTimerLocked(void* arg, grpc_error* error);
+
+    RefCountedPtr<PriorityLb> priority_policy_;
+    const std::string name_;
+
+    OrphanablePtr<LoadBalancingPolicy> child_policy_;
+
+    grpc_connectivity_state connectivity_state_ = GRPC_CHANNEL_CONNECTING;
+    RefCountedPtr<RefCountedPicker> picker_wrapper_;
+
+    // States for delayed removal.
+    grpc_timer deactivation_timer_;
+    grpc_closure on_deactivation_timer_;
+    bool deactivation_timer_callback_pending_ = false;
+
+    // States of failover.
+    grpc_timer failover_timer_;
+    grpc_closure on_failover_timer_;
+    grpc_closure on_failover_timer_locked_;
+    bool failover_timer_callback_pending_ = false;
+  };
+
+  ~PriorityLb();
+
+  void ShutdownLocked() override;
+
+  // Returns UINT32_MAX if child is not in current priority list.
+  uint32_t GetChildPriorityLocked(const std::string& child_name) const;
+
+  void HandleChildConnectivityStateChangeLocked(ChildPriority* child);
+  void DeleteChild(ChildPriority* child);
+
+  void TryNextPriorityLocked(bool report_connecting);
+  void SelectPriorityLocked(uint32_t priority);
+
+  const int child_failover_timeout_ms_;
+
+  // Current channel args and config from the resolver.
+  const grpc_channel_args* args_ = nullptr;
+  RefCountedPtr<PriorityLbConfig> config_;
+  HierarchicalAddressMap addresses_;
+
+  // Internal state.
+  bool shutting_down_ = false;
+
+  std::map<std::string, OrphanablePtr<ChildPriority>> children_;
+  // The priority that is being used.
+  uint32_t current_priority_ = UINT32_MAX;
+  // Points to the current child from before the most recent update.
+  // We will continue to use this child until we decide which of the new
+  // children to use.
+  ChildPriority* current_child_from_before_update_ = nullptr;
+};
+
+//
+// PriorityLb
+//
+
+PriorityLb::PriorityLb(Args args)
+    : LoadBalancingPolicy(std::move(args)),
+      child_failover_timeout_ms_(grpc_channel_args_find_integer(
+          args.args, GRPC_ARG_PRIORITY_FAILOVER_TIMEOUT_MS,
+          {kDefaultChildFailoverTimeoutMs, 0, INT_MAX})) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] created", this);
+  }
+}
+
+PriorityLb::~PriorityLb() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] destroying priority LB policy", this);
+  }
+  grpc_channel_args_destroy(args_);
+}
+
+void PriorityLb::ShutdownLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] shutting down", this);
+  }
+  shutting_down_ = true;
+  children_.clear();
+}
+
+void PriorityLb::ExitIdleLocked() {
+  if (current_priority_ != UINT32_MAX) {
+    const std::string& child_name = config_->priorities()[current_priority_];
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO,
+              "[priority_lb %p] exiting IDLE for current priority %d child %s",
+              this, current_priority_, child_name.c_str());
+    }
+    children_[child_name]->ExitIdleLocked();
+  }
+}
+
+void PriorityLb::ResetBackoffLocked() {
+  for (const auto& p : children_) p.second->ResetBackoffLocked();
+}
+
+void PriorityLb::UpdateLocked(UpdateArgs args) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] received update", this);
+  }
+  // Save current child.
+  if (current_priority_ != UINT32_MAX) {
+    const std::string& child_name = config_->priorities()[current_priority_];
+    current_child_from_before_update_ = children_[child_name].get();
+    // Unset current_priority_, since it was an index into the old
+    // config's priority list and may no longer be valid.  It will be
+    // reset later by TryNextPriorityLocked(), but we unset it here in
+    // case updating any of our children triggers a state update.
+    current_priority_ = UINT32_MAX;
+  }
+  // Update config.
+  config_ = std::move(args.config);
+  // Update args.
+  grpc_channel_args_destroy(args_);
+  args_ = args.args;
+  args.args = nullptr;
+  // Update addresses.
+  addresses_ = MakeHierarchicalAddressMap(args.addresses);
+  // Check all existing children against the new config.
+  for (const auto& p : children_) {
+    const std::string& child_name = p.first;
+    auto& child = p.second;
+    auto config_it = config_->children().find(child_name);
+    if (config_it == config_->children().end()) {
+      // Existing child not found in new config.  Deactivate it.
+      child->DeactivateLocked();
+    } else {
+      // Existing child found in new config.  Update it.
+      child->UpdateLocked(config_it->second);
+    }
+  }
+  // Try to get connected.
+  TryNextPriorityLocked(/*report_connecting=*/children_.empty());
+}
+
+uint32_t PriorityLb::GetChildPriorityLocked(
+    const std::string& child_name) const {
+  for (uint32_t priority = 0; priority < config_->priorities().size();
+       ++priority) {
+    if (config_->priorities()[priority] == child_name) return priority;
+  }
+  return UINT32_MAX;
+}
+
+void PriorityLb::HandleChildConnectivityStateChangeLocked(
+    ChildPriority* child) {
+  // Special case for the child that was the current child before the
+  // most recent update.
+  if (child == current_child_from_before_update_) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO,
+              "[priority_lb %p] state update for current child from before "
+              "config update",
+              this);
+    }
+    if (child->connectivity_state() == GRPC_CHANNEL_READY ||
+        child->connectivity_state() == GRPC_CHANNEL_IDLE) {
+      // If it's still READY or IDLE, we stick with this child, so pass
+      // the new picker up to our parent.
+      channel_control_helper()->UpdateState(child->connectivity_state(),
+                                            child->GetPicker());
+    } else {
+      // If it's no longer READY or IDLE, we should stop using it.
+      // We already started trying other priorities as a result of the
+      // update, but calling TryNextPriorityLocked() ensures that we will
+      // properly select between CONNECTING and TRANSIENT_FAILURE as the
+      // new state to report to our parent.
+      current_child_from_before_update_ = nullptr;
+      TryNextPriorityLocked(/*report_connecting=*/true);
+    }
+    return;
+  }
+  // Otherwise, find the child's priority.
+  uint32_t child_priority = GetChildPriorityLocked(child->name());
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] state update for priority %d, child %s",
+            this, child_priority, child->name().c_str());
+  }
+  // Ignore priorities not in the current config.
+  if (child_priority == UINT32_MAX) return;
+  // Ignore lower-than-current priorities.
+  if (child_priority > current_priority_) return;
+  // If a child reports TRANSIENT_FAILURE, start trying the next priority.
+  // Note that even if this is for a higher-than-current priority, we
+  // may still need to create some children between this priority and
+  // the current one (e.g., if we got an update that inserted new
+  // priorities ahead of the current one).
+  if (child->connectivity_state() == GRPC_CHANNEL_TRANSIENT_FAILURE) {
+    TryNextPriorityLocked(
+        /*report_connecting=*/child_priority == current_priority_);
+    return;
+  }
+  // The update is for a higher-than-current priority (or for any
+  // priority if we don't have any current priority).
+  if (child_priority < current_priority_) {
+    // If the child reports READY or IDLE, switch to that priority.
+    // Otherwise, ignore the update.
+    if (child->connectivity_state() == GRPC_CHANNEL_READY ||
+        child->connectivity_state() == GRPC_CHANNEL_IDLE) {
+      SelectPriorityLocked(child_priority);
+    }
+    return;
+  }
+  // The current priority has returned a new picker, so pass it up to
+  // our parent.
+  channel_control_helper()->UpdateState(child->connectivity_state(),
+                                        child->GetPicker());
+}
+
+void PriorityLb::DeleteChild(ChildPriority* child) {
+  // If this was the current child from before the most recent update,
+  // stop using it.  We already started trying other priorities as a
+  // result of the update, but calling TryNextPriorityLocked() ensures that
+  // we will properly select between CONNECTING and TRANSIENT_FAILURE as the
+  // new state to report to our parent.
+  if (current_child_from_before_update_ == child) {
+    current_child_from_before_update_ = nullptr;
+    TryNextPriorityLocked(/*report_connecting=*/true);
+  }
+  children_.erase(child->name());
+}
+
+void PriorityLb::TryNextPriorityLocked(bool report_connecting) {
+  for (uint32_t priority = 0; priority < config_->priorities().size();
+       ++priority) {
+    // If the child for the priority does not exist yet, create it.
+    const std::string& child_name = config_->priorities()[priority];
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO, "[priority_lb %p] trying priority %d, child %s", this,
+              priority, child_name.c_str());
+    }
+    auto& child = children_[child_name];
+    if (child == nullptr) {
+      if (report_connecting) {
+        channel_control_helper()->UpdateState(
+            GRPC_CHANNEL_CONNECTING,
+            absl::make_unique<QueuePicker>(Ref(DEBUG_LOCATION, "QueuePicker")));
+      }
+      child = MakeOrphanable<ChildPriority>(
+          Ref(DEBUG_LOCATION, "ChildPriority"), child_name);
+      child->UpdateLocked(config_->children().find(child_name)->second);
+      return;
+    }
+    // The child already exists.
+    child->MaybeReactivateLocked();
+    // If the child is in state READY or IDLE, switch to it.
+    if (child->connectivity_state() == GRPC_CHANNEL_READY ||
+        child->connectivity_state() == GRPC_CHANNEL_IDLE) {
+      SelectPriorityLocked(priority);
+      return;
+    }
+    // Child is not READY or IDLE.
+    // If its failover timer is still pending, give it time to fire.
+    if (child->failover_timer_callback_pending()) {
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+        gpr_log(GPR_INFO,
+                "[priority_lb %p] priority %d, child %s: child still "
+                "attempting to connect, will wait",
+                this, priority, child_name.c_str());
+      }
+      if (report_connecting) {
+        channel_control_helper()->UpdateState(
+            GRPC_CHANNEL_CONNECTING,
+            absl::make_unique<QueuePicker>(Ref(DEBUG_LOCATION, "QueuePicker")));
+      }
+      return;
+    }
+    // Child has been failing for a while.  Move on to the next priority.
+  }
+  // If there are no more priorities to try, report TRANSIENT_FAILURE.
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO,
+            "[priority_lb %p] no priority reachable, putting channel in "
+            "TRANSIENT_FAILURE",
+            this);
+  }
+  current_priority_ = UINT32_MAX;
+  current_child_from_before_update_ = nullptr;
+  grpc_error* error = grpc_error_set_int(
+      GRPC_ERROR_CREATE_FROM_STATIC_STRING("no ready priority"),
+      GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE);
+  channel_control_helper()->UpdateState(
+      GRPC_CHANNEL_TRANSIENT_FAILURE,
+      absl::make_unique<TransientFailurePicker>(error));
+}
+
+void PriorityLb::SelectPriorityLocked(uint32_t priority) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] selected priority %d, child %s", this,
+            priority, config_->priorities()[priority].c_str());
+  }
+  current_priority_ = priority;
+  current_child_from_before_update_ = nullptr;
+  // Deactivate lower priorities.
+  for (uint32_t p = priority + 1; p < config_->priorities().size(); ++p) {
+    const std::string& child_name = config_->priorities()[p];
+    auto it = children_.find(child_name);
+    if (it != children_.end()) it->second->DeactivateLocked();
+  }
+  // Update picker.
+  auto& child = children_[config_->priorities()[priority]];
+  channel_control_helper()->UpdateState(child->connectivity_state(),
+                                        child->GetPicker());
+}
+
+//
+// PriorityLb::ChildPriority
+//
+
+PriorityLb::ChildPriority::ChildPriority(
+    RefCountedPtr<PriorityLb> priority_policy, std::string name)
+    : priority_policy_(std::move(priority_policy)), name_(std::move(name)) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] creating child %s (%p)",
+            priority_policy_.get(), name_.c_str(), this);
+  }
+  GRPC_CLOSURE_INIT(&on_failover_timer_, OnFailoverTimer, this,
+                    grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&on_failover_timer_locked_, OnFailoverTimerLocked, this,
+                    nullptr);
+  // Start the failover timer.
+  StartFailoverTimerLocked();
+}
+
+void PriorityLb::ChildPriority::Orphan() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] child %s (%p): orphaned",
+            priority_policy_.get(), name_.c_str(), this);
+  }
+  MaybeCancelFailoverTimerLocked();
+  if (deactivation_timer_callback_pending_) {
+    grpc_timer_cancel(&deactivation_timer_);
+  }
+  // Remove the child policy's interested_parties pollset_set from the
+  // xDS policy.
+  grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
+                                   priority_policy_->interested_parties());
+  child_policy_.reset();
+  // Drop our ref to the child's picker, in case it's holding a ref to
+  // the child.
+  picker_wrapper_.reset();
+  if (deactivation_timer_callback_pending_) {
+    grpc_timer_cancel(&deactivation_timer_);
+  }
+  Unref(DEBUG_LOCATION, "ChildPriority+Orphan");
+}
+
+void PriorityLb::ChildPriority::UpdateLocked(
+    RefCountedPtr<LoadBalancingPolicy::Config> config) {
+  if (priority_policy_->shutting_down_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO, "[priority_lb %p] child %s (%p): start update",
+            priority_policy_.get(), name_.c_str(), this);
+  }
+  // Create policy if needed.
+  if (child_policy_ == nullptr) {
+    child_policy_ = CreateChildPolicyLocked(priority_policy_->args_);
+  }
+  // Construct update args.
+  UpdateArgs update_args;
+  update_args.config = std::move(config);
+  update_args.addresses = priority_policy_->addresses_[name_];
+  update_args.args = grpc_channel_args_copy(priority_policy_->args_);
+  // Update the policy.
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO,
+            "[priority_lb %p] child %s (%p): updating child policy handler %p",
+            priority_policy_.get(), name_.c_str(), this, child_policy_.get());
+  }
+  child_policy_->UpdateLocked(std::move(update_args));
+}
+
+OrphanablePtr<LoadBalancingPolicy>
+PriorityLb::ChildPriority::CreateChildPolicyLocked(
+    const grpc_channel_args* args) {
+  LoadBalancingPolicy::Args lb_policy_args;
+  lb_policy_args.combiner = priority_policy_->combiner();
+  lb_policy_args.args = args;
+  lb_policy_args.channel_control_helper =
+      absl::make_unique<Helper>(this->Ref(DEBUG_LOCATION, "Helper"));
+  OrphanablePtr<LoadBalancingPolicy> lb_policy =
+      MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args),
+                                         &grpc_lb_priority_trace);
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO,
+            "[priority_lb %p] child %s (%p): created new child policy "
+            "handler %p",
+            priority_policy_.get(), name_.c_str(), this, lb_policy.get());
+  }
+  // Add the parent's interested_parties pollset_set to that of the newly
+  // created child policy. This will make the child policy progress upon
+  // activity on the parent LB, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+                                   priority_policy_->interested_parties());
+  return lb_policy;
+}
+
+void PriorityLb::ChildPriority::ExitIdleLocked() {
+  if (connectivity_state_ == GRPC_CHANNEL_IDLE &&
+      !failover_timer_callback_pending_) {
+    StartFailoverTimerLocked();
+  }
+  child_policy_->ExitIdleLocked();
+}
+
+void PriorityLb::ChildPriority::ResetBackoffLocked() {
+  child_policy_->ResetBackoffLocked();
+}
+
+void PriorityLb::ChildPriority::OnConnectivityStateUpdateLocked(
+    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO,
+            "[priority_lb %p] child %s (%p): state update: %s, picker %p",
+            priority_policy_.get(), name_.c_str(), this,
+            ConnectivityStateName(state), picker.get());
+  }
+  // Store the state and picker.
+  connectivity_state_ = state;
+  picker_wrapper_ = MakeRefCounted<RefCountedPicker>(std::move(picker));
+  // If READY or TRANSIENT_FAILURE, cancel failover timer.
+  if (state == GRPC_CHANNEL_READY || state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
+    MaybeCancelFailoverTimerLocked();
+  }
+  // Notify the parent policy.
+  priority_policy_->HandleChildConnectivityStateChangeLocked(this);
+}
+
+void PriorityLb::ChildPriority::StartFailoverTimerLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO,
+            "[priority_lb %p] child %s (%p): starting failover timer for %d ms",
+            priority_policy_.get(), name_.c_str(), this,
+            priority_policy_->child_failover_timeout_ms_);
+  }
+  Ref(DEBUG_LOCATION, "ChildPriority+OnFailoverTimerLocked").release();
+  grpc_timer_init(
+      &failover_timer_,
+      ExecCtx::Get()->Now() + priority_policy_->child_failover_timeout_ms_,
+      &on_failover_timer_);
+  failover_timer_callback_pending_ = true;
+}
+
+void PriorityLb::ChildPriority::MaybeCancelFailoverTimerLocked() {
+  if (failover_timer_callback_pending_) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO,
+              "[priority_lb %p] child %s (%p): cancelling failover timer",
+              priority_policy_.get(), name_.c_str(), this);
+    }
+    grpc_timer_cancel(&failover_timer_);
+    failover_timer_callback_pending_ = false;
+  }
+}
+
+void PriorityLb::ChildPriority::OnFailoverTimer(void* arg, grpc_error* error) {
+  ChildPriority* self = static_cast<ChildPriority*>(arg);
+  self->priority_policy_->combiner()->Run(&self->on_failover_timer_locked_,
+                                          GRPC_ERROR_REF(error));
+}
+
+void PriorityLb::ChildPriority::OnFailoverTimerLocked(void* arg,
+                                                      grpc_error* error) {
+  ChildPriority* self = static_cast<ChildPriority*>(arg);
+  if (error == GRPC_ERROR_NONE && self->failover_timer_callback_pending_ &&
+      !self->priority_policy_->shutting_down_) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO,
+              "[priority_lb %p] child %s (%p): failover timer fired, "
+              "reporting TRANSIENT_FAILURE",
+              self->priority_policy_.get(), self->name_.c_str(), self);
+    }
+    self->failover_timer_callback_pending_ = false;
+    self->OnConnectivityStateUpdateLocked(GRPC_CHANNEL_TRANSIENT_FAILURE,
+                                          nullptr);
+  }
+  self->Unref(DEBUG_LOCATION, "ChildPriority+OnFailoverTimerLocked");
+}
+
+void PriorityLb::ChildPriority::DeactivateLocked() {
+  // If already deactivated, don't do it again.
+  if (deactivation_timer_callback_pending_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+    gpr_log(GPR_INFO,
+            "[priority_lb %p] child %s (%p): deactivating -- will remove in %d "
+            "ms.",
+            priority_policy_.get(), name_.c_str(), this,
+            kChildRetentionIntervalMs);
+  }
+  MaybeCancelFailoverTimerLocked();
+  // Start a timer to delete the child.
+  Ref(DEBUG_LOCATION, "ChildPriority+timer").release();
+  GRPC_CLOSURE_INIT(&on_deactivation_timer_, OnDeactivationTimer, this,
+                    grpc_schedule_on_exec_ctx);
+  grpc_timer_init(&deactivation_timer_,
+                  ExecCtx::Get()->Now() + kChildRetentionIntervalMs,
+                  &on_deactivation_timer_);
+  deactivation_timer_callback_pending_ = true;
+}
+
+void PriorityLb::ChildPriority::MaybeReactivateLocked() {
+  if (deactivation_timer_callback_pending_) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO, "[priority_lb %p] child %s (%p): reactivating",
+              priority_policy_.get(), name_.c_str(), this);
+    }
+    deactivation_timer_callback_pending_ = false;
+    grpc_timer_cancel(&deactivation_timer_);
+  }
+}
+
+void PriorityLb::ChildPriority::OnDeactivationTimer(void* arg,
+                                                    grpc_error* error) {
+  ChildPriority* self = static_cast<ChildPriority*>(arg);
+  self->priority_policy_->combiner()->Run(
+      GRPC_CLOSURE_INIT(&self->on_deactivation_timer_,
+                        OnDeactivationTimerLocked, self, nullptr),
+      GRPC_ERROR_REF(error));
+}
+
+void PriorityLb::ChildPriority::OnDeactivationTimerLocked(void* arg,
+                                                          grpc_error* error) {
+  ChildPriority* self = static_cast<ChildPriority*>(arg);
+  if (error == GRPC_ERROR_NONE && self->deactivation_timer_callback_pending_ &&
+      !self->priority_policy_->shutting_down_) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_priority_trace)) {
+      gpr_log(GPR_INFO,
+              "[priority_lb %p] child %s (%p): deactivation timer fired, "
+              "deleting child",
+              self->priority_policy_.get(), self->name_.c_str(), self);
+    }
+    self->deactivation_timer_callback_pending_ = false;
+    self->priority_policy_->DeleteChild(self);
+  }
+  self->Unref(DEBUG_LOCATION, "ChildPriority+timer");
+}
+
+//
+// PriorityLb::ChildPriority::Helper
+//
+
+void PriorityLb::ChildPriority::Helper::RequestReresolution() {
+  if (priority_->priority_policy_->shutting_down_) return;
+  priority_->priority_policy_->channel_control_helper()->RequestReresolution();
+}
+
+RefCountedPtr<SubchannelInterface>
+PriorityLb::ChildPriority::Helper::CreateSubchannel(
+    const grpc_channel_args& args) {
+  if (priority_->priority_policy_->shutting_down_) return nullptr;
+  return priority_->priority_policy_->channel_control_helper()
+      ->CreateSubchannel(args);
+}
+
+void PriorityLb::ChildPriority::Helper::UpdateState(
+    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
+  if (priority_->priority_policy_->shutting_down_) return;
+  // Notify the priority.
+  priority_->OnConnectivityStateUpdateLocked(state, std::move(picker));
+}
+
+void PriorityLb::ChildPriority::Helper::AddTraceEvent(TraceSeverity severity,
+                                                      StringView message) {
+  if (priority_->priority_policy_->shutting_down_) return;
+  priority_->priority_policy_->channel_control_helper()->AddTraceEvent(severity,
+                                                                       message);
+}
+
+//
+// factory
+//
+
+class PriorityLbFactory : public LoadBalancingPolicyFactory {
+ public:
+  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+      LoadBalancingPolicy::Args args) const override {
+    return MakeOrphanable<PriorityLb>(std::move(args));
+  }
+
+  const char* name() const override { return kPriority; }
+
+  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
+      const Json& json, grpc_error** error) const override {
+    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
+    if (json.type() == Json::Type::JSON_NULL) {
+      // priority was mentioned as a policy in the deprecated
+      // loadBalancingPolicy field or in the client API.
+      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:loadBalancingPolicy error:priority policy requires "
+          "configuration. Please use loadBalancingConfig field of service "
+          "config instead.");
+      return nullptr;
+    }
+    std::vector<grpc_error*> error_list;
+    // Children.
+    std::map<std::string, RefCountedPtr<LoadBalancingPolicy::Config>> children;
+    auto it = json.object_value().find("children");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:children error:required field missing"));
+    } else if (it->second.type() != Json::Type::OBJECT) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:children error:type should be object"));
+    } else {
+      const Json::Object& object = it->second.object_value();
+      for (const auto& p : object) {
+        const std::string& child_name = p.first;
+        const Json& element = p.second;
+        if (element.type() != Json::Type::OBJECT) {
+          error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrCat("field:children key:", child_name,
+                           " error:should be type object")
+                  .c_str()));
+        } else {
+          auto it2 = element.object_value().find("config");
+          if (it2 == element.object_value().end()) {
+            error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+                absl::StrCat("field:children key:", child_name,
+                             " error:missing 'config' field")
+                    .c_str()));
+          } else {
+            grpc_error* parse_error = GRPC_ERROR_NONE;
+            auto config = LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+                it2->second, &parse_error);
+            if (config == nullptr) {
+              GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+              error_list.push_back(
+                  GRPC_ERROR_CREATE_REFERENCING_FROM_COPIED_STRING(
+                      absl::StrCat("field:children key:", child_name).c_str(),
+                      &parse_error, 1));
+              GRPC_ERROR_UNREF(parse_error);
+            }
+            children[child_name] = std::move(config);
+          }
+        }
+      }
+    }
+    // Priorities.
+    std::vector<std::string> priorities;
+    it = json.object_value().find("priorities");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:priorities error:required field missing"));
+    } else if (it->second.type() != Json::Type::ARRAY) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:priorities error:type should be array"));
+    } else {
+      const Json::Array& array = it->second.array_value();
+      for (size_t i = 0; i < array.size(); ++i) {
+        const Json& element = array[i];
+        if (element.type() != Json::Type::STRING) {
+          error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrCat("field:priorities element:", i,
+                           " error:should be type string")
+                  .c_str()));
+        } else if (children.find(element.string_value()) == children.end()) {
+          error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrCat("field:priorities element:", i,
+                           " error:unknown child '", element.string_value(),
+                           "'")
+                  .c_str()));
+        } else {
+          priorities.emplace_back(element.string_value());
+        }
+      }
+      if (priorities.size() != children.size()) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrCat("field:priorities error:priorities size (",
+                         priorities.size(), ") != children size (",
+                         children.size(), ")")
+                .c_str()));
+      }
+    }
+    if (error_list.empty()) {
+      return MakeRefCounted<PriorityLbConfig>(std::move(children),
+                                              std::move(priorities));
+    } else {
+      *error = GRPC_ERROR_CREATE_FROM_VECTOR(
+          "priority_experimental LB policy config", &error_list);
+      return nullptr;
+    }
+  }
+};
+
+}  // namespace
+
+}  // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_priority_init() {
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          absl::make_unique<grpc_core::PriorityLbFactory>());
+}
+
+void grpc_lb_policy_priority_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc

@@ -0,0 +1,722 @@
+//
+// Copyright 2018 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <grpc/support/port_platform.h>
+
+#include <inttypes.h>
+#include <limits.h>
+#include <string.h>
+
+#include "absl/strings/str_cat.h"
+
+#include <grpc/grpc.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy.h"
+#include "src/core/ext/filters/client_channel/lb_policy/address_filtering.h"
+#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/timer.h"
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_weighted_target_trace(false, "weighted_target_lb");
+
+namespace {
+
+constexpr char kWeightedTarget[] = "weighted_target_experimental";
+
+// How long we keep a child around for after it has been removed from
+// the config.
+constexpr int kChildRetentionIntervalMs = 15 * 60 * 1000;
+
+// Config for weighted_target LB policy.
+class WeightedTargetLbConfig : public LoadBalancingPolicy::Config {
+ public:
+  struct ChildConfig {
+    uint32_t weight;
+    RefCountedPtr<LoadBalancingPolicy::Config> config;
+  };
+
+  using TargetMap = std::map<std::string, ChildConfig>;
+
+  explicit WeightedTargetLbConfig(TargetMap target_map)
+      : target_map_(std::move(target_map)) {}
+
+  const char* name() const override { return kWeightedTarget; }
+
+  const TargetMap& target_map() const { return target_map_; }
+
+ private:
+  TargetMap target_map_;
+};
+
+// weighted_target LB policy.
+class WeightedTargetLb : public LoadBalancingPolicy {
+ public:
+  explicit WeightedTargetLb(Args args);
+
+  const char* name() const override { return kWeightedTarget; }
+
+  void UpdateLocked(UpdateArgs args) override;
+  void ResetBackoffLocked() override;
+
+ private:
+  // A simple wrapper for ref-counting a picker from the child policy.
+  class ChildPickerWrapper : public RefCounted<ChildPickerWrapper> {
+   public:
+    explicit ChildPickerWrapper(std::unique_ptr<SubchannelPicker> picker)
+        : picker_(std::move(picker)) {}
+    PickResult Pick(PickArgs args) { return picker_->Pick(args); }
+
+   private:
+    std::unique_ptr<SubchannelPicker> picker_;
+  };
+
+  // Picks a child using stateless WRR and then delegates to that
+  // child's picker.
+  class WeightedPicker : public SubchannelPicker {
+   public:
+    // Maintains a weighted list of pickers from each child that is in
+    // ready state. The first element in the pair represents the end of a
+    // range proportional to the child's weight. The start of the range
+    // is the previous value in the vector and is 0 for the first element.
+    using PickerList =
+        InlinedVector<std::pair<uint32_t, RefCountedPtr<ChildPickerWrapper>>,
+                      1>;
+
+    explicit WeightedPicker(PickerList pickers)
+        : pickers_(std::move(pickers)) {}
+
+    PickResult Pick(PickArgs args) override;
+
+   private:
+    PickerList pickers_;
+  };
+
+  // Each WeightedChild holds a ref to its parent WeightedTargetLb.
+  class WeightedChild : public InternallyRefCounted<WeightedChild> {
+   public:
+    WeightedChild(RefCountedPtr<WeightedTargetLb> weighted_target_policy,
+                  const std::string& name);
+    ~WeightedChild();
+
+    void Orphan() override;
+
+    void UpdateLocked(const WeightedTargetLbConfig::ChildConfig& config,
+                      ServerAddressList addresses,
+                      const grpc_channel_args* args);
+    void ResetBackoffLocked();
+    void DeactivateLocked();
+
+    uint32_t weight() const { return weight_; }
+    grpc_connectivity_state connectivity_state() const {
+      return connectivity_state_;
+    }
+    RefCountedPtr<ChildPickerWrapper> picker_wrapper() const {
+      return picker_wrapper_;
+    }
+
+   private:
+    class Helper : public ChannelControlHelper {
+     public:
+      explicit Helper(RefCountedPtr<WeightedChild> weighted_child)
+          : weighted_child_(std::move(weighted_child)) {}
+
+      ~Helper() { weighted_child_.reset(DEBUG_LOCATION, "Helper"); }
+
+      RefCountedPtr<SubchannelInterface> CreateSubchannel(
+          const grpc_channel_args& args) override;
+      void UpdateState(grpc_connectivity_state state,
+                       std::unique_ptr<SubchannelPicker> picker) override;
+      void RequestReresolution() override;
+      void AddTraceEvent(TraceSeverity severity, StringView message) override;
+
+     private:
+      RefCountedPtr<WeightedChild> weighted_child_;
+    };
+
+    // Methods for dealing with the child policy.
+    OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
+        const grpc_channel_args* args);
+
+    void OnConnectivityStateUpdateLocked(
+        grpc_connectivity_state state,
+        std::unique_ptr<SubchannelPicker> picker);
+
+    static void OnDelayedRemovalTimer(void* arg, grpc_error* error);
+    static void OnDelayedRemovalTimerLocked(void* arg, grpc_error* error);
+
+    // The owning LB policy.
+    RefCountedPtr<WeightedTargetLb> weighted_target_policy_;
+
+    const std::string& name_;
+
+    uint32_t weight_;
+
+    OrphanablePtr<LoadBalancingPolicy> child_policy_;
+
+    RefCountedPtr<ChildPickerWrapper> picker_wrapper_;
+    grpc_connectivity_state connectivity_state_ = GRPC_CHANNEL_CONNECTING;
+    bool seen_failure_since_ready_ = false;
+
+    // States for delayed removal.
+    grpc_timer delayed_removal_timer_;
+    grpc_closure on_delayed_removal_timer_;
+    bool delayed_removal_timer_callback_pending_ = false;
+    bool shutdown_ = false;
+  };
+
+  ~WeightedTargetLb();
+
+  void ShutdownLocked() override;
+
+  void UpdateStateLocked();
+
+  // Current config from the resolver.
+  RefCountedPtr<WeightedTargetLbConfig> config_;
+
+  // Internal state.
+  bool shutting_down_ = false;
+
+  // Children.
+  std::map<std::string, OrphanablePtr<WeightedChild>> targets_;
+};
+
+//
+// WeightedTargetLb::WeightedPicker
+//
+
+WeightedTargetLb::PickResult WeightedTargetLb::WeightedPicker::Pick(
+    PickArgs args) {
+  // Generate a random number in [0, total weight).
+  const uint32_t key = rand() % pickers_[pickers_.size() - 1].first;
+  // Find the index in pickers_ corresponding to key.
+  size_t mid = 0;
+  size_t start_index = 0;
+  size_t end_index = pickers_.size() - 1;
+  size_t index = 0;
+  while (end_index > start_index) {
+    mid = (start_index + end_index) / 2;
+    if (pickers_[mid].first > key) {
+      end_index = mid;
+    } else if (pickers_[mid].first < key) {
+      start_index = mid + 1;
+    } else {
+      index = mid + 1;
+      break;
+    }
+  }
+  if (index == 0) index = start_index;
+  GPR_ASSERT(pickers_[index].first > key);
+  // Delegate to the child picker.
+  return pickers_[index].second->Pick(args);
+}
+
+//
+// WeightedTargetLb
+//
+
+WeightedTargetLb::WeightedTargetLb(Args args)
+    : LoadBalancingPolicy(std::move(args)) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO, "[weighted_target_lb %p] created", this);
+  }
+}
+
+WeightedTargetLb::~WeightedTargetLb() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] destroying weighted_target LB policy",
+            this);
+  }
+}
+
+void WeightedTargetLb::ShutdownLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO, "[weighted_target_lb %p] shutting down", this);
+  }
+  shutting_down_ = true;
+  targets_.clear();
+}
+
+void WeightedTargetLb::ResetBackoffLocked() {
+  for (auto& p : targets_) p.second->ResetBackoffLocked();
+}
+
+void WeightedTargetLb::UpdateLocked(UpdateArgs args) {
+  if (shutting_down_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO, "[weighted_target_lb %p] Received update", this);
+  }
+  // Update config.
+  config_ = std::move(args.config);
+  // Deactivate the targets not in the new config.
+  for (const auto& p : targets_) {
+    const std::string& name = p.first;
+    WeightedChild* child = p.second.get();
+    if (config_->target_map().find(name) == config_->target_map().end()) {
+      child->DeactivateLocked();
+    }
+  }
+  // Add or update the targets in the new config.
+  HierarchicalAddressMap address_map =
+      MakeHierarchicalAddressMap(args.addresses);
+  for (const auto& p : config_->target_map()) {
+    const std::string& name = p.first;
+    const WeightedTargetLbConfig::ChildConfig& config = p.second;
+    auto it = targets_.find(name);
+    if (it == targets_.end()) {
+      it = targets_.emplace(std::make_pair(name, nullptr)).first;
+      it->second = MakeOrphanable<WeightedChild>(
+          Ref(DEBUG_LOCATION, "WeightedChild"), it->first);
+    }
+    it->second->UpdateLocked(config, std::move(address_map[name]), args.args);
+  }
+}
+
+void WeightedTargetLb::UpdateStateLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] scanning children to determine "
+            "connectivity state",
+            this);
+  }
+  // Construct a new picker which maintains a map of all child pickers
+  // that are ready. Each child is represented by a portion of the range
+  // proportional to its weight, such that the total range is the sum of the
+  // weights of all children.
+  WeightedPicker::PickerList picker_list;
+  uint32_t end = 0;
+  // Also count the number of children in each state, to determine the
+  // overall state.
+  size_t num_connecting = 0;
+  size_t num_idle = 0;
+  size_t num_transient_failures = 0;
+  for (const auto& p : targets_) {
+    const std::string& child_name = p.first;
+    const WeightedChild* child = p.second.get();
+    // Skip the targets that are not in the latest update.
+    if (config_->target_map().find(child_name) == config_->target_map().end()) {
+      continue;
+    }
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+      gpr_log(GPR_INFO,
+              "[weighted_target_lb %p]   child=%s state=%s weight=%d picker=%p",
+              this, child_name.c_str(),
+              ConnectivityStateName(child->connectivity_state()),
+              child->weight(), child->picker_wrapper().get());
+    }
+    switch (child->connectivity_state()) {
+      case GRPC_CHANNEL_READY: {
+        end += child->weight();
+        picker_list.push_back(std::make_pair(end, child->picker_wrapper()));
+        break;
+      }
+      case GRPC_CHANNEL_CONNECTING: {
+        ++num_connecting;
+        break;
+      }
+      case GRPC_CHANNEL_IDLE: {
+        ++num_idle;
+        break;
+      }
+      case GRPC_CHANNEL_TRANSIENT_FAILURE: {
+        ++num_transient_failures;
+        break;
+      }
+      default:
+        GPR_UNREACHABLE_CODE(return );
+    }
+  }
+  // Determine aggregated connectivity state.
+  grpc_connectivity_state connectivity_state;
+  if (!picker_list.empty()) {
+    connectivity_state = GRPC_CHANNEL_READY;
+  } else if (num_connecting > 0) {
+    connectivity_state = GRPC_CHANNEL_CONNECTING;
+  } else if (num_idle > 0) {
+    connectivity_state = GRPC_CHANNEL_IDLE;
+  } else {
+    connectivity_state = GRPC_CHANNEL_TRANSIENT_FAILURE;
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO, "[weighted_target_lb %p] connectivity changed to %s",
+            this, ConnectivityStateName(connectivity_state));
+  }
+  std::unique_ptr<SubchannelPicker> picker;
+  switch (connectivity_state) {
+    case GRPC_CHANNEL_READY:
+      picker = absl::make_unique<WeightedPicker>(std::move(picker_list));
+      break;
+    case GRPC_CHANNEL_CONNECTING:
+    case GRPC_CHANNEL_IDLE:
+      picker =
+          absl::make_unique<QueuePicker>(Ref(DEBUG_LOCATION, "QueuePicker"));
+      break;
+    default:
+      picker = absl::make_unique<TransientFailurePicker>(
+          GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+              "weighted_target: all children report state TRANSIENT_FAILURE"));
+  }
+  channel_control_helper()->UpdateState(connectivity_state, std::move(picker));
+}
+
+//
+// WeightedTargetLb::WeightedChild
+//
+
+WeightedTargetLb::WeightedChild::WeightedChild(
+    RefCountedPtr<WeightedTargetLb> weighted_target_policy,
+    const std::string& name)
+    : weighted_target_policy_(std::move(weighted_target_policy)), name_(name) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO, "[weighted_target_lb %p] created WeightedChild %p for %s",
+            weighted_target_policy_.get(), this, name_.c_str());
+  }
+}
+
+WeightedTargetLb::WeightedChild::~WeightedChild() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] WeightedChild %p %s: destroying child",
+            weighted_target_policy_.get(), this, name_.c_str());
+  }
+  weighted_target_policy_.reset(DEBUG_LOCATION, "WeightedChild");
+}
+
+void WeightedTargetLb::WeightedChild::Orphan() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] WeightedChild %p %s: shutting down child",
+            weighted_target_policy_.get(), this, name_.c_str());
+  }
+  // Remove the child policy's interested_parties pollset_set from the
+  // xDS policy.
+  grpc_pollset_set_del_pollset_set(
+      child_policy_->interested_parties(),
+      weighted_target_policy_->interested_parties());
+  child_policy_.reset();
+  // Drop our ref to the child's picker, in case it's holding a ref to
+  // the child.
+  picker_wrapper_.reset();
+  if (delayed_removal_timer_callback_pending_) {
+    delayed_removal_timer_callback_pending_ = false;
+    grpc_timer_cancel(&delayed_removal_timer_);
+  }
+  shutdown_ = true;
+  Unref();
+}
+
+OrphanablePtr<LoadBalancingPolicy>
+WeightedTargetLb::WeightedChild::CreateChildPolicyLocked(
+    const grpc_channel_args* args) {
+  LoadBalancingPolicy::Args lb_policy_args;
+  lb_policy_args.combiner = weighted_target_policy_->combiner();
+  lb_policy_args.args = args;
+  lb_policy_args.channel_control_helper =
+      absl::make_unique<Helper>(this->Ref(DEBUG_LOCATION, "Helper"));
+  OrphanablePtr<LoadBalancingPolicy> lb_policy =
+      MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args),
+                                         &grpc_lb_weighted_target_trace);
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] WeightedChild %p %s: Created new child "
+            "policy handler %p",
+            weighted_target_policy_.get(), this, name_.c_str(),
+            lb_policy.get());
+  }
+  // Add the xDS's interested_parties pollset_set to that of the newly created
+  // child policy. This will make the child policy progress upon activity on
+  // xDS LB, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(
+      lb_policy->interested_parties(),
+      weighted_target_policy_->interested_parties());
+  return lb_policy;
+}
+
+void WeightedTargetLb::WeightedChild::UpdateLocked(
+    const WeightedTargetLbConfig::ChildConfig& config,
+    ServerAddressList addresses, const grpc_channel_args* args) {
+  if (weighted_target_policy_->shutting_down_) return;
+  // Update child weight.
+  weight_ = config.weight;
+  // Reactivate if needed.
+  if (delayed_removal_timer_callback_pending_) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+      gpr_log(GPR_INFO,
+              "[weighted_target_lb %p] WeightedChild %p %s: reactivating",
+              weighted_target_policy_.get(), this, name_.c_str());
+    }
+    delayed_removal_timer_callback_pending_ = false;
+    grpc_timer_cancel(&delayed_removal_timer_);
+  }
+  // Create child policy if needed.
+  if (child_policy_ == nullptr) {
+    child_policy_ = CreateChildPolicyLocked(args);
+  }
+  // Construct update args.
+  UpdateArgs update_args;
+  update_args.config = config.config;
+  update_args.addresses = std::move(addresses);
+  update_args.args = grpc_channel_args_copy(args);
+  // Update the policy.
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] WeightedChild %p %s: Updating child "
+            "policy handler %p",
+            weighted_target_policy_.get(), this, name_.c_str(),
+            child_policy_.get());
+  }
+  child_policy_->UpdateLocked(std::move(update_args));
+}
+
+void WeightedTargetLb::WeightedChild::ResetBackoffLocked() {
+  child_policy_->ResetBackoffLocked();
+}
+
+void WeightedTargetLb::WeightedChild::OnConnectivityStateUpdateLocked(
+    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
+  // Cache the picker in the WeightedChild.
+  picker_wrapper_ = MakeRefCounted<ChildPickerWrapper>(std::move(picker));
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] WeightedChild %p %s: connectivity "
+            "state update: state=%s picker_wrapper=%p",
+            weighted_target_policy_.get(), this, name_.c_str(),
+            ConnectivityStateName(state), picker_wrapper_.get());
+  }
+  // If the child reports IDLE, immediately tell it to exit idle.
+  if (state == GRPC_CHANNEL_IDLE) child_policy_->ExitIdleLocked();
+  // Decide what state to report for aggregation purposes.
+  // If we haven't seen a failure since the last time we were in state
+  // READY, then we report the state change as-is.  However, once we do see
+  // a failure, we report TRANSIENT_FAILURE and ignore any subsequent state
+  // changes until we go back into state READY.
+  if (!seen_failure_since_ready_) {
+    if (state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
+      seen_failure_since_ready_ = true;
+    }
+  } else {
+    if (state != GRPC_CHANNEL_READY) return;
+    seen_failure_since_ready_ = false;
+  }
+  connectivity_state_ = state;
+  // Notify the LB policy.
+  weighted_target_policy_->UpdateStateLocked();
+}
+
+void WeightedTargetLb::WeightedChild::DeactivateLocked() {
+  // If already deactivated, don't do that again.
+  if (weight_ == 0) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_weighted_target_trace)) {
+    gpr_log(GPR_INFO,
+            "[weighted_target_lb %p] WeightedChild %p %s: deactivating",
+            weighted_target_policy_.get(), this, name_.c_str());
+  }
+  // Set the child weight to 0 so that future picker won't contain this child.
+  weight_ = 0;
+  // Start a timer to delete the child.
+  Ref(DEBUG_LOCATION, "WeightedChild+timer").release();
+  GRPC_CLOSURE_INIT(&on_delayed_removal_timer_, OnDelayedRemovalTimer, this,
+                    grpc_schedule_on_exec_ctx);
+  delayed_removal_timer_callback_pending_ = true;
+  grpc_timer_init(&delayed_removal_timer_,
+                  ExecCtx::Get()->Now() + kChildRetentionIntervalMs,
+                  &on_delayed_removal_timer_);
+}
+
+void WeightedTargetLb::WeightedChild::OnDelayedRemovalTimer(void* arg,
+                                                            grpc_error* error) {
+  WeightedChild* self = static_cast<WeightedChild*>(arg);
+  self->weighted_target_policy_->combiner()->Run(
+      GRPC_CLOSURE_INIT(&self->on_delayed_removal_timer_,
+                        OnDelayedRemovalTimerLocked, self, nullptr),
+      GRPC_ERROR_REF(error));
+}
+
+void WeightedTargetLb::WeightedChild::OnDelayedRemovalTimerLocked(
+    void* arg, grpc_error* error) {
+  WeightedChild* self = static_cast<WeightedChild*>(arg);
+  if (error == GRPC_ERROR_NONE &&
+      self->delayed_removal_timer_callback_pending_ && !self->shutdown_ &&
+      self->weight_ == 0) {
+    self->delayed_removal_timer_callback_pending_ = false;
+    self->weighted_target_policy_->targets_.erase(self->name_);
+  }
+  self->Unref(DEBUG_LOCATION, "WeightedChild+timer");
+}
+
+//
+// WeightedTargetLb::WeightedChild::Helper
+//
+
+RefCountedPtr<SubchannelInterface>
+WeightedTargetLb::WeightedChild::Helper::CreateSubchannel(
+    const grpc_channel_args& args) {
+  if (weighted_child_->weighted_target_policy_->shutting_down_) return nullptr;
+  return weighted_child_->weighted_target_policy_->channel_control_helper()
+      ->CreateSubchannel(args);
+}
+
+void WeightedTargetLb::WeightedChild::Helper::UpdateState(
+    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
+  if (weighted_child_->weighted_target_policy_->shutting_down_) return;
+  weighted_child_->OnConnectivityStateUpdateLocked(state, std::move(picker));
+}
+
+void WeightedTargetLb::WeightedChild::Helper::RequestReresolution() {
+  if (weighted_child_->weighted_target_policy_->shutting_down_) return;
+  weighted_child_->weighted_target_policy_->channel_control_helper()
+      ->RequestReresolution();
+}
+
+void WeightedTargetLb::WeightedChild::Helper::AddTraceEvent(
+    TraceSeverity severity, StringView message) {
+  if (weighted_child_->weighted_target_policy_->shutting_down_) return;
+  weighted_child_->weighted_target_policy_->channel_control_helper()
+      ->AddTraceEvent(severity, message);
+}
+
+//
+// factory
+//
+
+class WeightedTargetLbFactory : public LoadBalancingPolicyFactory {
+ public:
+  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+      LoadBalancingPolicy::Args args) const override {
+    return MakeOrphanable<WeightedTargetLb>(std::move(args));
+  }
+
+  const char* name() const override { return kWeightedTarget; }
+
+  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
+      const Json& json, grpc_error** error) const override {
+    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
+    if (json.type() == Json::Type::JSON_NULL) {
+      // weighted_target was mentioned as a policy in the deprecated
+      // loadBalancingPolicy field or in the client API.
+      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:loadBalancingPolicy error:weighted_target policy requires "
+          "configuration.  Please use loadBalancingConfig field of service "
+          "config instead.");
+      return nullptr;
+    }
+    std::vector<grpc_error*> error_list;
+    // Weight map.
+    WeightedTargetLbConfig::TargetMap target_map;
+    auto it = json.object_value().find("targets");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:targets error:required field not present"));
+    } else if (it->second.type() != Json::Type::OBJECT) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:targets error:type should be object"));
+    } else {
+      for (const auto& p : it->second.object_value()) {
+        WeightedTargetLbConfig::ChildConfig child_config;
+        std::vector<grpc_error*> child_errors =
+            ParseChildConfig(p.second, &child_config);
+        if (!child_errors.empty()) {
+          // Can't use GRPC_ERROR_CREATE_FROM_VECTOR() here, because the error
+          // string is not static in this case.
+          grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrCat("field:targets key:", p.first).c_str());
+          for (grpc_error* child_error : child_errors) {
+            error = grpc_error_add_child(error, child_error);
+          }
+          error_list.push_back(error);
+        } else {
+          target_map[p.first] = std::move(child_config);
+        }
+      }
+    }
+    if (!error_list.empty()) {
+      *error = GRPC_ERROR_CREATE_FROM_VECTOR(
+          "weighted_target_experimental LB policy config", &error_list);
+      return nullptr;
+    }
+    return MakeRefCounted<WeightedTargetLbConfig>(std::move(target_map));
+  }
+
+ private:
+  static std::vector<grpc_error*> ParseChildConfig(
+      const Json& json, WeightedTargetLbConfig::ChildConfig* child_config) {
+    std::vector<grpc_error*> error_list;
+    if (json.type() != Json::Type::OBJECT) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "value should be of type object"));
+      return error_list;
+    }
+    // Weight.
+    auto it = json.object_value().find("weight");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "required field \"weight\" not specified"));
+    } else if (it->second.type() != Json::Type::NUMBER) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:weight error:must be of type number"));
+    } else {
+      child_config->weight =
+          gpr_parse_nonnegative_int(it->second.string_value().c_str());
+      if (child_config->weight == -1) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:weight error:unparseable value"));
+      } else if (child_config->weight == 0) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:weight error:value must be greater than zero"));
+      }
+    }
+    // Child policy.
+    it = json.object_value().find("childPolicy");
+    if (it != json.object_value().end()) {
+      grpc_error* parse_error = GRPC_ERROR_NONE;
+      child_config->config =
+          LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(it->second,
+                                                                &parse_error);
+      if (child_config->config == nullptr) {
+        GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+        std::vector<grpc_error*> child_errors;
+        child_errors.push_back(parse_error);
+        error_list.push_back(
+            GRPC_ERROR_CREATE_FROM_VECTOR("field:childPolicy", &child_errors));
+      }
+    }
+    return error_list;
+  }
+};
+
+}  // namespace
+
+}  // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_weighted_target_init() {
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          absl::make_unique<grpc_core::WeightedTargetLbFactory>());
+}
+
+void grpc_lb_policy_weighted_target_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/xds/cds.cc

@@ -37,9 +37,9 @@ namespace {
 constexpr char kCds[] = "cds_experimental";
 
 // Config for this LB policy.
-class CdsConfig : public LoadBalancingPolicy::Config {
+class CdsLbConfig : public LoadBalancingPolicy::Config {
  public:
-  explicit CdsConfig(std::string cluster) : cluster_(std::move(cluster)) {}
+  explicit CdsLbConfig(std::string cluster) : cluster_(std::move(cluster)) {}
   const std::string& cluster() const { return cluster_; }
   const char* name() const override { return kCds; }
 
@@ -50,7 +50,7 @@ class CdsConfig : public LoadBalancingPolicy::Config {
 // CDS LB policy.
 class CdsLb : public LoadBalancingPolicy {
  public:
-  explicit CdsLb(Args args);
+  CdsLb(RefCountedPtr<XdsClient> xds_client, Args args);
 
   const char* name() const override { return kCds; }
 
@@ -89,7 +89,7 @@ class CdsLb : public LoadBalancingPolicy {
 
   void ShutdownLocked() override;
 
-  RefCountedPtr<CdsConfig> config_;
+  RefCountedPtr<CdsLbConfig> config_;
 
   // Current channel args from the resolver.
   const grpc_channel_args* args_ = nullptr;
@@ -124,21 +124,37 @@ void CdsLb::ClusterWatcher::OnClusterChanged(XdsApi::CdsUpdate cluster_data) {
   }
   // Construct config for child policy.
   Json::Object child_config = {
-      {"edsServiceName",
-       (cluster_data.eds_service_name.empty() ? parent_->config_->cluster()
-                                              : cluster_data.eds_service_name)},
+      {"clusterName", parent_->config_->cluster()},
+      {"localityPickingPolicy",
+       Json::Array{
+           Json::Object{
+               {"weighted_target_experimental",
+                Json::Object{
+                    {"targets", Json::Object()},
+                }},
+           },
+       }},
+      {"endpointPickingPolicy",
+       Json::Array{
+           Json::Object{
+               {"round_robin", Json::Object()},
+           },
+       }},
   };
+  if (!cluster_data.eds_service_name.empty()) {
+    child_config["edsServiceName"] = cluster_data.eds_service_name;
+  }
   if (cluster_data.lrs_load_reporting_server_name.has_value()) {
     child_config["lrsLoadReportingServerName"] =
         cluster_data.lrs_load_reporting_server_name.value();
   }
   Json json = Json::Array{
       Json::Object{
-          {"xds_experimental", std::move(child_config)},
+          {"eds_experimental", std::move(child_config)},
       },
   };
   if (GRPC_TRACE_FLAG_ENABLED(grpc_cds_lb_trace)) {
-    std::string json_str = json.Dump();
+    std::string json_str = json.Dump(/*indent=*/1);
     gpr_log(GPR_INFO, "[cdslb %p] generated config for child policy: %s",
             parent_.get(), json_str.c_str());
   }
@@ -156,19 +172,19 @@ void CdsLb::ClusterWatcher::OnClusterChanged(XdsApi::CdsUpdate cluster_data) {
     args.args = parent_->args_;
     args.channel_control_helper = absl::make_unique<Helper>(parent_->Ref());
     parent_->child_policy_ =
-        LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
-            "xds_experimental", std::move(args));
+        LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(config->name(),
+                                                               std::move(args));
     if (parent_->child_policy_ == nullptr) {
       OnError(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-          "failed to create xds_experimental child policy"));
+          "failed to create child policy"));
       return;
     }
     grpc_pollset_set_add_pollset_set(
         parent_->child_policy_->interested_parties(),
         parent_->interested_parties());
     if (GRPC_TRACE_FLAG_ENABLED(grpc_cds_lb_trace)) {
-      gpr_log(GPR_INFO, "[cdslb %p] created child policy xds_experimental (%p)",
-              parent_.get(), parent_->child_policy_.get());
+      gpr_log(GPR_INFO, "[cdslb %p] created child policy %s (%p)",
+              parent_.get(), config->name(), parent_->child_policy_.get());
     }
   }
   // Update child policy.
@@ -232,9 +248,8 @@ void CdsLb::Helper::AddTraceEvent(TraceSeverity severity, StringView message) {
 // CdsLb
 //
 
-CdsLb::CdsLb(Args args)
-    : LoadBalancingPolicy(std::move(args)),
-      xds_client_(XdsClient::GetFromChannelArgs(*args.args)) {
+CdsLb::CdsLb(RefCountedPtr<XdsClient> xds_client, Args args)
+    : LoadBalancingPolicy(std::move(args)), xds_client_(std::move(xds_client)) {
   if (GRPC_TRACE_FLAG_ENABLED(grpc_cds_lb_trace)) {
     gpr_log(GPR_INFO, "[cdslb %p] created -- using xds client %p from channel",
             this, xds_client_.get());
@@ -313,11 +328,19 @@ void CdsLb::UpdateLocked(UpdateArgs args) {
 // factory
 //
 
-class CdsFactory : public LoadBalancingPolicyFactory {
+class CdsLbFactory : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {
-    return MakeOrphanable<CdsLb>(std::move(args));
+    RefCountedPtr<XdsClient> xds_client =
+        XdsClient::GetFromChannelArgs(*args.args);
+    if (xds_client == nullptr) {
+      gpr_log(GPR_ERROR,
+              "XdsClient not present in channel args -- cannot instantiate "
+              "cds LB policy");
+      return nullptr;
+    }
+    return MakeOrphanable<CdsLb>(std::move(xds_client), std::move(args));
   }
 
   const char* name() const override { return kCds; }
@@ -349,7 +372,7 @@ class CdsFactory : public LoadBalancingPolicyFactory {
       *error = GRPC_ERROR_CREATE_FROM_VECTOR("Cds Parser", &error_list);
       return nullptr;
     }
-    return MakeRefCounted<CdsConfig>(std::move(cluster));
+    return MakeRefCounted<CdsLbConfig>(std::move(cluster));
   }
 };
 
@@ -364,7 +387,7 @@ class CdsFactory : public LoadBalancingPolicyFactory {
 void grpc_lb_policy_cds_init() {
   grpc_core::LoadBalancingPolicyRegistry::Builder::
       RegisterLoadBalancingPolicyFactory(
-          absl::make_unique<grpc_core::CdsFactory>());
+          absl::make_unique<grpc_core::CdsLbFactory>());
 }
 
 void grpc_lb_policy_cds_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/xds/eds.cc

@@ -0,0 +1,1175 @@
+//
+// Copyright 2018 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <grpc/support/port_platform.h>
+
+#include <inttypes.h>
+#include <limits.h>
+
+#include "absl/strings/str_cat.h"
+#include "absl/types/optional.h"
+
+#include <grpc/grpc.h>
+
+#include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/ext/filters/client_channel/lb_policy.h"
+#include "src/core/ext/filters/client_channel/lb_policy/address_filtering.h"
+#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/ext/filters/client_channel/server_address.h"
+#include "src/core/ext/filters/client_channel/xds/xds_client.h"
+#include "src/core/ext/filters/client_channel/xds/xds_client_stats.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/uri/uri_parser.h"
+
+#define GRPC_EDS_DEFAULT_FALLBACK_TIMEOUT 10000
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_eds_trace(false, "eds_lb");
+
+namespace {
+
+constexpr char kXds[] = "xds_experimental";
+constexpr char kEds[] = "eds_experimental";
+
+// Config for EDS LB policy.
+class EdsLbConfig : public LoadBalancingPolicy::Config {
+ public:
+  EdsLbConfig(const char* name, std::string cluster_name,
+              std::string eds_service_name,
+              absl::optional<std::string> lrs_load_reporting_server_name,
+              Json locality_picking_policy, Json endpoint_picking_policy,
+              RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy)
+      : name_(name),
+        cluster_name_(std::move(cluster_name)),
+        eds_service_name_(std::move(eds_service_name)),
+        lrs_load_reporting_server_name_(
+            std::move(lrs_load_reporting_server_name)),
+        locality_picking_policy_(std::move(locality_picking_policy)),
+        endpoint_picking_policy_(std::move(endpoint_picking_policy)),
+        fallback_policy_(std::move(fallback_policy)) {}
+
+  const char* name() const override { return name_; }
+
+  const std::string& cluster_name() const { return cluster_name_; }
+  const std::string& eds_service_name() const { return eds_service_name_; }
+  const absl::optional<std::string>& lrs_load_reporting_server_name() const {
+    return lrs_load_reporting_server_name_;
+  };
+  const Json& locality_picking_policy() const {
+    return locality_picking_policy_;
+  }
+  const Json& endpoint_picking_policy() const {
+    return endpoint_picking_policy_;
+  }
+  RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy() const {
+    return fallback_policy_;
+  }
+
+ private:
+  const char* name_;
+  std::string cluster_name_;
+  std::string eds_service_name_;
+  absl::optional<std::string> lrs_load_reporting_server_name_;
+  Json locality_picking_policy_;
+  Json endpoint_picking_policy_;
+  RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy_;
+};
+
+// EDS LB policy.
+class EdsLb : public LoadBalancingPolicy {
+ public:
+  EdsLb(const char* name, Args args);
+
+  const char* name() const override { return name_; }
+
+  void UpdateLocked(UpdateArgs args) override;
+  void ResetBackoffLocked() override;
+
+ private:
+  class EndpointWatcher;
+
+  // A simple wrapper for ref-counting a picker from the child policy.
+  class ChildPickerWrapper : public RefCounted<ChildPickerWrapper> {
+   public:
+    explicit ChildPickerWrapper(std::unique_ptr<SubchannelPicker> picker)
+        : picker_(std::move(picker)) {}
+    PickResult Pick(PickArgs args) { return picker_->Pick(args); }
+
+   private:
+    std::unique_ptr<SubchannelPicker> picker_;
+  };
+
+  // A picker that handles drops.
+  class DropPicker : public SubchannelPicker {
+   public:
+    explicit DropPicker(EdsLb* eds_policy);
+
+    PickResult Pick(PickArgs args) override;
+
+   private:
+    RefCountedPtr<XdsApi::DropConfig> drop_config_;
+    RefCountedPtr<XdsClusterDropStats> drop_stats_;
+    RefCountedPtr<ChildPickerWrapper> child_picker_;
+  };
+
+  class Helper : public ChannelControlHelper {
+   public:
+    explicit Helper(RefCountedPtr<EdsLb> eds_policy)
+        : eds_policy_(std::move(eds_policy)) {}
+
+    ~Helper() { eds_policy_.reset(DEBUG_LOCATION, "Helper"); }
+
+    RefCountedPtr<SubchannelInterface> CreateSubchannel(
+        const grpc_channel_args& args) override;
+    void UpdateState(grpc_connectivity_state state,
+                     std::unique_ptr<SubchannelPicker> picker) override;
+    // This is a no-op, because we get the addresses from the xds
+    // client, which is a watch-based API.
+    void RequestReresolution() override {}
+    void AddTraceEvent(TraceSeverity severity, StringView message) override;
+
+   private:
+    RefCountedPtr<EdsLb> eds_policy_;
+  };
+
+  class FallbackHelper : public ChannelControlHelper {
+   public:
+    explicit FallbackHelper(RefCountedPtr<EdsLb> parent)
+        : parent_(std::move(parent)) {}
+
+    ~FallbackHelper() { parent_.reset(DEBUG_LOCATION, "FallbackHelper"); }
+
+    RefCountedPtr<SubchannelInterface> CreateSubchannel(
+        const grpc_channel_args& args) override;
+    void UpdateState(grpc_connectivity_state state,
+                     std::unique_ptr<SubchannelPicker> picker) override;
+    void RequestReresolution() override;
+    void AddTraceEvent(TraceSeverity severity, StringView message) override;
+
+   private:
+    RefCountedPtr<EdsLb> parent_;
+  };
+
+  ~EdsLb();
+
+  void ShutdownLocked() override;
+
+  void UpdatePriorityList(XdsApi::PriorityListUpdate priority_list_update);
+  void UpdateChildPolicyLocked();
+  OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
+      const grpc_channel_args* args);
+  ServerAddressList CreateChildPolicyAddressesLocked();
+  RefCountedPtr<Config> CreateChildPolicyConfigLocked();
+  grpc_channel_args* CreateChildPolicyArgsLocked(
+      const grpc_channel_args* args_in);
+  void MaybeUpdateDropPickerLocked();
+
+  // Methods for dealing with fallback state.
+  void MaybeCancelFallbackAtStartupChecks();
+  static void OnFallbackTimer(void* arg, grpc_error* error);
+  static void OnFallbackTimerLocked(void* arg, grpc_error* error);
+  void UpdateFallbackPolicyLocked();
+  OrphanablePtr<LoadBalancingPolicy> CreateFallbackPolicyLocked(
+      const grpc_channel_args* args);
+  void MaybeExitFallbackMode();
+
+  // Caller must ensure that config_ is set before calling.
+  const StringView GetEdsResourceName() const {
+    if (xds_client_from_channel_ == nullptr) return server_name_;
+    if (!config_->eds_service_name().empty()) {
+      return config_->eds_service_name();
+    }
+    return config_->cluster_name();
+  }
+
+  // Returns a pair containing the cluster and eds_service_name to use
+  // for LRS load reporting.
+  // Caller must ensure that config_ is set before calling.
+  std::pair<StringView, StringView> GetLrsClusterKey() const {
+    if (xds_client_from_channel_ == nullptr) return {server_name_, nullptr};
+    return {config_->cluster_name(), config_->eds_service_name()};
+  }
+
+  XdsClient* xds_client() const {
+    return xds_client_from_channel_ != nullptr ? xds_client_from_channel_.get()
+                                               : xds_client_.get();
+  }
+
+  // Policy name (kXds or kEds).
+  const char* name_;
+
+  // Server name from target URI.
+  std::string server_name_;
+
+  // Current channel args and config from the resolver.
+  const grpc_channel_args* args_ = nullptr;
+  RefCountedPtr<EdsLbConfig> config_;
+
+  // Internal state.
+  bool shutting_down_ = false;
+
+  // The xds client and endpoint watcher.
+  // If we get the XdsClient from the channel, we store it in
+  // xds_client_from_channel_; if we create it ourselves, we store it in
+  // xds_client_.
+  RefCountedPtr<XdsClient> xds_client_from_channel_;
+  OrphanablePtr<XdsClient> xds_client_;
+  // A pointer to the endpoint watcher, to be used when cancelling the watch.
+  // Note that this is not owned, so this pointer must never be derefernced.
+  EndpointWatcher* endpoint_watcher_ = nullptr;
+  // The latest data from the endpoint watcher.
+  XdsApi::PriorityListUpdate priority_list_update_;
+  // State used to retain child policy names for priority policy.
+  std::vector<size_t /*child_number*/> priority_child_numbers_;
+
+  RefCountedPtr<XdsApi::DropConfig> drop_config_;
+  RefCountedPtr<XdsClusterDropStats> drop_stats_;
+
+  OrphanablePtr<LoadBalancingPolicy> child_policy_;
+
+  // The latest state and picker returned from the child policy.
+  grpc_connectivity_state child_state_;
+  RefCountedPtr<ChildPickerWrapper> child_picker_;
+
+  // Non-null iff we are in fallback mode.
+  OrphanablePtr<LoadBalancingPolicy> fallback_policy_;
+
+  // Whether the checks for fallback at startup are ALL pending. There are
+  // several cases where this can be reset:
+  // 1. The fallback timer fires, we enter fallback mode.
+  // 2. Before the fallback timer fires, the endpoint watcher reports an
+  //    error, we enter fallback mode.
+  // 3. Before the fallback timer fires, if any child policy in the locality map
+  //    becomes READY, we cancel the fallback timer.
+  bool fallback_at_startup_checks_pending_ = false;
+  // Timeout in milliseconds for before using fallback backend addresses.
+  // 0 means not using fallback.
+  const grpc_millis lb_fallback_timeout_ms_;
+  // The backend addresses from the resolver.
+  ServerAddressList fallback_backend_addresses_;
+  // Fallback timer.
+  grpc_timer lb_fallback_timer_;
+  grpc_closure lb_on_fallback_;
+};
+
+//
+// EdsLb::DropPicker
+//
+
+EdsLb::DropPicker::DropPicker(EdsLb* eds_policy)
+    : drop_config_(eds_policy->drop_config_),
+      drop_stats_(eds_policy->drop_stats_),
+      child_picker_(eds_policy->child_picker_) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] constructed new drop picker %p", eds_policy,
+            this);
+  }
+}
+
+EdsLb::PickResult EdsLb::DropPicker::Pick(PickArgs args) {
+  // Handle drop.
+  const std::string* drop_category;
+  if (drop_config_->ShouldDrop(&drop_category)) {
+    if (drop_stats_ != nullptr) drop_stats_->AddCallDropped(*drop_category);
+    PickResult result;
+    result.type = PickResult::PICK_COMPLETE;
+    return result;
+  }
+  // If we're not dropping all calls, we should always have a child picker.
+  if (child_picker_ == nullptr) {  // Should never happen.
+    PickResult result;
+    result.type = PickResult::PICK_FAILED;
+    result.error =
+        grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+                               "eds drop picker not given any child picker"),
+                           GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_INTERNAL);
+    return result;
+  }
+  // Not dropping, so delegate to child's picker.
+  return child_picker_->Pick(args);
+}
+
+//
+// EdsLb::Helper
+//
+
+RefCountedPtr<SubchannelInterface> EdsLb::Helper::CreateSubchannel(
+    const grpc_channel_args& args) {
+  if (eds_policy_->shutting_down_) return nullptr;
+  return eds_policy_->channel_control_helper()->CreateSubchannel(args);
+}
+
+void EdsLb::Helper::UpdateState(grpc_connectivity_state state,
+                                std::unique_ptr<SubchannelPicker> picker) {
+  if (eds_policy_->shutting_down_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] child policy updated state=%s picker=%p",
+            eds_policy_.get(), ConnectivityStateName(state), picker.get());
+  }
+  // Save the state and picker.
+  eds_policy_->child_state_ = state;
+  eds_policy_->child_picker_ =
+      MakeRefCounted<ChildPickerWrapper>(std::move(picker));
+  // If the new state is READY, cancel the fallback-at-startup checks.
+  if (state == GRPC_CHANNEL_READY) {
+    eds_policy_->MaybeCancelFallbackAtStartupChecks();
+    eds_policy_->MaybeExitFallbackMode();
+  }
+  // TODO(roth): If the child reports TRANSIENT_FAILURE and the
+  // fallback-at-startup checks are pending, we should probably go into
+  // fallback mode immediately (cancelling the fallback-at-startup timer
+  // if needed).
+  // Wrap the picker in a DropPicker and pass it up.
+  eds_policy_->MaybeUpdateDropPickerLocked();
+}
+
+void EdsLb::Helper::AddTraceEvent(TraceSeverity severity, StringView message) {
+  if (eds_policy_->shutting_down_) return;
+  eds_policy_->channel_control_helper()->AddTraceEvent(severity, message);
+}
+
+//
+// EdsLb::FallbackHelper
+//
+
+RefCountedPtr<SubchannelInterface> EdsLb::FallbackHelper::CreateSubchannel(
+    const grpc_channel_args& args) {
+  if (parent_->shutting_down_) return nullptr;
+  return parent_->channel_control_helper()->CreateSubchannel(args);
+}
+
+void EdsLb::FallbackHelper::UpdateState(
+    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
+  if (parent_->shutting_down_) return;
+  parent_->channel_control_helper()->UpdateState(state, std::move(picker));
+}
+
+void EdsLb::FallbackHelper::RequestReresolution() {
+  if (parent_->shutting_down_) return;
+  parent_->channel_control_helper()->RequestReresolution();
+}
+
+void EdsLb::FallbackHelper::AddTraceEvent(TraceSeverity severity,
+                                          StringView message) {
+  if (parent_->shutting_down_) return;
+  parent_->channel_control_helper()->AddTraceEvent(severity, message);
+}
+
+//
+// EdsLb::EndpointWatcher
+//
+
+class EdsLb::EndpointWatcher : public XdsClient::EndpointWatcherInterface {
+ public:
+  explicit EndpointWatcher(RefCountedPtr<EdsLb> eds_policy)
+      : eds_policy_(std::move(eds_policy)) {}
+
+  ~EndpointWatcher() { eds_policy_.reset(DEBUG_LOCATION, "EndpointWatcher"); }
+
+  void OnEndpointChanged(XdsApi::EdsUpdate update) override {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+      gpr_log(GPR_INFO, "[edslb %p] Received EDS update from xds client",
+              eds_policy_.get());
+    }
+    // If the balancer tells us to drop all the calls, we should exit fallback
+    // mode immediately.
+    if (update.drop_config->drop_all()) eds_policy_->MaybeExitFallbackMode();
+    // Update the drop config.
+    const bool drop_config_changed =
+        eds_policy_->drop_config_ == nullptr ||
+        *eds_policy_->drop_config_ != *update.drop_config;
+    if (drop_config_changed) {
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+        gpr_log(GPR_INFO, "[edslb %p] Updating drop config", eds_policy_.get());
+      }
+      eds_policy_->drop_config_ = std::move(update.drop_config);
+      eds_policy_->MaybeUpdateDropPickerLocked();
+    } else if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+      gpr_log(GPR_INFO, "[edslb %p] Drop config unchanged, ignoring",
+              eds_policy_.get());
+    }
+    // Update priority and locality info.
+    if (eds_policy_->child_policy_ == nullptr ||
+        eds_policy_->priority_list_update_ != update.priority_list_update) {
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+        gpr_log(GPR_INFO, "[edslb %p] Updating priority list",
+                eds_policy_.get());
+      }
+      eds_policy_->UpdatePriorityList(std::move(update.priority_list_update));
+    } else if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+      gpr_log(GPR_INFO, "[edslb %p] Priority list unchanged, ignoring",
+              eds_policy_.get());
+    }
+  }
+
+  void OnError(grpc_error* error) override {
+    // If the fallback-at-startup checks are pending, go into fallback mode
+    // immediately.  This short-circuits the timeout for the
+    // fallback-at-startup case.
+    if (eds_policy_->fallback_at_startup_checks_pending_) {
+      gpr_log(GPR_ERROR,
+              "[edslb %p] xds watcher reported error; entering fallback "
+              "mode: %s",
+              eds_policy_.get(), grpc_error_string(error));
+      eds_policy_->fallback_at_startup_checks_pending_ = false;
+      grpc_timer_cancel(&eds_policy_->lb_fallback_timer_);
+      eds_policy_->UpdateFallbackPolicyLocked();
+      // If the xds call failed, request re-resolution.
+      // TODO(roth): We check the error string contents here to
+      // differentiate between the xds call failing and the xds channel
+      // going into TRANSIENT_FAILURE.  This is a pretty ugly hack,
+      // but it's okay for now, since we're not yet sure whether we will
+      // continue to support the current fallback functionality.  If we
+      // decide to keep the fallback approach, then we should either
+      // find a cleaner way to expose the difference between these two
+      // cases or decide that we're okay re-resolving in both cases.
+      // Note that even if we do keep the current fallback functionality,
+      // this re-resolution will only be necessary if we are going to be
+      // using this LB policy with resolvers other than the xds resolver.
+      if (strstr(grpc_error_string(error), "xds call failed")) {
+        eds_policy_->channel_control_helper()->RequestReresolution();
+      }
+    }
+    GRPC_ERROR_UNREF(error);
+  }
+
+ private:
+  RefCountedPtr<EdsLb> eds_policy_;
+};
+
+//
+// EdsLb public methods
+//
+
+EdsLb::EdsLb(const char* name, Args args)
+    : LoadBalancingPolicy(std::move(args)),
+      name_(name),
+      xds_client_from_channel_(XdsClient::GetFromChannelArgs(*args.args)),
+      lb_fallback_timeout_ms_(grpc_channel_args_find_integer(
+          args.args, GRPC_ARG_XDS_FALLBACK_TIMEOUT_MS,
+          {GRPC_EDS_DEFAULT_FALLBACK_TIMEOUT, 0, INT_MAX})) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] created -- xds client from channel: %p", this,
+            xds_client_from_channel_.get());
+  }
+  // Record server name.
+  const grpc_arg* arg = grpc_channel_args_find(args.args, GRPC_ARG_SERVER_URI);
+  const char* server_uri = grpc_channel_arg_get_string(arg);
+  GPR_ASSERT(server_uri != nullptr);
+  grpc_uri* uri = grpc_uri_parse(server_uri, true);
+  GPR_ASSERT(uri->path[0] != '\0');
+  server_name_ = uri->path[0] == '/' ? uri->path + 1 : uri->path;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] server name from channel: %s", this,
+            server_name_.c_str());
+  }
+  grpc_uri_destroy(uri);
+}
+
+EdsLb::~EdsLb() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] destroying xds LB policy", this);
+  }
+  grpc_channel_args_destroy(args_);
+}
+
+void EdsLb::ShutdownLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] shutting down", this);
+  }
+  shutting_down_ = true;
+  MaybeCancelFallbackAtStartupChecks();
+  // Drop our ref to the child's picker, in case it's holding a ref to
+  // the child.
+  child_picker_.reset();
+  if (child_policy_ != nullptr) {
+    grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
+                                     interested_parties());
+    child_policy_.reset();
+  }
+  if (fallback_policy_ != nullptr) {
+    grpc_pollset_set_del_pollset_set(fallback_policy_->interested_parties(),
+                                     interested_parties());
+    fallback_policy_.reset();
+  }
+  drop_stats_.reset();
+  // Cancel the endpoint watch here instead of in our dtor if we are using the
+  // xds resolver, because the watcher holds a ref to us and we might not be
+  // destroying the XdsClient, leading to a situation where this LB policy is
+  // never destroyed.
+  if (xds_client_from_channel_ != nullptr) {
+    if (config_ != nullptr) {
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+        gpr_log(GPR_INFO, "[edslb %p] cancelling xds watch for %s", this,
+                std::string(GetEdsResourceName()).c_str());
+      }
+      xds_client()->CancelEndpointDataWatch(GetEdsResourceName(),
+                                            endpoint_watcher_);
+    }
+    xds_client_from_channel_.reset();
+  }
+  xds_client_.reset();
+}
+
+void EdsLb::UpdateLocked(UpdateArgs args) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] Received update", this);
+  }
+  const bool is_initial_update = args_ == nullptr;
+  // Update config.
+  auto old_config = std::move(config_);
+  config_ = std::move(args.config);
+  // Update fallback address list.
+  fallback_backend_addresses_ = std::move(args.addresses);
+  // Update args.
+  grpc_channel_args_destroy(args_);
+  args_ = args.args;
+  args.args = nullptr;
+  // Update the existing fallback policy. The fallback policy config and/or the
+  // fallback addresses may be new.
+  if (fallback_policy_ != nullptr) UpdateFallbackPolicyLocked();
+  if (is_initial_update) {
+    // Initialize XdsClient.
+    if (xds_client_from_channel_ == nullptr) {
+      grpc_error* error = GRPC_ERROR_NONE;
+      xds_client_ = MakeOrphanable<XdsClient>(
+          combiner(), interested_parties(), GetEdsResourceName(),
+          nullptr /* service config watcher */, *args_, &error);
+      // TODO(roth): If we decide that we care about fallback mode, add
+      // proper error handling here.
+      GPR_ASSERT(error == GRPC_ERROR_NONE);
+      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+        gpr_log(GPR_INFO, "[edslb %p] Created xds client %p", this,
+                xds_client_.get());
+      }
+    }
+    // Start fallback-at-startup checks.
+    grpc_millis deadline = ExecCtx::Get()->Now() + lb_fallback_timeout_ms_;
+    Ref(DEBUG_LOCATION, "on_fallback_timer").release();  // Held by closure
+    GRPC_CLOSURE_INIT(&lb_on_fallback_, &EdsLb::OnFallbackTimer, this,
+                      grpc_schedule_on_exec_ctx);
+    fallback_at_startup_checks_pending_ = true;
+    grpc_timer_init(&lb_fallback_timer_, deadline, &lb_on_fallback_);
+  }
+  // Update drop stats for load reporting if needed.
+  if (is_initial_update || config_->lrs_load_reporting_server_name() !=
+                               old_config->lrs_load_reporting_server_name()) {
+    drop_stats_.reset();
+    if (config_->lrs_load_reporting_server_name().has_value()) {
+      const auto key = GetLrsClusterKey();
+      drop_stats_ = xds_client()->AddClusterDropStats(
+          config_->lrs_load_reporting_server_name().value(),
+          key.first /*cluster_name*/, key.second /*eds_service_name*/);
+    }
+    MaybeUpdateDropPickerLocked();
+  }
+  // Update child policy if needed.
+  // Note that this comes after updating drop_stats_, since we want that
+  // to be used by any new picker we create here.
+  if (child_policy_ != nullptr) UpdateChildPolicyLocked();
+  // Create endpoint watcher if needed.
+  if (is_initial_update) {
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+      gpr_log(GPR_INFO, "[edslb %p] starting xds watch for %s", this,
+              std::string(GetEdsResourceName()).c_str());
+    }
+    auto watcher = absl::make_unique<EndpointWatcher>(
+        Ref(DEBUG_LOCATION, "EndpointWatcher"));
+    endpoint_watcher_ = watcher.get();
+    xds_client()->WatchEndpointData(GetEdsResourceName(), std::move(watcher));
+  }
+}
+
+void EdsLb::ResetBackoffLocked() {
+  // When the XdsClient is instantiated in the resolver instead of in this
+  // LB policy, this is done via the resolver, so we don't need to do it
+  // for xds_client_from_channel_ here.
+  if (xds_client_ != nullptr) xds_client_->ResetBackoff();
+  if (child_policy_ != nullptr) {
+    child_policy_->ResetBackoffLocked();
+  }
+  if (fallback_policy_ != nullptr) {
+    fallback_policy_->ResetBackoffLocked();
+  }
+}
+
+//
+// child policy-related methods
+//
+
+void EdsLb::UpdatePriorityList(
+    XdsApi::PriorityListUpdate priority_list_update) {
+  // Build some maps from locality to child number and the reverse from
+  // the old data in priority_list_update_ and priority_child_numbers_.
+  std::map<XdsLocalityName*, size_t /*child_number*/, XdsLocalityName::Less>
+      locality_child_map;
+  std::map<size_t, std::set<XdsLocalityName*>> child_locality_map;
+  for (uint32_t priority = 0; priority < priority_list_update_.size();
+       ++priority) {
+    auto* locality_map = priority_list_update_.Find(priority);
+    GPR_ASSERT(locality_map != nullptr);
+    size_t child_number = priority_child_numbers_[priority];
+    for (const auto& p : locality_map->localities) {
+      XdsLocalityName* locality_name = p.first.get();
+      locality_child_map[locality_name] = child_number;
+      child_locality_map[child_number].insert(locality_name);
+    }
+  }
+  // Construct new list of children.
+  std::vector<size_t> priority_child_numbers;
+  for (uint32_t priority = 0; priority < priority_list_update.size();
+       ++priority) {
+    auto* locality_map = priority_list_update.Find(priority);
+    GPR_ASSERT(locality_map != nullptr);
+    absl::optional<size_t> child_number;
+    // If one of the localities in this priority already existed, reuse its
+    // child number.
+    for (const auto& p : locality_map->localities) {
+      XdsLocalityName* locality_name = p.first.get();
+      if (!child_number.has_value()) {
+        auto it = locality_child_map.find(locality_name);
+        if (it != locality_child_map.end()) {
+          child_number = it->second;
+          locality_child_map.erase(it);
+          // Remove localities that *used* to be in this child number, so
+          // that we don't incorrectly reuse this child number for a
+          // subsequent priority.
+          for (XdsLocalityName* old_locality :
+               child_locality_map[*child_number]) {
+            locality_child_map.erase(old_locality);
+          }
+        }
+      } else {
+        // Remove all localities that are now in this child number, so
+        // that we don't accidentally reuse this child number for a
+        // subsequent priority.
+        locality_child_map.erase(locality_name);
+      }
+    }
+    // If we didn't find an existing child number, assign a new one.
+    if (!child_number.has_value()) {
+      for (child_number = 0;
+           child_locality_map.find(*child_number) != child_locality_map.end();
+           ++(*child_number))
+        ;
+      // Add entry so we know that the child number is in use.
+      // (Don't need to add the list of localities, since we won't use them.)
+      child_locality_map[*child_number];
+    }
+    priority_child_numbers.push_back(*child_number);
+  }
+  // Save update.
+  priority_list_update_ = std::move(priority_list_update);
+  priority_child_numbers_ = std::move(priority_child_numbers);
+  // Update child policy.
+  UpdateChildPolicyLocked();
+}
+
+ServerAddressList EdsLb::CreateChildPolicyAddressesLocked() {
+  ServerAddressList addresses;
+  for (uint32_t priority = 0; priority < priority_list_update_.size();
+       ++priority) {
+    std::string priority_child_name =
+        absl::StrCat("child", priority_child_numbers_[priority]);
+    const auto* locality_map = priority_list_update_.Find(priority);
+    GPR_ASSERT(locality_map != nullptr);
+    for (const auto& p : locality_map->localities) {
+      const auto& locality_name = p.first;
+      const auto& locality = p.second;
+      std::vector<std::string> hierarchical_path = {
+          priority_child_name, locality_name->AsHumanReadableString()};
+      for (size_t i = 0; i < locality.serverlist.size(); ++i) {
+        const ServerAddress& address = locality.serverlist[i];
+        grpc_arg new_arg = MakeHierarchicalPathArg(hierarchical_path);
+        grpc_channel_args* args =
+            grpc_channel_args_copy_and_add(address.args(), &new_arg, 1);
+        addresses.emplace_back(address.address(), args);
+      }
+    }
+  }
+  return addresses;
+}
+
+RefCountedPtr<LoadBalancingPolicy::Config>
+EdsLb::CreateChildPolicyConfigLocked() {
+  Json::Object priority_children;
+  Json::Array priority_priorities;
+  for (uint32_t priority = 0; priority < priority_list_update_.size();
+       ++priority) {
+    const auto* locality_map = priority_list_update_.Find(priority);
+    GPR_ASSERT(locality_map != nullptr);
+    Json::Object weighted_targets;
+    for (const auto& p : locality_map->localities) {
+      XdsLocalityName* locality_name = p.first.get();
+      const auto& locality = p.second;
+      // Construct JSON object containing locality name.
+      Json::Object locality_name_json;
+      if (!locality_name->region().empty()) {
+        locality_name_json["region"] = locality_name->region();
+      }
+      if (!locality_name->zone().empty()) {
+        locality_name_json["zone"] = locality_name->zone();
+      }
+      if (!locality_name->sub_zone().empty()) {
+        locality_name_json["subzone"] = locality_name->sub_zone();
+      }
+      // Construct endpoint-picking policy.
+      // Wrap it in the LRS policy if load reporting is enabled.
+      Json endpoint_picking_policy;
+      if (config_->lrs_load_reporting_server_name().has_value()) {
+        const auto key = GetLrsClusterKey();
+        Json::Object lrs_config = {
+            {"clusterName", std::string(key.first)},
+            {"locality", std::move(locality_name_json)},
+            {"lrsLoadReportingServerName",
+             config_->lrs_load_reporting_server_name().value()},
+            {"childPolicy", config_->endpoint_picking_policy()},
+        };
+        if (!key.second.empty()) {
+          lrs_config["edsServiceName"] = std::string(key.second);
+        }
+        endpoint_picking_policy = Json::Array{Json::Object{
+            {"lrs_experimental", std::move(lrs_config)},
+        }};
+      } else {
+        endpoint_picking_policy = config_->endpoint_picking_policy();
+      }
+      // Add weighted target entry.
+      weighted_targets[locality_name->AsHumanReadableString()] = Json::Object{
+          {"weight", locality.lb_weight},
+          {"childPolicy", std::move(endpoint_picking_policy)},
+      };
+    }
+    // Add priority entry.
+    const size_t child_number = priority_child_numbers_[priority];
+    std::string child_name = absl::StrCat("child", child_number);
+    priority_priorities.emplace_back(child_name);
+    Json locality_picking_config = config_->locality_picking_policy();
+    Json::Object& config =
+        *(*locality_picking_config.mutable_array())[0].mutable_object();
+    auto it = config.begin();
+    GPR_ASSERT(it != config.end());
+    (*it->second.mutable_object())["targets"] = std::move(weighted_targets);
+    priority_children[child_name] = Json::Object{
+        {"config", std::move(locality_picking_config)},
+    };
+  }
+  Json json = Json::Array{Json::Object{
+      {"priority_experimental",
+       Json::Object{
+           {"children", std::move(priority_children)},
+           {"priorities", std::move(priority_priorities)},
+       }},
+  }};
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    std::string json_str = json.Dump(/*indent=*/1);
+    gpr_log(GPR_INFO, "[edslb %p] generated config for child policy: %s", this,
+            json_str.c_str());
+  }
+  grpc_error* error = GRPC_ERROR_NONE;
+  RefCountedPtr<LoadBalancingPolicy::Config> config =
+      LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(json, &error);
+  if (error != GRPC_ERROR_NONE) {
+    // This should never happen, but if it does, we basically have no
+    // way to fix it, so we put the channel in TRANSIENT_FAILURE.
+    gpr_log(GPR_ERROR,
+            "[edslb %p] error parsing generated child policy config -- "
+            "will put channel in TRANSIENT_FAILURE: %s",
+            this, grpc_error_string(error));
+    error = grpc_error_set_int(
+        grpc_error_add_child(
+            GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+                "eds LB policy: error parsing generated child policy config"),
+            error),
+        GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_INTERNAL);
+    channel_control_helper()->UpdateState(
+        GRPC_CHANNEL_TRANSIENT_FAILURE,
+        absl::make_unique<TransientFailurePicker>(error));
+    return nullptr;
+  }
+  return config;
+}
+
+void EdsLb::UpdateChildPolicyLocked() {
+  if (shutting_down_) return;
+  UpdateArgs update_args;
+  update_args.config = CreateChildPolicyConfigLocked();
+  if (update_args.config == nullptr) return;
+  update_args.addresses = CreateChildPolicyAddressesLocked();
+  update_args.args = CreateChildPolicyArgsLocked(args_);
+  if (child_policy_ == nullptr) {
+    child_policy_ = CreateChildPolicyLocked(update_args.args);
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] Updating child policy %p", this,
+            child_policy_.get());
+  }
+  child_policy_->UpdateLocked(std::move(update_args));
+}
+
+grpc_channel_args* EdsLb::CreateChildPolicyArgsLocked(
+    const grpc_channel_args* args) {
+  absl::InlinedVector<grpc_arg, 3> args_to_add = {
+      // A channel arg indicating if the target is a backend inferred from an
+      // xds load balancer.
+      grpc_channel_arg_integer_create(
+          const_cast<char*>(GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER),
+          1),
+      // Inhibit client-side health checking, since the balancer does
+      // this for us.
+      grpc_channel_arg_integer_create(
+          const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1),
+  };
+  if (xds_client_from_channel_ == nullptr) {
+    args_to_add.emplace_back(xds_client_->MakeChannelArg());
+  }
+  return grpc_channel_args_copy_and_add(args, args_to_add.data(),
+                                        args_to_add.size());
+}
+
+OrphanablePtr<LoadBalancingPolicy> EdsLb::CreateChildPolicyLocked(
+    const grpc_channel_args* args) {
+  LoadBalancingPolicy::Args lb_policy_args;
+  lb_policy_args.combiner = combiner();
+  lb_policy_args.args = args;
+  lb_policy_args.channel_control_helper =
+      absl::make_unique<Helper>(Ref(DEBUG_LOCATION, "Helper"));
+  OrphanablePtr<LoadBalancingPolicy> lb_policy =
+      LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
+          "priority_experimental", std::move(lb_policy_args));
+  if (GPR_UNLIKELY(lb_policy == nullptr)) {
+    gpr_log(GPR_ERROR, "[edslb %p] failure creating child policy", this);
+    return nullptr;
+  }
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p]: Created new child policy %p", this,
+            lb_policy.get());
+  }
+  // Add our interested_parties pollset_set to that of the newly created
+  // child policy. This will make the child policy progress upon activity on
+  // this policy, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+                                   interested_parties());
+  return lb_policy;
+}
+
+void EdsLb::MaybeUpdateDropPickerLocked() {
+  // If we are in fallback mode, don't override the picker.
+  if (fallback_policy_ != nullptr) return;
+  // If we're dropping all calls, report READY, regardless of what (or
+  // whether) the child has reported.
+  if (drop_config_ != nullptr && drop_config_->drop_all()) {
+    channel_control_helper()->UpdateState(GRPC_CHANNEL_READY,
+                                          absl::make_unique<DropPicker>(this));
+    return;
+  }
+  // Update only if we have a child picker.
+  if (child_picker_ != nullptr) {
+    channel_control_helper()->UpdateState(child_state_,
+                                          absl::make_unique<DropPicker>(this));
+  }
+}
+
+//
+// fallback-related methods
+//
+
+void EdsLb::MaybeCancelFallbackAtStartupChecks() {
+  if (!fallback_at_startup_checks_pending_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] Cancelling fallback timer", this);
+  }
+  grpc_timer_cancel(&lb_fallback_timer_);
+  fallback_at_startup_checks_pending_ = false;
+}
+
+void EdsLb::OnFallbackTimer(void* arg, grpc_error* error) {
+  EdsLb* edslb_policy = static_cast<EdsLb*>(arg);
+  edslb_policy->combiner()->Run(
+      GRPC_CLOSURE_INIT(&edslb_policy->lb_on_fallback_,
+                        &EdsLb::OnFallbackTimerLocked, edslb_policy, nullptr),
+      GRPC_ERROR_REF(error));
+}
+
+void EdsLb::OnFallbackTimerLocked(void* arg, grpc_error* error) {
+  EdsLb* edslb_policy = static_cast<EdsLb*>(arg);
+  // If some fallback-at-startup check is done after the timer fires but before
+  // this callback actually runs, don't fall back.
+  if (edslb_policy->fallback_at_startup_checks_pending_ &&
+      !edslb_policy->shutting_down_ && error == GRPC_ERROR_NONE) {
+    gpr_log(GPR_INFO,
+            "[edslb %p] Child policy not ready after fallback timeout; "
+            "entering fallback mode",
+            edslb_policy);
+    edslb_policy->fallback_at_startup_checks_pending_ = false;
+    edslb_policy->UpdateFallbackPolicyLocked();
+  }
+  edslb_policy->Unref(DEBUG_LOCATION, "on_fallback_timer");
+}
+
+void EdsLb::UpdateFallbackPolicyLocked() {
+  if (shutting_down_) return;
+  // Create policy if needed.
+  if (fallback_policy_ == nullptr) {
+    fallback_policy_ = CreateFallbackPolicyLocked(args_);
+  }
+  // Construct update args.
+  UpdateArgs update_args;
+  update_args.addresses = fallback_backend_addresses_;
+  update_args.config = config_->fallback_policy();
+  update_args.args = grpc_channel_args_copy(args_);
+  // Update the policy.
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] Updating fallback child policy handler %p",
+            this, fallback_policy_.get());
+  }
+  fallback_policy_->UpdateLocked(std::move(update_args));
+}
+
+OrphanablePtr<LoadBalancingPolicy> EdsLb::CreateFallbackPolicyLocked(
+    const grpc_channel_args* args) {
+  LoadBalancingPolicy::Args lb_policy_args;
+  lb_policy_args.combiner = combiner();
+  lb_policy_args.args = args;
+  lb_policy_args.channel_control_helper =
+      absl::make_unique<FallbackHelper>(Ref(DEBUG_LOCATION, "FallbackHelper"));
+  OrphanablePtr<LoadBalancingPolicy> lb_policy =
+      MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args),
+                                         &grpc_lb_eds_trace);
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_eds_trace)) {
+    gpr_log(GPR_INFO, "[edslb %p] Created new fallback child policy handler %p",
+            this, lb_policy.get());
+  }
+  // Add our interested_parties pollset_set to that of the newly created
+  // child policy. This will make the child policy progress upon activity on
+  // this policy, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+                                   interested_parties());
+  return lb_policy;
+}
+
+void EdsLb::MaybeExitFallbackMode() {
+  if (fallback_policy_ == nullptr) return;
+  gpr_log(GPR_INFO, "[edslb %p] Exiting fallback mode", this);
+  fallback_policy_.reset();
+}
+
+//
+// factory
+//
+
+class EdsLbFactory : public LoadBalancingPolicyFactory {
+ public:
+  explicit EdsLbFactory(const char* name) : name_(name) {}
+
+  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+      LoadBalancingPolicy::Args args) const override {
+    return MakeOrphanable<EdsChildHandler>(std::move(args), &grpc_lb_eds_trace,
+                                           name_);
+  }
+
+  const char* name() const override { return name_; }
+
+  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
+      const Json& json, grpc_error** error) const override {
+    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
+    if (json.type() == Json::Type::JSON_NULL) {
+      // xds was mentioned as a policy in the deprecated loadBalancingPolicy
+      // field or in the client API.
+      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:loadBalancingPolicy error:eds policy requires configuration. "
+          "Please use loadBalancingConfig field of service config instead.");
+      return nullptr;
+    }
+    std::vector<grpc_error*> error_list;
+    // EDS service name.
+    std::string eds_service_name;
+    auto it = json.object_value().find("edsServiceName");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:edsServiceName error:type should be string"));
+      } else {
+        eds_service_name = it->second.string_value();
+      }
+    }
+    // Cluster name.
+    std::string cluster_name;
+    if (name_ == kEds) {
+      it = json.object_value().find("clusterName");
+      if (it == json.object_value().end()) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:clusterName error:required field missing"));
+      } else if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:clusterName error:type should be string"));
+      } else {
+        cluster_name = it->second.string_value();
+      }
+    } else {
+      // For xds policy, this field does not exist in the config, so it
+      // will always be set to the same value as edsServiceName.
+      cluster_name = eds_service_name;
+    }
+    // LRS load reporting server name.
+    absl::optional<std::string> lrs_load_reporting_server_name;
+    it = json.object_value().find("lrsLoadReportingServerName");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:lrsLoadReportingServerName error:type should be string"));
+      } else {
+        lrs_load_reporting_server_name.emplace(it->second.string_value());
+      }
+    }
+    // Locality-picking policy.  Not supported for xds policy.
+    Json locality_picking_policy = Json::Array{
+        Json::Object{
+            {"weighted_target_experimental",
+             Json::Object{
+                 {"targets", Json::Object()},
+             }},
+        },
+    };
+    if (name_ == kEds) {
+      it = json.object_value().find("localityPickingPolicy");
+      if (it != json.object_value().end()) {
+        locality_picking_policy = it->second;
+      }
+    }
+    grpc_error* parse_error = GRPC_ERROR_NONE;
+    if (LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+            locality_picking_policy, &parse_error) == nullptr) {
+      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+          "localityPickingPolicy", &parse_error, 1));
+      GRPC_ERROR_UNREF(parse_error);
+    }
+    // Endpoint-picking policy.  Called "childPolicy" for xds policy.
+    const char* field_name =
+        name_ == kEds ? "endpointPickingPolicy" : "childPolicy";
+    Json endpoint_picking_policy;
+    it = json.object_value().find(field_name);
+    if (it == json.object_value().end()) {
+      endpoint_picking_policy = Json::Array{
+          Json::Object{
+              {"round_robin", Json::Object()},
+          },
+      };
+    } else {
+      endpoint_picking_policy = it->second;
+    }
+    parse_error = GRPC_ERROR_NONE;
+    if (LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+            endpoint_picking_policy, &parse_error) == nullptr) {
+      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+          field_name, &parse_error, 1));
+      GRPC_ERROR_UNREF(parse_error);
+    }
+    // Fallback policy.
+    Json fallback_policy_config;
+    it = json.object_value().find("fallbackPolicy");
+    if (it == json.object_value().end()) {
+      fallback_policy_config = Json::Array{Json::Object{
+          {"round_robin", Json::Object()},
+      }};
+    } else {
+      fallback_policy_config = it->second;
+    }
+    parse_error = GRPC_ERROR_NONE;
+    RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy =
+        LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+            fallback_policy_config, &parse_error);
+    if (fallback_policy == nullptr) {
+      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+      error_list.push_back(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+          "fallbackPolicy", &parse_error, 1));
+      GRPC_ERROR_UNREF(parse_error);
+      error_list.push_back(parse_error);
+    }
+    if (error_list.empty()) {
+      return MakeRefCounted<EdsLbConfig>(
+          name_, std::move(cluster_name), std::move(eds_service_name),
+          std::move(lrs_load_reporting_server_name),
+          std::move(locality_picking_policy),
+          std::move(endpoint_picking_policy), std::move(fallback_policy));
+    } else {
+      *error = GRPC_ERROR_CREATE_FROM_VECTOR(
+          "eds_experimental LB policy config", &error_list);
+      return nullptr;
+    }
+  }
+
+ private:
+  class EdsChildHandler : public ChildPolicyHandler {
+   public:
+    EdsChildHandler(Args args, TraceFlag* tracer, const char* name)
+        : ChildPolicyHandler(std::move(args), tracer), name_(name) {}
+
+    bool ConfigChangeRequiresNewPolicyInstance(
+        LoadBalancingPolicy::Config* old_config,
+        LoadBalancingPolicy::Config* new_config) const override {
+      GPR_ASSERT(old_config->name() == name_);
+      GPR_ASSERT(new_config->name() == name_);
+      EdsLbConfig* old_eds_config = static_cast<EdsLbConfig*>(old_config);
+      EdsLbConfig* new_eds_config = static_cast<EdsLbConfig*>(new_config);
+      return old_eds_config->cluster_name() != new_eds_config->cluster_name() ||
+             old_eds_config->eds_service_name() !=
+                 new_eds_config->eds_service_name();
+    }
+
+    OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+        const char* name, LoadBalancingPolicy::Args args) const override {
+      return MakeOrphanable<EdsLb>(name_, std::move(args));
+    }
+
+   private:
+    const char* name_;
+  };
+
+  const char* name_;
+};
+
+}  // namespace
+
+}  // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_eds_init() {
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          absl::make_unique<grpc_core::EdsLbFactory>(grpc_core::kEds));
+  // TODO(roth): This is here just for backward compatibility with some
+  // old tests we have internally.  Remove this once they are upgraded
+  // to use the new policy name and config.
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          absl::make_unique<grpc_core::EdsLbFactory>(grpc_core::kXds));
+}
+
+void grpc_lb_policy_eds_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc

@@ -0,0 +1,524 @@
+//
+// Copyright 2018 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <grpc/support/port_platform.h>
+
+#include <grpc/grpc.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy.h"
+#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/ext/filters/client_channel/xds/xds_client.h"
+#include "src/core/ext/filters/client_channel/xds/xds_client_stats.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/combiner.h"
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_lrs_trace(false, "lrs_lb");
+
+namespace {
+
+constexpr char kLrs[] = "lrs_experimental";
+
+// Config for LRS LB policy.
+class LrsLbConfig : public LoadBalancingPolicy::Config {
+ public:
+  LrsLbConfig(RefCountedPtr<LoadBalancingPolicy::Config> child_policy,
+              std::string cluster_name, std::string eds_service_name,
+              std::string lrs_load_reporting_server_name,
+              RefCountedPtr<XdsLocalityName> locality_name)
+      : child_policy_(std::move(child_policy)),
+        cluster_name_(std::move(cluster_name)),
+        eds_service_name_(std::move(eds_service_name)),
+        lrs_load_reporting_server_name_(
+            std::move(lrs_load_reporting_server_name)),
+        locality_name_(std::move(locality_name)) {}
+
+  const char* name() const override { return kLrs; }
+
+  RefCountedPtr<LoadBalancingPolicy::Config> child_policy() const {
+    return child_policy_;
+  }
+  const std::string& cluster_name() const { return cluster_name_; }
+  const std::string& eds_service_name() const { return eds_service_name_; }
+  const std::string& lrs_load_reporting_server_name() const {
+    return lrs_load_reporting_server_name_;
+  };
+  RefCountedPtr<XdsLocalityName> locality_name() const {
+    return locality_name_;
+  }
+
+ private:
+  RefCountedPtr<LoadBalancingPolicy::Config> child_policy_;
+  std::string cluster_name_;
+  std::string eds_service_name_;
+  std::string lrs_load_reporting_server_name_;
+  RefCountedPtr<XdsLocalityName> locality_name_;
+};
+
+// LRS LB policy.
+class LrsLb : public LoadBalancingPolicy {
+ public:
+  LrsLb(RefCountedPtr<XdsClient> xds_client, Args args);
+
+  const char* name() const override { return kLrs; }
+
+  void UpdateLocked(UpdateArgs args) override;
+  void ExitIdleLocked() override;
+  void ResetBackoffLocked() override;
+
+ private:
+  // A simple wrapper for ref-counting a picker from the child policy.
+  class RefCountedPicker : public RefCounted<RefCountedPicker> {
+   public:
+    explicit RefCountedPicker(std::unique_ptr<SubchannelPicker> picker)
+        : picker_(std::move(picker)) {}
+    PickResult Pick(PickArgs args) { return picker_->Pick(args); }
+
+   private:
+    std::unique_ptr<SubchannelPicker> picker_;
+  };
+
+  // A picker that wraps the picker from the child to perform load reporting.
+  class LoadReportingPicker : public SubchannelPicker {
+   public:
+    LoadReportingPicker(RefCountedPtr<RefCountedPicker> picker,
+                        RefCountedPtr<XdsClusterLocalityStats> locality_stats)
+        : picker_(std::move(picker)),
+          locality_stats_(std::move(locality_stats)) {}
+
+    PickResult Pick(PickArgs args);
+
+   private:
+    RefCountedPtr<RefCountedPicker> picker_;
+    RefCountedPtr<XdsClusterLocalityStats> locality_stats_;
+  };
+
+  class Helper : public ChannelControlHelper {
+   public:
+    explicit Helper(RefCountedPtr<LrsLb> lrs_policy)
+        : lrs_policy_(std::move(lrs_policy)) {}
+
+    ~Helper() { lrs_policy_.reset(DEBUG_LOCATION, "Helper"); }
+
+    RefCountedPtr<SubchannelInterface> CreateSubchannel(
+        const grpc_channel_args& args) override;
+    void UpdateState(grpc_connectivity_state state,
+                     std::unique_ptr<SubchannelPicker> picker) override;
+    void RequestReresolution() override;
+    void AddTraceEvent(TraceSeverity severity, StringView message) override;
+
+   private:
+    RefCountedPtr<LrsLb> lrs_policy_;
+  };
+
+  ~LrsLb();
+
+  void ShutdownLocked() override;
+
+  OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
+      const grpc_channel_args* args);
+  void UpdateChildPolicyLocked(ServerAddressList addresses,
+                               const grpc_channel_args* args);
+
+  void MaybeUpdatePickerLocked();
+
+  // Current config from the resolver.
+  RefCountedPtr<LrsLbConfig> config_;
+
+  // Internal state.
+  bool shutting_down_ = false;
+
+  // The xds client.
+  RefCountedPtr<XdsClient> xds_client_;
+
+  // The stats for client-side load reporting.
+  RefCountedPtr<XdsClusterLocalityStats> locality_stats_;
+
+  OrphanablePtr<LoadBalancingPolicy> child_policy_;
+
+  // Latest state and picker reported by the child policy.
+  grpc_connectivity_state state_ = GRPC_CHANNEL_IDLE;
+  RefCountedPtr<RefCountedPicker> picker_;
+};
+
+//
+// LrsLb::LoadReportingPicker
+//
+
+LoadBalancingPolicy::PickResult LrsLb::LoadReportingPicker::Pick(
+    LoadBalancingPolicy::PickArgs args) {
+  // Forward the pick to the picker returned from the child policy.
+  PickResult result = picker_->Pick(args);
+  if (result.type == PickResult::PICK_COMPLETE &&
+      result.subchannel != nullptr) {
+    // Record a call started.
+    locality_stats_->AddCallStarted();
+    // Intercept the recv_trailing_metadata op to record call completion.
+    XdsClusterLocalityStats* locality_stats =
+        locality_stats_->Ref(DEBUG_LOCATION, "LocalityStats+call").release();
+    result.recv_trailing_metadata_ready =
+        // Note: This callback does not run in either the control plane
+        // combiner or in the data plane mutex.
+        [locality_stats](grpc_error* error, MetadataInterface* /*metadata*/,
+                         CallState* /*call_state*/) {
+          const bool call_failed = error != GRPC_ERROR_NONE;
+          locality_stats->AddCallFinished(call_failed);
+          locality_stats->Unref(DEBUG_LOCATION, "LocalityStats+call");
+        };
+  }
+  return result;
+}
+
+//
+// LrsLb
+//
+
+LrsLb::LrsLb(RefCountedPtr<XdsClient> xds_client, Args args)
+    : LoadBalancingPolicy(std::move(args)), xds_client_(std::move(xds_client)) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO, "[lrs_lb %p] created -- using xds client %p from channel",
+            this, xds_client_.get());
+  }
+}
+
+LrsLb::~LrsLb() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO, "[lrs_lb %p] destroying xds LB policy", this);
+  }
+}
+
+void LrsLb::ShutdownLocked() {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO, "[lrs_lb %p] shutting down", this);
+  }
+  shutting_down_ = true;
+  // Remove the child policy's interested_parties pollset_set from the
+  // xDS policy.
+  if (child_policy_ != nullptr) {
+    grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
+                                     interested_parties());
+    child_policy_.reset();
+  }
+  // Drop our ref to the child's picker, in case it's holding a ref to
+  // the child.
+  picker_.reset();
+  locality_stats_.reset();
+  xds_client_.reset();
+}
+
+void LrsLb::ExitIdleLocked() {
+  if (child_policy_ != nullptr) child_policy_->ExitIdleLocked();
+}
+
+void LrsLb::ResetBackoffLocked() {
+  // The XdsClient will have its backoff reset by the xds resolver, so we
+  // don't need to do it here.
+  if (child_policy_ != nullptr) child_policy_->ResetBackoffLocked();
+}
+
+void LrsLb::UpdateLocked(UpdateArgs args) {
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO, "[lrs_lb %p] Received update", this);
+  }
+  // Update config.
+  auto old_config = std::move(config_);
+  config_ = std::move(args.config);
+  // Update load reporting if needed.
+  if (old_config == nullptr ||
+      config_->lrs_load_reporting_server_name() !=
+          old_config->lrs_load_reporting_server_name() ||
+      config_->cluster_name() != old_config->cluster_name() ||
+      config_->eds_service_name() != old_config->eds_service_name() ||
+      *config_->locality_name() != *old_config->locality_name()) {
+    locality_stats_ = xds_client_->AddClusterLocalityStats(
+        config_->lrs_load_reporting_server_name(), config_->cluster_name(),
+        config_->eds_service_name(), config_->locality_name());
+    MaybeUpdatePickerLocked();
+  }
+  // Update child policy.
+  UpdateChildPolicyLocked(std::move(args.addresses), args.args);
+  args.args = nullptr;  // Ownership passed to UpdateChildPolicyLocked().
+}
+
+void LrsLb::MaybeUpdatePickerLocked() {
+  if (picker_ != nullptr) {
+    auto lrs_picker =
+        absl::make_unique<LoadReportingPicker>(picker_, locality_stats_);
+    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+      gpr_log(GPR_INFO, "[lrs_lb %p] updating connectivity: state=%s picker=%p",
+              this, ConnectivityStateName(state_), lrs_picker.get());
+    }
+    channel_control_helper()->UpdateState(state_, std::move(lrs_picker));
+  }
+}
+
+OrphanablePtr<LoadBalancingPolicy> LrsLb::CreateChildPolicyLocked(
+    const grpc_channel_args* args) {
+  LoadBalancingPolicy::Args lb_policy_args;
+  lb_policy_args.combiner = combiner();
+  lb_policy_args.args = args;
+  lb_policy_args.channel_control_helper =
+      absl::make_unique<Helper>(Ref(DEBUG_LOCATION, "Helper"));
+  OrphanablePtr<LoadBalancingPolicy> lb_policy =
+      MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args),
+                                         &grpc_lb_lrs_trace);
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO, "[lrs_lb %p] Created new child policy handler %p", this,
+            lb_policy.get());
+  }
+  // Add our interested_parties pollset_set to that of the newly created
+  // child policy. This will make the child policy progress upon activity on
+  // this policy, which in turn is tied to the application's call.
+  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+                                   interested_parties());
+  return lb_policy;
+}
+
+void LrsLb::UpdateChildPolicyLocked(ServerAddressList addresses,
+                                    const grpc_channel_args* args) {
+  // Create policy if needed.
+  if (child_policy_ == nullptr) {
+    child_policy_ = CreateChildPolicyLocked(args);
+  }
+  // Construct update args.
+  UpdateArgs update_args;
+  update_args.addresses = std::move(addresses);
+  update_args.config = config_->child_policy();
+  update_args.args = args;
+  // Update the policy.
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO, "[lrs_lb %p] Updating child policy handler %p", this,
+            child_policy_.get());
+  }
+  child_policy_->UpdateLocked(std::move(update_args));
+}
+
+//
+// LrsLb::Helper
+//
+
+RefCountedPtr<SubchannelInterface> LrsLb::Helper::CreateSubchannel(
+    const grpc_channel_args& args) {
+  if (lrs_policy_->shutting_down_) return nullptr;
+  return lrs_policy_->channel_control_helper()->CreateSubchannel(args);
+}
+
+void LrsLb::Helper::UpdateState(grpc_connectivity_state state,
+                                std::unique_ptr<SubchannelPicker> picker) {
+  if (lrs_policy_->shutting_down_) return;
+  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_lrs_trace)) {
+    gpr_log(GPR_INFO,
+            "[lrs_lb %p] child connectivity state update: state=%s picker=%p",
+            lrs_policy_.get(), ConnectivityStateName(state), picker.get());
+  }
+  // Save the state and picker.
+  lrs_policy_->state_ = state;
+  lrs_policy_->picker_ = MakeRefCounted<RefCountedPicker>(std::move(picker));
+  // Wrap the picker and return it to the channel.
+  lrs_policy_->MaybeUpdatePickerLocked();
+}
+
+void LrsLb::Helper::RequestReresolution() {
+  if (lrs_policy_->shutting_down_) return;
+  lrs_policy_->channel_control_helper()->RequestReresolution();
+}
+
+void LrsLb::Helper::AddTraceEvent(TraceSeverity severity, StringView message) {
+  if (lrs_policy_->shutting_down_) return;
+  lrs_policy_->channel_control_helper()->AddTraceEvent(severity, message);
+}
+
+//
+// factory
+//
+
+class LrsLbFactory : public LoadBalancingPolicyFactory {
+ public:
+  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+      LoadBalancingPolicy::Args args) const override {
+    RefCountedPtr<XdsClient> xds_client =
+        XdsClient::GetFromChannelArgs(*args.args);
+    if (xds_client == nullptr) {
+      gpr_log(GPR_ERROR,
+              "XdsClient not present in channel args -- cannot instantiate "
+              "lrs LB policy");
+      return nullptr;
+    }
+    return MakeOrphanable<LrsLb>(std::move(xds_client), std::move(args));
+  }
+
+  const char* name() const override { return kLrs; }
+
+  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
+      const Json& json, grpc_error** error) const override {
+    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
+    if (json.type() == Json::Type::JSON_NULL) {
+      // lrs was mentioned as a policy in the deprecated loadBalancingPolicy
+      // field or in the client API.
+      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:loadBalancingPolicy error:lrs policy requires configuration. "
+          "Please use loadBalancingConfig field of service config instead.");
+      return nullptr;
+    }
+    std::vector<grpc_error*> error_list;
+    // Child policy.
+    RefCountedPtr<LoadBalancingPolicy::Config> child_policy;
+    auto it = json.object_value().find("childPolicy");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:childPolicy error:required field missing"));
+    } else {
+      grpc_error* parse_error = GRPC_ERROR_NONE;
+      child_policy = LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+          it->second, &parse_error);
+      if (child_policy == nullptr) {
+        GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+        std::vector<grpc_error*> child_errors;
+        child_errors.push_back(parse_error);
+        error_list.push_back(
+            GRPC_ERROR_CREATE_FROM_VECTOR("field:childPolicy", &child_errors));
+      }
+    }
+    // Cluster name.
+    std::string cluster_name;
+    it = json.object_value().find("clusterName");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:clusterName error:required field missing"));
+    } else if (it->second.type() != Json::Type::STRING) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:clusterName error:type should be string"));
+    } else {
+      cluster_name = it->second.string_value();
+    }
+    // EDS service name.
+    std::string eds_service_name;
+    it = json.object_value().find("edsServiceName");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "field:edsServiceName error:type should be string"));
+      } else {
+        eds_service_name = it->second.string_value();
+      }
+    }
+    // Locality.
+    RefCountedPtr<XdsLocalityName> locality_name;
+    it = json.object_value().find("locality");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:locality error:required field missing"));
+    } else {
+      std::vector<grpc_error*> child_errors =
+          ParseLocality(it->second, &locality_name);
+      if (!child_errors.empty()) {
+        error_list.push_back(
+            GRPC_ERROR_CREATE_FROM_VECTOR("field:locality", &child_errors));
+      }
+    }
+    // LRS load reporting server name.
+    std::string lrs_load_reporting_server_name;
+    it = json.object_value().find("lrsLoadReportingServerName");
+    if (it == json.object_value().end()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:lrsLoadReportingServerName error:required field missing"));
+    } else if (it->second.type() != Json::Type::STRING) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "field:lrsLoadReportingServerName error:type should be string"));
+    } else {
+      lrs_load_reporting_server_name = it->second.string_value();
+    }
+    if (!error_list.empty()) {
+      *error = GRPC_ERROR_CREATE_FROM_VECTOR(
+          "lrs_experimental LB policy config", &error_list);
+      return nullptr;
+    }
+    return MakeRefCounted<LrsLbConfig>(
+        std::move(child_policy), std::move(cluster_name),
+        std::move(eds_service_name), std::move(lrs_load_reporting_server_name),
+        std::move(locality_name));
+  }
+
+ private:
+  static std::vector<grpc_error*> ParseLocality(
+      const Json& json, RefCountedPtr<XdsLocalityName>* name) {
+    std::vector<grpc_error*> error_list;
+    if (json.type() != Json::Type::OBJECT) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "locality field is not an object"));
+      return error_list;
+    }
+    std::string region;
+    auto it = json.object_value().find("region");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "\"region\" field is not a string"));
+      } else {
+        region = it->second.string_value();
+      }
+    }
+    std::string zone;
+    it = json.object_value().find("zone");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "\"zone\" field is not a string"));
+      } else {
+        zone = it->second.string_value();
+      }
+    }
+    std::string subzone;
+    it = json.object_value().find("subzone");
+    if (it != json.object_value().end()) {
+      if (it->second.type() != Json::Type::STRING) {
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+            "\"subzone\" field is not a string"));
+      } else {
+        subzone = it->second.string_value();
+      }
+    }
+    if (region.empty() && zone.empty() && subzone.empty()) {
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+          "at least one of region, zone, or subzone must be set"));
+    }
+    if (error_list.empty()) {
+      *name = MakeRefCounted<XdsLocalityName>(region, zone, subzone);
+    }
+    return error_list;
+  }
+};
+
+}  // namespace
+
+}  // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_lrs_init() {
+  grpc_core::LoadBalancingPolicyRegistry::Builder::
+      RegisterLoadBalancingPolicyFactory(
+          absl::make_unique<grpc_core::LrsLbFactory>());
+}
+
+void grpc_lb_policy_lrs_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/xds/xds.cc

@@ -1,1754 +0,0 @@
-/*
- *
- * Copyright 2018 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/lib/iomgr/sockaddr.h"
-#include "src/core/lib/iomgr/socket_utils.h"
-
-#include <inttypes.h>
-#include <limits.h>
-#include <string.h>
-
-#include "absl/types/optional.h"
-
-#include <grpc/grpc.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/time.h>
-
-#include "src/core/ext/filters/client_channel/client_channel.h"
-#include "src/core/ext/filters/client_channel/lb_policy.h"
-#include "src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h"
-#include "src/core/ext/filters/client_channel/lb_policy/xds/xds.h"
-#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
-#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
-#include "src/core/ext/filters/client_channel/parse_address.h"
-#include "src/core/ext/filters/client_channel/server_address.h"
-#include "src/core/ext/filters/client_channel/service_config.h"
-#include "src/core/ext/filters/client_channel/xds/xds_client.h"
-#include "src/core/ext/filters/client_channel/xds/xds_client_stats.h"
-#include "src/core/lib/backoff/backoff.h"
-#include "src/core/lib/channel/channel_args.h"
-#include "src/core/lib/channel/channel_stack.h"
-#include "src/core/lib/gpr/string.h"
-#include "src/core/lib/gprpp/manual_constructor.h"
-#include "src/core/lib/gprpp/map.h"
-#include "src/core/lib/gprpp/memory.h"
-#include "src/core/lib/gprpp/orphanable.h"
-#include "src/core/lib/gprpp/ref_counted_ptr.h"
-#include "src/core/lib/gprpp/sync.h"
-#include "src/core/lib/iomgr/combiner.h"
-#include "src/core/lib/iomgr/sockaddr.h"
-#include "src/core/lib/iomgr/sockaddr_utils.h"
-#include "src/core/lib/iomgr/timer.h"
-#include "src/core/lib/slice/slice_hash_table.h"
-#include "src/core/lib/slice/slice_internal.h"
-#include "src/core/lib/slice/slice_string_helpers.h"
-#include "src/core/lib/surface/call.h"
-#include "src/core/lib/surface/channel.h"
-#include "src/core/lib/surface/channel_init.h"
-#include "src/core/lib/transport/static_metadata.h"
-
-#define GRPC_XDS_DEFAULT_FALLBACK_TIMEOUT_MS 10000
-#define GRPC_XDS_DEFAULT_LOCALITY_RETENTION_INTERVAL_MS (15 * 60 * 1000)
-#define GRPC_XDS_DEFAULT_FAILOVER_TIMEOUT_MS 10000
-
-namespace grpc_core {
-
-TraceFlag grpc_lb_xds_trace(false, "xds_lb");
-
-namespace {
-
-constexpr char kXds[] = "xds_experimental";
-
-class XdsConfig : public LoadBalancingPolicy::Config {
- public:
-  XdsConfig(RefCountedPtr<LoadBalancingPolicy::Config> child_policy,
-            RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy,
-            std::string eds_service_name,
-            absl::optional<std::string> lrs_load_reporting_server_name)
-      : child_policy_(std::move(child_policy)),
-        fallback_policy_(std::move(fallback_policy)),
-        eds_service_name_(std::move(eds_service_name)),
-        lrs_load_reporting_server_name_(
-            std::move(lrs_load_reporting_server_name)) {}
-
-  const char* name() const override { return kXds; }
-
-  RefCountedPtr<LoadBalancingPolicy::Config> child_policy() const {
-    return child_policy_;
-  }
-
-  RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy() const {
-    return fallback_policy_;
-  }
-
-  const char* eds_service_name() const {
-    return eds_service_name_.empty() ? nullptr : eds_service_name_.c_str();
-  };
-
-  const absl::optional<std::string>& lrs_load_reporting_server_name() const {
-    return lrs_load_reporting_server_name_;
-  };
-
- private:
-  RefCountedPtr<LoadBalancingPolicy::Config> child_policy_;
-  RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy_;
-  std::string eds_service_name_;
-  absl::optional<std::string> lrs_load_reporting_server_name_;
-};
-
-class XdsLb : public LoadBalancingPolicy {
- public:
-  explicit XdsLb(Args args);
-
-  const char* name() const override { return kXds; }
-
-  void UpdateLocked(UpdateArgs args) override;
-  void ResetBackoffLocked() override;
-
- private:
-  class EndpointWatcher;
-
-  // A simple wrapper to convert the picker returned from a locality's child
-  // policy as a unique_ptr<> to a RefCountedPtr<>.  This allows it to be
-  // referenced by both the picker and the locality.
-  class RefCountedEndpointPicker : public RefCounted<RefCountedEndpointPicker> {
-   public:
-    explicit RefCountedEndpointPicker(std::unique_ptr<SubchannelPicker> picker)
-        : picker_(std::move(picker)) {}
-    PickResult Pick(PickArgs args) { return picker_->Pick(args); }
-
-   private:
-    std::unique_ptr<SubchannelPicker> picker_;
-  };
-
-  // A picker that wraps the RefCountedEndpointPicker and performs load
-  // reporting for the locality.
-  class LoadReportingPicker : public RefCounted<LoadReportingPicker> {
-   public:
-    LoadReportingPicker(RefCountedPtr<RefCountedEndpointPicker> picker,
-                        RefCountedPtr<XdsClusterLocalityStats> locality_stats)
-        : picker_(std::move(picker)),
-          locality_stats_(std::move(locality_stats)) {}
-
-    PickResult Pick(PickArgs args);
-
-    RefCountedEndpointPicker* picker() const { return picker_.get(); }
-    XdsClusterLocalityStats* locality_stats() const {
-      return locality_stats_.get();
-    }
-
-   private:
-    RefCountedPtr<RefCountedEndpointPicker> picker_;
-    RefCountedPtr<XdsClusterLocalityStats> locality_stats_;
-  };
-
-  // A picker that uses a stateless weighting algorithm to pick the locality
-  // to use for each request.
-  class LocalityPicker : public SubchannelPicker {
-   public:
-    // Maintains a weighted list of pickers from each locality that is in ready
-    // state. The first element in the pair represents the end of a range
-    // proportional to the locality's weight. The start of the range is the
-    // previous value in the vector and is 0 for the first element.
-    using PickerList =
-        InlinedVector<std::pair<uint32_t, RefCountedPtr<LoadReportingPicker>>,
-                      1>;
-    LocalityPicker(XdsLb* xds_policy, PickerList pickers)
-        : drop_stats_(xds_policy->drop_stats_),
-          drop_config_(xds_policy->drop_config_),
-          pickers_(std::move(pickers)) {}
-
-    PickResult Pick(PickArgs args) override;
-
-   private:
-    // Calls the picker of the locality that the key falls within.
-    PickResult PickFromLocality(const uint32_t key, PickArgs args);
-
-    RefCountedPtr<XdsClusterDropStats> drop_stats_;
-    RefCountedPtr<XdsApi::DropConfig> drop_config_;
-    PickerList pickers_;
-  };
-
-  class FallbackHelper : public ChannelControlHelper {
-   public:
-    explicit FallbackHelper(RefCountedPtr<XdsLb> parent)
-        : parent_(std::move(parent)) {}
-
-    ~FallbackHelper() { parent_.reset(DEBUG_LOCATION, "FallbackHelper"); }
-
-    RefCountedPtr<SubchannelInterface> CreateSubchannel(
-        const grpc_channel_args& args) override;
-    void UpdateState(grpc_connectivity_state state,
-                     std::unique_ptr<SubchannelPicker> picker) override;
-    void RequestReresolution() override;
-    void AddTraceEvent(TraceSeverity severity, StringView message) override;
-
-   private:
-    RefCountedPtr<XdsLb> parent_;
-  };
-
-  // Each LocalityMap holds a ref to the XdsLb.
-  class LocalityMap : public InternallyRefCounted<LocalityMap> {
-   public:
-    // Each Locality holds a ref to the LocalityMap it is in.
-    class Locality : public InternallyRefCounted<Locality> {
-     public:
-      Locality(RefCountedPtr<LocalityMap> locality_map,
-               RefCountedPtr<XdsLocalityName> name);
-      ~Locality();
-
-      void UpdateLocked(uint32_t locality_weight, ServerAddressList serverlist,
-                        bool update_locality_stats);
-      void ShutdownLocked();
-      void ResetBackoffLocked();
-      void DeactivateLocked();
-      void Orphan() override;
-
-      uint32_t weight() const { return weight_; }
-
-      grpc_connectivity_state connectivity_state() const {
-        return connectivity_state_;
-      }
-
-      RefCountedPtr<LoadReportingPicker> GetLoadReportingPicker() {
-        // Recreate load reporting picker if stats object has changed.
-        if (load_reporting_picker_ == nullptr ||
-            load_reporting_picker_->picker() != picker_wrapper_.get() ||
-            load_reporting_picker_->locality_stats() != stats_.get()) {
-          load_reporting_picker_ =
-              MakeRefCounted<LoadReportingPicker>(picker_wrapper_, stats_);
-        }
-        return load_reporting_picker_;
-      }
-
-      void set_locality_map(RefCountedPtr<LocalityMap> locality_map) {
-        locality_map_ = std::move(locality_map);
-      }
-
-     private:
-      class Helper : public ChannelControlHelper {
-       public:
-        explicit Helper(RefCountedPtr<Locality> locality)
-            : locality_(std::move(locality)) {}
-
-        ~Helper() { locality_.reset(DEBUG_LOCATION, "Helper"); }
-
-        RefCountedPtr<SubchannelInterface> CreateSubchannel(
-            const grpc_channel_args& args) override;
-        void UpdateState(grpc_connectivity_state state,
-                         std::unique_ptr<SubchannelPicker> picker) override;
-        // This is a no-op, because we get the addresses from the xds
-        // client, which is a watch-based API.
-        void RequestReresolution() override {}
-        void AddTraceEvent(TraceSeverity severity, StringView message) override;
-
-       private:
-        RefCountedPtr<Locality> locality_;
-      };
-
-      // Methods for dealing with the child policy.
-      OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
-          const grpc_channel_args* args);
-      grpc_channel_args* CreateChildPolicyArgsLocked(
-          const grpc_channel_args* args);
-
-      void UpdateLocalityStats();
-
-      static void OnDelayedRemovalTimer(void* arg, grpc_error* error);
-      static void OnDelayedRemovalTimerLocked(void* arg, grpc_error* error);
-
-      XdsLb* xds_policy() const { return locality_map_->xds_policy(); }
-
-      // The owning locality map.
-      RefCountedPtr<LocalityMap> locality_map_;
-
-      RefCountedPtr<XdsLocalityName> name_;
-      RefCountedPtr<XdsClusterLocalityStats> stats_;
-      OrphanablePtr<LoadBalancingPolicy> child_policy_;
-      RefCountedPtr<RefCountedEndpointPicker> picker_wrapper_;
-      RefCountedPtr<LoadReportingPicker> load_reporting_picker_;
-      grpc_connectivity_state connectivity_state_ = GRPC_CHANNEL_IDLE;
-      uint32_t weight_;
-
-      // States for delayed removal.
-      grpc_timer delayed_removal_timer_;
-      grpc_closure on_delayed_removal_timer_;
-      bool delayed_removal_timer_callback_pending_ = false;
-      bool shutdown_ = false;
-    };
-
-    LocalityMap(RefCountedPtr<XdsLb> xds_policy, uint32_t priority);
-
-    ~LocalityMap() { xds_policy_.reset(DEBUG_LOCATION, "LocalityMap"); }
-
-    void UpdateLocked(
-        const XdsApi::PriorityListUpdate::LocalityMap& priority_update,
-        bool update_locality_stats);
-    void ResetBackoffLocked();
-    void UpdateXdsPickerLocked();
-    OrphanablePtr<Locality> ExtractLocalityLocked(
-        const RefCountedPtr<XdsLocalityName>& name);
-    void DeactivateLocked();
-    // Returns true if this locality map becomes the currently used one (i.e.,
-    // its priority is selected) after reactivation.
-    bool MaybeReactivateLocked();
-    void MaybeCancelFailoverTimerLocked();
-
-    void Orphan() override;
-
-    XdsLb* xds_policy() const { return xds_policy_.get(); }
-    uint32_t priority() const { return priority_; }
-    grpc_connectivity_state connectivity_state() const {
-      return connectivity_state_;
-    }
-    bool failover_timer_callback_pending() const {
-      return failover_timer_callback_pending_;
-    }
-
-   private:
-    void OnLocalityStateUpdateLocked();
-    void UpdateConnectivityStateLocked();
-    static void OnDelayedRemovalTimer(void* arg, grpc_error* error);
-    static void OnFailoverTimer(void* arg, grpc_error* error);
-    static void OnDelayedRemovalTimerLocked(void* arg, grpc_error* error);
-    static void OnFailoverTimerLocked(void* arg, grpc_error* error);
-
-    const XdsApi::PriorityListUpdate& priority_list_update() const {
-      return xds_policy_->priority_list_update_;
-    }
-    const XdsApi::PriorityListUpdate::LocalityMap* locality_map_update() const {
-      return xds_policy_->priority_list_update_.Find(priority_);
-    }
-
-    RefCountedPtr<XdsLb> xds_policy_;
-
-    std::map<RefCountedPtr<XdsLocalityName>, OrphanablePtr<Locality>,
-             XdsLocalityName::Less>
-        localities_;
-    const uint32_t priority_;
-    grpc_connectivity_state connectivity_state_ = GRPC_CHANNEL_IDLE;
-
-    // States for delayed removal.
-    grpc_timer delayed_removal_timer_;
-    grpc_closure on_delayed_removal_timer_;
-    bool delayed_removal_timer_callback_pending_ = false;
-
-    // States of failover.
-    grpc_timer failover_timer_;
-    grpc_closure on_failover_timer_;
-    bool failover_timer_callback_pending_ = false;
-  };
-
-  ~XdsLb();
-
-  void ShutdownLocked() override;
-
-  const char* eds_service_name() const {
-    if (config_ != nullptr && config_->eds_service_name() != nullptr) {
-      return config_->eds_service_name();
-    }
-    return server_name_.c_str();
-  }
-
-  XdsClient* xds_client() const {
-    return xds_client_from_channel_ != nullptr ? xds_client_from_channel_.get()
-                                               : xds_client_.get();
-  }
-
-  void UpdatePrioritiesLocked(bool update_locality_stats);
-  void UpdateXdsPickerLocked();
-  void MaybeCreateLocalityMapLocked(uint32_t priority);
-  void FailoverOnConnectionFailureLocked();
-  void FailoverOnDisconnectionLocked(uint32_t failed_priority);
-  void SwitchToHigherPriorityLocked(uint32_t priority);
-  void DeactivatePrioritiesLowerThan(uint32_t priority);
-  OrphanablePtr<LocalityMap::Locality> ExtractLocalityLocked(
-      const RefCountedPtr<XdsLocalityName>& name, uint32_t exclude_priority);
-  // Callers should make sure the priority list is non-empty.
-  uint32_t LowestPriority() const {
-    return static_cast<uint32_t>(priorities_.size()) - 1;
-  }
-  bool Contains(uint32_t priority) { return priority < priorities_.size(); }
-
-  // Methods for dealing with fallback state.
-  void MaybeCancelFallbackAtStartupChecks();
-  static void OnFallbackTimer(void* arg, grpc_error* error);
-  static void OnFallbackTimerLocked(void* arg, grpc_error* error);
-  void UpdateFallbackPolicyLocked();
-  OrphanablePtr<LoadBalancingPolicy> CreateFallbackPolicyLocked(
-      const grpc_channel_args* args);
-  void MaybeExitFallbackMode();
-
-  // Server name from target URI.
-  std::string server_name_;
-
-  // Current channel args and config from the resolver.
-  const grpc_channel_args* args_ = nullptr;
-  RefCountedPtr<XdsConfig> config_;
-
-  // Internal state.
-  bool shutting_down_ = false;
-
-  // The xds client and endpoint watcher.
-  // If we get the XdsClient from the channel, we store it in
-  // xds_client_from_channel_; if we create it ourselves, we store it in
-  // xds_client_.
-  RefCountedPtr<XdsClient> xds_client_from_channel_;
-  OrphanablePtr<XdsClient> xds_client_;
-  // A pointer to the endpoint watcher, to be used when cancelling the watch.
-  // Note that this is not owned, so this pointer must never be derefernced.
-  EndpointWatcher* endpoint_watcher_ = nullptr;
-
-  // Whether the checks for fallback at startup are ALL pending. There are
-  // several cases where this can be reset:
-  // 1. The fallback timer fires, we enter fallback mode.
-  // 2. Before the fallback timer fires, the endpoint watcher reports an
-  //    error, we enter fallback mode.
-  // 3. Before the fallback timer fires, if any child policy in the locality map
-  //    becomes READY, we cancel the fallback timer.
-  bool fallback_at_startup_checks_pending_ = false;
-  // Timeout in milliseconds for before using fallback backend addresses.
-  // 0 means not using fallback.
-  const grpc_millis lb_fallback_timeout_ms_;
-  // The backend addresses from the resolver.
-  ServerAddressList fallback_backend_addresses_;
-  // Fallback timer.
-  grpc_timer lb_fallback_timer_;
-  grpc_closure lb_on_fallback_;
-
-  // Non-null iff we are in fallback mode.
-  OrphanablePtr<LoadBalancingPolicy> fallback_policy_;
-
-  const grpc_millis locality_retention_interval_ms_;
-  const grpc_millis locality_map_failover_timeout_ms_;
-  // The list of locality maps, indexed by priority. P0 is the highest
-  // priority.
-  InlinedVector<OrphanablePtr<LocalityMap>, 2> priorities_;
-  // The priority that is being used.
-  uint32_t current_priority_ = UINT32_MAX;
-  // The update for priority_list_.
-  XdsApi::PriorityListUpdate priority_list_update_;
-
-  // The config for dropping calls.
-  RefCountedPtr<XdsApi::DropConfig> drop_config_;
-
-  // Drop stats for client-side load reporting.
-  RefCountedPtr<XdsClusterDropStats> drop_stats_;
-};
-
-//
-// XdsLb::LoadReportingPicker
-//
-
-LoadBalancingPolicy::PickResult XdsLb::LoadReportingPicker::Pick(
-    LoadBalancingPolicy::PickArgs args) {
-  // Forward the pick to the picker returned from the child policy.
-  PickResult result = picker_->Pick(args);
-  if (result.type != PickResult::PICK_COMPLETE ||
-      result.subchannel == nullptr || locality_stats_ == nullptr) {
-    return result;
-  }
-  // Record a call started.
-  locality_stats_->AddCallStarted();
-  // Intercept the recv_trailing_metadata op to record call completion.
-  XdsClusterLocalityStats* locality_stats =
-      locality_stats_->Ref(DEBUG_LOCATION, "LocalityStats+call").release();
-  result.recv_trailing_metadata_ready =
-      // Note: This callback does not run in either the control plane
-      // combiner or in the data plane mutex.
-      [locality_stats](grpc_error* error, MetadataInterface* /*metadata*/,
-                       CallState* /*call_state*/) {
-        const bool call_failed = error != GRPC_ERROR_NONE;
-        locality_stats->AddCallFinished(call_failed);
-        locality_stats->Unref(DEBUG_LOCATION, "LocalityStats+call");
-      };
-  return result;
-}
-
-//
-// XdsLb::LocalityPicker
-//
-
-XdsLb::PickResult XdsLb::LocalityPicker::Pick(PickArgs args) {
-  // Handle drop.
-  const std::string* drop_category;
-  if (drop_config_->ShouldDrop(&drop_category)) {
-    if (drop_stats_ != nullptr) drop_stats_->AddCallDropped(*drop_category);
-    PickResult result;
-    result.type = PickResult::PICK_COMPLETE;
-    return result;
-  }
-  // If we didn't drop, we better have some localities to pick from.
-  if (pickers_.empty()) {  // Should never happen.
-    PickResult result;
-    result.type = PickResult::PICK_FAILED;
-    result.error =
-        grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-                               "xds picker not given any localities"),
-                           GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_INTERNAL);
-    return result;
-  }
-  // Generate a random number in [0, total weight).
-  const uint32_t key = rand() % pickers_[pickers_.size() - 1].first;
-  // Forward pick to whichever locality maps to the range in which the
-  // random number falls in.
-  return PickFromLocality(key, args);
-}
-
-XdsLb::PickResult XdsLb::LocalityPicker::PickFromLocality(const uint32_t key,
-                                                          PickArgs args) {
-  size_t mid = 0;
-  size_t start_index = 0;
-  size_t end_index = pickers_.size() - 1;
-  size_t index = 0;
-  while (end_index > start_index) {
-    mid = (start_index + end_index) / 2;
-    if (pickers_[mid].first > key) {
-      end_index = mid;
-    } else if (pickers_[mid].first < key) {
-      start_index = mid + 1;
-    } else {
-      index = mid + 1;
-      break;
-    }
-  }
-  if (index == 0) index = start_index;
-  GPR_ASSERT(pickers_[index].first > key);
-  return pickers_[index].second->Pick(args);
-}
-
-//
-// XdsLb::FallbackHelper
-//
-
-RefCountedPtr<SubchannelInterface> XdsLb::FallbackHelper::CreateSubchannel(
-    const grpc_channel_args& args) {
-  if (parent_->shutting_down_) return nullptr;
-  return parent_->channel_control_helper()->CreateSubchannel(args);
-}
-
-void XdsLb::FallbackHelper::UpdateState(
-    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
-  if (parent_->shutting_down_) return;
-  parent_->channel_control_helper()->UpdateState(state, std::move(picker));
-}
-
-void XdsLb::FallbackHelper::RequestReresolution() {
-  if (parent_->shutting_down_) return;
-  parent_->channel_control_helper()->RequestReresolution();
-}
-
-void XdsLb::FallbackHelper::AddTraceEvent(TraceSeverity severity,
-                                          StringView message) {
-  if (parent_->shutting_down_) return;
-  parent_->channel_control_helper()->AddTraceEvent(severity, message);
-}
-
-//
-// XdsLb::EndpointWatcher
-//
-
-class XdsLb::EndpointWatcher : public XdsClient::EndpointWatcherInterface {
- public:
-  explicit EndpointWatcher(RefCountedPtr<XdsLb> xds_policy)
-      : xds_policy_(std::move(xds_policy)) {}
-
-  ~EndpointWatcher() { xds_policy_.reset(DEBUG_LOCATION, "EndpointWatcher"); }
-
-  void OnEndpointChanged(XdsApi::EdsUpdate update) override {
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-      gpr_log(GPR_INFO, "[xdslb %p] Received EDS update from xds client",
-              xds_policy_.get());
-    }
-    // If the balancer tells us to drop all the calls, we should exit fallback
-    // mode immediately.
-    if (update.drop_config->drop_all()) xds_policy_->MaybeExitFallbackMode();
-    // Update the drop config.
-    const bool drop_config_changed =
-        xds_policy_->drop_config_ == nullptr ||
-        *xds_policy_->drop_config_ != *update.drop_config;
-    xds_policy_->drop_config_ = std::move(update.drop_config);
-    // Ignore identical locality update.
-    if (xds_policy_->priority_list_update_ == update.priority_list_update) {
-      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-        gpr_log(GPR_INFO,
-                "[xdslb %p] Incoming locality update identical to current, "
-                "ignoring. (drop_config_changed=%d)",
-                xds_policy_.get(), drop_config_changed);
-      }
-      if (drop_config_changed) {
-        xds_policy_->UpdateXdsPickerLocked();
-      }
-      return;
-    }
-    // Update the priority list.
-    xds_policy_->priority_list_update_ = std::move(update.priority_list_update);
-    xds_policy_->UpdatePrioritiesLocked(false /*update_locality_stats*/);
-  }
-
-  void OnError(grpc_error* error) override {
-    // If the fallback-at-startup checks are pending, go into fallback mode
-    // immediately.  This short-circuits the timeout for the
-    // fallback-at-startup case.
-    if (xds_policy_->fallback_at_startup_checks_pending_) {
-      gpr_log(GPR_INFO,
-              "[xdslb %p] xds watcher reported error; entering fallback "
-              "mode: %s",
-              xds_policy_.get(), grpc_error_string(error));
-      xds_policy_->fallback_at_startup_checks_pending_ = false;
-      grpc_timer_cancel(&xds_policy_->lb_fallback_timer_);
-      xds_policy_->UpdateFallbackPolicyLocked();
-      // If the xds call failed, request re-resolution.
-      // TODO(roth): We check the error string contents here to
-      // differentiate between the xds call failing and the xds channel
-      // going into TRANSIENT_FAILURE.  This is a pretty ugly hack,
-      // but it's okay for now, since we're not yet sure whether we will
-      // continue to support the current fallback functionality.  If we
-      // decide to keep the fallback approach, then we should either
-      // find a cleaner way to expose the difference between these two
-      // cases or decide that we're okay re-resolving in both cases.
-      // Note that even if we do keep the current fallback functionality,
-      // this re-resolution will only be necessary if we are going to be
-      // using this LB policy with resolvers other than the xds resolver.
-      if (strstr(grpc_error_string(error), "xds call failed")) {
-        xds_policy_->channel_control_helper()->RequestReresolution();
-      }
-    } else if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-      gpr_log(GPR_INFO, "[xdslb %p] xds watcher reported error (ignoring): %s",
-              xds_policy_.get(), grpc_error_string(error));
-    }
-    GRPC_ERROR_UNREF(error);
-  }
-
- private:
-  RefCountedPtr<XdsLb> xds_policy_;
-};
-
-//
-// ctor and dtor
-//
-
-XdsLb::XdsLb(Args args)
-    : LoadBalancingPolicy(std::move(args)),
-      xds_client_from_channel_(XdsClient::GetFromChannelArgs(*args.args)),
-      lb_fallback_timeout_ms_(grpc_channel_args_find_integer(
-          args.args, GRPC_ARG_XDS_FALLBACK_TIMEOUT_MS,
-          {GRPC_XDS_DEFAULT_FALLBACK_TIMEOUT_MS, 0, INT_MAX})),
-      locality_retention_interval_ms_(grpc_channel_args_find_integer(
-          args.args, GRPC_ARG_LOCALITY_RETENTION_INTERVAL_MS,
-          {GRPC_XDS_DEFAULT_LOCALITY_RETENTION_INTERVAL_MS, 0, INT_MAX})),
-      locality_map_failover_timeout_ms_(grpc_channel_args_find_integer(
-          args.args, GRPC_ARG_XDS_FAILOVER_TIMEOUT_MS,
-          {GRPC_XDS_DEFAULT_FAILOVER_TIMEOUT_MS, 0, INT_MAX})) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] created -- xds client from channel: %p", this,
-            xds_client_from_channel_.get());
-  }
-  // Record server name.
-  const grpc_arg* arg = grpc_channel_args_find(args.args, GRPC_ARG_SERVER_URI);
-  const char* server_uri = grpc_channel_arg_get_string(arg);
-  GPR_ASSERT(server_uri != nullptr);
-  grpc_uri* uri = grpc_uri_parse(server_uri, true);
-  GPR_ASSERT(uri->path[0] != '\0');
-  server_name_ = uri->path[0] == '/' ? uri->path + 1 : uri->path;
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] server name from channel: %s", this,
-            server_name_.c_str());
-  }
-  grpc_uri_destroy(uri);
-}
-
-XdsLb::~XdsLb() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] destroying xds LB policy", this);
-  }
-  grpc_channel_args_destroy(args_);
-}
-
-void XdsLb::ShutdownLocked() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] shutting down", this);
-  }
-  shutting_down_ = true;
-  MaybeCancelFallbackAtStartupChecks();
-  priorities_.clear();
-  drop_stats_.reset();
-  if (fallback_policy_ != nullptr) {
-    grpc_pollset_set_del_pollset_set(fallback_policy_->interested_parties(),
-                                     interested_parties());
-    fallback_policy_.reset();
-  }
-  // Cancel the endpoint watch here instead of in our dtor if we are using the
-  // XdsResolver, because the watcher holds a ref to us and we might not be
-  // destroying the Xds client leading to a situation where the Xds lb policy is
-  // never destroyed.
-  if (xds_client_from_channel_ != nullptr) {
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-      gpr_log(GPR_INFO, "[xdslb %p] cancelling watch for %s", this,
-              eds_service_name());
-    }
-    xds_client()->CancelEndpointDataWatch(StringView(eds_service_name()),
-                                          endpoint_watcher_);
-    xds_client_from_channel_.reset();
-  }
-  xds_client_.reset();
-}
-
-//
-// public methods
-//
-
-void XdsLb::ResetBackoffLocked() {
-  // When the XdsClient is instantiated in the resolver instead of in this
-  // LB policy, this is done via the resolver, so we don't need to do it
-  // for xds_client_from_channel_ here.
-  if (xds_client_ != nullptr) xds_client_->ResetBackoff();
-  for (size_t i = 0; i < priorities_.size(); ++i) {
-    priorities_[i]->ResetBackoffLocked();
-  }
-  if (fallback_policy_ != nullptr) {
-    fallback_policy_->ResetBackoffLocked();
-  }
-}
-
-void XdsLb::UpdateLocked(UpdateArgs args) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Received update", this);
-  }
-  const bool is_initial_update = args_ == nullptr;
-  // Update config.
-  auto old_config = std::move(config_);
-  config_ = std::move(args.config);
-  // Update fallback address list.
-  fallback_backend_addresses_ = std::move(args.addresses);
-  // Update args.
-  grpc_channel_args_destroy(args_);
-  args_ = args.args;
-  args.args = nullptr;
-  // Update the existing fallback policy. The fallback policy config and/or the
-  // fallback addresses may be new.
-  if (fallback_policy_ != nullptr) UpdateFallbackPolicyLocked();
-  if (is_initial_update) {
-    // Initialize XdsClient.
-    if (xds_client_from_channel_ == nullptr) {
-      grpc_error* error = GRPC_ERROR_NONE;
-      xds_client_ = MakeOrphanable<XdsClient>(
-          combiner(), interested_parties(), StringView(eds_service_name()),
-          nullptr /* service config watcher */, *args_, &error);
-      // TODO(roth): If we decide that we care about fallback mode, add
-      // proper error handling here.
-      GPR_ASSERT(error == GRPC_ERROR_NONE);
-      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-        gpr_log(GPR_INFO, "[xdslb %p] Created xds client %p", this,
-                xds_client_.get());
-      }
-    }
-    // Start fallback-at-startup checks.
-    grpc_millis deadline = ExecCtx::Get()->Now() + lb_fallback_timeout_ms_;
-    Ref(DEBUG_LOCATION, "on_fallback_timer").release();  // Held by closure
-    GRPC_CLOSURE_INIT(&lb_on_fallback_, &XdsLb::OnFallbackTimer, this,
-                      grpc_schedule_on_exec_ctx);
-    fallback_at_startup_checks_pending_ = true;
-    grpc_timer_init(&lb_fallback_timer_, deadline, &lb_on_fallback_);
-  }
-  // Update drop stats for load reporting if needed.
-  if (is_initial_update || config_->lrs_load_reporting_server_name() !=
-                               old_config->lrs_load_reporting_server_name()) {
-    drop_stats_.reset();
-    if (config_->lrs_load_reporting_server_name().has_value()) {
-      drop_stats_ = xds_client()->AddClusterDropStats(
-          config_->lrs_load_reporting_server_name().value(),
-          // TODO(roth): We currently hard-code the assumption that
-          // cluster name and EDS service name are the same.  Fix this
-          // as part of refectoring this LB policy.
-          eds_service_name(), eds_service_name());
-    }
-  }
-  // On the initial update, create the endpoint watcher.
-  if (is_initial_update) {
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-      gpr_log(GPR_INFO, "[xdslb %p] starting watch for %s", this,
-              eds_service_name());
-    }
-    auto watcher = absl::make_unique<EndpointWatcher>(
-        Ref(DEBUG_LOCATION, "EndpointWatcher"));
-    endpoint_watcher_ = watcher.get();
-    xds_client()->WatchEndpointData(StringView(eds_service_name()),
-                                    std::move(watcher));
-  } else {
-    // Update priority list.
-    // Note that this comes after updating drop_stats_, since we want that
-    // to be used by any new picker we create here.
-    // No need to do this on the initial update, since there won't be any
-    // priorities to update yet.
-    const bool update_locality_stats =
-        config_->lrs_load_reporting_server_name() !=
-        old_config->lrs_load_reporting_server_name();
-    UpdatePrioritiesLocked(update_locality_stats);
-  }
-}
-
-//
-// fallback-related methods
-//
-
-void XdsLb::MaybeCancelFallbackAtStartupChecks() {
-  if (!fallback_at_startup_checks_pending_) return;
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Cancelling fallback timer", this);
-  }
-  grpc_timer_cancel(&lb_fallback_timer_);
-  fallback_at_startup_checks_pending_ = false;
-}
-
-void XdsLb::OnFallbackTimer(void* arg, grpc_error* error) {
-  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
-  xdslb_policy->combiner()->Run(
-      GRPC_CLOSURE_INIT(&xdslb_policy->lb_on_fallback_,
-                        &XdsLb::OnFallbackTimerLocked, xdslb_policy, nullptr),
-      GRPC_ERROR_REF(error));
-}
-
-void XdsLb::OnFallbackTimerLocked(void* arg, grpc_error* error) {
-  XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
-  // If some fallback-at-startup check is done after the timer fires but before
-  // this callback actually runs, don't fall back.
-  if (xdslb_policy->fallback_at_startup_checks_pending_ &&
-      !xdslb_policy->shutting_down_ && error == GRPC_ERROR_NONE) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p] Child policy not ready after fallback timeout; "
-            "entering fallback mode",
-            xdslb_policy);
-    xdslb_policy->fallback_at_startup_checks_pending_ = false;
-    xdslb_policy->UpdateFallbackPolicyLocked();
-  }
-  xdslb_policy->Unref(DEBUG_LOCATION, "on_fallback_timer");
-}
-
-void XdsLb::UpdateFallbackPolicyLocked() {
-  if (shutting_down_) return;
-  // Create policy if needed.
-  if (fallback_policy_ == nullptr) {
-    fallback_policy_ = CreateFallbackPolicyLocked(args_);
-    GPR_ASSERT(fallback_policy_ != nullptr);
-  }
-  // Perform update.
-  UpdateArgs update_args;
-  update_args.addresses = fallback_backend_addresses_;
-  update_args.config = config_->fallback_policy();
-  update_args.args = grpc_channel_args_copy(args_);
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Updating fallback child policy handler %p",
-            this, fallback_policy_.get());
-  }
-  fallback_policy_->UpdateLocked(std::move(update_args));
-}
-
-OrphanablePtr<LoadBalancingPolicy> XdsLb::CreateFallbackPolicyLocked(
-    const grpc_channel_args* args) {
-  LoadBalancingPolicy::Args lb_policy_args;
-  lb_policy_args.combiner = combiner();
-  lb_policy_args.args = args;
-  lb_policy_args.channel_control_helper =
-      absl::make_unique<FallbackHelper>(Ref(DEBUG_LOCATION, "FallbackHelper"));
-  OrphanablePtr<LoadBalancingPolicy> lb_policy =
-      MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args),
-                                         &grpc_lb_xds_trace);
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p] Created new fallback child policy handler (%p)", this,
-            lb_policy.get());
-  }
-  // Add the xDS's interested_parties pollset_set to that of the newly created
-  // child policy. This will make the child policy progress upon activity on xDS
-  // LB, which in turn is tied to the application's call.
-  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
-                                   interested_parties());
-  return lb_policy;
-}
-
-void XdsLb::MaybeExitFallbackMode() {
-  if (fallback_policy_ == nullptr) return;
-  gpr_log(GPR_INFO, "[xdslb %p] Exiting fallback mode", this);
-  fallback_policy_.reset();
-}
-
-//
-// priority list-related methods
-//
-
-void XdsLb::UpdatePrioritiesLocked(bool update_locality_stats) {
-  // 1. Remove from the priority list the priorities that are not in the update.
-  DeactivatePrioritiesLowerThan(priority_list_update_.LowestPriority());
-  // 2. Update all the existing priorities.
-  for (uint32_t priority = 0; priority < priorities_.size(); ++priority) {
-    LocalityMap* locality_map = priorities_[priority].get();
-    const auto* locality_map_update = priority_list_update_.Find(priority);
-    // If we have more current priorities than exist in the update, stop here.
-    if (locality_map_update == nullptr) break;
-    // Propagate locality_map_update.
-    // TODO(juanlishen): Find a clean way to skip duplicate update for a
-    // priority.
-    locality_map->UpdateLocked(*locality_map_update, update_locality_stats);
-  }
-  // 3. Only create a new locality map if all the existing ones have failed.
-  if (priorities_.empty() ||
-      !priorities_[priorities_.size() - 1]->failover_timer_callback_pending()) {
-    const uint32_t new_priority = static_cast<uint32_t>(priorities_.size());
-    // Create a new locality map. Note that in some rare cases (e.g., the
-    // locality map reports TRANSIENT_FAILURE synchronously due to subchannel
-    // sharing), the following invocation may result in multiple locality maps
-    // to be created.
-    MaybeCreateLocalityMapLocked(new_priority);
-  }
-  // 4. If we updated locality stats and we already have at least one
-  // priority, update the picker to start using the new stats object(s).
-  if (update_locality_stats && !priorities_.empty()) {
-    UpdateXdsPickerLocked();
-  }
-}
-
-void XdsLb::UpdateXdsPickerLocked() {
-  // If we are in fallback mode, don't generate an xds picker from localities.
-  if (fallback_policy_ != nullptr) return;
-  // If we're dropping all calls, report READY, even though we won't
-  // have a selected priority.
-  if (drop_config_ != nullptr && drop_config_->drop_all()) {
-    channel_control_helper()->UpdateState(
-        GRPC_CHANNEL_READY,
-        absl::make_unique<LocalityPicker>(this, LocalityPicker::PickerList{}));
-    return;
-  }
-  // If we don't have a selected priority, report TRANSIENT_FAILURE.
-  if (current_priority_ == UINT32_MAX) {
-    if (fallback_policy_ == nullptr) {
-      grpc_error* error = grpc_error_set_int(
-          GRPC_ERROR_CREATE_FROM_STATIC_STRING("no ready locality map"),
-          GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE);
-      channel_control_helper()->UpdateState(
-          GRPC_CHANNEL_TRANSIENT_FAILURE,
-          absl::make_unique<TransientFailurePicker>(error));
-    }
-    return;
-  }
-  priorities_[current_priority_]->UpdateXdsPickerLocked();
-}
-
-void XdsLb::MaybeCreateLocalityMapLocked(uint32_t priority) {
-  // Exhausted priorities in the update.
-  if (!priority_list_update_.Contains(priority)) return;
-  auto new_locality_map =
-      new LocalityMap(Ref(DEBUG_LOCATION, "LocalityMap"), priority);
-  priorities_.emplace_back(OrphanablePtr<LocalityMap>(new_locality_map));
-  new_locality_map->UpdateLocked(*priority_list_update_.Find(priority),
-                                 false /*update_locality_stats*/);
-}
-
-void XdsLb::FailoverOnConnectionFailureLocked() {
-  const uint32_t failed_priority = LowestPriority();
-  // If we're failing over from the lowest priority, report TRANSIENT_FAILURE.
-  if (failed_priority == priority_list_update_.LowestPriority()) {
-    UpdateXdsPickerLocked();
-  }
-  MaybeCreateLocalityMapLocked(failed_priority + 1);
-}
-
-void XdsLb::FailoverOnDisconnectionLocked(uint32_t failed_priority) {
-  current_priority_ = UINT32_MAX;
-  for (uint32_t next_priority = failed_priority + 1;
-       next_priority <= priority_list_update_.LowestPriority();
-       ++next_priority) {
-    if (!Contains(next_priority)) {
-      MaybeCreateLocalityMapLocked(next_priority);
-      return;
-    }
-    if (priorities_[next_priority]->MaybeReactivateLocked()) return;
-  }
-}
-
-void XdsLb::SwitchToHigherPriorityLocked(uint32_t priority) {
-  current_priority_ = priority;
-  DeactivatePrioritiesLowerThan(current_priority_);
-  UpdateXdsPickerLocked();
-}
-
-void XdsLb::DeactivatePrioritiesLowerThan(uint32_t priority) {
-  if (priorities_.empty()) return;
-  // Deactivate the locality maps from the lowest priority.
-  for (uint32_t p = LowestPriority(); p > priority; --p) {
-    if (locality_retention_interval_ms_ == 0) {
-      priorities_.pop_back();
-    } else {
-      priorities_[p]->DeactivateLocked();
-    }
-  }
-}
-
-OrphanablePtr<XdsLb::LocalityMap::Locality> XdsLb::ExtractLocalityLocked(
-    const RefCountedPtr<XdsLocalityName>& name, uint32_t exclude_priority) {
-  for (uint32_t priority = 0; priority < priorities_.size(); ++priority) {
-    if (priority == exclude_priority) continue;
-    LocalityMap* locality_map = priorities_[priority].get();
-    auto locality = locality_map->ExtractLocalityLocked(name);
-    if (locality != nullptr) {
-      if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-        gpr_log(GPR_INFO,
-                "[xdslb %p] moving locality %p %s to new priority (%" PRIu32
-                " -> %" PRIu32 ")",
-                this, locality.get(), name->AsHumanReadableString(),
-                exclude_priority, priority);
-      }
-      return locality;
-    }
-  }
-  return nullptr;
-}
-
-//
-// XdsLb::LocalityMap
-//
-
-XdsLb::LocalityMap::LocalityMap(RefCountedPtr<XdsLb> xds_policy,
-                                uint32_t priority)
-    : xds_policy_(std::move(xds_policy)), priority_(priority) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Creating priority %" PRIu32,
-            xds_policy_.get(), priority_);
-  }
-  GRPC_CLOSURE_INIT(&on_failover_timer_, OnFailoverTimer, this,
-                    grpc_schedule_on_exec_ctx);
-  // Start the failover timer.
-  Ref(DEBUG_LOCATION, "LocalityMap+OnFailoverTimerLocked").release();
-  grpc_timer_init(
-      &failover_timer_,
-      ExecCtx::Get()->Now() + xds_policy_->locality_map_failover_timeout_ms_,
-      &on_failover_timer_);
-  failover_timer_callback_pending_ = true;
-  // This is the first locality map ever created, report CONNECTING.
-  if (priority_ == 0 && xds_policy_->fallback_policy_ == nullptr) {
-    xds_policy_->channel_control_helper()->UpdateState(
-        GRPC_CHANNEL_CONNECTING,
-        absl::make_unique<QueuePicker>(
-            xds_policy_->Ref(DEBUG_LOCATION, "QueuePicker")));
-  }
-}
-
-void XdsLb::LocalityMap::UpdateLocked(
-    const XdsApi::PriorityListUpdate::LocalityMap& priority_update,
-    bool update_locality_stats) {
-  if (xds_policy_->shutting_down_) return;
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Start Updating priority %" PRIu32,
-            xds_policy(), priority_);
-  }
-  // Maybe reactivate the locality map in case all the active locality maps have
-  // failed.
-  MaybeReactivateLocked();
-  // Remove (later) the localities not in priority_update.
-  for (auto iter = localities_.begin(); iter != localities_.end();) {
-    const auto& name = iter->first;
-    Locality* locality = iter->second.get();
-    if (priority_update.Contains(name)) {
-      ++iter;
-      continue;
-    }
-    if (xds_policy()->locality_retention_interval_ms_ == 0) {
-      iter = localities_.erase(iter);
-    } else {
-      locality->DeactivateLocked();
-      ++iter;
-    }
-  }
-  // Add or update the localities in priority_update.
-  for (const auto& p : priority_update.localities) {
-    const auto& name = p.first;
-    const auto& locality_update = p.second;
-    OrphanablePtr<Locality>& locality = localities_[name];
-    if (locality == nullptr) {
-      // Move from another locality map if possible.
-      locality = xds_policy_->ExtractLocalityLocked(name, priority_);
-      if (locality != nullptr) {
-        locality->set_locality_map(
-            Ref(DEBUG_LOCATION, "LocalityMap+Locality_move"));
-      } else {
-        locality = MakeOrphanable<Locality>(
-            Ref(DEBUG_LOCATION, "LocalityMap+Locality"), name);
-      }
-    }
-    // Keep a copy of serverlist in the update so that we can compare it
-    // with the future ones.
-    locality->UpdateLocked(locality_update.lb_weight,
-                           locality_update.serverlist, update_locality_stats);
-  }
-  // If this is the current priority and we removed all of the READY
-  // localities, go into state CONNECTING.
-  // TODO(roth): Ideally, we should model this as a graceful policy
-  // switch: we should keep using the old localities for a short period
-  // of time, long enough to give the new localities a chance to get
-  // connected.  As part of refactoring this policy, we should try to
-  // fix that.
-  if (priority_ == xds_policy()->current_priority_) {
-    bool found_ready = false;
-    for (auto& p : localities_) {
-      const auto& locality_name = p.first;
-      Locality* locality = p.second.get();
-      if (!locality_map_update()->Contains(locality_name)) continue;
-      if (locality->connectivity_state() == GRPC_CHANNEL_READY) {
-        found_ready = true;
-        break;
-      }
-    }
-    if (!found_ready) {
-      xds_policy_->channel_control_helper()->UpdateState(
-          GRPC_CHANNEL_CONNECTING,
-          absl::make_unique<QueuePicker>(
-              xds_policy_->Ref(DEBUG_LOCATION, "QueuePicker")));
-      xds_policy_->current_priority_ = UINT32_MAX;
-    }
-  }
-}
-
-void XdsLb::LocalityMap::ResetBackoffLocked() {
-  for (auto& p : localities_) p.second->ResetBackoffLocked();
-}
-
-void XdsLb::LocalityMap::UpdateXdsPickerLocked() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] constructing new picker", xds_policy());
-  }
-  // Construct a new xds picker which maintains a map of all locality pickers
-  // that are ready. Each locality is represented by a portion of the range
-  // proportional to its weight, such that the total range is the sum of the
-  // weights of all localities.
-  LocalityPicker::PickerList picker_list;
-  uint32_t end = 0;
-  for (auto& p : localities_) {
-    const auto& locality_name = p.first;
-    Locality* locality = p.second.get();
-    // Skip the localities that are not in the latest locality map update.
-    const auto* locality_update = locality_map_update();
-    if (locality_update == nullptr) continue;
-    if (!locality_update->Contains(locality_name)) continue;
-    if (locality->connectivity_state() != GRPC_CHANNEL_READY) continue;
-    end += locality->weight();
-    picker_list.push_back(
-        std::make_pair(end, locality->GetLoadReportingPicker()));
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-      gpr_log(GPR_INFO, "[xdslb %p]   locality=%s weight=%d picker=%p",
-              xds_policy(), locality_name->AsHumanReadableString(),
-              locality->weight(), picker_list.back().second.get());
-    }
-  }
-  xds_policy()->channel_control_helper()->UpdateState(
-      GRPC_CHANNEL_READY,
-      absl::make_unique<LocalityPicker>(xds_policy(), std::move(picker_list)));
-}
-
-OrphanablePtr<XdsLb::LocalityMap::Locality>
-XdsLb::LocalityMap::ExtractLocalityLocked(
-    const RefCountedPtr<XdsLocalityName>& name) {
-  for (auto iter = localities_.begin(); iter != localities_.end(); ++iter) {
-    const auto& name_in_map = iter->first;
-    if (*name_in_map == *name) {
-      auto locality = std::move(iter->second);
-      localities_.erase(iter);
-      return locality;
-    }
-  }
-  return nullptr;
-}
-
-void XdsLb::LocalityMap::DeactivateLocked() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] deactivating priority %" PRIu32, xds_policy(),
-            priority_);
-  }
-  // If already deactivated, don't do it again.
-  if (delayed_removal_timer_callback_pending_) return;
-  MaybeCancelFailoverTimerLocked();
-  // Start a timer to delete the locality.
-  Ref(DEBUG_LOCATION, "LocalityMap+timer").release();
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p] Will remove priority %" PRIu32 " in %" PRId64 " ms.",
-            xds_policy(), priority_,
-            xds_policy()->locality_retention_interval_ms_);
-  }
-  GRPC_CLOSURE_INIT(&on_delayed_removal_timer_, OnDelayedRemovalTimer, this,
-                    grpc_schedule_on_exec_ctx);
-  grpc_timer_init(
-      &delayed_removal_timer_,
-      ExecCtx::Get()->Now() + xds_policy()->locality_retention_interval_ms_,
-      &on_delayed_removal_timer_);
-  delayed_removal_timer_callback_pending_ = true;
-}
-
-bool XdsLb::LocalityMap::MaybeReactivateLocked() {
-  // Don't reactivate a priority that is not higher than the current one.
-  if (priority_ >= xds_policy_->current_priority_) return false;
-  // Reactivate this priority by cancelling deletion timer.
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] reactivating priority %" PRIu32, xds_policy(),
-            priority_);
-  }
-  if (delayed_removal_timer_callback_pending_) {
-    grpc_timer_cancel(&delayed_removal_timer_);
-  }
-  // Switch to this higher priority if it's READY.
-  if (connectivity_state_ != GRPC_CHANNEL_READY) return false;
-  xds_policy_->SwitchToHigherPriorityLocked(priority_);
-  return true;
-}
-
-void XdsLb::LocalityMap::MaybeCancelFailoverTimerLocked() {
-  if (failover_timer_callback_pending_) grpc_timer_cancel(&failover_timer_);
-}
-
-void XdsLb::LocalityMap::Orphan() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Priority %" PRIu32 " orphaned.", xds_policy(),
-            priority_);
-  }
-  MaybeCancelFailoverTimerLocked();
-  if (delayed_removal_timer_callback_pending_) {
-    grpc_timer_cancel(&delayed_removal_timer_);
-  }
-  localities_.clear();
-  Unref(DEBUG_LOCATION, "LocalityMap+Orphan");
-}
-
-void XdsLb::LocalityMap::OnLocalityStateUpdateLocked() {
-  UpdateConnectivityStateLocked();
-  // Ignore priorities not in priority_list_update.
-  if (!priority_list_update().Contains(priority_)) return;
-  const uint32_t current_priority = xds_policy_->current_priority_;
-  // Ignore lower-than-current priorities.
-  if (priority_ > current_priority) return;
-  // Maybe update fallback state.
-  if (connectivity_state_ == GRPC_CHANNEL_READY) {
-    xds_policy_->MaybeCancelFallbackAtStartupChecks();
-    xds_policy_->MaybeExitFallbackMode();
-  }
-  // Update is for a higher-than-current priority. (Special case: update is for
-  // any active priority if there is no current priority.)
-  if (priority_ < current_priority) {
-    if (connectivity_state_ == GRPC_CHANNEL_READY) {
-      MaybeCancelFailoverTimerLocked();
-      // If a higher-than-current priority becomes READY, switch to use it.
-      xds_policy_->SwitchToHigherPriorityLocked(priority_);
-    } else if (connectivity_state_ == GRPC_CHANNEL_TRANSIENT_FAILURE) {
-      // If a higher-than-current priority becomes TRANSIENT_FAILURE, only
-      // handle it if it's the priority that is still in failover timeout.
-      if (failover_timer_callback_pending_) {
-        MaybeCancelFailoverTimerLocked();
-        xds_policy_->FailoverOnConnectionFailureLocked();
-      }
-    }
-    return;
-  }
-  // Update is for current priority.
-  if (connectivity_state_ != GRPC_CHANNEL_READY) {
-    // Fail over if it's no longer READY.
-    xds_policy_->FailoverOnDisconnectionLocked(priority_);
-  }
-  // At this point, one of the following things has happened to the current
-  // priority.
-  // 1. It remained the same (but received picker update from its localities).
-  // 2. It changed to a lower priority due to failover.
-  // 3. It became invalid because failover didn't yield a READY priority.
-  // In any case, update the xds picker.
-  xds_policy_->UpdateXdsPickerLocked();
-}
-
-void XdsLb::LocalityMap::UpdateConnectivityStateLocked() {
-  size_t num_ready = 0;
-  size_t num_connecting = 0;
-  size_t num_idle = 0;
-  size_t num_transient_failures = 0;
-  for (const auto& p : localities_) {
-    const auto& locality_name = p.first;
-    const Locality* locality = p.second.get();
-    // Skip the localities that are not in the latest locality map update.
-    if (!locality_map_update()->Contains(locality_name)) continue;
-    switch (locality->connectivity_state()) {
-      case GRPC_CHANNEL_READY: {
-        ++num_ready;
-        break;
-      }
-      case GRPC_CHANNEL_CONNECTING: {
-        ++num_connecting;
-        break;
-      }
-      case GRPC_CHANNEL_IDLE: {
-        ++num_idle;
-        break;
-      }
-      case GRPC_CHANNEL_TRANSIENT_FAILURE: {
-        ++num_transient_failures;
-        break;
-      }
-      default:
-        GPR_UNREACHABLE_CODE(return );
-    }
-  }
-  if (num_ready > 0) {
-    connectivity_state_ = GRPC_CHANNEL_READY;
-  } else if (num_connecting > 0) {
-    connectivity_state_ = GRPC_CHANNEL_CONNECTING;
-  } else if (num_idle > 0) {
-    connectivity_state_ = GRPC_CHANNEL_IDLE;
-  } else {
-    connectivity_state_ = GRPC_CHANNEL_TRANSIENT_FAILURE;
-  }
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p] Priority %" PRIu32 " (%p) connectivity changed to %s",
-            xds_policy(), priority_, this,
-            ConnectivityStateName(connectivity_state_));
-  }
-}
-
-void XdsLb::LocalityMap::OnDelayedRemovalTimer(void* arg, grpc_error* error) {
-  LocalityMap* self = static_cast<LocalityMap*>(arg);
-  self->xds_policy_->combiner()->Run(
-      GRPC_CLOSURE_INIT(&self->on_delayed_removal_timer_,
-                        OnDelayedRemovalTimerLocked, self, nullptr),
-      GRPC_ERROR_REF(error));
-}
-
-void XdsLb::LocalityMap::OnDelayedRemovalTimerLocked(void* arg,
-                                                     grpc_error* error) {
-  LocalityMap* self = static_cast<LocalityMap*>(arg);
-  self->delayed_removal_timer_callback_pending_ = false;
-  if (error == GRPC_ERROR_NONE && !self->xds_policy_->shutting_down_) {
-    const bool keep = self->priority_list_update().Contains(self->priority_) &&
-                      self->priority_ <= self->xds_policy_->current_priority_;
-    if (!keep) {
-      // This check is to make sure we always delete the locality maps from
-      // the lowest priority even if the closures of the back-to-back timers
-      // are not run in FIFO order.
-      // TODO(juanlishen): Eliminate unnecessary maintenance overhead for some
-      // deactivated locality maps when out-of-order closures are run.
-      // TODO(juanlishen): Check the timer implementation to see if this
-      // defense is necessary.
-      if (self->priority_ == self->xds_policy_->LowestPriority()) {
-        self->xds_policy_->priorities_.pop_back();
-      } else {
-        gpr_log(GPR_ERROR,
-                "[xdslb %p] Priority %" PRIu32
-                " is not the lowest priority (highest numeric value) but is "
-                "attempted to be deleted.",
-                self->xds_policy(), self->priority_);
-      }
-    }
-  }
-  self->Unref(DEBUG_LOCATION, "LocalityMap+timer");
-}
-
-void XdsLb::LocalityMap::OnFailoverTimer(void* arg, grpc_error* error) {
-  LocalityMap* self = static_cast<LocalityMap*>(arg);
-  self->xds_policy_->combiner()->Run(
-      GRPC_CLOSURE_INIT(&self->on_failover_timer_, OnFailoverTimerLocked, self,
-                        nullptr),
-      GRPC_ERROR_REF(error));
-}
-
-void XdsLb::LocalityMap::OnFailoverTimerLocked(void* arg, grpc_error* error) {
-  LocalityMap* self = static_cast<LocalityMap*>(arg);
-  self->failover_timer_callback_pending_ = false;
-  if (error == GRPC_ERROR_NONE && !self->xds_policy_->shutting_down_) {
-    self->xds_policy_->FailoverOnConnectionFailureLocked();
-  }
-  self->Unref(DEBUG_LOCATION, "LocalityMap+OnFailoverTimerLocked");
-}
-
-//
-// XdsLb::LocalityMap::Locality
-//
-
-XdsLb::LocalityMap::Locality::Locality(RefCountedPtr<LocalityMap> locality_map,
-                                       RefCountedPtr<XdsLocalityName> name)
-    : locality_map_(std::move(locality_map)), name_(std::move(name)) {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] created Locality %p for %s", xds_policy(),
-            this, name_->AsHumanReadableString());
-  }
-  // Initialize locality stats if load reporting is enabled.
-  UpdateLocalityStats();
-}
-
-XdsLb::LocalityMap::Locality::~Locality() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Locality %p %s: destroying locality",
-            xds_policy(), this, name_->AsHumanReadableString());
-  }
-  locality_map_.reset(DEBUG_LOCATION, "Locality");
-}
-
-void XdsLb::LocalityMap::Locality::UpdateLocalityStats() {
-  stats_.reset();
-  if (xds_policy()->config_->lrs_load_reporting_server_name().has_value()) {
-    stats_ = xds_policy()->xds_client()->AddClusterLocalityStats(
-        xds_policy()->config_->lrs_load_reporting_server_name().value(),
-        // TODO(roth): We currently hard-code the assumption that
-        // cluster name and EDS service name are the same.  Fix this
-        // as part of refectoring this LB policy.
-        xds_policy()->eds_service_name(), xds_policy()->eds_service_name(),
-        name_);
-  }
-}
-
-grpc_channel_args* XdsLb::LocalityMap::Locality::CreateChildPolicyArgsLocked(
-    const grpc_channel_args* args_in) {
-  const grpc_arg args_to_add[] = {
-      // A channel arg indicating if the target is a backend inferred from a
-      // grpclb load balancer.
-      grpc_channel_arg_integer_create(
-          const_cast<char*>(GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER),
-          1),
-      // Inhibit client-side health checking, since the balancer does
-      // this for us.
-      grpc_channel_arg_integer_create(
-          const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1),
-  };
-  return grpc_channel_args_copy_and_add(args_in, args_to_add,
-                                        GPR_ARRAY_SIZE(args_to_add));
-}
-
-OrphanablePtr<LoadBalancingPolicy>
-XdsLb::LocalityMap::Locality::CreateChildPolicyLocked(
-    const grpc_channel_args* args) {
-  LoadBalancingPolicy::Args lb_policy_args;
-  lb_policy_args.combiner = xds_policy()->combiner();
-  lb_policy_args.args = args;
-  lb_policy_args.channel_control_helper =
-      absl::make_unique<Helper>(this->Ref(DEBUG_LOCATION, "Helper"));
-  OrphanablePtr<LoadBalancingPolicy> lb_policy =
-      MakeOrphanable<ChildPolicyHandler>(std::move(lb_policy_args),
-                                         &grpc_lb_xds_trace);
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p] Locality %p %s: Created new child policy handler (%p)",
-            xds_policy(), this, name_->AsHumanReadableString(),
-            lb_policy.get());
-  }
-  // Add the xDS's interested_parties pollset_set to that of the newly created
-  // child policy. This will make the child policy progress upon activity on
-  // xDS LB, which in turn is tied to the application's call.
-  grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
-                                   xds_policy()->interested_parties());
-  return lb_policy;
-}
-
-void XdsLb::LocalityMap::Locality::UpdateLocked(uint32_t locality_weight,
-                                                ServerAddressList serverlist,
-                                                bool update_locality_stats) {
-  if (xds_policy()->shutting_down_) return;
-  // Update locality weight.
-  weight_ = locality_weight;
-  if (delayed_removal_timer_callback_pending_) {
-    if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-      gpr_log(GPR_INFO, "[xdslb %p] Locality %p %s: reactivating", xds_policy(),
-              this, name_->AsHumanReadableString());
-    }
-    grpc_timer_cancel(&delayed_removal_timer_);
-  }
-  // Update locality stats.
-  if (update_locality_stats) UpdateLocalityStats();
-  // Construct update args.
-  UpdateArgs update_args;
-  update_args.addresses = std::move(serverlist);
-  update_args.config = xds_policy()->config_->child_policy();
-  update_args.args = CreateChildPolicyArgsLocked(xds_policy()->args_);
-  // Create child policy if needed.
-  if (child_policy_ == nullptr) {
-    child_policy_ = CreateChildPolicyLocked(update_args.args);
-    GPR_ASSERT(child_policy_ != nullptr);
-  }
-  // Update the policy.
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p] Locality %p %s: Updating child policy handler %p",
-            xds_policy(), this, name_->AsHumanReadableString(),
-            child_policy_.get());
-  }
-  child_policy_->UpdateLocked(std::move(update_args));
-}
-
-void XdsLb::LocalityMap::Locality::ShutdownLocked() {
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Locality %p %s: shutting down locality",
-            xds_policy(), this, name_->AsHumanReadableString());
-  }
-  stats_.reset();
-  // Remove the child policy's interested_parties pollset_set from the
-  // xDS policy.
-  grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
-                                   xds_policy()->interested_parties());
-  child_policy_.reset();
-  // Drop our ref to the child's picker, in case it's holding a ref to
-  // the child.
-  load_reporting_picker_.reset();
-  picker_wrapper_.reset();
-  if (delayed_removal_timer_callback_pending_) {
-    grpc_timer_cancel(&delayed_removal_timer_);
-  }
-  shutdown_ = true;
-}
-
-void XdsLb::LocalityMap::Locality::ResetBackoffLocked() {
-  child_policy_->ResetBackoffLocked();
-}
-
-void XdsLb::LocalityMap::Locality::Orphan() {
-  ShutdownLocked();
-  Unref();
-}
-
-void XdsLb::LocalityMap::Locality::DeactivateLocked() {
-  // If already deactivated, don't do that again.
-  if (weight_ == 0) return;
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO, "[xdslb %p] Locality %p %s: deactivating", xds_policy(),
-            this, name_->AsHumanReadableString());
-  }
-  // Set the locality weight to 0 so that future xds picker won't contain this
-  // locality.
-  weight_ = 0;
-  // Start a timer to delete the locality.
-  Ref(DEBUG_LOCATION, "Locality+timer").release();
-  GRPC_CLOSURE_INIT(&on_delayed_removal_timer_, OnDelayedRemovalTimer, this,
-                    grpc_schedule_on_exec_ctx);
-  grpc_timer_init(
-      &delayed_removal_timer_,
-      ExecCtx::Get()->Now() + xds_policy()->locality_retention_interval_ms_,
-      &on_delayed_removal_timer_);
-  delayed_removal_timer_callback_pending_ = true;
-}
-
-void XdsLb::LocalityMap::Locality::OnDelayedRemovalTimer(void* arg,
-                                                         grpc_error* error) {
-  Locality* self = static_cast<Locality*>(arg);
-  self->xds_policy()->combiner()->Run(
-      GRPC_CLOSURE_INIT(&self->on_delayed_removal_timer_,
-                        OnDelayedRemovalTimerLocked, self, nullptr),
-      GRPC_ERROR_REF(error));
-}
-
-void XdsLb::LocalityMap::Locality::OnDelayedRemovalTimerLocked(
-    void* arg, grpc_error* error) {
-  Locality* self = static_cast<Locality*>(arg);
-  self->delayed_removal_timer_callback_pending_ = false;
-  if (error == GRPC_ERROR_NONE && !self->shutdown_ && self->weight_ == 0) {
-    self->locality_map_->localities_.erase(self->name_);
-  }
-  self->Unref(DEBUG_LOCATION, "Locality+timer");
-}
-
-//
-// XdsLb::LocalityMap::Locality::Helper
-//
-
-RefCountedPtr<SubchannelInterface>
-XdsLb::LocalityMap::Locality::Helper::CreateSubchannel(
-    const grpc_channel_args& args) {
-  if (locality_->xds_policy()->shutting_down_) return nullptr;
-  return locality_->xds_policy()->channel_control_helper()->CreateSubchannel(
-      args);
-}
-
-void XdsLb::LocalityMap::Locality::Helper::UpdateState(
-    grpc_connectivity_state state, std::unique_ptr<SubchannelPicker> picker) {
-  if (locality_->xds_policy()->shutting_down_) return;
-  if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
-    gpr_log(GPR_INFO,
-            "[xdslb %p helper %p] child policy handler %p reports state=%s",
-            locality_->xds_policy(), this, locality_->child_policy_.get(),
-            ConnectivityStateName(state));
-  }
-  // Cache the state and picker in the locality.
-  locality_->connectivity_state_ = state;
-  locality_->picker_wrapper_ =
-      MakeRefCounted<RefCountedEndpointPicker>(std::move(picker));
-  // Notify the locality map.
-  locality_->locality_map_->OnLocalityStateUpdateLocked();
-}
-
-void XdsLb::LocalityMap::Locality::Helper::AddTraceEvent(TraceSeverity severity,
-                                                         StringView message) {
-  if (locality_->xds_policy()->shutting_down_) return;
-  locality_->xds_policy()->channel_control_helper()->AddTraceEvent(severity,
-                                                                   message);
-}
-
-//
-// factory
-//
-
-class XdsFactory : public LoadBalancingPolicyFactory {
- public:
-  OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
-      LoadBalancingPolicy::Args args) const override {
-    return MakeOrphanable<XdsChildHandler>(std::move(args), &grpc_lb_xds_trace);
-  }
-
-  const char* name() const override { return kXds; }
-
-  RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
-      const Json& json, grpc_error** error) const override {
-    GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
-    if (json.type() == Json::Type::JSON_NULL) {
-      // xds was mentioned as a policy in the deprecated loadBalancingPolicy
-      // field or in the client API.
-      *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-          "field:loadBalancingPolicy error:xds policy requires configuration. "
-          "Please use loadBalancingConfig field of service config instead.");
-      return nullptr;
-    }
-    std::vector<grpc_error*> error_list;
-    // Child policy.
-    Json json_tmp;
-    const Json* child_policy_json;
-    auto it = json.object_value().find("childPolicy");
-    if (it == json.object_value().end()) {
-      json_tmp = Json::Array{Json::Object{
-          {"round_robin", Json::Object()},
-      }};
-      child_policy_json = &json_tmp;
-    } else {
-      child_policy_json = &it->second;
-    }
-    grpc_error* parse_error = GRPC_ERROR_NONE;
-    RefCountedPtr<LoadBalancingPolicy::Config> child_policy =
-        LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
-            *child_policy_json, &parse_error);
-    if (child_policy == nullptr) {
-      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
-      std::vector<grpc_error*> child_errors;
-      child_errors.push_back(parse_error);
-      error_list.push_back(
-          GRPC_ERROR_CREATE_FROM_VECTOR("field:childPolicy", &child_errors));
-    }
-    // Fallback policy.
-    const Json* fallback_policy_json;
-    it = json.object_value().find("fallbackPolicy");
-    if (it == json.object_value().end()) {
-      json_tmp = Json::Array{Json::Object{
-          {"round_robin", Json::Object()},
-      }};
-      fallback_policy_json = &json_tmp;
-    } else {
-      fallback_policy_json = &it->second;
-    }
-    RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy =
-        LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
-            *fallback_policy_json, &parse_error);
-    if (fallback_policy == nullptr) {
-      GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
-      std::vector<grpc_error*> child_errors;
-      child_errors.push_back(parse_error);
-      error_list.push_back(
-          GRPC_ERROR_CREATE_FROM_VECTOR("field:fallbackPolicy", &child_errors));
-    }
-    // EDS service name.
-    const char* eds_service_name = nullptr;
-    it = json.object_value().find("edsServiceName");
-    if (it != json.object_value().end()) {
-      if (it->second.type() != Json::Type::STRING) {
-        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-            "field:edsServiceName error:type should be string"));
-      } else {
-        eds_service_name = it->second.string_value().c_str();
-      }
-    }
-    // LRS load reporting server name.
-    const char* lrs_load_reporting_server_name = nullptr;
-    it = json.object_value().find("lrsLoadReportingServerName");
-    if (it != json.object_value().end()) {
-      if (it->second.type() != Json::Type::STRING) {
-        error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-            "field:lrsLoadReportingServerName error:type should be string"));
-      } else {
-        lrs_load_reporting_server_name = it->second.string_value().c_str();
-      }
-    }
-    if (error_list.empty()) {
-      absl::optional<std::string> optional_lrs_load_reporting_server_name;
-      if (lrs_load_reporting_server_name != nullptr) {
-        optional_lrs_load_reporting_server_name.emplace(
-            std::string(lrs_load_reporting_server_name));
-      }
-      return MakeRefCounted<XdsConfig>(
-          std::move(child_policy), std::move(fallback_policy),
-          eds_service_name == nullptr ? "" : eds_service_name,
-          std::move(optional_lrs_load_reporting_server_name));
-    } else {
-      *error = GRPC_ERROR_CREATE_FROM_VECTOR("Xds Parser", &error_list);
-      return nullptr;
-    }
-  }
-
- private:
-  class XdsChildHandler : public ChildPolicyHandler {
-   public:
-    XdsChildHandler(Args args, TraceFlag* tracer)
-        : ChildPolicyHandler(std::move(args), tracer) {}
-
-    bool ConfigChangeRequiresNewPolicyInstance(
-        LoadBalancingPolicy::Config* old_config,
-        LoadBalancingPolicy::Config* new_config) const override {
-      GPR_ASSERT(old_config->name() == kXds);
-      GPR_ASSERT(new_config->name() == kXds);
-      XdsConfig* old_xds_config = static_cast<XdsConfig*>(old_config);
-      XdsConfig* new_xds_config = static_cast<XdsConfig*>(new_config);
-      const char* old_eds_service_name =
-          old_xds_config->eds_service_name() == nullptr
-              ? ""
-              : old_xds_config->eds_service_name();
-      const char* new_eds_service_name =
-          new_xds_config->eds_service_name() == nullptr
-              ? ""
-              : new_xds_config->eds_service_name();
-      return strcmp(old_eds_service_name, new_eds_service_name) != 0;
-    }
-
-    OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
-        const char* name, LoadBalancingPolicy::Args args) const override {
-      return MakeOrphanable<XdsLb>(std::move(args));
-    }
-  };
-};
-
-}  // namespace
-
-}  // namespace grpc_core
-
-//
-// Plugin registration
-//
-
-void grpc_lb_policy_xds_init() {
-  grpc_core::LoadBalancingPolicyRegistry::Builder::
-      RegisterLoadBalancingPolicyFactory(
-          absl::make_unique<grpc_core::XdsFactory>());
-}
-
-void grpc_lb_policy_xds_shutdown() {}

src/core/ext/filters/client_channel/lb_policy/xds/xds.h

@@ -29,5 +29,4 @@
 #define GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER \
   "grpc.address_is_backend_from_xds_load_balancer"
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_H \
-        */
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_H */

src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc

@@ -199,8 +199,6 @@ class XdsRoutingLb : public LoadBalancingPolicy {
 
   void UpdateStateLocked();
 
-  const grpc_millis child_retention_interval_ms_;
-
   // Current config from the resolver.
   RefCountedPtr<XdsRoutingLbConfig> config_;
 
@@ -247,11 +245,7 @@ XdsRoutingLb::PickResult XdsRoutingLb::RoutePicker::Pick(PickArgs args) {
 //
 
 XdsRoutingLb::XdsRoutingLb(Args args)
-    : LoadBalancingPolicy(std::move(args)),
-      // FIXME: new channel arg
-      child_retention_interval_ms_(grpc_channel_args_find_integer(
-          args.args, GRPC_ARG_LOCALITY_RETENTION_INTERVAL_MS,
-          {GRPC_XDS_ROUTING_CHILD_RETENTION_INTERVAL_MS, 0, INT_MAX})) {}
+    : LoadBalancingPolicy(std::move(args)) {}
 
 XdsRoutingLb::~XdsRoutingLb() {
   if (GRPC_TRACE_FLAG_ENABLED(grpc_xds_routing_lb_trace)) {
@@ -284,18 +278,11 @@ void XdsRoutingLb::UpdateLocked(UpdateArgs args) {
   // Update config.
   config_ = std::move(args.config);
   // Deactivate the actions not in the new config.
-  for (auto it = actions_.begin(); it != actions_.end();) {
-    const std::string& name = it->first;
-    XdsRoutingChild* child = it->second.get();
-    if (config_->action_map().find(name) != config_->action_map().end()) {
-      ++it;
-      continue;
-    }
-    if (child_retention_interval_ms_ == 0) {
-      it = actions_.erase(it);
-    } else {
+  for (const auto& p : actions_) {
+    const std::string& name = p.first;
+    XdsRoutingChild* child = p.second.get();
+    if (config_->action_map().find(name) == config_->action_map().end()) {
       child->DeactivateLocked();
-      ++it;
     }
   }
   // Add or update the actions in the new config.
@@ -515,7 +502,7 @@ void XdsRoutingLb::XdsRoutingChild::DeactivateLocked() {
                     grpc_schedule_on_exec_ctx);
   grpc_timer_init(
       &delayed_removal_timer_,
-      ExecCtx::Get()->Now() + xds_routing_policy_->child_retention_interval_ms_,
+      ExecCtx::Get()->Now() + GRPC_XDS_ROUTING_CHILD_RETENTION_INTERVAL_MS,
       &on_delayed_removal_timer_);
   delayed_removal_timer_callback_pending_ = true;
 }

src/core/ext/filters/client_channel/lb_policy_registry.cc

@@ -35,6 +35,8 @@ class RegistryState {
 
   void RegisterLoadBalancingPolicyFactory(
       std::unique_ptr<LoadBalancingPolicyFactory> factory) {
+    gpr_log(GPR_DEBUG, "registering LB policy factory for \"%s\"",
+            factory->name());
     for (size_t i = 0; i < factories_.size(); ++i) {
       GPR_ASSERT(strcmp(factories_[i]->name(), factory->name()) != 0);
     }

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc

@@ -87,25 +87,32 @@ typedef struct grpc_ares_hostbyname_request {
   bool is_balancer;
 } grpc_ares_hostbyname_request;
 
-static void log_address_sorting_list(const ServerAddressList& addresses,
+static void log_address_sorting_list(const grpc_ares_request* r,
+                                     const ServerAddressList& addresses,
                                      const char* input_output_str) {
   for (size_t i = 0; i < addresses.size(); i++) {
     char* addr_str;
     if (grpc_sockaddr_to_string(&addr_str, &addresses[i].address(), true)) {
-      gpr_log(GPR_INFO, "c-ares address sorting: %s[%" PRIuPTR "]=%s",
-              input_output_str, i, addr_str);
+      gpr_log(
+          GPR_INFO,
+          "(c-ares resolver) request:%p c-ares address sorting: %s[%" PRIuPTR
+          "]=%s",
+          r, input_output_str, i, addr_str);
       gpr_free(addr_str);
     } else {
-      gpr_log(GPR_INFO,
-              "c-ares address sorting: %s[%" PRIuPTR "]=<unprintable>",
-              input_output_str, i);
+      gpr_log(
+          GPR_INFO,
+          "(c-ares resolver) request:%p c-ares address sorting: %s[%" PRIuPTR
+          "]=<unprintable>",
+          r, input_output_str, i);
     }
   }
 }
 
-void grpc_cares_wrapper_address_sorting_sort(ServerAddressList* addresses) {
+void grpc_cares_wrapper_address_sorting_sort(const grpc_ares_request* r,
+                                             ServerAddressList* addresses) {
   if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_cares_address_sorting)) {
-    log_address_sorting_list(*addresses, "input");
+    log_address_sorting_list(r, *addresses, "input");
   }
   address_sorting_sortable* sortables = (address_sorting_sortable*)gpr_zalloc(
       sizeof(address_sorting_sortable) * addresses->size());
@@ -124,7 +131,7 @@ void grpc_cares_wrapper_address_sorting_sort(ServerAddressList* addresses) {
   gpr_free(sortables);
   *addresses = std::move(sorted);
   if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_cares_address_sorting)) {
-    log_address_sorting_list(*addresses, "output");
+    log_address_sorting_list(r, *addresses, "output");
   }
 }
 
@@ -145,7 +152,7 @@ void grpc_ares_complete_request_locked(grpc_ares_request* r) {
   r->ev_driver = nullptr;
   ServerAddressList* addresses = r->addresses_out->get();
   if (addresses != nullptr) {
-    grpc_cares_wrapper_address_sorting_sort(addresses);
+    grpc_cares_wrapper_address_sorting_sort(r, addresses);
     GRPC_ERROR_UNREF(r->error);
     r->error = GRPC_ERROR_NONE;
     // TODO(apolcyn): allow c-ares to return a service config
@@ -523,7 +530,7 @@ static bool target_matches_localhost(const char* name) {
 
 #ifdef GRPC_ARES_RESOLVE_LOCALHOST_MANUALLY
 static bool inner_maybe_resolve_localhost_manually_locked(
-    const char* name, const char* default_port,
+    const grpc_ares_request* r, const char* name, const char* default_port,
     std::unique_ptr<grpc_core::ServerAddressList>* addrs,
     grpc_core::UniquePtr<char>* host, grpc_core::UniquePtr<char>* port) {
   grpc_core::SplitHostPort(name, host, port);
@@ -566,23 +573,24 @@ static bool inner_maybe_resolve_localhost_manually_locked(
     (*addrs)->emplace_back(&ipv4_loopback_addr, sizeof(ipv4_loopback_addr),
                            nullptr /* args */);
     // Let the address sorter figure out which one should be tried first.
-    grpc_cares_wrapper_address_sorting_sort(addrs->get());
+    grpc_cares_wrapper_address_sorting_sort(r, addrs->get());
     return true;
   }
   return false;
 }
 
 static bool grpc_ares_maybe_resolve_localhost_manually_locked(
-    const char* name, const char* default_port,
+    const grpc_ares_request* r, const char* name, const char* default_port,
     std::unique_ptr<grpc_core::ServerAddressList>* addrs) {
   grpc_core::UniquePtr<char> host;
   grpc_core::UniquePtr<char> port;
-  return inner_maybe_resolve_localhost_manually_locked(name, default_port,
+  return inner_maybe_resolve_localhost_manually_locked(r, name, default_port,
                                                        addrs, &host, &port);
 }
 #else  /* GRPC_ARES_RESOLVE_LOCALHOST_MANUALLY */
 static bool grpc_ares_maybe_resolve_localhost_manually_locked(
-    const char* /*name*/, const char* /*default_port*/,
+    const grpc_ares_request* r, const char* /*name*/,
+    const char* /*default_port*/,
     std::unique_ptr<grpc_core::ServerAddressList>* /*addrs*/) {
   return false;
 }
@@ -614,7 +622,7 @@ static grpc_ares_request* grpc_dns_lookup_ares_locked_impl(
     return r;
   }
   // Early out if the target is localhost and we're on Windows.
-  if (grpc_ares_maybe_resolve_localhost_manually_locked(name, default_port,
+  if (grpc_ares_maybe_resolve_localhost_manually_locked(r, name, default_port,
                                                         addrs)) {
     grpc_ares_complete_request_locked(r);
     return r;

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h

@@ -90,7 +90,7 @@ bool grpc_ares_query_ipv6();
 
 /* Sorts destinations in lb_addrs according to RFC 6724. */
 void grpc_cares_wrapper_address_sorting_sort(
-    grpc_core::ServerAddressList* addresses);
+    const grpc_ares_request* request, grpc_core::ServerAddressList* addresses);
 
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_WRAPPER_H \
         */

src/core/ext/filters/client_channel/xds/xds_api.cc

@@ -1452,13 +1452,6 @@ grpc_error* EdsResponseParse(
         if (error != GRPC_ERROR_NONE) return error;
       }
     }
-    // Validate the update content.
-    if (eds_update.priority_list_update.empty() &&
-        !eds_update.drop_config->drop_all()) {
-      return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
-          "EDS response doesn't contain any valid "
-          "locality but doesn't require to drop all calls.");
-    }
     eds_update_map->emplace(std::string(cluster_name.data, cluster_name.size),
                             std::move(eds_update));
   }

src/core/ext/filters/client_channel/xds/xds_client_stats.h

@@ -42,11 +42,7 @@ class XdsLocalityName : public RefCounted<XdsLocalityName> {
   struct Less {
     bool operator()(const XdsLocalityName* lhs,
                     const XdsLocalityName* rhs) const {
-      int cmp_result = lhs->region_.compare(rhs->region_);
-      if (cmp_result != 0) return cmp_result < 0;
-      cmp_result = lhs->zone_.compare(rhs->zone_);
-      if (cmp_result != 0) return cmp_result < 0;
-      return lhs->sub_zone_.compare(rhs->sub_zone_) < 0;
+      return lhs->Compare(*rhs) < 0;
     }
 
     bool operator()(const RefCountedPtr<XdsLocalityName>& lhs,
@@ -65,6 +61,18 @@ class XdsLocalityName : public RefCounted<XdsLocalityName> {
            sub_zone_ == other.sub_zone_;
   }
 
+  bool operator!=(const XdsLocalityName& other) const {
+    return !(*this == other);
+  }
+
+  int Compare(const XdsLocalityName& other) const {
+    int cmp_result = region_.compare(other.region_);
+    if (cmp_result != 0) return cmp_result;
+    cmp_result = zone_.compare(other.zone_);
+    if (cmp_result != 0) return cmp_result;
+    return sub_zone_.compare(other.sub_zone_);
+  }
+
   const std::string& region() const { return region_; }
   const std::string& zone() const { return zone_; }
   const std::string& sub_zone() const { return sub_zone_; }

src/core/ext/transport/cronet/transport/cronet_transport.cc

@@ -1072,9 +1072,11 @@ static enum e_op_result execute_stream_op(struct op_and_state* oas) {
              op_can_be_run(stream_op, s, &oas->state, OP_SEND_MESSAGE)) {
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_SEND_MESSAGE", oas);
     stream_state->pending_send_message = false;
-    if (stream_state->state_callback_received[OP_FAILED]) {
+    if (stream_state->state_op_done[OP_CANCEL_ERROR] ||
+        stream_state->state_callback_received[OP_FAILED] ||
+        stream_state->state_callback_received[OP_SUCCEEDED]) {
       result = NO_ACTION_POSSIBLE;
-      CRONET_LOG(GPR_DEBUG, "Stream is either cancelled or failed.");
+      CRONET_LOG(GPR_DEBUG, "Stream is either cancelled, failed or finished");
     } else {
       grpc_slice_buffer write_slice_buffer;
       grpc_slice slice;
@@ -1131,9 +1133,11 @@ static enum e_op_result execute_stream_op(struct op_and_state* oas) {
              op_can_be_run(stream_op, s, &oas->state,
                            OP_SEND_TRAILING_METADATA)) {
     CRONET_LOG(GPR_DEBUG, "running: %p  OP_SEND_TRAILING_METADATA", oas);
-    if (stream_state->state_callback_received[OP_FAILED]) {
+    if (stream_state->state_op_done[OP_CANCEL_ERROR] ||
+        stream_state->state_callback_received[OP_FAILED] ||
+        stream_state->state_callback_received[OP_SUCCEEDED]) {
       result = NO_ACTION_POSSIBLE;
-      CRONET_LOG(GPR_DEBUG, "Stream is either cancelled or failed.");
+      CRONET_LOG(GPR_DEBUG, "Stream is either cancelled, failed or finished");
     } else {
       CRONET_LOG(GPR_DEBUG, "bidirectional_stream_write (%p, 0)", s->cbs);
       stream_state->state_callback_received[OP_SEND_MESSAGE] = false;

src/core/lib/channel/channel_stack.h

@@ -31,7 +31,18 @@
    chains are linear, then channel stacks provide a mechanism to minimize
    allocations for that chain.
    Call stacks are created by channel stacks and represent the per-call data
-   for that stack. */
+   for that stack.
+
+   Implementations should take care of the following details for a batch -
+   1. Synchronization is achieved with a CallCombiner. View
+   src/core/lib/iomgr/call_combiner.h for more details.
+   2. If the filter wants to inject an error on the way down, it needs to call
+   grpc_transport_stream_op_batch_finish_with_failure from within the call
+   combiner. This will cause any batch callbacks to be called with that error.
+   3. If the filter wants to inject an error on the way up (from a callback), it
+   should also inject that error in the recv_trailing_metadata callback so that
+   it can have an effect on the call status.
+*/
 
 #include <grpc/support/port_platform.h>
 

src/core/lib/security/credentials/credentials.cc

@@ -45,90 +45,6 @@ void grpc_channel_credentials_release(grpc_channel_credentials* creds) {
   if (creds) creds->Unref();
 }
 
-static std::map<grpc_core::UniquePtr<char>,
-                grpc_core::RefCountedPtr<grpc_channel_credentials>,
-                grpc_core::StringLess>* g_grpc_control_plane_creds;
-static gpr_mu g_control_plane_creds_mu;
-
-static void do_control_plane_creds_init() {
-  gpr_mu_init(&g_control_plane_creds_mu);
-  GPR_ASSERT(g_grpc_control_plane_creds == nullptr);
-  g_grpc_control_plane_creds =
-      new std::map<grpc_core::UniquePtr<char>,
-                   grpc_core::RefCountedPtr<grpc_channel_credentials>,
-                   grpc_core::StringLess>();
-}
-
-void grpc_control_plane_credentials_init() {
-  static gpr_once once_init_control_plane_creds = GPR_ONCE_INIT;
-  gpr_once_init(&once_init_control_plane_creds, do_control_plane_creds_init);
-}
-
-void grpc_test_only_control_plane_credentials_destroy() {
-  delete g_grpc_control_plane_creds;
-  g_grpc_control_plane_creds = nullptr;
-  gpr_mu_destroy(&g_control_plane_creds_mu);
-}
-
-void grpc_test_only_control_plane_credentials_force_init() {
-  if (g_grpc_control_plane_creds == nullptr) {
-    do_control_plane_creds_init();
-  }
-}
-
-bool grpc_channel_credentials_attach_credentials(
-    grpc_channel_credentials* credentials, const char* authority,
-    grpc_channel_credentials* control_plane_creds) {
-  grpc_core::ExecCtx exec_ctx;
-  return credentials->attach_credentials(authority, control_plane_creds->Ref());
-}
-
-bool grpc_control_plane_credentials_register(
-    const char* authority, grpc_channel_credentials* control_plane_creds) {
-  grpc_core::ExecCtx exec_ctx;
-  {
-    grpc_core::MutexLock lock(&g_control_plane_creds_mu);
-    auto key = grpc_core::UniquePtr<char>(gpr_strdup(authority));
-    if (g_grpc_control_plane_creds->find(key) !=
-        g_grpc_control_plane_creds->end()) {
-      return false;
-    }
-    (*g_grpc_control_plane_creds)[std::move(key)] = control_plane_creds->Ref();
-  }
-  return true;
-}
-
-bool grpc_channel_credentials::attach_credentials(
-    const char* authority,
-    grpc_core::RefCountedPtr<grpc_channel_credentials> control_plane_creds) {
-  auto key = grpc_core::UniquePtr<char>(gpr_strdup(authority));
-  if (local_control_plane_creds_.find(key) !=
-      local_control_plane_creds_.end()) {
-    return false;
-  }
-  local_control_plane_creds_[std::move(key)] = std::move(control_plane_creds);
-  return true;
-}
-
-grpc_core::RefCountedPtr<grpc_channel_credentials>
-grpc_channel_credentials::get_control_plane_credentials(const char* authority) {
-  {
-    auto key = grpc_core::UniquePtr<char>(gpr_strdup(authority));
-    auto local_lookup = local_control_plane_creds_.find(key);
-    if (local_lookup != local_control_plane_creds_.end()) {
-      return local_lookup->second;
-    }
-    {
-      grpc_core::MutexLock lock(&g_control_plane_creds_mu);
-      auto global_lookup = g_grpc_control_plane_creds->find(key);
-      if (global_lookup != g_grpc_control_plane_creds->end()) {
-        return global_lookup->second;
-      }
-    }
-  }
-  return duplicate_without_call_credentials();
-}
-
 void grpc_call_credentials_release(grpc_call_credentials* creds) {
   GRPC_API_TRACE("grpc_call_credentials_release(creds=%p)", 1, (creds));
   grpc_core::ExecCtx exec_ctx;

src/core/lib/security/credentials/credentials.h

@@ -28,9 +28,7 @@
 #include <grpc/support/sync.h>
 #include "src/core/lib/transport/metadata_batch.h"
 
-#include "src/core/lib/gprpp/map.h"
 #include "src/core/lib/gprpp/ref_counted.h"
-#include "src/core/lib/gprpp/sync.h"
 #include "src/core/lib/http/httpcli.h"
 #include "src/core/lib/http/parser.h"
 #include "src/core/lib/iomgr/polling_entity.h"
@@ -131,29 +129,10 @@ struct grpc_channel_credentials
     return args;
   }
 
-  // Attaches control_plane_creds to the local registry, under authority,
-  // if no other creds are currently registered under authority. Returns
-  // true if registered successfully and false if not.
-  bool attach_credentials(
-      const char* authority,
-      grpc_core::RefCountedPtr<grpc_channel_credentials> control_plane_creds);
-
-  // Gets the control plane credentials registered under authority. This
-  // prefers the local control plane creds registry but falls back to the
-  // global registry. Lastly, this returns self but with any attached
-  // call credentials stripped off, in the case that neither the local
-  // registry nor the global registry have an entry for authority.
-  grpc_core::RefCountedPtr<grpc_channel_credentials>
-  get_control_plane_credentials(const char* authority);
-
   const char* type() const { return type_; }
 
  private:
   const char* type_;
-  std::map<grpc_core::UniquePtr<char>,
-           grpc_core::RefCountedPtr<grpc_channel_credentials>,
-           grpc_core::StringLess>
-      local_control_plane_creds_;
 };
 
 /* Util to encapsulate the channel credentials in a channel arg. */
@@ -167,41 +146,6 @@ grpc_channel_credentials* grpc_channel_credentials_from_arg(
 grpc_channel_credentials* grpc_channel_credentials_find_in_args(
     const grpc_channel_args* args);
 
-/** EXPERIMENTAL.  API MAY CHANGE IN THE FUTURE.
-    Attaches \a control_plane_creds to \a credentials
-    under the key \a authority. Returns false if \a authority
-    is already present, in which case no changes are made.
-    Note that this API is not thread safe. Only one thread may
-    attach control plane creds to a given credentials object at
-    any one time, and new control plane creds must not be
-    attached after \a credentials has been used to create a channel. */
-bool grpc_channel_credentials_attach_credentials(
-    grpc_channel_credentials* credentials, const char* authority,
-    grpc_channel_credentials* control_plane_creds);
-
-/** EXPERIMENTAL.  API MAY CHANGE IN THE FUTURE.
-    Registers \a control_plane_creds in the global registry
-    under the key \a authority. Returns false if \a authority
-    is already present, in which case no changes are made. */
-bool grpc_control_plane_credentials_register(
-    const char* authority, grpc_channel_credentials* control_plane_creds);
-
-/* Initializes global control plane credentials data. */
-void grpc_control_plane_credentials_init();
-
-/* Test only: destroy global control plane credentials data.
- * This API is meant for use by a few tests that need to
- * satisdy grpc_core::LeakDetector. */
-void grpc_test_only_control_plane_credentials_destroy();
-
-/* Test only: force re-initialization of global control
- * plane credentials data if it was previously destroyed.
- * This API is meant to be used in
- * tandem with the
- * grpc_test_only_control_plane_credentials_destroy, for
- * the few tests that need it. */
-void grpc_test_only_control_plane_credentials_force_init();
-
 /* --- grpc_credentials_mdelem_array. --- */
 
 typedef struct {

src/core/lib/surface/init_secure.cc

@@ -78,7 +78,4 @@ void grpc_register_security_filters(void) {
                                    maybe_prepend_server_auth_filter, nullptr);
 }
 
-void grpc_security_init() {
-  grpc_core::SecurityRegisterHandshakerFactories();
-  grpc_control_plane_credentials_init();
-}
+void grpc_security_init() { grpc_core::SecurityRegisterHandshakerFactories(); }

src/core/plugin_registry/grpc_plugin_registry.cc

@@ -36,8 +36,14 @@ void grpc_lb_policy_grpclb_init(void);
 void grpc_lb_policy_grpclb_shutdown(void);
 void grpc_lb_policy_cds_init(void);
 void grpc_lb_policy_cds_shutdown(void);
-void grpc_lb_policy_xds_init(void);
-void grpc_lb_policy_xds_shutdown(void);
+void grpc_lb_policy_eds_init(void);
+void grpc_lb_policy_eds_shutdown(void);
+void grpc_lb_policy_lrs_init(void);
+void grpc_lb_policy_lrs_shutdown(void);
+void grpc_lb_policy_priority_init(void);
+void grpc_lb_policy_priority_shutdown(void);
+void grpc_lb_policy_weighted_target_init(void);
+void grpc_lb_policy_weighted_target_shutdown(void);
 void grpc_lb_policy_xds_routing_init(void);
 void grpc_lb_policy_xds_routing_shutdown(void);
 void grpc_lb_policy_pick_first_init(void);
@@ -80,8 +86,14 @@ void grpc_register_built_in_plugins(void) {
                        grpc_lb_policy_grpclb_shutdown);
   grpc_register_plugin(grpc_lb_policy_cds_init,
                        grpc_lb_policy_cds_shutdown);
-  grpc_register_plugin(grpc_lb_policy_xds_init,
-                       grpc_lb_policy_xds_shutdown);
+  grpc_register_plugin(grpc_lb_policy_eds_init,
+                       grpc_lb_policy_eds_shutdown);
+  grpc_register_plugin(grpc_lb_policy_lrs_init,
+                       grpc_lb_policy_lrs_shutdown);
+  grpc_register_plugin(grpc_lb_policy_priority_init,
+                       grpc_lb_policy_priority_shutdown);
+  grpc_register_plugin(grpc_lb_policy_weighted_target_init,
+                       grpc_lb_policy_weighted_target_shutdown);
   grpc_register_plugin(grpc_lb_policy_xds_routing_init,
                        grpc_lb_policy_xds_routing_shutdown);
   grpc_register_plugin(grpc_lb_policy_pick_first_init,

src/core/plugin_registry/grpc_unsecure_plugin_registry.cc

@@ -44,8 +44,14 @@ void grpc_lb_policy_grpclb_init(void);
 void grpc_lb_policy_grpclb_shutdown(void);
 void grpc_lb_policy_cds_init(void);
 void grpc_lb_policy_cds_shutdown(void);
-void grpc_lb_policy_xds_init(void);
-void grpc_lb_policy_xds_shutdown(void);
+void grpc_lb_policy_eds_init(void);
+void grpc_lb_policy_eds_shutdown(void);
+void grpc_lb_policy_lrs_init(void);
+void grpc_lb_policy_lrs_shutdown(void);
+void grpc_lb_policy_priority_init(void);
+void grpc_lb_policy_priority_shutdown(void);
+void grpc_lb_policy_weighted_target_init(void);
+void grpc_lb_policy_weighted_target_shutdown(void);
 void grpc_lb_policy_xds_routing_init(void);
 void grpc_lb_policy_xds_routing_shutdown(void);
 void grpc_lb_policy_pick_first_init(void);
@@ -88,8 +94,14 @@ void grpc_register_built_in_plugins(void) {
                        grpc_lb_policy_grpclb_shutdown);
   grpc_register_plugin(grpc_lb_policy_cds_init,
                        grpc_lb_policy_cds_shutdown);
-  grpc_register_plugin(grpc_lb_policy_xds_init,
-                       grpc_lb_policy_xds_shutdown);
+  grpc_register_plugin(grpc_lb_policy_eds_init,
+                       grpc_lb_policy_eds_shutdown);
+  grpc_register_plugin(grpc_lb_policy_lrs_init,
+                       grpc_lb_policy_lrs_shutdown);
+  grpc_register_plugin(grpc_lb_policy_priority_init,
+                       grpc_lb_policy_priority_shutdown);
+  grpc_register_plugin(grpc_lb_policy_weighted_target_init,
+                       grpc_lb_policy_weighted_target_shutdown);
   grpc_register_plugin(grpc_lb_policy_xds_routing_init,
                        grpc_lb_policy_xds_routing_shutdown);
   grpc_register_plugin(grpc_lb_policy_pick_first_init,

src/php/README.md

@@ -58,7 +58,7 @@ $ git clone -b RELEASE_TAG_HERE https://github.com/grpc/grpc
 ```sh
 $ cd grpc
 $ git submodule update --init
-$ make
+$ EXTRA_DEFINES=GRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK make
 $ [sudo] make install
 ```
 

src/python/grpcio/grpc/_cython/_cygrpc/aio/grpc_aio.pyx.pxi

@@ -105,7 +105,7 @@ cdef _actual_aio_shutdown():
         )
         future.add_done_callback(_grpc_shutdown_wrapper)
     elif _global_aio_state.engine is AsyncIOEngine.POLLER:
-        _global_aio_state.cq.shutdown()
+        (<PollerCompletionQueue>_global_aio_state.cq).shutdown()
         grpc_shutdown_blocking()
     else:
         raise ValueError('Unsupported engine type [%s]' % _global_aio_state.engine)

src/python/grpcio/grpc/experimental/__init__.py

@@ -85,6 +85,6 @@ __all__ = (
     'insecure_channel_credentials',
 )
 
-if sys.version_info[0] >= 3:
+if sys.version_info[0] == 3 and sys.version_info[1] >= 6:
     from grpc._simple_stubs import unary_unary, unary_stream, stream_unary, stream_stream
     __all__ = __all__ + (unary_unary, unary_stream, stream_unary, stream_stream)

src/python/grpcio/grpc/experimental/aio/_base_call.py

@@ -117,6 +117,19 @@ class Call(RpcContext, metaclass=ABCMeta):
           The details string of the RPC.
         """
 
+    @abstractmethod
+    async def wait_for_connection(self) -> None:
+        """Waits until connected to peer and raises aio.AioRpcError if failed.
+
+        This is an EXPERIMENTAL method.
+
+        This method ensures the RPC has been successfully connected. Otherwise,
+        an AioRpcError will be raised to explain the reason of the connection
+        failure.
+
+        This method is recommended for building retry mechanisms.
+        """
+
 
 class UnaryUnaryCall(Generic[RequestType, ResponseType],
                      Call,

src/python/grpcio/grpc/experimental/aio/_base_channel.py

@@ -14,12 +14,13 @@
 """Abstract base classes for Channel objects and Multicallable objects."""
 
 import abc
-from typing import Any, AsyncIterable, Optional
+from typing import Any, Optional
 
 import grpc
 
 from . import _base_call
-from ._typing import DeserializingFunction, MetadataType, SerializingFunction
+from ._typing import (DeserializingFunction, MetadataType, RequestIterableType,
+                      SerializingFunction)
 
 _IMMUTABLE_EMPTY_TUPLE = tuple()
 
@@ -105,7 +106,7 @@ class StreamUnaryMultiCallable(abc.ABC):
 
     @abc.abstractmethod
     def __call__(self,
-                 request_async_iterator: Optional[AsyncIterable[Any]] = None,
+                 request_iterator: Optional[RequestIterableType] = None,
                  timeout: Optional[float] = None,
                  metadata: Optional[MetadataType] = _IMMUTABLE_EMPTY_TUPLE,
                  credentials: Optional[grpc.CallCredentials] = None,
@@ -115,7 +116,8 @@ class StreamUnaryMultiCallable(abc.ABC):
         """Asynchronously invokes the underlying RPC.
 
         Args:
-          request: The request value for the RPC.
+          request_iterator: An optional async iterable or iterable of request
+            messages for the RPC.
           timeout: An optional duration of time in seconds to allow
             for the RPC.
           metadata: Optional :term:`metadata` to be transmitted to the
@@ -142,7 +144,7 @@ class StreamStreamMultiCallable(abc.ABC):
 
     @abc.abstractmethod
     def __call__(self,
-                 request_async_iterator: Optional[AsyncIterable[Any]] = None,
+                 request_iterator: Optional[RequestIterableType] = None,
                  timeout: Optional[float] = None,
                  metadata: Optional[MetadataType] = _IMMUTABLE_EMPTY_TUPLE,
                  credentials: Optional[grpc.CallCredentials] = None,
@@ -152,7 +154,8 @@ class StreamStreamMultiCallable(abc.ABC):
         """Asynchronously invokes the underlying RPC.
 
         Args:
-          request: The request value for the RPC.
+          request_iterator: An optional async iterable or iterable of request
+            messages for the RPC.
           timeout: An optional duration of time in seconds to allow
             for the RPC.
           metadata: Optional :term:`metadata` to be transmitted to the

src/python/grpcio/grpc/experimental/aio/_call.py

@@ -14,10 +14,11 @@
 """Invocation-side implementation of gRPC Asyncio Python."""
 
 import asyncio
-from functools import partial
-import logging
 import enum
-from typing import AsyncIterable, Awaitable, Dict, Optional
+import inspect
+import logging
+from functools import partial
+from typing import AsyncIterable, Optional, Tuple
 
 import grpc
 from grpc import _common
@@ -25,7 +26,8 @@ from grpc._cython import cygrpc
 
 from . import _base_call
 from ._typing import (DeserializingFunction, DoneCallbackType, MetadataType,
-                      RequestType, ResponseType, SerializingFunction)
+                      MetadatumType, RequestIterableType, RequestType,
+                      ResponseType, SerializingFunction)
 
 __all__ = 'AioRpcError', 'Call', 'UnaryUnaryCall', 'UnaryStreamCall'
 
@@ -105,7 +107,7 @@ class AioRpcError(grpc.RpcError):
         """
         return self._details
 
-    def initial_metadata(self) -> Optional[Dict]:
+    def initial_metadata(self) -> Optional[MetadataType]:
         """Accesses the initial metadata sent by the server.
 
         Returns:
@@ -113,7 +115,7 @@ class AioRpcError(grpc.RpcError):
         """
         return self._initial_metadata
 
-    def trailing_metadata(self) -> Optional[Dict]:
+    def trailing_metadata(self) -> Optional[MetadataType]:
         """Accesses the trailing metadata sent by the server.
 
         Returns:
@@ -161,7 +163,7 @@ class Call:
     _loop: asyncio.AbstractEventLoop
     _code: grpc.StatusCode
     _cython_call: cygrpc._AioCall
-    _metadata: MetadataType
+    _metadata: Tuple[MetadatumType]
     _request_serializer: SerializingFunction
     _response_deserializer: DeserializingFunction
 
@@ -171,7 +173,7 @@ class Call:
                  loop: asyncio.AbstractEventLoop) -> None:
         self._loop = loop
         self._cython_call = cython_call
-        self._metadata = metadata
+        self._metadata = tuple(metadata)
         self._request_serializer = request_serializer
         self._response_deserializer = response_deserializer
 
@@ -248,9 +250,8 @@ class _APIStyle(enum.IntEnum):
 class _UnaryResponseMixin(Call):
     _call_response: asyncio.Task
 
-    def _init_unary_response_mixin(self,
-                                   response_coro: Awaitable[ResponseType]):
-        self._call_response = self._loop.create_task(response_coro)
+    def _init_unary_response_mixin(self, response_task: asyncio.Task):
+        self._call_response = response_task
 
     def cancel(self) -> bool:
         if super().cancel():
@@ -362,14 +363,14 @@ class _StreamRequestMixin(Call):
     _request_style: _APIStyle
 
     def _init_stream_request_mixin(
-            self, request_async_iterator: Optional[AsyncIterable[RequestType]]):
+            self, request_iterator: Optional[RequestIterableType]):
         self._metadata_sent = asyncio.Event(loop=self._loop)
         self._done_writing_flag = False
 
         # If user passes in an async iterator, create a consumer Task.
-        if request_async_iterator is not None:
+        if request_iterator is not None:
             self._async_request_poller = self._loop.create_task(
-                self._consume_request_iterator(request_async_iterator))
+                self._consume_request_iterator(request_iterator))
             self._request_style = _APIStyle.ASYNC_GENERATOR
         else:
             self._async_request_poller = None
@@ -391,11 +392,17 @@ class _StreamRequestMixin(Call):
     def _metadata_sent_observer(self):
         self._metadata_sent.set()
 
-    async def _consume_request_iterator(
-            self, request_async_iterator: AsyncIterable[RequestType]) -> None:
+    async def _consume_request_iterator(self,
+                                        request_iterator: RequestIterableType
+                                       ) -> None:
         try:
-            async for request in request_async_iterator:
-                await self._write(request)
+            if inspect.isasyncgen(request_iterator):
+                async for request in request_iterator:
+                    await self._write(request)
+            else:
+                for request in request_iterator:
+                    await self._write(request)
+
             await self._done_writing()
         except AioRpcError as rpc_error:
             # Rpc status should be exposed through other API. Exceptions raised
@@ -450,6 +457,11 @@ class _StreamRequestMixin(Call):
         self._raise_for_different_style(_APIStyle.READER_WRITER)
         await self._done_writing()
 
+    async def wait_for_connection(self) -> None:
+        await self._metadata_sent.wait()
+        if self.done():
+            await self._raise_for_status()
+
 
 class UnaryUnaryCall(_UnaryResponseMixin, Call, _base_call.UnaryUnaryCall):
     """Object for managing unary-unary RPC calls.
@@ -457,6 +469,7 @@ class UnaryUnaryCall(_UnaryResponseMixin, Call, _base_call.UnaryUnaryCall):
     Returned when an instance of `UnaryUnaryMultiCallable` object is called.
     """
     _request: RequestType
+    _invocation_task: asyncio.Task
 
     # pylint: disable=too-many-arguments
     def __init__(self, request: RequestType, deadline: Optional[float],
@@ -470,7 +483,8 @@ class UnaryUnaryCall(_UnaryResponseMixin, Call, _base_call.UnaryUnaryCall):
             channel.call(method, deadline, credentials, wait_for_ready),
             metadata, request_serializer, response_deserializer, loop)
         self._request = request
-        self._init_unary_response_mixin(self._invoke())
+        self._invocation_task = loop.create_task(self._invoke())
+        self._init_unary_response_mixin(self._invocation_task)
 
     async def _invoke(self) -> ResponseType:
         serialized_request = _common.serialize(self._request,
@@ -492,6 +506,11 @@ class UnaryUnaryCall(_UnaryResponseMixin, Call, _base_call.UnaryUnaryCall):
         else:
             return cygrpc.EOF
 
+    async def wait_for_connection(self) -> None:
+        await self._invocation_task
+        if self.done():
+            await self._raise_for_status()
+
 
 class UnaryStreamCall(_StreamResponseMixin, Call, _base_call.UnaryStreamCall):
     """Object for managing unary-stream RPC calls.
@@ -528,6 +547,11 @@ class UnaryStreamCall(_StreamResponseMixin, Call, _base_call.UnaryStreamCall):
                 self.cancel()
             raise
 
+    async def wait_for_connection(self) -> None:
+        await self._send_unary_request_task
+        if self.done():
+            await self._raise_for_status()
+
 
 class StreamUnaryCall(_StreamRequestMixin, _UnaryResponseMixin, Call,
                       _base_call.StreamUnaryCall):
@@ -537,8 +561,7 @@ class StreamUnaryCall(_StreamRequestMixin, _UnaryResponseMixin, Call,
     """
 
     # pylint: disable=too-many-arguments
-    def __init__(self,
-                 request_async_iterator: Optional[AsyncIterable[RequestType]],
+    def __init__(self, request_iterator: Optional[RequestIterableType],
                  deadline: Optional[float], metadata: MetadataType,
                  credentials: Optional[grpc.CallCredentials],
                  wait_for_ready: Optional[bool], channel: cygrpc.AioChannel,
@@ -549,8 +572,8 @@ class StreamUnaryCall(_StreamRequestMixin, _UnaryResponseMixin, Call,
             channel.call(method, deadline, credentials, wait_for_ready),
             metadata, request_serializer, response_deserializer, loop)
 
-        self._init_stream_request_mixin(request_async_iterator)
-        self._init_unary_response_mixin(self._conduct_rpc())
+        self._init_stream_request_mixin(request_iterator)
+        self._init_unary_response_mixin(loop.create_task(self._conduct_rpc()))
 
     async def _conduct_rpc(self) -> ResponseType:
         try:
@@ -576,8 +599,7 @@ class StreamStreamCall(_StreamRequestMixin, _StreamResponseMixin, Call,
     _initializer: asyncio.Task
 
     # pylint: disable=too-many-arguments
-    def __init__(self,
-                 request_async_iterator: Optional[AsyncIterable[RequestType]],
+    def __init__(self, request_iterator: Optional[RequestIterableType],
                  deadline: Optional[float], metadata: MetadataType,
                  credentials: Optional[grpc.CallCredentials],
                  wait_for_ready: Optional[bool], channel: cygrpc.AioChannel,
@@ -588,7 +610,7 @@ class StreamStreamCall(_StreamRequestMixin, _StreamResponseMixin, Call,
             channel.call(method, deadline, credentials, wait_for_ready),
             metadata, request_serializer, response_deserializer, loop)
         self._initializer = self._loop.create_task(self._prepare_rpc())
-        self._init_stream_request_mixin(request_async_iterator)
+        self._init_stream_request_mixin(request_iterator)
         self._init_stream_response_mixin(self._initializer)
 
     async def _prepare_rpc(self):

src/python/grpcio/grpc/experimental/aio/_channel.py

@@ -15,7 +15,7 @@
 
 import asyncio
 import sys
-from typing import Any, AsyncIterable, Iterable, Optional, Sequence
+from typing import Any, Iterable, Optional, Sequence
 
 import grpc
 from grpc import _common, _compression, _grpcio_metadata
@@ -27,7 +27,7 @@ from ._call import (StreamStreamCall, StreamUnaryCall, UnaryStreamCall,
 from ._interceptor import (InterceptedUnaryUnaryCall,
                            UnaryUnaryClientInterceptor)
 from ._typing import (ChannelArgumentType, DeserializingFunction, MetadataType,
-                      SerializingFunction)
+                      SerializingFunction, RequestIterableType)
 from ._utils import _timeout_to_deadline
 
 _IMMUTABLE_EMPTY_TUPLE = tuple()
@@ -146,7 +146,7 @@ class StreamUnaryMultiCallable(_BaseMultiCallable,
                                _base_channel.StreamUnaryMultiCallable):
 
     def __call__(self,
-                 request_async_iterator: Optional[AsyncIterable[Any]] = None,
+                 request_iterator: Optional[RequestIterableType] = None,
                  timeout: Optional[float] = None,
                  metadata: Optional[MetadataType] = _IMMUTABLE_EMPTY_TUPLE,
                  credentials: Optional[grpc.CallCredentials] = None,
@@ -158,7 +158,7 @@ class StreamUnaryMultiCallable(_BaseMultiCallable,
 
         deadline = _timeout_to_deadline(timeout)
 
-        call = StreamUnaryCall(request_async_iterator, deadline, metadata,
+        call = StreamUnaryCall(request_iterator, deadline, metadata,
                                credentials, wait_for_ready, self._channel,
                                self._method, self._request_serializer,
                                self._response_deserializer, self._loop)
@@ -170,7 +170,7 @@ class StreamStreamMultiCallable(_BaseMultiCallable,
                                 _base_channel.StreamStreamMultiCallable):
 
     def __call__(self,
-                 request_async_iterator: Optional[AsyncIterable[Any]] = None,
+                 request_iterator: Optional[RequestIterableType] = None,
                  timeout: Optional[float] = None,
                  metadata: Optional[MetadataType] = _IMMUTABLE_EMPTY_TUPLE,
                  credentials: Optional[grpc.CallCredentials] = None,
@@ -182,7 +182,7 @@ class StreamStreamMultiCallable(_BaseMultiCallable,
 
         deadline = _timeout_to_deadline(timeout)
 
-        call = StreamStreamCall(request_async_iterator, deadline, metadata,
+        call = StreamStreamCall(request_iterator, deadline, metadata,
                                 credentials, wait_for_ready, self._channel,
                                 self._method, self._request_serializer,
                                 self._response_deserializer, self._loop)

src/python/grpcio/grpc/experimental/aio/_interceptor.py

@@ -330,6 +330,10 @@ class InterceptedUnaryUnaryCall(_base_call.UnaryUnaryCall):
         response = yield from call.__await__()
         return response
 
+    async def wait_for_connection(self) -> None:
+        call = await self._interceptors_task
+        return await call.wait_for_connection()
+
 
 class UnaryUnaryCallResponse(_base_call.UnaryUnaryCall):
     """Final UnaryUnaryCall class finished with a response."""
@@ -374,3 +378,6 @@ class UnaryUnaryCallResponse(_base_call.UnaryUnaryCall):
             # for telling the interpreter that __await__ is a generator.
             yield None
         return self._response
+
+    async def wait_for_connection(self) -> None:
+        pass

src/python/grpcio/grpc/experimental/aio/_typing.py

@@ -13,7 +13,9 @@
 # limitations under the License.
 """Common types for gRPC Async API"""
 
-from typing import Any, AnyStr, Callable, Sequence, Tuple, TypeVar
+from typing import (Any, AnyStr, AsyncIterable, Callable, Iterable, Sequence,
+                    Tuple, TypeVar, Union)
+
 from grpc._cython.cygrpc import EOF
 
 RequestType = TypeVar('RequestType')
@@ -25,3 +27,4 @@ MetadataType = Sequence[MetadatumType]
 ChannelArgumentType = Sequence[Tuple[str, Any]]
 EOFType = type(EOF)
 DoneCallbackType = Callable[[Any], None]
+RequestIterableType = Union[Iterable[Any], AsyncIterable[Any]]

src/python/grpcio/grpc_core_dependencies.py

@@ -28,6 +28,7 @@ CORE_SOURCE_FILES = [
     'src/core/ext/filters/client_channel/http_connect_handshaker.cc',
     'src/core/ext/filters/client_channel/http_proxy.cc',
     'src/core/ext/filters/client_channel/lb_policy.cc',
+    'src/core/ext/filters/client_channel/lb_policy/address_filtering.cc',
     'src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc',
     'src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc',
     'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc',
@@ -36,9 +37,12 @@ CORE_SOURCE_FILES = [
     'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc',
     'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc',
     'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc',
+    'src/core/ext/filters/client_channel/lb_policy/priority/priority.cc',
     'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc',
+    'src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc',
     'src/core/ext/filters/client_channel/lb_policy/xds/cds.cc',
-    'src/core/ext/filters/client_channel/lb_policy/xds/xds.cc',
+    'src/core/ext/filters/client_channel/lb_policy/xds/eds.cc',
+    'src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc',
     'src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc',
     'src/core/ext/filters/client_channel/lb_policy_registry.cc',
     'src/core/ext/filters/client_channel/local_subchannel_pool.cc',

src/python/grpcio_tests/tests/protoc_plugin/_python_plugin_test.py

@@ -504,7 +504,8 @@ class PythonPluginTest(unittest.TestCase):
         service.server.stop(None)
 
 
-@unittest.skipIf(sys.version_info[0] < 3, "Unsupported on Python 2.")
+@unittest.skipIf(sys.version_info[0] < 3 or sys.version_info[1] < 6,
+                 "Unsupported on Python 2.")
 class SimpleStubsPluginTest(unittest.TestCase):
     servicer_methods = _ServicerMethods()
 

src/python/grpcio_tests/tests_aio/tests.json

@@ -28,5 +28,6 @@
   "unit.server_interceptor_test.TestServerInterceptor",
   "unit.server_test.TestServer",
   "unit.timeout_test.TestTimeout",
+  "unit.wait_for_connection_test.TestWaitForConnection",
   "unit.wait_for_ready_test.TestWaitForReady"
 ]

src/python/grpcio_tests/tests_aio/unit/call_test.py

@@ -16,23 +16,23 @@
 import asyncio
 import logging
 import unittest
+import datetime
 
 import grpc
 from grpc.experimental import aio
 
 from src.proto.grpc.testing import messages_pb2, test_pb2_grpc
-from tests.unit.framework.common import test_constants
 from tests_aio.unit._test_base import AioTestBase
-from tests.unit import resources
-
 from tests_aio.unit._test_server import start_test_server
+from tests_aio.unit._constants import UNREACHABLE_TARGET
+
+_SHORT_TIMEOUT_S = datetime.timedelta(seconds=1).total_seconds()
 
 _NUM_STREAM_RESPONSES = 5
 _RESPONSE_PAYLOAD_SIZE = 42
 _REQUEST_PAYLOAD_SIZE = 7
 _LOCAL_CANCEL_DETAILS_EXPECTATION = 'Locally cancelled by application!'
-_RESPONSE_INTERVAL_US = test_constants.SHORT_TIMEOUT * 1000 * 1000
-_UNREACHABLE_TARGET = '0.1:1111'
+_RESPONSE_INTERVAL_US = int(_SHORT_TIMEOUT_S * 1000 * 1000)
 _INFINITE_INTERVAL_US = 2**31 - 1
 
 
@@ -78,7 +78,7 @@ class TestUnaryUnaryCall(_MulticallableTestMixin, AioTestBase):
         self.assertIs(response, response_retry)
 
     async def test_call_rpc_error(self):
-        async with aio.insecure_channel(_UNREACHABLE_TARGET) as channel:
+        async with aio.insecure_channel(UNREACHABLE_TARGET) as channel:
             stub = test_pb2_grpc.TestServiceStub(channel)
 
             call = stub.UnaryCall(messages_pb2.SimpleRequest())
@@ -434,24 +434,24 @@ class TestUnaryStreamCall(_MulticallableTestMixin, AioTestBase):
                 interval_us=_RESPONSE_INTERVAL_US,
             ))
 
-        call = self._stub.StreamingOutputCall(
-            request, timeout=test_constants.SHORT_TIMEOUT * 2)
+        call = self._stub.StreamingOutputCall(request,
+                                              timeout=_SHORT_TIMEOUT_S * 2)
 
         response = await call.read()
         self.assertEqual(_RESPONSE_PAYLOAD_SIZE, len(response.payload.body))
 
         # Should be around the same as the timeout
         remained_time = call.time_remaining()
-        self.assertGreater(remained_time, test_constants.SHORT_TIMEOUT * 3 / 2)
-        self.assertLess(remained_time, test_constants.SHORT_TIMEOUT * 5 / 2)
+        self.assertGreater(remained_time, _SHORT_TIMEOUT_S * 3 / 2)
+        self.assertLess(remained_time, _SHORT_TIMEOUT_S * 5 / 2)
 
         response = await call.read()
         self.assertEqual(_RESPONSE_PAYLOAD_SIZE, len(response.payload.body))
 
         # Should be around the timeout minus a unit of wait time
         remained_time = call.time_remaining()
-        self.assertGreater(remained_time, test_constants.SHORT_TIMEOUT / 2)
-        self.assertLess(remained_time, test_constants.SHORT_TIMEOUT * 3 / 2)
+        self.assertGreater(remained_time, _SHORT_TIMEOUT_S / 2)
+        self.assertLess(remained_time, _SHORT_TIMEOUT_S * 3 / 2)
 
         self.assertEqual(grpc.StatusCode.OK, await call.code())
 
@@ -538,14 +538,14 @@ class TestStreamUnaryCall(_MulticallableTestMixin, AioTestBase):
             with self.assertRaises(asyncio.CancelledError):
                 for _ in range(_NUM_STREAM_RESPONSES):
                     yield request
-                    await asyncio.sleep(test_constants.SHORT_TIMEOUT)
+                    await asyncio.sleep(_SHORT_TIMEOUT_S)
             request_iterator_received_the_exception.set()
 
         call = self._stub.StreamingInputCall(request_iterator())
 
         # Cancel the RPC after at least one response
         async def cancel_later():
-            await asyncio.sleep(test_constants.SHORT_TIMEOUT * 2)
+            await asyncio.sleep(_SHORT_TIMEOUT_S * 2)
             call.cancel()
 
         cancel_later_task = self.loop.create_task(cancel_later())
@@ -559,6 +559,50 @@ class TestStreamUnaryCall(_MulticallableTestMixin, AioTestBase):
         # No failures in the cancel later task!
         await cancel_later_task
 
+    async def test_normal_iterable_requests(self):
+        # Prepares the request
+        payload = messages_pb2.Payload(body=b'\0' * _REQUEST_PAYLOAD_SIZE)
+        request = messages_pb2.StreamingInputCallRequest(payload=payload)
+        requests = [request] * _NUM_STREAM_RESPONSES
+
+        # Sends out requests
+        call = self._stub.StreamingInputCall(requests)
+
+        # RPC should succeed
+        response = await call
+        self.assertIsInstance(response, messages_pb2.StreamingInputCallResponse)
+        self.assertEqual(_NUM_STREAM_RESPONSES * _REQUEST_PAYLOAD_SIZE,
+                         response.aggregated_payload_size)
+
+        self.assertEqual(await call.code(), grpc.StatusCode.OK)
+
+    async def test_call_rpc_error(self):
+        async with aio.insecure_channel(UNREACHABLE_TARGET) as channel:
+            stub = test_pb2_grpc.TestServiceStub(channel)
+
+            # The error should be raised automatically without any traffic.
+            call = stub.StreamingInputCall()
+            with self.assertRaises(aio.AioRpcError) as exception_context:
+                await call
+
+            self.assertEqual(grpc.StatusCode.UNAVAILABLE,
+                             exception_context.exception.code())
+
+            self.assertTrue(call.done())
+            self.assertEqual(grpc.StatusCode.UNAVAILABLE, await call.code())
+
+    async def test_timeout(self):
+        call = self._stub.StreamingInputCall(timeout=_SHORT_TIMEOUT_S)
+
+        # The error should be raised automatically without any traffic.
+        with self.assertRaises(aio.AioRpcError) as exception_context:
+            await call
+
+        rpc_error = exception_context.exception
+        self.assertEqual(grpc.StatusCode.DEADLINE_EXCEEDED, rpc_error.code())
+        self.assertTrue(call.done())
+        self.assertEqual(grpc.StatusCode.DEADLINE_EXCEEDED, await call.code())
+
 
 # Prepares the request that stream in a ping-pong manner.
 _STREAM_OUTPUT_REQUEST_ONE_RESPONSE = messages_pb2.StreamingOutputCallRequest()
@@ -716,14 +760,14 @@ class TestStreamStreamCall(_MulticallableTestMixin, AioTestBase):
             with self.assertRaises(asyncio.CancelledError):
                 for _ in range(_NUM_STREAM_RESPONSES):
                     yield request
-                    await asyncio.sleep(test_constants.SHORT_TIMEOUT)
+                    await asyncio.sleep(_SHORT_TIMEOUT_S)
             request_iterator_received_the_exception.set()
 
         call = self._stub.FullDuplexCall(request_iterator())
 
         # Cancel the RPC after at least one response
         async def cancel_later():
-            await asyncio.sleep(test_constants.SHORT_TIMEOUT * 2)
+            await asyncio.sleep(_SHORT_TIMEOUT_S * 2)
             call.cancel()
 
         cancel_later_task = self.loop.create_task(cancel_later())
@@ -738,6 +782,15 @@ class TestStreamStreamCall(_MulticallableTestMixin, AioTestBase):
         # No failures in the cancel later task!
         await cancel_later_task
 
+    async def test_normal_iterable_requests(self):
+        requests = [_STREAM_OUTPUT_REQUEST_ONE_RESPONSE] * _NUM_STREAM_RESPONSES
+
+        call = self._stub.FullDuplexCall(iter(requests))
+        async for response in call:
+            self.assertEqual(_RESPONSE_PAYLOAD_SIZE, len(response.payload.body))
+
+        self.assertEqual(await call.code(), grpc.StatusCode.OK)
+
 
 if __name__ == '__main__':
     logging.basicConfig(level=logging.DEBUG)

src/python/grpcio_tests/tests_aio/unit/metadata_test.py

@@ -210,14 +210,21 @@ class TestMetadata(AioTestBase):
         self.assertEqual(_RESPONSE, await call)
         self.assertEqual(grpc.StatusCode.OK, await call.code())
 
+    async def test_from_client_to_server_with_list(self):
+        multicallable = self._client.unary_unary(_TEST_CLIENT_TO_SERVER)
+        call = multicallable(
+            _REQUEST, metadata=list(_INITIAL_METADATA_FROM_CLIENT_TO_SERVER))
+        self.assertEqual(_RESPONSE, await call)
+        self.assertEqual(grpc.StatusCode.OK, await call.code())
+
     @unittest.skipIf(platform.system() == 'Windows',
                      'https://github.com/grpc/grpc/issues/21943')
     async def test_invalid_metadata(self):
         multicallable = self._client.unary_unary(_TEST_CLIENT_TO_SERVER)
         for exception_type, metadata in _INVALID_METADATA_TEST_CASES:
             with self.subTest(metadata=metadata):
-                call = multicallable(_REQUEST, metadata=metadata)
                 with self.assertRaises(exception_type):
+                    call = multicallable(_REQUEST, metadata=metadata)
                     await call
 
     async def test_generic_handler(self):

src/python/grpcio_tests/tests_aio/unit/wait_for_connection_test.py

@@ -0,0 +1,159 @@
+# Copyright 2020 The gRPC Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Tests behavior of the wait for connection API on client side."""
+
+import asyncio
+import logging
+import unittest
+import datetime
+from typing import Callable, Tuple
+
+import grpc
+from grpc.experimental import aio
+
+from tests_aio.unit._test_base import AioTestBase
+from tests_aio.unit._test_server import start_test_server
+from tests_aio.unit import _common
+from src.proto.grpc.testing import messages_pb2, test_pb2_grpc
+from tests_aio.unit._constants import UNREACHABLE_TARGET
+
+_REQUEST = b'\x01\x02\x03'
+_TEST_METHOD = '/test/Test'
+
+_NUM_STREAM_RESPONSES = 5
+_REQUEST_PAYLOAD_SIZE = 7
+_RESPONSE_PAYLOAD_SIZE = 42
+
+
+class TestWaitForConnection(AioTestBase):
+    """Tests if wait_for_connection raises connectivity issue."""
+
+    async def setUp(self):
+        address, self._server = await start_test_server()
+        self._channel = aio.insecure_channel(address)
+        self._dummy_channel = aio.insecure_channel(UNREACHABLE_TARGET)
+        self._stub = test_pb2_grpc.TestServiceStub(self._channel)
+
+    async def tearDown(self):
+        await self._dummy_channel.close()
+        await self._channel.close()
+        await self._server.stop(None)
+
+    async def test_unary_unary_ok(self):
+        call = self._stub.UnaryCall(messages_pb2.SimpleRequest())
+
+        # No exception raised and no message swallowed.
+        await call.wait_for_connection()
+
+        response = await call
+        self.assertIsInstance(response, messages_pb2.SimpleResponse)
+
+    async def test_unary_stream_ok(self):
+        request = messages_pb2.StreamingOutputCallRequest()
+        for _ in range(_NUM_STREAM_RESPONSES):
+            request.response_parameters.append(
+                messages_pb2.ResponseParameters(size=_RESPONSE_PAYLOAD_SIZE))
+
+        call = self._stub.StreamingOutputCall(request)
+
+        # No exception raised and no message swallowed.
+        await call.wait_for_connection()
+
+        response_cnt = 0
+        async for response in call:
+            response_cnt += 1
+            self.assertIs(type(response),
+                          messages_pb2.StreamingOutputCallResponse)
+            self.assertEqual(_RESPONSE_PAYLOAD_SIZE, len(response.payload.body))
+
+        self.assertEqual(_NUM_STREAM_RESPONSES, response_cnt)
+        self.assertEqual(await call.code(), grpc.StatusCode.OK)
+
+    async def test_stream_unary_ok(self):
+        call = self._stub.StreamingInputCall()
+
+        # No exception raised and no message swallowed.
+        await call.wait_for_connection()
+
+        payload = messages_pb2.Payload(body=b'\0' * _REQUEST_PAYLOAD_SIZE)
+        request = messages_pb2.StreamingInputCallRequest(payload=payload)
+
+        for _ in range(_NUM_STREAM_RESPONSES):
+            await call.write(request)
+        await call.done_writing()
+
+        response = await call
+        self.assertIsInstance(response, messages_pb2.StreamingInputCallResponse)
+        self.assertEqual(_NUM_STREAM_RESPONSES * _REQUEST_PAYLOAD_SIZE,
+                         response.aggregated_payload_size)
+
+        self.assertEqual(await call.code(), grpc.StatusCode.OK)
+
+    async def test_stream_stream_ok(self):
+        call = self._stub.FullDuplexCall()
+
+        # No exception raised and no message swallowed.
+        await call.wait_for_connection()
+
+        request = messages_pb2.StreamingOutputCallRequest()
+        request.response_parameters.append(
+            messages_pb2.ResponseParameters(size=_RESPONSE_PAYLOAD_SIZE))
+
+        for _ in range(_NUM_STREAM_RESPONSES):
+            await call.write(request)
+            response = await call.read()
+            self.assertIsInstance(response,
+                                  messages_pb2.StreamingOutputCallResponse)
+            self.assertEqual(_RESPONSE_PAYLOAD_SIZE, len(response.payload.body))
+
+        await call.done_writing()
+
+        self.assertEqual(grpc.StatusCode.OK, await call.code())
+
+    async def test_unary_unary_error(self):
+        call = self._dummy_channel.unary_unary(_TEST_METHOD)(_REQUEST)
+
+        with self.assertRaises(aio.AioRpcError) as exception_context:
+            await call.wait_for_connection()
+        rpc_error = exception_context.exception
+        self.assertEqual(grpc.StatusCode.UNAVAILABLE, rpc_error.code())
+
+    async def test_unary_stream_error(self):
+        call = self._dummy_channel.unary_stream(_TEST_METHOD)(_REQUEST)
+
+        with self.assertRaises(aio.AioRpcError) as exception_context:
+            await call.wait_for_connection()
+        rpc_error = exception_context.exception
+        self.assertEqual(grpc.StatusCode.UNAVAILABLE, rpc_error.code())
+
+    async def test_stream_unary_error(self):
+        call = self._dummy_channel.stream_unary(_TEST_METHOD)()
+
+        with self.assertRaises(aio.AioRpcError) as exception_context:
+            await call.wait_for_connection()
+        rpc_error = exception_context.exception
+        self.assertEqual(grpc.StatusCode.UNAVAILABLE, rpc_error.code())
+
+    async def test_stream_stream_error(self):
+        call = self._dummy_channel.stream_stream(_TEST_METHOD)()
+
+        with self.assertRaises(aio.AioRpcError) as exception_context:
+            await call.wait_for_connection()
+        rpc_error = exception_context.exception
+        self.assertEqual(grpc.StatusCode.UNAVAILABLE, rpc_error.code())
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.DEBUG)
+    unittest.main(verbosity=2)

templates/test/cpp/naming/resolver_component_tests_defs.include

@@ -55,7 +55,7 @@ if cur_resolver and cur_resolver != 'ares':
       'needs to use GRPC_DNS_RESOLVER=ares.'))
   test_runner_log('Exit 1 without running tests.')
   sys.exit(1)
-os.environ.update({'GRPC_TRACE': 'cares_resolver'})
+os.environ.update({'GRPC_TRACE': 'cares_resolver,cares_address_sorting'})
 
 def wait_until_dns_server_is_up(args,
                                 dns_server_subprocess,

templates/tools/dockerfile/interoptest/grpc_interop_dart/Dockerfile.template

@@ -14,10 +14,7 @@
   # See the License for the specific language governing permissions and
   # limitations under the License.
 
-  FROM google/dart:2.3
-
-  # Upgrade Dart to version 2.
-  RUN apt-get update && apt-get upgrade -y dart
+  FROM google/dart:2.7
 
   # Define the default command.
   CMD ["bash"]

templates/tools/dockerfile/test/python_stretch_default_x64/Dockerfile.template

@@ -16,7 +16,11 @@
 
   <%include file="../../python_stretch.include"/>
   <%include file="../../compile_python_36.include"/>
-  
+  <%include file="../../compile_python_38.include"/>
+
+  RUN apt-get update && apt-get install -y python3.5 python3.5-dev
+  RUN curl https://bootstrap.pypa.io/get-pip.py | python3.5
+
   RUN apt-get update && apt-get -t buster install -y python3.7 python3-all-dev
   RUN curl https://bootstrap.pypa.io/get-pip.py | python3.7
 

test/core/client_channel/service_config_test.cc

@@ -464,7 +464,7 @@ TEST_F(ClientChannelParserTest, ValidLoadBalancingConfigXds) {
       "{\n"
       "  \"loadBalancingConfig\":[\n"
       "    { \"does_not_exist\":{} },\n"
-      "    { \"xds_experimental\":{ \"balancerName\": \"fake:///lb\" } }\n"
+      "    { \"eds_experimental\":{ \"clusterName\": \"foo\" } }\n"
       "  ]\n"
       "}";
   grpc_error* error = GRPC_ERROR_NONE;
@@ -474,7 +474,7 @@ TEST_F(ClientChannelParserTest, ValidLoadBalancingConfigXds) {
       static_cast<grpc_core::internal::ClientChannelGlobalParsedConfig*>(
           svc_cfg->GetGlobalParsedConfig(0));
   auto lb_config = parsed_config->parsed_lb_config();
-  EXPECT_STREQ(lb_config->name(), "xds_experimental");
+  EXPECT_STREQ(lb_config->name(), "eds_experimental");
 }
 
 TEST_F(ClientChannelParserTest, UnknownLoadBalancingConfig) {
@@ -544,14 +544,14 @@ TEST_F(ClientChannelParserTest, UnknownLoadBalancingPolicy) {
 }
 
 TEST_F(ClientChannelParserTest, LoadBalancingPolicyXdsNotAllowed) {
-  const char* test_json = "{\"loadBalancingPolicy\":\"xds_experimental\"}";
+  const char* test_json = "{\"loadBalancingPolicy\":\"eds_experimental\"}";
   grpc_error* error = GRPC_ERROR_NONE;
   auto svc_cfg = ServiceConfig::Create(test_json, &error);
   std::regex regex(
       "Service config parsing error.*referenced_errors.*"
       "Global Params.*referenced_errors.*"
       "Client channel global parser.*referenced_errors.*"
-      "field:loadBalancingPolicy error:xds_experimental requires "
+      "field:loadBalancingPolicy error:eds_experimental requires "
       "a config. Please use loadBalancingConfig instead.");
   VerifyRegexMatch(error, regex);
 }

test/core/compression/message_compress_fuzzer.cc

@@ -39,7 +39,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   grpc_core::testing::LeakDetector leak_detector(true);
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   grpc_slice_buffer input_buffer;
   grpc_slice_buffer_init(&input_buffer);
   grpc_slice_buffer_add(&input_buffer,
@@ -52,7 +51,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   grpc_slice_buffer_destroy(&input_buffer);
   grpc_slice_buffer_destroy(&output_buffer);
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
   return 0;
 }

test/core/compression/message_decompress_fuzzer.cc

@@ -39,7 +39,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   grpc_core::testing::LeakDetector leak_detector(true);
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   grpc_slice_buffer input_buffer;
   grpc_slice_buffer_init(&input_buffer);
   grpc_slice_buffer_add(&input_buffer,
@@ -52,7 +51,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   grpc_slice_buffer_destroy(&input_buffer);
   grpc_slice_buffer_destroy(&output_buffer);
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
   return 0;
 }

test/core/compression/stream_compression_fuzzer.cc

@@ -31,7 +31,6 @@ bool leak_check = true;
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_core::testing::LeakDetector leak_detector(true);
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   auto* context = grpc_stream_compression_context_create(
       GRPC_STREAM_COMPRESSION_GZIP_COMPRESS);
   grpc_slice_buffer input_buffer;
@@ -48,7 +47,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_stream_compression_context_destroy(context);
   grpc_slice_buffer_destroy(&input_buffer);
   grpc_slice_buffer_destroy(&output_buffer);
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
   return 0;
 }

test/core/compression/stream_decompression_fuzzer.cc

@@ -31,7 +31,6 @@ bool leak_check = true;
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_core::testing::LeakDetector leak_detector(true);
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   auto* context = grpc_stream_compression_context_create(
       GRPC_STREAM_COMPRESSION_GZIP_DECOMPRESS);
   grpc_slice_buffer input_buffer;
@@ -49,7 +48,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_stream_compression_context_destroy(context);
   grpc_slice_buffer_destroy(&input_buffer);
   grpc_slice_buffer_destroy(&output_buffer);
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
   return 0;
 }

test/core/end2end/BUILD

@@ -190,6 +190,13 @@ grpc_end2end_nosec_tests()
 grpc_cc_test(
     name = "h2_ssl_session_reuse_test",
     srcs = ["h2_ssl_session_reuse_test.cc"],
+    data = [
+        "//src/core/tsi/test_creds:ca.pem",
+        "//src/core/tsi/test_creds:client.key",
+        "//src/core/tsi/test_creds:client.pem",
+        "//src/core/tsi/test_creds:server1.key",
+        "//src/core/tsi/test_creds:server1.pem",
+    ],
     external_deps = [
         "gtest",
     ],

test/core/end2end/README

@@ -3,5 +3,5 @@ forms a complete end-to-end test.
 
 To add a new test or fixture:
 - add the code to the relevant directory
-- update gen_build_yaml.py to reflect the change
+- update generate_tests.bzl to reflect the change
 - regenerate projects

test/core/end2end/fixtures/h2_oauth2.cc

@@ -16,22 +16,26 @@
  *
  */
 
-#include "test/core/end2end/end2end_tests.h"
-
-#include <stdio.h>
-#include <string.h>
-
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <stdio.h>
+#include <string.h>
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gprpp/host_port.h"
 #include "src/core/lib/iomgr/iomgr.h"
+#include "src/core/lib/iomgr/load_file.h"
 #include "src/core/lib/security/credentials/credentials.h"
-#include "test/core/end2end/data/ssl_test_data.h"
+#include "test/core/end2end/end2end_tests.h"
 #include "test/core/util/port.h"
 #include "test/core/util/test_config.h"
 
+#define CA_CERT_PATH "src/core/tsi/test_creds/ca.pem"
+#define CLIENT_CERT_PATH "src/core/tsi/test_creds/client.pem"
+#define CLIENT_KEY_PATH "src/core/tsi/test_creds/client.key"
+#define SERVER_CERT_PATH "src/core/tsi/test_creds/server1.pem"
+#define SERVER_KEY_PATH "src/core/tsi/test_creds/server1.key"
+
 static const char oauth2_md[] = "Bearer aaslkfjs424535asdf";
 static const char* client_identity_property_name = "smurf_name";
 static const char* client_identity = "Brainy Smurf";
@@ -139,6 +143,11 @@ void chttp2_tear_down_secure_fullstack(grpc_end2end_test_fixture* f) {
 static void chttp2_init_client_simple_ssl_with_oauth2_secure_fullstack(
     grpc_end2end_test_fixture* f, grpc_channel_args* client_args) {
   grpc_core::ExecCtx exec_ctx;
+  grpc_slice ca_slice;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(CA_CERT_PATH, 1, &ca_slice)));
+  const char* test_root_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(ca_slice);
   grpc_channel_credentials* ssl_creds =
       grpc_ssl_credentials_create(test_root_cert, nullptr, nullptr, nullptr);
   grpc_call_credentials* oauth2_creds = grpc_md_only_test_credentials_create(
@@ -156,6 +165,7 @@ static void chttp2_init_client_simple_ssl_with_oauth2_secure_fullstack(
   grpc_channel_args_destroy(new_client_args);
   grpc_channel_credentials_release(ssl_creds);
   grpc_call_credentials_release(oauth2_creds);
+  grpc_slice_unref(ca_slice);
 }
 
 static int fail_server_auth_check(grpc_channel_args* server_args) {
@@ -193,13 +203,23 @@ static grpc_auth_metadata_processor test_processor_create(int failing) {
 
 static void chttp2_init_server_simple_ssl_secure_fullstack(
     grpc_end2end_test_fixture* f, grpc_channel_args* server_args) {
-  grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {test_server1_key,
-                                                  test_server1_cert};
+  grpc_slice cert_slice, key_slice;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "load_file", grpc_load_file(SERVER_CERT_PATH, 1, &cert_slice)));
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(SERVER_KEY_PATH, 1, &key_slice)));
+  const char* server_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(cert_slice);
+  const char* server_key =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(key_slice);
+  grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {server_key, server_cert};
   grpc_server_credentials* ssl_creds = grpc_ssl_server_credentials_create(
       nullptr, &pem_key_cert_pair, 1, 0, nullptr);
   grpc_server_credentials_set_auth_metadata_processor(
       ssl_creds, test_processor_create(fail_server_auth_check(server_args)));
   chttp2_init_server_secure_fullstack(f, server_args, ssl_creds);
+  grpc_slice_unref(cert_slice);
+  grpc_slice_unref(key_slice);
 }
 
 /* All test configurations */

test/core/end2end/fixtures/h2_ssl.cc

@@ -16,23 +16,26 @@
  *
  */
 
-#include "test/core/end2end/end2end_tests.h"
-
-#include <stdio.h>
-#include <string.h>
-
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <stdio.h>
+#include <string.h>
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gpr/tmpfile.h"
 #include "src/core/lib/gprpp/host_port.h"
+#include "src/core/lib/iomgr/load_file.h"
 #include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/security/security_connector/ssl_utils_config.h"
-#include "test/core/end2end/data/ssl_test_data.h"
+#include "test/core/end2end/end2end_tests.h"
 #include "test/core/util/port.h"
 #include "test/core/util/test_config.h"
+#define CA_CERT_PATH "src/core/tsi/test_creds/ca.pem"
+#define CLIENT_CERT_PATH "src/core/tsi/test_creds/client.pem"
+#define CLIENT_KEY_PATH "src/core/tsi/test_creds/client.key"
+#define SERVER_CERT_PATH "src/core/tsi/test_creds/server1.pem"
+#define SERVER_KEY_PATH "src/core/tsi/test_creds/server1.key"
 
 struct fullstack_secure_fixture_data {
   grpc_core::UniquePtr<char> localaddr;
@@ -124,10 +127,20 @@ static int fail_server_auth_check(grpc_channel_args* server_args) {
 
 static void chttp2_init_server_simple_ssl_secure_fullstack(
     grpc_end2end_test_fixture* f, grpc_channel_args* server_args) {
-  grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {test_server1_key,
-                                                  test_server1_cert};
+  grpc_slice cert_slice, key_slice;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "load_file", grpc_load_file(SERVER_CERT_PATH, 1, &cert_slice)));
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(SERVER_KEY_PATH, 1, &key_slice)));
+  const char* server_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(cert_slice);
+  const char* server_key =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(key_slice);
+  grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {server_key, server_cert};
   grpc_server_credentials* ssl_creds = grpc_ssl_server_credentials_create(
-      nullptr, &pem_cert_key_pair, 1, 0, nullptr);
+      nullptr, &pem_key_cert_pair, 1, 0, nullptr);
+  grpc_slice_unref(cert_slice);
+  grpc_slice_unref(key_slice);
   if (fail_server_auth_check(server_args)) {
     grpc_auth_metadata_processor processor = {process_auth_failure, nullptr,
                                               nullptr};
@@ -152,20 +165,9 @@ static grpc_end2end_test_config configs[] = {
 
 int main(int argc, char** argv) {
   size_t i;
-  FILE* roots_file;
-  size_t roots_size = strlen(test_root_cert);
-  char* roots_filename;
-
   grpc::testing::TestEnvironment env(argc, argv);
   grpc_end2end_tests_pre_init();
-
-  /* Set the SSL roots env var. */
-  roots_file = gpr_tmpfile("chttp2_simple_ssl_fullstack_test", &roots_filename);
-  GPR_ASSERT(roots_filename != nullptr);
-  GPR_ASSERT(roots_file != nullptr);
-  GPR_ASSERT(fwrite(test_root_cert, 1, roots_size, roots_file) == roots_size);
-  fclose(roots_file);
-  GPR_GLOBAL_CONFIG_SET(grpc_default_ssl_roots_file_path, roots_filename);
+  GPR_GLOBAL_CONFIG_SET(grpc_default_ssl_roots_file_path, CA_CERT_PATH);
 
   grpc_init();
 
@@ -174,10 +176,5 @@ int main(int argc, char** argv) {
   }
 
   grpc_shutdown();
-
-  /* Cleanup. */
-  remove(roots_filename);
-  gpr_free(roots_filename);
-
   return 0;
 }

test/core/end2end/fuzzers/client_fuzzer.cc

@@ -24,7 +24,6 @@
 
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/iomgr/executor.h"
-#include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/channel.h"
 #include "test/core/util/mock_endpoint.h"
@@ -42,7 +41,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_test_only_set_slice_hash_seed(0);
   if (squelch) gpr_set_log_function(dont_log);
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   {
     grpc_core::ExecCtx exec_ctx;
     grpc_core::Executor::SetThreadingAll(false);
@@ -158,7 +156,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
       grpc_byte_buffer_destroy(response_payload_recv);
     }
   }
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
   return 0;
 }

test/core/end2end/fuzzers/server_fuzzer.cc

@@ -20,7 +20,6 @@
 
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/iomgr/executor.h"
-#include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/server.h"
 #include "test/core/util/mock_endpoint.h"
@@ -39,7 +38,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_test_only_set_slice_hash_seed(0);
   if (squelch) gpr_set_log_function(dont_log);
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   {
     grpc_core::ExecCtx exec_ctx;
     grpc_core::Executor::SetThreadingAll(false);
@@ -133,7 +131,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
     grpc_server_destroy(server);
     grpc_completion_queue_destroy(cq);
   }
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown();
   return 0;
 }

test/core/end2end/gen_build_yaml.py

@@ -11,408 +11,36 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-"""Generates the appropriate build.json data for all the end2end tests."""
-
-from __future__ import print_function
+"""Generates the list of end2end test cases from generate_tests.bzl"""
 
+import os
+import sys
 import yaml
-import collections
-import hashlib
-
-FixtureOptions = collections.namedtuple(
-    'FixtureOptions',
-    'fullstack includes_proxy dns_resolver name_resolution secure platforms ci_mac tracing exclude_configs exclude_iomgrs large_writes enables_compression supports_compression is_inproc is_http2 supports_proxy_auth supports_write_buffering client_channel'
-)
-default_unsecure_fixture_options = FixtureOptions(
-    True, False, True, True, False, ['windows', 'linux', 'mac', 'posix'], True,
-    False, [], [], True, False, True, False, True, False, True, True)
-socketpair_unsecure_fixture_options = default_unsecure_fixture_options._replace(
-    fullstack=False, dns_resolver=False, client_channel=False)
-default_secure_fixture_options = default_unsecure_fixture_options._replace(
-    secure=True)
-uds_fixture_options = default_unsecure_fixture_options._replace(
-    dns_resolver=False,
-    platforms=['linux', 'mac', 'posix'],
-    exclude_iomgrs=['uv'])
-local_fixture_options = default_secure_fixture_options._replace(
-    dns_resolver=False,
-    platforms=['linux', 'mac', 'posix'],
-    exclude_iomgrs=['uv'])
-fd_unsecure_fixture_options = default_unsecure_fixture_options._replace(
-    dns_resolver=False,
-    fullstack=False,
-    platforms=['linux', 'mac', 'posix'],
-    exclude_iomgrs=['uv'],
-    client_channel=False)
-inproc_fixture_options = default_secure_fixture_options._replace(
-    dns_resolver=False,
-    fullstack=False,
-    name_resolution=False,
-    supports_compression=False,
-    is_inproc=True,
-    is_http2=False,
-    supports_write_buffering=False,
-    client_channel=False)
-
-# maps fixture name to whether it requires the security library
-END2END_FIXTURES = {
-    'h2_compress':
-        default_unsecure_fixture_options._replace(enables_compression=True),
-    'h2_census':
-        default_unsecure_fixture_options,
-    # This cmake target is disabled for now because it depends on OpenCensus,
-    # which is Bazel-only.
-    # 'h2_load_reporting': default_unsecure_fixture_options,
-    'h2_fakesec':
-        default_secure_fixture_options._replace(ci_mac=False),
-    'h2_fd':
-        fd_unsecure_fixture_options,
-    'h2_full':
-        default_unsecure_fixture_options,
-    'h2_full+pipe':
-        default_unsecure_fixture_options._replace(platforms=['linux'],
-                                                  exclude_iomgrs=['uv']),
-    'h2_full+trace':
-        default_unsecure_fixture_options._replace(tracing=True),
-    'h2_full+workarounds':
-        default_unsecure_fixture_options,
-    'h2_http_proxy':
-        default_unsecure_fixture_options._replace(ci_mac=False,
-                                                  exclude_iomgrs=['uv'],
-                                                  supports_proxy_auth=True),
-    'h2_oauth2':
-        default_secure_fixture_options._replace(ci_mac=False,
-                                                exclude_iomgrs=['uv']),
-    'h2_proxy':
-        default_unsecure_fixture_options._replace(includes_proxy=True,
-                                                  ci_mac=False,
-                                                  exclude_iomgrs=['uv']),
-    'h2_sockpair_1byte':
-        socketpair_unsecure_fixture_options._replace(ci_mac=False,
-                                                     exclude_configs=['msan'],
-                                                     large_writes=False,
-                                                     exclude_iomgrs=['uv']),
-    'h2_sockpair':
-        socketpair_unsecure_fixture_options._replace(ci_mac=False,
-                                                     exclude_iomgrs=['uv']),
-    'h2_sockpair+trace':
-        socketpair_unsecure_fixture_options._replace(ci_mac=False,
-                                                     tracing=True,
-                                                     large_writes=False,
-                                                     exclude_iomgrs=['uv']),
-    'h2_ssl':
-        default_secure_fixture_options,
-    'h2_ssl_cred_reload':
-        default_secure_fixture_options,
-    'h2_tls':
-        default_secure_fixture_options,
-    'h2_local_uds':
-        local_fixture_options,
-    'h2_local_ipv4':
-        local_fixture_options,
-    'h2_local_ipv6':
-        local_fixture_options,
-    'h2_ssl_proxy':
-        default_secure_fixture_options._replace(includes_proxy=True,
-                                                ci_mac=False,
-                                                exclude_iomgrs=['uv']),
-    'h2_uds':
-        uds_fixture_options,
-    'inproc':
-        inproc_fixture_options
-}
 
-TestOptions = collections.namedtuple(
-    'TestOptions',
-    'needs_fullstack needs_dns needs_names proxyable secure traceable cpu_cost exclude_iomgrs large_writes flaky allows_compression needs_compression exclude_inproc needs_http2 needs_proxy_auth needs_write_buffering needs_client_channel'
-)
-default_test_options = TestOptions(False, False, False, True, False, True, 1.0,
-                                   [], False, False, True, False, False, False,
-                                   False, False, False)
-connectivity_test_options = default_test_options._replace(needs_fullstack=True)
+_ROOT = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '../../..'))
+os.chdir(_ROOT)
 
-LOWCPU = 0.1
 
-# maps test names to options
-END2END_TESTS = {
-    'authority_not_supported':
-        default_test_options,
-    'bad_hostname':
-        default_test_options._replace(needs_names=True),
-    'bad_ping':
-        connectivity_test_options._replace(proxyable=False),
-    'binary_metadata':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'resource_quota_server':
-        default_test_options._replace(large_writes=True,
-                                      proxyable=False,
-                                      allows_compression=False),
-    'call_creds':
-        default_test_options._replace(secure=True),
-    'cancel_after_accept':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'cancel_after_client_done':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'cancel_after_invoke':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'cancel_after_round_trip':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'cancel_before_invoke':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'cancel_in_a_vacuum':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'cancel_with_status':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'compressed_payload':
-        default_test_options._replace(proxyable=False, needs_compression=True),
-    'connectivity':
-        connectivity_test_options._replace(needs_names=True,
-                                           proxyable=False,
-                                           cpu_cost=LOWCPU,
-                                           exclude_iomgrs=['uv']),
-    'channelz':
-        default_test_options,
-    'default_host':
-        default_test_options._replace(needs_fullstack=True,
-                                      needs_dns=True,
-                                      needs_names=True),
-    'call_host_override':
-        default_test_options._replace(needs_fullstack=True,
-                                      needs_dns=True,
-                                      needs_names=True),
-    'disappearing_server':
-        connectivity_test_options._replace(flaky=True, needs_names=True),
-    'empty_batch':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'filter_causes_close':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'filter_call_init_fails':
-        default_test_options,
-    'filter_context':
-        default_test_options,
-    'filter_latency':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'filter_status_code':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'graceful_server_shutdown':
-        default_test_options._replace(cpu_cost=LOWCPU, exclude_inproc=True),
-    'hpack_size':
-        default_test_options._replace(proxyable=False,
-                                      traceable=False,
-                                      cpu_cost=LOWCPU),
-    'high_initial_seqno':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'idempotent_request':
-        default_test_options,
-    'invoke_large_request':
-        default_test_options,
-    'keepalive_timeout':
-        default_test_options._replace(proxyable=False,
-                                      cpu_cost=LOWCPU,
-                                      needs_http2=True),
-    'large_metadata':
-        default_test_options,
-    'max_concurrent_streams':
-        default_test_options._replace(proxyable=False,
-                                      cpu_cost=LOWCPU,
-                                      exclude_inproc=True),
-    'max_connection_age':
-        default_test_options._replace(cpu_cost=LOWCPU, exclude_inproc=True),
-    'max_connection_idle':
-        connectivity_test_options._replace(proxyable=False,
-                                           exclude_iomgrs=['uv'],
-                                           cpu_cost=LOWCPU),
-    'max_message_length':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'negative_deadline':
-        default_test_options,
-    'no_error_on_hotpath':
-        default_test_options._replace(proxyable=False),
-    'no_logging':
-        default_test_options._replace(traceable=False),
-    'no_op':
-        default_test_options,
-    'payload':
-        default_test_options,
-    # This cmake target is disabled for now because it depends on OpenCensus,
-    # which is Bazel-only.
-    # 'load_reporting_hook': default_test_options,
-    'ping_pong_streaming':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'ping':
-        connectivity_test_options._replace(proxyable=False, cpu_cost=LOWCPU),
-    'proxy_auth':
-        default_test_options._replace(needs_proxy_auth=True),
-    'registered_call':
-        default_test_options,
-    'request_with_flags':
-        default_test_options._replace(proxyable=False, cpu_cost=LOWCPU),
-    'request_with_payload':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    # TODO(roth): Remove proxyable=False for all retry tests once we
-    # have a way for the proxy to propagate the fact that trailing
-    # metadata is available when initial metadata is returned.
-    # See https://github.com/grpc/grpc/issues/14467 for context.
-    'retry':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_cancellation':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_disabled':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_exceeds_buffer_size_in_initial_batch':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_exceeds_buffer_size_in_subsequent_batch':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_non_retriable_status':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_non_retriable_status_before_recv_trailing_metadata_started':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_recv_initial_metadata':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_recv_message':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_server_pushback_delay':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_server_pushback_disabled':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_streaming':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_streaming_after_commit':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_streaming_succeeds_before_replay_finished':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_throttled':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'retry_too_many_attempts':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_client_channel=True,
-                                      proxyable=False),
-    'server_finishes_request':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'shutdown_finishes_calls':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'shutdown_finishes_tags':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'simple_cacheable_request':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'stream_compression_compressed_payload':
-        default_test_options._replace(proxyable=False, exclude_inproc=True),
-    'stream_compression_payload':
-        default_test_options._replace(exclude_inproc=True),
-    'stream_compression_ping_pong_streaming':
-        default_test_options._replace(exclude_inproc=True),
-    'simple_delayed_request':
-        connectivity_test_options,
-    'simple_metadata':
-        default_test_options,
-    'simple_request':
-        default_test_options,
-    'streaming_error_response':
-        default_test_options._replace(cpu_cost=LOWCPU),
-    'trailing_metadata':
-        default_test_options,
-    'workaround_cronet_compression':
-        default_test_options,
-    'write_buffering':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_write_buffering=True),
-    'write_buffering_at_end':
-        default_test_options._replace(cpu_cost=LOWCPU,
-                                      needs_write_buffering=True),
-}
+def load(*args):
+    """Replacement of bazel's load() function"""
+    pass
 
 
-def compatible(f, t):
-    if END2END_TESTS[t].needs_fullstack:
-        if not END2END_FIXTURES[f].fullstack:
-            return False
-    if END2END_TESTS[t].needs_dns:
-        if not END2END_FIXTURES[f].dns_resolver:
-            return False
-    if END2END_TESTS[t].needs_names:
-        if not END2END_FIXTURES[f].name_resolution:
-            return False
-    if not END2END_TESTS[t].proxyable:
-        if END2END_FIXTURES[f].includes_proxy:
-            return False
-    if not END2END_TESTS[t].traceable:
-        if END2END_FIXTURES[f].tracing:
-            return False
-    if END2END_TESTS[t].large_writes:
-        if not END2END_FIXTURES[f].large_writes:
-            return False
-    if not END2END_TESTS[t].allows_compression:
-        if END2END_FIXTURES[f].enables_compression:
-            return False
-    if END2END_TESTS[t].needs_compression:
-        if not END2END_FIXTURES[f].supports_compression:
-            return False
-    if END2END_TESTS[t].exclude_inproc:
-        if END2END_FIXTURES[f].is_inproc:
-            return False
-    if END2END_TESTS[t].needs_http2:
-        if not END2END_FIXTURES[f].is_http2:
-            return False
-    if END2END_TESTS[t].needs_proxy_auth:
-        if not END2END_FIXTURES[f].supports_proxy_auth:
-            return False
-    if END2END_TESTS[t].needs_write_buffering:
-        if not END2END_FIXTURES[f].supports_write_buffering:
-            return False
-    if END2END_TESTS[t].needs_client_channel:
-        if not END2END_FIXTURES[f].client_channel:
-            return False
-    return True
+def struct(**kwargs):
+    return kwargs  # all the args as a dict
 
 
-def without(l, e):
-    l = l[:]
-    l.remove(e)
-    return l
+# generate_tests.bzl is now the source of truth for end2end tests.
+# The .bzl file is basically a python file and we can "execute" it
+# to get access to the variables it defines.
+execfile('test/core/end2end/generate_tests.bzl')
 
 
-# Originally, this method was used to generate end2end test cases for build.yaml,
-# but since the test cases are now extracted from bazel BUILD file,
-# this is not used for generating run_tests.py test cases anymore.
-# Nevertheless, subset of the output is still used by end2end_tests.cc.template
-# and end2end_nosec_tests.cc.template
-# TODO(jtattermusch): cleanup this file, so that it only generates the data we need.
-# Right now there's some duplication between generate_tests.bzl and this file.
 def main():
     json = {
         # needed by end2end_tests.cc.template and end2end_nosec_tests.cc.template
         'core_end2end_tests':
-            dict((t, END2END_TESTS[t].secure) for t in END2END_TESTS.keys())
+            dict((t, END2END_TESTS[t]['secure']) for t in END2END_TESTS.keys())
     }
     print(yaml.dump(json))
 

test/core/end2end/generate_tests.bzl

@@ -282,6 +282,9 @@ END2END_TESTS = {
     "retry_exceeds_buffer_size_in_initial_batch": _test_options(
         needs_client_channel = True,
         proxyable = False,
+        # TODO(jtattermusch): too long bazel test name makes the test flaky on Windows RBE
+        # See b/151617965
+        short_name = "retry_exceeds_buffer_size_in_init",
     ),
     "retry_exceeds_buffer_size_in_subsequent_batch": _test_options(
         needs_client_channel = True,
@@ -429,6 +432,13 @@ def grpc_end2end_tests():
             name = "%s_test" % f,
             srcs = ["fixtures/%s.cc" % f],
             language = "C++",
+            data = [
+                "//src/core/tsi/test_creds:ca.pem",
+                "//src/core/tsi/test_creds:client.key",
+                "//src/core/tsi/test_creds:client.pem",
+                "//src/core/tsi/test_creds:server1.key",
+                "//src/core/tsi/test_creds:server1.pem",
+            ],
             deps = [
                 ":end2end_tests",
                 "//test/core/util:grpc_test_util",
@@ -499,6 +509,13 @@ def grpc_end2end_nosec_tests():
             name = "%s_nosec_test" % f,
             srcs = ["fixtures/%s.cc" % f],
             language = "C++",
+            data = [
+                "//src/core/tsi/test_creds:ca.pem",
+                "//src/core/tsi/test_creds:client.key",
+                "//src/core/tsi/test_creds:client.pem",
+                "//src/core/tsi/test_creds:server1.key",
+                "//src/core/tsi/test_creds:server1.pem",
+            ],
             deps = [
                 ":end2end_nosec_tests",
                 "//test/core/util:grpc_test_util_unsecure",

test/core/end2end/h2_ssl_session_reuse_test.cc

@@ -16,26 +16,29 @@
  *
  */
 
-#include "test/core/end2end/end2end_tests.h"
-
-#include <stdio.h>
-#include <string.h>
-
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <gtest/gtest.h>
+#include <stdio.h>
+#include <string.h>
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gpr/tmpfile.h"
 #include "src/core/lib/gprpp/host_port.h"
+#include "src/core/lib/iomgr/load_file.h"
 #include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/security/security_connector/ssl_utils_config.h"
 #include "test/core/end2end/cq_verifier.h"
-#include "test/core/end2end/data/ssl_test_data.h"
+#include "test/core/end2end/end2end_tests.h"
 #include "test/core/util/port.h"
 #include "test/core/util/test_config.h"
 
-#include <gtest/gtest.h>
+#define CA_CERT_PATH "src/core/tsi/test_creds/ca.pem"
+#define CLIENT_CERT_PATH "src/core/tsi/test_creds/client.pem"
+#define CLIENT_KEY_PATH "src/core/tsi/test_creds/client.key"
+#define SERVER_CERT_PATH "src/core/tsi/test_creds/server1.pem"
+#define SERVER_KEY_PATH "src/core/tsi/test_creds/server1.key"
 
 namespace grpc {
 namespace testing {
@@ -46,10 +49,22 @@ void* tag(intptr_t t) { return (void*)t; }
 gpr_timespec five_seconds_time() { return grpc_timeout_seconds_to_deadline(5); }
 
 grpc_server* server_create(grpc_completion_queue* cq, char* server_addr) {
-  grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {test_server1_key,
-                                                  test_server1_cert};
+  grpc_slice ca_slice, cert_slice, key_slice;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(CA_CERT_PATH, 1, &ca_slice)));
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "load_file", grpc_load_file(SERVER_CERT_PATH, 1, &cert_slice)));
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(SERVER_KEY_PATH, 1, &key_slice)));
+  const char* ca_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(ca_slice);
+  const char* server_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(cert_slice);
+  const char* server_key =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(key_slice);
+  grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {server_key, server_cert};
   grpc_server_credentials* server_creds = grpc_ssl_server_credentials_create_ex(
-      test_root_cert, &pem_cert_key_pair, 1,
+      ca_cert, &pem_cert_key_pair, 1,
       GRPC_SSL_REQUEST_CLIENT_CERTIFICATE_AND_VERIFY, nullptr);
 
   grpc_server* server = grpc_server_create(nullptr, nullptr);
@@ -59,14 +74,30 @@ grpc_server* server_create(grpc_completion_queue* cq, char* server_addr) {
   grpc_server_credentials_release(server_creds);
   grpc_server_start(server);
 
+  grpc_slice_unref(cert_slice);
+  grpc_slice_unref(key_slice);
+  grpc_slice_unref(ca_slice);
   return server;
 }
 
 grpc_channel* client_create(char* server_addr, grpc_ssl_session_cache* cache) {
-  grpc_ssl_pem_key_cert_pair signed_client_key_cert_pair = {
-      test_signed_client_key, test_signed_client_cert};
+  grpc_slice ca_slice, cert_slice, key_slice;
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(CA_CERT_PATH, 1, &ca_slice)));
+  GPR_ASSERT(GRPC_LOG_IF_ERROR(
+      "load_file", grpc_load_file(CLIENT_CERT_PATH, 1, &cert_slice)));
+  GPR_ASSERT(GRPC_LOG_IF_ERROR("load_file",
+                               grpc_load_file(CLIENT_KEY_PATH, 1, &key_slice)));
+  const char* ca_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(ca_slice);
+  const char* client_cert =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(cert_slice);
+  const char* client_key =
+      reinterpret_cast<const char*> GRPC_SLICE_START_PTR(key_slice);
+  grpc_ssl_pem_key_cert_pair signed_client_key_cert_pair = {client_key,
+                                                            client_cert};
   grpc_channel_credentials* client_creds = grpc_ssl_credentials_create(
-      test_root_cert, &signed_client_key_cert_pair, nullptr, nullptr);
+      ca_cert, &signed_client_key_cert_pair, nullptr, nullptr);
 
   grpc_arg args[] = {
       grpc_channel_arg_string_create(
@@ -88,6 +119,9 @@ grpc_channel* client_create(char* server_addr, grpc_ssl_session_cache* cache) {
     grpc_channel_args_destroy(client_args);
   }
 
+  grpc_slice_unref(cert_slice);
+  grpc_slice_unref(key_slice);
+  grpc_slice_unref(ca_slice);
   return client;
 }
 
@@ -253,27 +287,13 @@ TEST(H2SessionReuseTest, SingleReuse) {
 }  // namespace grpc
 
 int main(int argc, char** argv) {
-  FILE* roots_file;
-  size_t roots_size = strlen(test_root_cert);
-  char* roots_filename;
-
   grpc::testing::TestEnvironment env(argc, argv);
-  /* Set the SSL roots env var. */
-  roots_file = gpr_tmpfile("chttp2_ssl_session_reuse_test", &roots_filename);
-  GPR_ASSERT(roots_filename != nullptr);
-  GPR_ASSERT(roots_file != nullptr);
-  GPR_ASSERT(fwrite(test_root_cert, 1, roots_size, roots_file) == roots_size);
-  fclose(roots_file);
-  GPR_GLOBAL_CONFIG_SET(grpc_default_ssl_roots_file_path, roots_filename);
+  GPR_GLOBAL_CONFIG_SET(grpc_default_ssl_roots_file_path, CA_CERT_PATH);
 
   grpc_init();
   ::testing::InitGoogleTest(&argc, argv);
   int ret = RUN_ALL_TESTS();
   grpc_shutdown();
 
-  /* Cleanup. */
-  remove(roots_filename);
-  gpr_free(roots_filename);
-
   return ret;
 }

test/core/security/BUILD

@@ -79,19 +79,6 @@ grpc_cc_test(
     ],
 )
 
-grpc_cc_test(
-    name = "control_plane_credentials_test",
-    srcs = ["control_plane_credentials_test.cc"],
-    language = "C++",
-    deps = [
-        "//:gpr",
-        "//:grpc",
-        "//test/core/end2end:cq_verifier",
-        "//test/core/end2end:ssl_test_data",
-        "//test/core/util:grpc_test_util",
-    ],
-)
-
 grpc_cc_test(
     name = "json_token_test",
     srcs = ["json_token_test.cc"],

test/core/security/alts_credentials_fuzzer.cc

@@ -29,7 +29,6 @@
 #include "src/core/lib/security/credentials/alts/alts_credentials.h"
 #include "src/core/lib/security/credentials/alts/check_gcp_environment.h"
 #include "src/core/lib/security/credentials/alts/grpc_alts_credentials_options.h"
-#include "src/core/lib/security/credentials/credentials.h"
 
 using grpc_core::testing::grpc_fuzzer_get_next_byte;
 using grpc_core::testing::grpc_fuzzer_get_next_string;
@@ -68,7 +67,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   gpr_free(grpc_trace_fuzzer);
   input_stream inp = {data, data + size};
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   bool is_on_gcp = grpc_alts_is_running_on_gcp();
   while (inp.cur != inp.end) {
     bool enable_untrusted_alts = grpc_fuzzer_get_next_byte(&inp) & 0x01;
@@ -107,7 +105,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
     }
     gpr_free(handshaker_service_url);
   }
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown();
   return 0;
 }

test/core/security/control_plane_credentials_test.cc

@@ -1,458 +0,0 @@
-/*
- *
- * Copyright 2019 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/lib/security/credentials/credentials.h"
-
-#include <openssl/rsa.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <grpc/grpc_security.h>
-#include <grpc/slice.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/time.h>
-
-#include "src/core/lib/gprpp/host_port.h"
-#include "src/core/lib/iomgr/error.h"
-#include "src/core/lib/security/credentials/composite/composite_credentials.h"
-#include "src/core/lib/slice/slice_string_helpers.h"
-
-#include "test/core/util/port.h"
-#include "test/core/util/test_config.h"
-
-#include "test/core/end2end/cq_verifier.h"
-#include "test/core/end2end/data/ssl_test_data.h"
-
-namespace {
-
-grpc_completion_queue* g_cq;
-grpc_server* g_server;
-int g_port;
-
-void drain_cq(grpc_completion_queue* cq) {
-  grpc_event ev;
-  do {
-    ev = grpc_completion_queue_next(
-        cq, grpc_timeout_milliseconds_to_deadline(5000), nullptr);
-  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
-}
-
-void* tag(int i) { return (void*)static_cast<intptr_t>(i); }
-
-grpc_channel_credentials* create_test_ssl_plus_token_channel_creds(
-    const char* token) {
-  grpc_channel_credentials* channel_creds =
-      grpc_ssl_credentials_create(test_root_cert, nullptr, nullptr, nullptr);
-  grpc_call_credentials* call_creds =
-      grpc_access_token_credentials_create(token, nullptr);
-  grpc_channel_credentials* composite_creds =
-      grpc_composite_channel_credentials_create(channel_creds, call_creds,
-                                                nullptr);
-  grpc_channel_credentials_release(channel_creds);
-  grpc_call_credentials_release(call_creds);
-  return composite_creds;
-}
-
-grpc_server_credentials* create_test_ssl_server_creds() {
-  grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {test_server1_key,
-                                                  test_server1_cert};
-  return grpc_ssl_server_credentials_create_ex(
-      test_root_cert, &pem_cert_key_pair, 1,
-      GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE, nullptr);
-}
-
-// Perform a simple RPC and capture the ASCII value of the
-// authorization metadata sent to the server, if any. Return
-// nullptr if no authorization metadata was sent to the server.
-grpc_core::UniquePtr<char> perform_call_and_get_authorization_header(
-    grpc_channel_credentials* channel_creds) {
-  // Create a new channel and call
-  grpc_core::UniquePtr<char> server_addr = nullptr;
-  grpc_core::JoinHostPort(&server_addr, "localhost", g_port);
-  grpc_arg ssl_name_override = {
-      GRPC_ARG_STRING,
-      const_cast<char*>(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG),
-      {const_cast<char*>("foo.test.google.fr")}};
-  grpc_channel_args* channel_args =
-      grpc_channel_args_copy_and_add(nullptr, &ssl_name_override, 1);
-  grpc_channel* channel = grpc_secure_channel_create(
-      channel_creds, server_addr.get(), channel_args, nullptr);
-  grpc_channel_args_destroy(channel_args);
-  grpc_call* c;
-  grpc_call* s;
-  cq_verifier* cqv = cq_verifier_create(g_cq);
-  grpc_op ops[6];
-  grpc_op* op;
-  grpc_metadata_array initial_metadata_recv;
-  grpc_metadata_array trailing_metadata_recv;
-  grpc_metadata_array request_metadata_recv;
-  grpc_call_details call_details;
-  grpc_status_code status;
-  grpc_call_error error;
-  grpc_slice details;
-  gpr_timespec deadline = grpc_timeout_seconds_to_deadline(5);
-  grpc_slice request_payload_slice = grpc_slice_from_copied_string("request");
-  grpc_byte_buffer* request_payload =
-      grpc_raw_byte_buffer_create(&request_payload_slice, 1);
-  grpc_slice response_payload_slice = grpc_slice_from_copied_string("response");
-  grpc_byte_buffer* response_payload =
-      grpc_raw_byte_buffer_create(&response_payload_slice, 1);
-  grpc_byte_buffer* request_payload_recv = nullptr;
-  grpc_byte_buffer* response_payload_recv = nullptr;
-  // Start a call
-  c = grpc_channel_create_call(channel, nullptr, GRPC_PROPAGATE_DEFAULTS, g_cq,
-                               grpc_slice_from_static_string("/foo"), nullptr,
-                               deadline, nullptr);
-  GPR_ASSERT(c);
-  grpc_metadata_array_init(&initial_metadata_recv);
-  grpc_metadata_array_init(&trailing_metadata_recv);
-  grpc_metadata_array_init(&request_metadata_recv);
-  grpc_call_details_init(&call_details);
-  memset(ops, 0, sizeof(ops));
-  op = ops;
-  op->op = GRPC_OP_SEND_INITIAL_METADATA;
-  op->data.send_initial_metadata.count = 0;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  op->op = GRPC_OP_SEND_MESSAGE;
-  op->data.send_message.send_message = request_payload;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  op->op = GRPC_OP_RECV_INITIAL_METADATA;
-  op->data.recv_initial_metadata.recv_initial_metadata = &initial_metadata_recv;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  op->op = GRPC_OP_RECV_MESSAGE;
-  op->data.recv_message.recv_message = &response_payload_recv;
-  op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
-  op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
-  op->data.recv_status_on_client.status = &status;
-  op->data.recv_status_on_client.status_details = &details;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  error = grpc_call_start_batch(c, ops, static_cast<size_t>(op - ops), tag(1),
-                                nullptr);
-  GPR_ASSERT(GRPC_CALL_OK == error);
-  // Request a call on the server
-  error =
-      grpc_server_request_call(g_server, &s, &call_details,
-                               &request_metadata_recv, g_cq, g_cq, tag(101));
-  GPR_ASSERT(GRPC_CALL_OK == error);
-  CQ_EXPECT_COMPLETION(cqv, tag(101), 1);
-  cq_verify(cqv);
-  memset(ops, 0, sizeof(ops));
-  op = ops;
-  op->op = GRPC_OP_SEND_INITIAL_METADATA;
-  op->data.send_initial_metadata.count = 0;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  op->op = GRPC_OP_SEND_MESSAGE;
-  op->data.send_message.send_message = response_payload;
-  op->flags = 0;
-  op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
-  op->data.send_status_from_server.trailing_metadata_count = 0;
-  op->data.send_status_from_server.status = GRPC_STATUS_OK;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  op->op = GRPC_OP_RECV_MESSAGE;
-  op->data.recv_message.recv_message = &request_payload_recv;
-  op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
-  op->flags = 0;
-  op->reserved = nullptr;
-  op++;
-  error = grpc_call_start_batch(s, ops, static_cast<size_t>(op - ops), tag(102),
-                                nullptr);
-  GPR_ASSERT(GRPC_CALL_OK == error);
-  CQ_EXPECT_COMPLETION(cqv, tag(102), 1);
-  CQ_EXPECT_COMPLETION(cqv, tag(1), 1);
-  cq_verify(cqv);
-  GPR_ASSERT(status == GRPC_STATUS_OK);
-  // Extract the ascii value of the authorization header, if present
-  grpc_core::UniquePtr<char> authorization_header_val;
-  gpr_log(GPR_DEBUG, "RPC done. Now examine received metadata on server...");
-  for (size_t i = 0; i < request_metadata_recv.count; i++) {
-    char* cur_key =
-        grpc_dump_slice(request_metadata_recv.metadata[i].key, GPR_DUMP_ASCII);
-    char* cur_val = grpc_dump_slice(request_metadata_recv.metadata[i].value,
-                                    GPR_DUMP_ASCII);
-    gpr_log(GPR_DEBUG, "key[%" PRIdPTR "]=%s val[%" PRIdPTR "]=%s", i, cur_key,
-            i, cur_val);
-    if (gpr_stricmp(cur_key, "authorization") == 0) {
-      // This test is broken if we found multiple authorization headers.
-      GPR_ASSERT(authorization_header_val == nullptr);
-      authorization_header_val.reset(gpr_strdup(cur_val));
-      gpr_log(GPR_DEBUG, "Found authorization header: %s",
-              authorization_header_val.get());
-    }
-    gpr_free(cur_key);
-    gpr_free(cur_val);
-  }
-  // cleanup
-  grpc_slice_unref(details);
-  grpc_metadata_array_destroy(&initial_metadata_recv);
-  grpc_metadata_array_destroy(&trailing_metadata_recv);
-  grpc_metadata_array_destroy(&request_metadata_recv);
-  grpc_call_details_destroy(&call_details);
-  grpc_byte_buffer_destroy(request_payload);
-  grpc_byte_buffer_destroy(response_payload);
-  grpc_byte_buffer_destroy(request_payload_recv);
-  grpc_byte_buffer_destroy(response_payload_recv);
-  grpc_call_unref(c);
-  grpc_call_unref(s);
-  cq_verifier_destroy(cqv);
-  grpc_channel_destroy(channel);
-  return authorization_header_val;
-}
-
-void test_attach_and_get() {
-  grpc_channel_credentials* main_creds =
-      create_test_ssl_plus_token_channel_creds("main-auth-header");
-  grpc_channel_credentials* foo_creds =
-      create_test_ssl_plus_token_channel_creds("foo-auth-header");
-  grpc_channel_credentials* bar_creds =
-      create_test_ssl_plus_token_channel_creds("bar-auth-header");
-  auto foo_key = grpc_core::UniquePtr<char>(gpr_strdup("foo"));
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(
-                 main_creds, foo_key.get(), foo_creds) == true);
-  auto bar_key = grpc_core::UniquePtr<char>(gpr_strdup("bar"));
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(
-                 main_creds, bar_key.get(), bar_creds) == true);
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(main_creds, "foo",
-                                                         foo_creds) == false);
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(main_creds, "bar",
-                                                         bar_creds) == false);
-  grpc_channel_credentials_release(foo_creds);
-  grpc_channel_credentials_release(bar_creds);
-  {
-    // Creds that send auth header with value "foo-auth-header" are attached on
-    // main creds under key "foo"
-    auto foo_auth_header = perform_call_and_get_authorization_header(
-        main_creds->get_control_plane_credentials("foo").get());
-    GPR_ASSERT(foo_auth_header != nullptr &&
-               gpr_stricmp(foo_auth_header.get(), "Bearer foo-auth-header") ==
-                   0);
-  }
-  {
-    // Creds that send auth header with value "bar-auth-header" are attached on
-    // main creds under key "bar"
-    auto bar_auth_header = perform_call_and_get_authorization_header(
-        main_creds->get_control_plane_credentials("bar").get());
-    GPR_ASSERT(bar_auth_header != nullptr &&
-               gpr_stricmp(bar_auth_header.get(), "Bearer bar-auth-header") ==
-                   0);
-  }
-  {
-    // Sanity check that the main creds themselves send an authorization header
-    // with value "main".
-    auto main_auth_header =
-        perform_call_and_get_authorization_header(main_creds);
-    GPR_ASSERT(main_auth_header != nullptr &&
-               gpr_stricmp(main_auth_header.get(), "Bearer main-auth-header") ==
-                   0);
-  }
-  {
-    // If a key isn't mapped in the per channel or global registries, then the
-    // credentials should be returned but with their per-call creds stripped.
-    // The end effect is that we shouldn't see any authorization metadata
-    // sent from client to server.
-    auto unmapped_auth_header = perform_call_and_get_authorization_header(
-        main_creds->get_control_plane_credentials("unmapped").get());
-    GPR_ASSERT(unmapped_auth_header == nullptr);
-  }
-  grpc_channel_credentials_release(main_creds);
-}
-
-void test_registering_same_creds_under_different_keys() {
-  grpc_channel_credentials* main_creds =
-      create_test_ssl_plus_token_channel_creds("main-auth-header");
-  grpc_channel_credentials* foo_creds =
-      create_test_ssl_plus_token_channel_creds("foo-auth-header");
-  auto foo_key = grpc_core::UniquePtr<char>(gpr_strdup("foo"));
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(
-                 main_creds, foo_key.get(), foo_creds) == true);
-  auto foo2_key = grpc_core::UniquePtr<char>(gpr_strdup("foo2"));
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(
-                 main_creds, foo2_key.get(), foo_creds) == true);
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(main_creds, "foo",
-                                                         foo_creds) == false);
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(main_creds, "foo2",
-                                                         foo_creds) == false);
-  grpc_channel_credentials_release(foo_creds);
-  {
-    // Access foo creds via foo
-    auto foo_auth_header = perform_call_and_get_authorization_header(
-        main_creds->get_control_plane_credentials("foo").get());
-    GPR_ASSERT(foo_auth_header != nullptr &&
-               gpr_stricmp(foo_auth_header.get(), "Bearer foo-auth-header") ==
-                   0);
-  }
-  {
-    // Access foo creds via foo2
-    auto foo_auth_header = perform_call_and_get_authorization_header(
-        main_creds->get_control_plane_credentials("foo2").get());
-    GPR_ASSERT(foo_auth_header != nullptr &&
-               gpr_stricmp(foo_auth_header.get(), "Bearer foo-auth-header") ==
-                   0);
-  }
-  grpc_channel_credentials_release(main_creds);
-}
-
-// Note that this test uses control plane creds registered in the global
-// map. This global registration is done before this and any other
-// test is invoked.
-void test_attach_and_get_with_global_registry() {
-  grpc_channel_credentials* main_creds =
-      create_test_ssl_plus_token_channel_creds("main-auth-header");
-  grpc_channel_credentials* global_override_creds =
-      create_test_ssl_plus_token_channel_creds("global-override-auth-header");
-  grpc_channel_credentials* random_creds =
-      create_test_ssl_plus_token_channel_creds("random-auth-header");
-  auto global_key = grpc_core::UniquePtr<char>(gpr_strdup("global"));
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(
-                 main_creds, global_key.get(), global_override_creds) == true);
-  GPR_ASSERT(grpc_channel_credentials_attach_credentials(
-                 main_creds, "global", global_override_creds) == false);
-  grpc_channel_credentials_release(global_override_creds);
-  {
-    // The global registry should be used if a key isn't registered on the per
-    // channel registry
-    auto global_auth_header = perform_call_and_get_authorization_header(
-        random_creds->get_control_plane_credentials("global").get());
-    GPR_ASSERT(global_auth_header != nullptr &&
-               gpr_stricmp(global_auth_header.get(),
-                           "Bearer global-auth-header") == 0);
-  }
-  {
-    // The per-channel registry should be preferred over the global registry
-    auto override_auth_header = perform_call_and_get_authorization_header(
-        main_creds->get_control_plane_credentials("global").get());
-    GPR_ASSERT(override_auth_header != nullptr &&
-               gpr_stricmp(override_auth_header.get(),
-                           "Bearer global-override-auth-header") == 0);
-  }
-  {
-    // Sanity check that random creds themselves send authorization header with
-    // value "random".
-    auto random_auth_header =
-        perform_call_and_get_authorization_header(random_creds);
-    GPR_ASSERT(random_auth_header != nullptr &&
-               gpr_stricmp(random_auth_header.get(),
-                           "Bearer random-auth-header") == 0);
-  }
-  {
-    // If a key isn't mapped in the per channel or global registries, then the
-    // credentials should be returned but with their per-call creds stripped.
-    // The end effect is that we shouldn't see any authorization metadata
-    // sent from client to server.
-    auto unmapped_auth_header = perform_call_and_get_authorization_header(
-        random_creds->get_control_plane_credentials("unmapped").get());
-    GPR_ASSERT(unmapped_auth_header == nullptr);
-  }
-  grpc_channel_credentials_release(main_creds);
-  grpc_channel_credentials_release(random_creds);
-}
-
-}  // namespace
-
-int main(int argc, char** argv) {
-  {
-    grpc::testing::TestEnvironment env(argc, argv);
-    grpc_init();
-    // First setup a global server for all tests to use
-    g_cq = grpc_completion_queue_create_for_next(nullptr);
-    grpc_server_credentials* server_creds = create_test_ssl_server_creds();
-    g_server = grpc_server_create(nullptr, nullptr);
-    g_port = grpc_pick_unused_port_or_die();
-    grpc_server_register_completion_queue(g_server, g_cq, nullptr);
-    grpc_core::UniquePtr<char> localaddr;
-    grpc_core::JoinHostPort(&localaddr, "localhost", g_port);
-    GPR_ASSERT(grpc_server_add_secure_http2_port(g_server, localaddr.get(),
-                                                 server_creds));
-    grpc_server_credentials_release(server_creds);
-    grpc_server_start(g_server);
-    {
-      // First, Register one channel creds in the global registry; all tests
-      // will have access.
-      grpc_channel_credentials* global_creds =
-          create_test_ssl_plus_token_channel_creds("global-auth-header");
-      auto global_key = grpc_core::UniquePtr<char>(gpr_strdup("global"));
-      GPR_ASSERT(grpc_control_plane_credentials_register(global_key.get(),
-                                                         global_creds) == true);
-      GPR_ASSERT(grpc_control_plane_credentials_register(
-                     "global", global_creds) == false);
-      grpc_channel_credentials_release(global_creds);
-    }
-    // Run tests
-    {
-      test_attach_and_get();
-      test_registering_same_creds_under_different_keys();
-      test_attach_and_get_with_global_registry();
-    }
-    // cleanup
-    grpc_completion_queue* shutdown_cq =
-        grpc_completion_queue_create_for_pluck(nullptr);
-    grpc_server_shutdown_and_notify(g_server, shutdown_cq, tag(1000));
-    GPR_ASSERT(grpc_completion_queue_pluck(shutdown_cq, tag(1000),
-                                           grpc_timeout_seconds_to_deadline(5),
-                                           nullptr)
-                   .type == GRPC_OP_COMPLETE);
-    grpc_server_destroy(g_server);
-    grpc_completion_queue_shutdown(shutdown_cq);
-    grpc_completion_queue_destroy(shutdown_cq);
-    grpc_completion_queue_shutdown(g_cq);
-    drain_cq(g_cq);
-    grpc_completion_queue_destroy(g_cq);
-    grpc_shutdown();
-  }
-  {
-    grpc::testing::TestEnvironment env(argc, argv);
-    grpc_init();
-    // The entries in the global registry must still persist through
-    // a full shutdown and restart of the library.
-    grpc_channel_credentials* global_creds =
-        create_test_ssl_plus_token_channel_creds("global-auth-header");
-    auto global_key = grpc_core::UniquePtr<char>(gpr_strdup("global"));
-    GPR_ASSERT(grpc_control_plane_credentials_register(global_key.get(),
-                                                       global_creds) == false);
-    grpc_channel_credentials_release(global_creds);
-    // Sanity check that unmapped authorities can still register in
-    // the global registry.
-    grpc_channel_credentials* global_creds_2 =
-        create_test_ssl_plus_token_channel_creds("global-auth-header");
-    GPR_ASSERT(grpc_control_plane_credentials_register("global_2",
-                                                       global_creds_2) == true);
-    GPR_ASSERT(grpc_control_plane_credentials_register(
-                   "global_2", global_creds_2) == false);
-    grpc_channel_credentials_release(global_creds_2);
-    grpc_shutdown();
-  }
-  return 0;
-}

test/core/slice/percent_decode_fuzzer.cc

@@ -24,7 +24,6 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
-#include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/slice/percent_encoding.h"
 
 bool squelch = true;
@@ -32,7 +31,6 @@ bool leak_check = true;
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   grpc_slice input = grpc_slice_from_copied_buffer((const char*)data, size);
   grpc_slice output;
   if (grpc_strict_percent_decode_slice(
@@ -45,7 +43,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   }
   grpc_slice_unref(grpc_permissive_percent_decode_slice(input));
   grpc_slice_unref(input);
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
   return 0;
 }

test/core/slice/percent_encode_fuzzer.cc

@@ -24,7 +24,6 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
-#include "src/core/lib/security/credentials/credentials.h"
 #include "src/core/lib/slice/percent_encoding.h"
 
 bool squelch = true;
@@ -32,7 +31,6 @@ bool leak_check = true;
 
 static void test(const uint8_t* data, size_t size, const uint8_t* dict) {
   grpc_init();
-  grpc_test_only_control_plane_credentials_force_init();
   grpc_slice input =
       grpc_slice_from_copied_buffer(reinterpret_cast<const char*>(data), size);
   grpc_slice output = grpc_percent_encode_slice(input, dict);
@@ -48,7 +46,6 @@ static void test(const uint8_t* data, size_t size, const uint8_t* dict) {
   grpc_slice_unref(output);
   grpc_slice_unref(decoded_output);
   grpc_slice_unref(permissive_decoded_output);
-  grpc_test_only_control_plane_credentials_destroy();
   grpc_shutdown_blocking();
 }
 

test/core/surface/BUILD

@@ -55,6 +55,7 @@ grpc_cc_test(
 grpc_cc_test(
     name = "completion_queue_threading_test",
     srcs = ["completion_queue_threading_test.cc"],
+    flaky = True,  # TODO(b/153064668)
     language = "C++",
     deps = [
         "//:gpr",

test/cpp/client/BUILD

@@ -34,13 +34,19 @@ grpc_cc_test(
 
 grpc_cc_test(
     name = "client_channel_stress_test",
-    size = "large",
     srcs = ["client_channel_stress_test.cc"],
+    flaky = True,  # TODO(b/153136407)
     # TODO(jtattermusch): test fails frequently on Win RBE, but passes locally
     # reenable the tests once it works reliably on Win RBE.
+    # TODO(roth): Test disabled on msan and tsan due to variable
+    # duration problem triggered by https://github.com/grpc/grpc/pull/22481.
+    # Re-enable once the problem is diagnosed and fixed.  Tracked
+    # internally in b/153136407.
     tags = [
         "no_test_android",  # fails on android due to "Too many open files".
         "no_windows",
+        "nomsan",
+        "notsan",
     ],
     deps = [
         "//:gpr",

test/cpp/end2end/grpclb_end2end_test.cc

@@ -16,6 +16,7 @@
  *
  */
 
+#include <deque>
 #include <memory>
 #include <mutex>
 #include <set>
@@ -261,30 +262,31 @@ class BalancerServiceImpl : public BalancerService {
 
       if (client_load_reporting_interval_seconds_ > 0) {
         request.Clear();
-        if (stream->Read(&request)) {
+        while (stream->Read(&request)) {
           gpr_log(GPR_INFO, "LB[%p]: received client load report message '%s'",
                   this, request.DebugString().c_str());
           GPR_ASSERT(request.has_client_stats());
-          // We need to acquire the lock here in order to prevent the notify_one
-          // below from firing before its corresponding wait is executed.
-          grpc::internal::MutexLock lock(&mu_);
-          client_stats_.num_calls_started +=
+          ClientStats load_report;
+          load_report.num_calls_started =
               request.client_stats().num_calls_started();
-          client_stats_.num_calls_finished +=
+          load_report.num_calls_finished =
               request.client_stats().num_calls_finished();
-          client_stats_.num_calls_finished_with_client_failed_to_send +=
+          load_report.num_calls_finished_with_client_failed_to_send =
               request.client_stats()
                   .num_calls_finished_with_client_failed_to_send();
-          client_stats_.num_calls_finished_known_received +=
+          load_report.num_calls_finished_known_received =
               request.client_stats().num_calls_finished_known_received();
           for (const auto& drop_token_count :
                request.client_stats().calls_finished_with_drop()) {
-            client_stats_
-                .drop_token_counts[drop_token_count.load_balance_token()] +=
+            load_report
+                .drop_token_counts[drop_token_count.load_balance_token()] =
                 drop_token_count.num_calls();
           }
-          load_report_ready_ = true;
-          load_report_cond_.Signal();
+          // We need to acquire the lock here in order to prevent the notify_one
+          // below from firing before its corresponding wait is executed.
+          grpc::internal::MutexLock lock(&mu_);
+          load_report_queue_.emplace_back(std::move(load_report));
+          if (load_report_cond_ != nullptr) load_report_cond_->Signal();
         }
       }
     }
@@ -301,9 +303,8 @@ class BalancerServiceImpl : public BalancerService {
   void Start() {
     grpc::internal::MutexLock lock(&mu_);
     serverlist_done_ = false;
-    load_report_ready_ = false;
     responses_and_delays_.clear();
-    client_stats_.Reset();
+    load_report_queue_.clear();
   }
 
   void Shutdown() {
@@ -335,11 +336,18 @@ class BalancerServiceImpl : public BalancerService {
     return response;
   }
 
-  const ClientStats& WaitForLoadReport() {
+  ClientStats WaitForLoadReport() {
     grpc::internal::MutexLock lock(&mu_);
-    load_report_cond_.WaitUntil(&mu_, [this] { return load_report_ready_; });
-    load_report_ready_ = false;
-    return client_stats_;
+    grpc::internal::CondVar cv;
+    if (load_report_queue_.empty()) {
+      load_report_cond_ = &cv;
+      load_report_cond_->WaitUntil(
+          &mu_, [this] { return !load_report_queue_.empty(); });
+      load_report_cond_ = nullptr;
+    }
+    ClientStats load_report = std::move(load_report_queue_.front());
+    load_report_queue_.pop_front();
+    return load_report;
   }
 
   void NotifyDoneWithServerlists() {
@@ -365,12 +373,12 @@ class BalancerServiceImpl : public BalancerService {
 
   const int client_load_reporting_interval_seconds_;
   std::vector<ResponseDelayPair> responses_and_delays_;
+
   grpc::internal::Mutex mu_;
-  grpc::internal::CondVar load_report_cond_;
-  bool load_report_ready_ = false;
   grpc::internal::CondVar serverlist_cond_;
   bool serverlist_done_ = false;
-  ClientStats client_stats_;
+  grpc::internal::CondVar* load_report_cond_ = nullptr;
+  std::deque<ClientStats> load_report_queue_;
 };
 
 class GrpclbEnd2endTest : public ::testing::Test {
@@ -1702,6 +1710,13 @@ class UpdatesWithClientLoadReportingTest : public GrpclbEnd2endTest {
 };
 
 TEST_F(UpdatesWithClientLoadReportingTest, ReresolveDeadBalancer) {
+  const std::vector<int> first_backend{GetBackendPorts()[0]};
+  const std::vector<int> second_backend{GetBackendPorts()[1]};
+  ScheduleResponseForBalancer(
+      0, BalancerServiceImpl::BuildResponseForBackends(first_backend, {}), 0);
+  ScheduleResponseForBalancer(
+      1, BalancerServiceImpl::BuildResponseForBackends(second_backend, {}), 0);
+
   // Ask channel to connect to trigger resolver creation.
   channel_->GetState(true);
   std::vector<AddressData> addresses;
@@ -1710,13 +1725,6 @@ TEST_F(UpdatesWithClientLoadReportingTest, ReresolveDeadBalancer) {
   addresses.clear();
   addresses.emplace_back(AddressData{balancers_[1]->port_, ""});
   SetNextReresolutionResponse(addresses);
-  const std::vector<int> first_backend{GetBackendPorts()[0]};
-  const std::vector<int> second_backend{GetBackendPorts()[1]};
-
-  ScheduleResponseForBalancer(
-      0, BalancerServiceImpl::BuildResponseForBackends(first_backend, {}), 0);
-  ScheduleResponseForBalancer(
-      1, BalancerServiceImpl::BuildResponseForBackends(second_backend, {}), 0);
 
   // Start servers and send 10 RPCs per server.
   gpr_log(GPR_INFO, "========= BEFORE FIRST BATCH ==========");
@@ -1885,7 +1893,11 @@ TEST_F(SingleBalancerWithClientLoadReportingTest, Vanilla) {
   // and sent a single response.
   EXPECT_EQ(1U, balancers_[0]->service_.response_count());
 
-  const ClientStats client_stats = WaitForLoadReports();
+  ClientStats client_stats;
+  do {
+    client_stats += WaitForLoadReports();
+  } while (client_stats.num_calls_finished !=
+           kNumRpcsPerAddress * num_backends_ + num_ok);
   EXPECT_EQ(kNumRpcsPerAddress * num_backends_ + num_ok,
             client_stats.num_calls_started);
   EXPECT_EQ(kNumRpcsPerAddress * num_backends_ + num_ok,

test/cpp/end2end/xds_end2end_test.cc

@@ -1189,7 +1189,7 @@ class XdsEnd2endTest : public ::testing::TestWithParam<TestType> {
       args.SetInt(GRPC_ARG_XDS_FALLBACK_TIMEOUT_MS, fallback_timeout);
     }
     if (failover_timeout > 0) {
-      args.SetInt(GRPC_ARG_XDS_FAILOVER_TIMEOUT_MS, failover_timeout);
+      args.SetInt(GRPC_ARG_PRIORITY_FAILOVER_TIMEOUT_MS, failover_timeout);
     }
     if (xds_resource_does_not_exist_timeout > 0) {
       args.SetInt(GRPC_ARG_XDS_RESOURCE_DOES_NOT_EXIST_TIMEOUT_MS,
@@ -1321,7 +1321,8 @@ class XdsEnd2endTest : public ::testing::TestWithParam<TestType> {
             : kDefaultServiceConfigWithoutLoadReporting_;
     result.service_config =
         grpc_core::ServiceConfig::Create(service_config_json, &error);
-    GRPC_ERROR_UNREF(error);
+    ASSERT_NE(result.service_config.get(), nullptr);
+    ASSERT_EQ(error, GRPC_ERROR_NONE) << grpc_error_string(error);
     grpc_arg arg = grpc_core::FakeResolverResponseGenerator::MakeChannelArg(
         lb_channel_response_generator == nullptr
             ? lb_channel_response_generator_.get()
@@ -1353,7 +1354,8 @@ class XdsEnd2endTest : public ::testing::TestWithParam<TestType> {
       grpc_error* error = GRPC_ERROR_NONE;
       result.service_config =
           grpc_core::ServiceConfig::Create(service_config_json, &error);
-      GRPC_ERROR_UNREF(error);
+      ASSERT_NE(result.service_config.get(), nullptr);
+      ASSERT_EQ(error, GRPC_ERROR_NONE) << grpc_error_string(error);
     }
     if (lb_channel_response_generator == nullptr) {
       lb_channel_response_generator = lb_channel_response_generator_.get();
@@ -1379,11 +1381,15 @@ class XdsEnd2endTest : public ::testing::TestWithParam<TestType> {
   }
 
   Status SendRpc(EchoResponse* response = nullptr, int timeout_ms = 1000,
-                 bool wait_for_ready = false) {
+                 bool wait_for_ready = false, bool server_fail = false) {
     const bool local_response = (response == nullptr);
     if (local_response) response = new EchoResponse;
     EchoRequest request;
     request.set_message(kRequestMessage_);
+    if (server_fail) {
+      request.mutable_param()->mutable_expected_error()->set_code(
+          GRPC_STATUS_FAILED_PRECONDITION);
+    }
     ClientContext context;
     context.set_deadline(grpc_timeout_milliseconds_to_deadline(timeout_ms));
     if (wait_for_ready) context.set_wait_for_ready(true);
@@ -1431,9 +1437,11 @@ class XdsEnd2endTest : public ::testing::TestWithParam<TestType> {
     }
   }
 
-  void CheckRpcSendFailure() {
-    const Status status = SendRpc();
-    EXPECT_FALSE(status.ok());
+  void CheckRpcSendFailure(const size_t times = 1, bool server_fail = false) {
+    for (size_t i = 0; i < times; ++i) {
+      const Status status = SendRpc(nullptr, 1000, false, server_fail);
+      EXPECT_FALSE(status.ok());
+    }
   }
 
   void CheckEcho1RpcSendOk(const size_t times = 1, const int timeout_ms = 1000,
@@ -2619,19 +2627,6 @@ TEST_P(EdsTest, Timeout) {
   CheckRpcSendFailure();
 }
 
-// Tests that EDS client should send a NACK if the EDS update contains
-// no localities but does not say to drop all calls.
-TEST_P(EdsTest, NacksNoLocalitiesWithoutDropAll) {
-  SetNextResolution({});
-  SetNextResolutionForLbChannelAllBalancers();
-  AdsServiceImpl::EdsResourceArgs args;
-  balancers_[0]->ads_service()->SetEdsResource(
-      AdsServiceImpl::BuildEdsResource(args), kDefaultResourceName);
-  CheckRpcSendFailure();
-  EXPECT_EQ(balancers_[0]->ads_service()->eds_response_state(),
-            AdsServiceImpl::NACKED);
-}
-
 // Tests that EDS client should send a NACK if the EDS update contains
 // sparse priorities.
 TEST_P(EdsTest, NacksSparsePriorityList) {
@@ -2718,6 +2713,18 @@ TEST_P(LocalityMapTest, LocalityContainingNoEndpoints) {
             kNumRpcs / backends_.size());
 }
 
+// EDS update with no localities.
+TEST_P(LocalityMapTest, NoLocalities) {
+  SetNextResolution({});
+  SetNextResolutionForLbChannelAllBalancers();
+  // EDS response contains 2 localities, one with no endpoints.
+  balancers_[0]->ads_service()->SetEdsResource(
+      AdsServiceImpl::BuildEdsResource({}), kDefaultResourceName);
+  Status status = SendRpc();
+  EXPECT_FALSE(status.ok());
+  EXPECT_EQ(status.error_code(), GRPC_STATUS_UNAVAILABLE);
+}
+
 // Tests that the locality map can work properly even when it contains a large
 // number of localities.
 TEST_P(LocalityMapTest, StressTest) {
@@ -3758,7 +3765,8 @@ class ClientLoadReportingTest : public XdsEnd2endTest {
 TEST_P(ClientLoadReportingTest, Vanilla) {
   SetNextResolution({});
   SetNextResolutionForLbChannel({balancers_[0]->port()});
-  const size_t kNumRpcsPerAddress = 100;
+  const size_t kNumRpcsPerAddress = 10;
+  const size_t kNumFailuresPerAddress = 3;
   // TODO(juanlishen): Partition the backends after multiple localities is
   // tested.
   AdsServiceImpl::EdsResourceArgs args({
@@ -3773,9 +3781,11 @@ TEST_P(ClientLoadReportingTest, Vanilla) {
   std::tie(num_ok, num_failure, num_drops) = WaitForAllBackends();
   // Send kNumRpcsPerAddress RPCs per server.
   CheckRpcSendOk(kNumRpcsPerAddress * num_backends_);
-  // Each backend should have gotten 100 requests.
+  CheckRpcSendFailure(kNumFailuresPerAddress * num_backends_,
+                      /*server_fail=*/true);
+  // Check that each backend got the right number of requests.
   for (size_t i = 0; i < backends_.size(); ++i) {
-    EXPECT_EQ(kNumRpcsPerAddress,
+    EXPECT_EQ(kNumRpcsPerAddress + kNumFailuresPerAddress,
               backends_[i]->backend_service()->request_count());
   }
   // The LRS service got a single request, and sent a single response.
@@ -3789,9 +3799,11 @@ TEST_P(ClientLoadReportingTest, Vanilla) {
   EXPECT_EQ(kNumRpcsPerAddress * num_backends_ + num_ok,
             client_stats.total_successful_requests());
   EXPECT_EQ(0U, client_stats.total_requests_in_progress());
-  EXPECT_EQ(kNumRpcsPerAddress * num_backends_ + num_ok,
+  EXPECT_EQ((kNumRpcsPerAddress + kNumFailuresPerAddress) * num_backends_ +
+                num_ok + num_failure,
             client_stats.total_issued_requests());
-  EXPECT_EQ(0U, client_stats.total_error_requests());
+  EXPECT_EQ(kNumFailuresPerAddress * num_backends_ + num_failure,
+            client_stats.total_error_requests());
   EXPECT_EQ(0U, client_stats.total_dropped_requests());
 }
 

test/cpp/microbenchmarks/bm_fullstack_streaming_pump.cc

@@ -34,8 +34,6 @@ BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, UDS)
     ->Range(0, 128 * 1024 * 1024);
 BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, InProcess)
     ->Range(0, 128 * 1024 * 1024);
-BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, SockPair)
-    ->Range(0, 128 * 1024 * 1024);
 BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, InProcessCHTTP2)
     ->Range(0, 128 * 1024 * 1024);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, TCP)
@@ -44,19 +42,15 @@ BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, UDS)
     ->Range(0, 128 * 1024 * 1024);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, InProcess)
     ->Range(0, 128 * 1024 * 1024);
-BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, SockPair)
-    ->Range(0, 128 * 1024 * 1024);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, InProcessCHTTP2)
     ->Range(0, 128 * 1024 * 1024);
 BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, MinTCP)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, MinUDS)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, MinInProcess)->Arg(0);
-BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, MinSockPair)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamClientToServer, MinInProcessCHTTP2)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, MinTCP)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, MinUDS)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, MinInProcess)->Arg(0);
-BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, MinSockPair)->Arg(0);
 BENCHMARK_TEMPLATE(BM_PumpStreamServerToClient, MinInProcessCHTTP2)->Arg(0);
 
 }  // namespace testing

test/cpp/naming/address_sorting_test.cc

@@ -212,7 +212,7 @@ TEST_F(AddressSortingTest, TestDepriotizesUnreachableAddresses) {
       {"1.2.3.4:443", AF_INET},
       {"5.6.7.8:443", AF_INET},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "1.2.3.4:443",
                                     "5.6.7.8:443",
@@ -231,7 +231,7 @@ TEST_F(AddressSortingTest, TestDepriotizesUnsupportedDomainIpv6) {
       {"[2607:f8b0:400a:801::1002]:443", AF_INET6},
       {"1.2.3.4:443", AF_INET},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "1.2.3.4:443",
                                     "[2607:f8b0:400a:801::1002]:443",
@@ -251,7 +251,7 @@ TEST_F(AddressSortingTest, TestDepriotizesUnsupportedDomainIpv4) {
       {"[2607:f8b0:400a:801::1002]:443", AF_INET6},
       {"1.2.3.4:443", AF_INET},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[2607:f8b0:400a:801::1002]:443",
                                     "1.2.3.4:443",
@@ -275,7 +275,7 @@ TEST_F(AddressSortingTest, TestDepriotizesNonMatchingScope) {
       {"[2000:f8b0:400a:801::1002]:443", AF_INET6},
       {"[fec0::5000]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[fec0::5000]:443",
                                     "[2000:f8b0:400a:801::1002]:443",
@@ -298,7 +298,7 @@ TEST_F(AddressSortingTest, TestUsesLabelFromDefaultTable) {
       {"[2002::5001]:443", AF_INET6},
       {"[2001::5001]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[2001::5001]:443",
                                     "[2002::5001]:443",
@@ -321,7 +321,7 @@ TEST_F(AddressSortingTest, TestUsesLabelFromDefaultTableInputFlipped) {
       {"[2001::5001]:443", AF_INET6},
       {"[2002::5001]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[2001::5001]:443",
                                     "[2002::5001]:443",
@@ -344,7 +344,7 @@ TEST_F(AddressSortingTest,
       {"[3ffe::5001]:443", AF_INET6},
       {"1.2.3.4:443", AF_INET},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(
       lb_addrs, {
                     // The AF_INET address should be IPv4-mapped by the sort,
@@ -377,7 +377,7 @@ TEST_F(AddressSortingTest,
       {v4_compat_dest, AF_INET6},
       {"[::1]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[::1]:443",
                                     v4_compat_dest,
@@ -400,7 +400,7 @@ TEST_F(AddressSortingTest,
       {"[1234::2]:443", AF_INET6},
       {"[::1]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(
       lb_addrs,
       {
@@ -424,7 +424,7 @@ TEST_F(AddressSortingTest,
       {"[2001::1234]:443", AF_INET6},
       {"[2000::5001]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(
       lb_addrs, {
                     // The 2000::/16 address should match the ::/0 prefix rule
@@ -448,7 +448,7 @@ TEST_F(
       {"[2001::1231]:443", AF_INET6},
       {"[2000::5001]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[2000::5001]:443",
                                     "[2001::1231]:443",
@@ -469,7 +469,7 @@ TEST_F(AddressSortingTest,
       {"[fec0::1234]:443", AF_INET6},
       {"[fc00::5001]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[fc00::5001]:443",
                                     "[fec0::1234]:443",
@@ -494,7 +494,7 @@ TEST_F(
       {"[::ffff:1.1.1.2]:443", AF_INET6},
       {"[1234::2]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     // ::ffff:0:2 should match the v4-mapped
                                     // precedence entry and be deprioritized.
@@ -521,7 +521,7 @@ TEST_F(AddressSortingTest, TestPrefersSmallerScope) {
       {"[3ffe::5001]:443", AF_INET6},
       {"[fec0::1234]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[fec0::1234]:443",
                                     "[3ffe::5001]:443",
@@ -546,7 +546,7 @@ TEST_F(AddressSortingTest, TestPrefersLongestMatchingSrcDstPrefix) {
       {"[3ffe:5001::]:443", AF_INET6},
       {"[3ffe:1234::]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe:1234::]:443",
                                     "[3ffe:5001::]:443",
@@ -567,7 +567,7 @@ TEST_F(AddressSortingTest,
       {"[3ffe::5001]:443", AF_INET6},
       {"[3ffe::1234]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe::1234]:443",
                                     "[3ffe::5001]:443",
@@ -587,7 +587,7 @@ TEST_F(AddressSortingTest, TestPrefersLongestPrefixStressInnerBytePrefix) {
       {"[3ffe:8000::]:443", AF_INET6},
       {"[3ffe:2000::]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe:2000::]:443",
                                     "[3ffe:8000::]:443",
@@ -607,7 +607,7 @@ TEST_F(AddressSortingTest, TestPrefersLongestPrefixDiffersOnHighestBitOfByte) {
       {"[3ffe:6::]:443", AF_INET6},
       {"[3ffe:c::]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe:c::]:443",
                                     "[3ffe:6::]:443",
@@ -629,7 +629,7 @@ TEST_F(AddressSortingTest, TestPrefersLongestPrefixDiffersByLastBit) {
       {"[3ffe:1111:1111:1110::]:443", AF_INET6},
       {"[3ffe:1111:1111:1111::]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe:1111:1111:1111::]:443",
                                     "[3ffe:1111:1111:1110::]:443",
@@ -651,7 +651,7 @@ TEST_F(AddressSortingTest, TestStableSort) {
       {"[3ffe::1234]:443", AF_INET6},
       {"[3ffe::1235]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe::1234]:443",
                                     "[3ffe::1235]:443",
@@ -677,7 +677,7 @@ TEST_F(AddressSortingTest, TestStableSortFiveElements) {
       {"[3ffe::1234]:443", AF_INET6},
       {"[3ffe::1235]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe::1231]:443",
                                     "[3ffe::1232]:443",
@@ -698,7 +698,7 @@ TEST_F(AddressSortingTest, TestStableSortNoSrcAddrsExist) {
       {"[3ffe::1234]:443", AF_INET6},
       {"[3ffe::1235]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[3ffe::1231]:443",
                                     "[3ffe::1232]:443",
@@ -716,7 +716,7 @@ TEST_F(AddressSortingTest, TestStableSortNoSrcAddrsExistWithIpv4) {
       {"[::ffff:5.6.7.8]:443", AF_INET6},
       {"1.2.3.4:443", AF_INET},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[::ffff:5.6.7.8]:443",
                                     "1.2.3.4:443",
@@ -744,7 +744,7 @@ TEST_F(AddressSortingTest, TestStableSortV4CompatAndSiteLocalAddresses) {
       {"[fec0::2000]:443", AF_INET6},
       {v4_compat_dest, AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs,
                       {
                           // The sort should be stable since
@@ -765,7 +765,7 @@ TEST_F(AddressSortingTest, TestPrefersIpv6Loopback) {
       {"[::1]:443", AF_INET6},
       {"127.0.0.1:443", AF_INET},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[::1]:443",
                                     "127.0.0.1:443",
@@ -779,7 +779,7 @@ TEST_F(AddressSortingTest, TestPrefersIpv6LoopbackInputsFlipped) {
       {"127.0.0.1:443", AF_INET},
       {"[::1]:443", AF_INET6},
   });
-  grpc_cares_wrapper_address_sorting_sort(&lb_addrs);
+  grpc_cares_wrapper_address_sorting_sort(nullptr, &lb_addrs);
   VerifyLbAddrOutputs(lb_addrs, {
                                     "[::1]:443",
                                     "127.0.0.1:443",

test/cpp/naming/resolver_component_tests_runner.py

@@ -55,7 +55,7 @@ if cur_resolver and cur_resolver != 'ares':
       'needs to use GRPC_DNS_RESOLVER=ares.'))
   test_runner_log('Exit 1 without running tests.')
   sys.exit(1)
-os.environ.update({'GRPC_TRACE': 'cares_resolver'})
+os.environ.update({'GRPC_TRACE': 'cares_resolver,cares_address_sorting'})
 
 def wait_until_dns_server_is_up(args,
                                 dns_server_subprocess,

test/cpp/qps/driver.cc

@@ -313,11 +313,10 @@ std::unique_ptr<ScenarioResult> RunScenario(
     gpr_log(GPR_INFO, "Starting server on %s (worker #%" PRIuPTR ")",
             workers[i].c_str(), i);
     if (!run_inproc) {
-      servers[i].stub = WorkerService::NewStub(grpc::CreateChannel(
-          workers[i], GetCredentialsProvider()->GetChannelCredentials(
-                          GetCredType(workers[i], per_worker_credential_types,
-                                      credential_type),
-                          &channel_args)));
+      servers[i].stub = WorkerService::NewStub(grpc::CreateTestChannel(
+          workers[i],
+          GetCredType(workers[i], per_worker_credential_types, credential_type),
+          nullptr /* call creds */, {} /* interceptor creators */));
     } else {
       servers[i].stub = WorkerService::NewStub(
           local_workers[i]->InProcessChannel(channel_args));
@@ -373,11 +372,10 @@ std::unique_ptr<ScenarioResult> RunScenario(
     gpr_log(GPR_INFO, "Starting client on %s (worker #%" PRIuPTR ")",
             worker.c_str(), i + num_servers);
     if (!run_inproc) {
-      clients[i].stub = WorkerService::NewStub(grpc::CreateChannel(
+      clients[i].stub = WorkerService::NewStub(grpc::CreateTestChannel(
           worker,
-          GetCredentialsProvider()->GetChannelCredentials(
-              GetCredType(worker, per_worker_credential_types, credential_type),
-              &channel_args)));
+          GetCredType(worker, per_worker_credential_types, credential_type),
+          nullptr /* call creds */, {} /* interceptor creators */));
     } else {
       clients[i].stub = WorkerService::NewStub(
           local_workers[i + num_servers]->InProcessChannel(channel_args));
@@ -588,13 +586,11 @@ bool RunQuit(
     return false;
   }
 
-  ChannelArguments channel_args;
   for (size_t i = 0; i < workers.size(); i++) {
-    auto stub = WorkerService::NewStub(grpc::CreateChannel(
-        workers[i], GetCredentialsProvider()->GetChannelCredentials(
-                        GetCredType(workers[i], per_worker_credential_types,
-                                    credential_type),
-                        &channel_args)));
+    auto stub = WorkerService::NewStub(grpc::CreateTestChannel(
+        workers[i],
+        GetCredType(workers[i], per_worker_credential_types, credential_type),
+        nullptr /* call creds */, {} /* interceptor creators */));
     Void dummy;
     grpc::ClientContext ctx;
     ctx.set_wait_for_ready(true);

test/cpp/util/create_test_channel.cc

@@ -18,12 +18,21 @@
 
 #include "test/cpp/util/create_test_channel.h"
 
+#include <gflags/gflags.h>
+
 #include <grpc/support/log.h>
 #include <grpcpp/create_channel.h>
 #include <grpcpp/security/credentials.h>
 
 #include "test/cpp/util/test_credentials_provider.h"
 
+DEFINE_string(
+    grpc_test_use_grpclb_with_child_policy, "",
+    "If non-empty, set a static service config on channels created by "
+    "grpc::CreateTestChannel, that configures the grpclb LB policy "
+    "with a child policy being the value of this flag (e.g. round_robin "
+    "or pick_first).");
+
 namespace grpc {
 
 namespace {
@@ -49,6 +58,16 @@ void AddProdSslType() {
                                    new SslCredentialProvider));
 }
 
+void MaybeSetCustomChannelArgs(grpc::ChannelArguments* args) {
+  if (FLAGS_grpc_test_use_grpclb_with_child_policy.size() > 0) {
+    args->SetString("grpc.service_config",
+                    "{\"loadBalancingConfig\":[{\"grpclb\":{\"childPolicy\":[{"
+                    "\"" +
+                        FLAGS_grpc_test_use_grpclb_with_child_policy +
+                        "\":{}}]}}]}");
+  }
+}
+
 }  // namespace
 
 // When cred_type is 'ssl', if server is empty, override_hostname is used to
@@ -111,6 +130,7 @@ std::shared_ptr<Channel> CreateTestChannel(
     const grpc::string& server, const grpc::string& credential_type,
     const std::shared_ptr<CallCredentials>& creds) {
   ChannelArguments channel_args;
+  MaybeSetCustomChannelArgs(&channel_args);
   std::shared_ptr<ChannelCredentials> channel_creds =
       testing::GetCredentialsProvider()->GetChannelCredentials(credential_type,
                                                                &channel_args);
@@ -129,14 +149,15 @@ std::shared_ptr<Channel> CreateTestChannel(
         std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
         interceptor_creators) {
   ChannelArguments channel_args(args);
+  MaybeSetCustomChannelArgs(&channel_args);
   std::shared_ptr<ChannelCredentials> channel_creds;
   if (cred_type.empty()) {
     if (interceptor_creators.empty()) {
       return ::grpc::CreateCustomChannel(server, InsecureChannelCredentials(),
-                                         args);
+                                         channel_args);
     } else {
       return experimental::CreateCustomChannelWithInterceptors(
-          server, InsecureChannelCredentials(), args,
+          server, InsecureChannelCredentials(), channel_args,
           std::move(interceptor_creators));
     }
   } else if (cred_type == testing::kTlsCredentialsType) {  // cred_type == "ssl"
@@ -173,10 +194,10 @@ std::shared_ptr<Channel> CreateTestChannel(
     GPR_ASSERT(channel_creds != nullptr);
 
     if (interceptor_creators.empty()) {
-      return ::grpc::CreateCustomChannel(server, channel_creds, args);
+      return ::grpc::CreateCustomChannel(server, channel_creds, channel_args);
     } else {
       return experimental::CreateCustomChannelWithInterceptors(
-          server, channel_creds, args, std::move(interceptor_creators));
+          server, channel_creds, channel_args, std::move(interceptor_creators));
     }
   }
 }
@@ -217,6 +238,7 @@ std::shared_ptr<Channel> CreateTestChannel(
         std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
         interceptor_creators) {
   ChannelArguments channel_args;
+  MaybeSetCustomChannelArgs(&channel_args);
   std::shared_ptr<ChannelCredentials> channel_creds =
       testing::GetCredentialsProvider()->GetChannelCredentials(credential_type,
                                                                &channel_args);

tools/bazel.rc

@@ -1,7 +1,4 @@
 # bazelrc file
-# bazel >= 0.18 looks for %workspace%/.bazelrc (which redirects here)
-# Older bazel versions look for %workspace%/tools/bazel.rc (this file)
-# See https://github.com/bazelbuild/bazel/issues/6319
 
 build --client_env=CC=clang
 build --copt=-DGRPC_BAZEL_BUILD

tools/buildgen/generate_build_additions.sh

@@ -23,7 +23,7 @@ gen_build_yaml_dirs="  \
   src/upb              \
   src/zlib             \
   src/c-ares           \
-  test/core/end2end     \
+  test/core/end2end    \
   test/cpp/naming      \
   tools/run_tests/lb_interop_tests"
 

tools/dockerfile/interoptest/grpc_interop_dart/Dockerfile

@@ -12,10 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM google/dart:2.3
-
-# Upgrade Dart to version 2.
-RUN apt-get update && apt-get upgrade -y dart
+FROM google/dart:2.7
 
 # Define the default command.
 CMD ["bash"]

tools/dockerfile/test/python_stretch_default_x64/Dockerfile

@@ -84,6 +84,29 @@ RUN cd /tmp && \
 RUN python3.6 -m ensurepip && \
     python3.6 -m pip install coverage
 
+#=================
+# Compile CPython 3.8.0b4 from source
+
+RUN apt-get update && apt-get install -y zlib1g-dev libssl-dev
+RUN apt-get update && apt-get install -y jq build-essential libffi-dev
+
+RUN cd /tmp && \
+    wget -q https://www.python.org/ftp/python/3.8.0/Python-3.8.0b4.tgz && \
+    tar xzvf Python-3.8.0b4.tgz && \
+    cd Python-3.8.0b4 && \
+    ./configure && \
+    make install
+
+RUN cd /tmp && \
+    echo "b8f4f897df967014ddb42033b90c3058 Python-3.8.0b4.tgz" > checksum.md5 && \
+    md5sum -c checksum.md5
+
+RUN python3.8 -m ensurepip && \
+    python3.8 -m pip install coverage
+
+
+RUN apt-get update && apt-get install -y python3.5 python3.5-dev
+RUN curl https://bootstrap.pypa.io/get-pip.py | python3.5
 
 RUN apt-get update && apt-get -t buster install -y python3.7 python3-all-dev
 RUN curl https://bootstrap.pypa.io/get-pip.py | python3.7

tools/doxygen/Doxyfile.c++.internal

@@ -1091,6 +1091,8 @@ src/core/ext/filters/client_channel/http_proxy.cc \
 src/core/ext/filters/client_channel/http_proxy.h \
 src/core/ext/filters/client_channel/lb_policy.cc \
 src/core/ext/filters/client_channel/lb_policy.h \
+src/core/ext/filters/client_channel/lb_policy/address_filtering.cc \
+src/core/ext/filters/client_channel/lb_policy/address_filtering.h \
 src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc \
 src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h \
 src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc \
@@ -1106,10 +1108,13 @@ src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h \
 src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
 src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h \
 src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
+src/core/ext/filters/client_channel/lb_policy/priority/priority.cc \
 src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
 src/core/ext/filters/client_channel/lb_policy/subchannel_list.h \
+src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
 src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
+src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc \
 src/core/ext/filters/client_channel/lb_policy/xds/xds.h \
 src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc \
 src/core/ext/filters/client_channel/lb_policy_factory.h \

tools/doxygen/Doxyfile.core.internal

@@ -888,6 +888,8 @@ src/core/ext/filters/client_channel/http_proxy.cc \
 src/core/ext/filters/client_channel/http_proxy.h \
 src/core/ext/filters/client_channel/lb_policy.cc \
 src/core/ext/filters/client_channel/lb_policy.h \
+src/core/ext/filters/client_channel/lb_policy/address_filtering.cc \
+src/core/ext/filters/client_channel/lb_policy/address_filtering.h \
 src/core/ext/filters/client_channel/lb_policy/child_policy_handler.cc \
 src/core/ext/filters/client_channel/lb_policy/child_policy_handler.h \
 src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc \
@@ -903,10 +905,13 @@ src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h \
 src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc \
 src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h \
 src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc \
+src/core/ext/filters/client_channel/lb_policy/priority/priority.cc \
 src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc \
 src/core/ext/filters/client_channel/lb_policy/subchannel_list.h \
+src/core/ext/filters/client_channel/lb_policy/weighted_target/weighted_target.cc \
 src/core/ext/filters/client_channel/lb_policy/xds/cds.cc \
-src/core/ext/filters/client_channel/lb_policy/xds/xds.cc \
+src/core/ext/filters/client_channel/lb_policy/xds/eds.cc \
+src/core/ext/filters/client_channel/lb_policy/xds/lrs.cc \
 src/core/ext/filters/client_channel/lb_policy/xds/xds.h \
 src/core/ext/filters/client_channel/lb_policy/xds/xds_routing.cc \
 src/core/ext/filters/client_channel/lb_policy_factory.h \

tools/internal_ci/linux/grpc_xds_bazel_python_test_in_docker.sh

@@ -25,6 +25,7 @@ cd /var/local/git/grpc
 VIRTUAL_ENV=$(mktemp -d)
 virtualenv "$VIRTUAL_ENV"
 PYTHON="$VIRTUAL_ENV"/bin/python
+"$PYTHON" -m pip install --upgrade pip
 "$PYTHON" -m pip install --upgrade grpcio-tools google-api-python-client google-auth-httplib2 oauth2client
 
 # Prepare generated Python code.
@@ -47,10 +48,12 @@ touch "$TOOLS_DIR"/src/proto/grpc/testing/__init__.py
 
 bazel build //src/python/grpcio_tests/tests_py3_only/interop:xds_interop_client
 
-GRPC_VERBOSITY=debug GRPC_TRACE=xds_client,xds_resolver,cds_lb,xds_lb "$PYTHON" \
+GRPC_VERBOSITY=debug GRPC_TRACE=xds_client,xds_resolver,cds_lb,eds_lb,priority_lb,weighted_target_lb,lrs_lb "$PYTHON" \
   tools/run_tests/run_xds_tests.py \
     --test_case=all \
     --project_id=grpc-testing \
+    --source_image=projects/grpc-testing/global/images/xds-test-server \
+    --path_to_server_binary=/java_server/grpc-java/interop-testing/build/install/grpc-interop-testing/bin/xds-test-server \
     --gcp_suffix=$(date '+%s') \
     --verbose \
     --client_cmd='bazel run //src/python/grpcio_tests/tests_py3_only/interop:xds_interop_client -- --server=xds-experimental:///{server_uri} --stats_port={stats_port} --qps={qps} --verbose'

tools/internal_ci/linux/grpc_xds_bazel_test_in_docker.sh

@@ -25,6 +25,7 @@ cd /var/local/git/grpc
 VIRTUAL_ENV=$(mktemp -d)
 virtualenv "$VIRTUAL_ENV"
 PYTHON="$VIRTUAL_ENV"/bin/python
+"$PYTHON" -m pip install --upgrade pip
 "$PYTHON" -m pip install --upgrade grpcio grpcio-tools google-api-python-client google-auth-httplib2 oauth2client
 
 # Prepare generated Python code.
@@ -47,10 +48,12 @@ touch "$TOOLS_DIR"/src/proto/grpc/testing/__init__.py
 
 bazel build test/cpp/interop:xds_interop_client
 
-GRPC_VERBOSITY=debug GRPC_TRACE=xds_client,xds_resolver,cds_lb,xds_lb "$PYTHON" \
+GRPC_VERBOSITY=debug GRPC_TRACE=xds_client,xds_resolver,cds_lb,eds_lb,priority_lb,weighted_target_lb,lrs_lb "$PYTHON" \
   tools/run_tests/run_xds_tests.py \
     --test_case=all \
     --project_id=grpc-testing \
+    --source_image=projects/grpc-testing/global/images/xds-test-server \
+    --path_to_server_binary=/java_server/grpc-java/interop-testing/build/install/grpc-interop-testing/bin/xds-test-server \
     --gcp_suffix=$(date '+%s') \
     --verbose \
     --client_cmd='bazel-bin/test/cpp/interop/xds_interop_client --server=xds-experimental:///{server_uri} --stats_port={stats_port} --qps={qps}'

tools/remote_build/README.md

@@ -17,30 +17,55 @@ and tests run by Kokoro CI.
 
 ## Running remote build manually from dev workstation
 
-Run from repository root (opt, dbg):
+IMPORTANT: The OS from which you run the bazel command needs to always match your desired build & execution platform. If you want to run tests on linux, you need to run bazel from a linux machine, to execute tests on windows you need to be on windows etc. If you don't follow this guideline, the build might still appear like it's working, but you'll get nonsensical results (e.g. will be test configured as if on mac, but actually running on linux).
+
+### Linux
+
+For `opt` or `dbg` run this command:
 ```
 # manual run of bazel tests remotely on Foundry
 bazel --bazelrc=tools/remote_build/manual.bazelrc test --config=opt //test/...
 ```
 
-Sanitizer runs (asan, msan, tsan, ubsan):
+This also works for sanitizer runs (`asan`, `msan`, `tsan`, `ubsan`):
 ```
 # manual run of bazel tests remotely on Foundry with given sanitizer
 bazel --bazelrc=tools/remote_build/manual.bazelrc test --config=asan //test/...
 ```
 
-Run on Windows MSVC:
+### Windows
+
 ```
 # manual run of bazel tests remotely on RBE Windows (must be run from Windows machine)
 bazel --bazelrc=tools/remote_build/windows.bazelrc test --config=windows_opt //test/...
 ```
 
-Run on MacOS (experimental for now):
+NOTE: Unlike on Linux and Mac, the bazel version won't get autoselected for you,
+so check that you're using the [right bazel version](https://github.com/grpc/grpc/blob/master/tools/bazel).
+
+### MacOS
+
+There is no such thing as Mac RBE cluster, so a real remote build on Macs is currently impossible.
+The following setup will build and run test on you local mac machine, but will give
+you the RBE-like look & feel (e.g. a results link will be generated and some extra configuration will
+be used).
+
 ```
 # manual run of bazel tests on Mac (must be run from Mac machine)
 # NOTE: it's not really a "remote execution", but uploads results to ResultStore
 bazel --bazelrc=tools/remote_build/mac.bazelrc test --config=opt //test/...
 ```
 
+NOTE: Because this is essentially a local run, you'll need to run start port server first (`tools/run_tests/start_port_server.py`)
+
+## Running local builds with bazel
+
+On all platforms, you can generally still use bazel builds & tests locally without any extra settings, but you might need to 
+start port server first (`tools/run_tests/start_port_server.py`) to be able to run the tests locally.
+
+E.g.: `bazel test --config=opt //test/...`
+
+## Bazel command line options
+
 Available command line options can be found in
 [Bazel command line reference](https://docs.bazel.build/versions/master/command-line-reference.html)

tools/run_tests/generated/tests.json

@@ -785,30 +785,6 @@
     ], 
     "uses_polling": true
   }, 
-  {
-    "args": [], 
-    "benchmark": false, 
-    "ci_platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "cpu_cost": 1.0, 
-    "exclude_configs": [], 
-    "exclude_iomgrs": [], 
-    "flaky": false, 
-    "gtest": false, 
-    "language": "c", 
-    "name": "completion_queue_threading_test", 
-    "platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "uses_polling": true
-  }, 
   {
     "args": [], 
     "benchmark": false, 
@@ -881,30 +857,6 @@
     ], 
     "uses_polling": true
   }, 
-  {
-    "args": [], 
-    "benchmark": false, 
-    "ci_platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "cpu_cost": 1.0, 
-    "exclude_configs": [], 
-    "exclude_iomgrs": [], 
-    "flaky": false, 
-    "gtest": false, 
-    "language": "c", 
-    "name": "control_plane_credentials_test", 
-    "platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "uses_polling": true
-  }, 
   {
     "args": [], 
     "benchmark": false, 
@@ -4125,28 +4077,6 @@
     ], 
     "uses_polling": true
   }, 
-  {
-    "args": [], 
-    "benchmark": false, 
-    "ci_platforms": [
-      "linux", 
-      "mac", 
-      "posix"
-    ], 
-    "cpu_cost": 1.0, 
-    "exclude_configs": [], 
-    "exclude_iomgrs": [], 
-    "flaky": false, 
-    "gtest": true, 
-    "language": "c++", 
-    "name": "client_channel_stress_test", 
-    "platforms": [
-      "linux", 
-      "mac", 
-      "posix"
-    ], 
-    "uses_polling": true
-  }, 
   {
     "args": [], 
     "benchmark": false, 

tools/run_tests/helper_scripts/build_python.sh

@@ -165,24 +165,33 @@ pip_install_dir() {
   cd "$PWD"
 }
 
+# On library/version/platforms combo that do not have a binary
+# published, we may end up building a dependency from source. In that
+# case, several of our build environment variables may disrupt the
+# third-party build process. This function pipes through only the
+# minimal environment necessary.
+pip_install() {
+  /usr/bin/env -i PATH="$PATH" "$VENV_PYTHON" -m pip install "$@"
+}
+
 case "$VENV" in
   *py36_gevent*)
   # TODO(https://github.com/grpc/grpc/issues/15411) unpin this
-  $VENV_PYTHON -m pip install gevent==1.3.b1
+  pip_install gevent==1.3.b1
   ;;
   *gevent*)
-  $VENV_PYTHON -m pip install -U gevent
+  pip_install -U gevent
   ;;
 esac
 
-$VENV_PYTHON -m pip install --upgrade pip==19.3.1
-$VENV_PYTHON -m pip install --upgrade setuptools
-$VENV_PYTHON -m pip install --upgrade cython
-$VENV_PYTHON -m pip install --upgrade six enum34 protobuf
+pip_install --upgrade pip==19.3.1
+pip_install --upgrade setuptools
+pip_install --upgrade cython
+pip_install --upgrade six enum34 protobuf
 
 if [ "$("$VENV_PYTHON" -c "import sys; print(sys.version_info[0])")" == "2" ]
 then
-  $VENV_PYTHON -m pip install futures
+  pip_install futures
 fi
 
 pip_install_dir "$ROOT"
@@ -214,9 +223,9 @@ pip_install_dir "$ROOT/src/python/grpcio_status"
 pip_install_dir "$ROOT/src/python/grpcio_testing"
 
 # Build/install tests
-$VENV_PYTHON -m pip install coverage==4.4 oauth2client==4.1.0 \
-                            google-auth==1.0.0 requests==2.14.2 \
-                            googleapis-common-protos==1.5.5
+pip_install coverage==4.4 oauth2client==4.1.0 \
+            google-auth==1.0.0 requests==2.14.2 \
+            googleapis-common-protos==1.5.5
 $VENV_PYTHON "$ROOT/src/python/grpcio_tests/setup.py" preprocess
 $VENV_PYTHON "$ROOT/src/python/grpcio_tests/setup.py" build_package_protos
 pip_install_dir "$ROOT/src/python/grpcio_tests"

tools/run_tests/helper_scripts/prep_xds.sh

@@ -19,6 +19,7 @@ set -ex
 cd "$(dirname "$0")/../../.."
 
 sudo apt-get install -y python3-pip
+sudo python3 -m pip install --upgrade pip
 sudo python3 -m pip install grpcio grpcio-tools google-api-python-client google-auth-httplib2 oauth2client
 
 # Prepare generated Python code.

tools/run_tests/helper_scripts/run_grpc-node.sh

@@ -27,4 +27,7 @@ rm -rf ./../grpc-node
 git clone --recursive https://github.com/grpc/grpc-node ./../grpc-node
 cd ./../grpc-node
 
-./test-grpc-submodule.sh "$CURRENT_COMMIT"
+echo "TODO(jtattermusch): Skipping grpc-node's ./test-grpc-submodule.sh $CURRENT_COMMIT"
+echo "because it currently doesn't provide any useful signal."
+echo "See b/152833238"
+#./test-grpc-submodule.sh "$CURRENT_COMMIT"

tools/run_tests/run_tests.py

@@ -866,9 +866,19 @@ class PythonLanguage(object):
             else:
                 if args.iomgr_platform == 'asyncio':
                     return (python36_config,)
+                elif os.uname()[0] == 'Darwin':
+                    # NOTE(rbellevi): Testing takes significantly longer on
+                    # MacOS, so we restrict the number of interpreter versions
+                    # tested.
+                    return (
+                        python27_config,
+                        python36_config,
+                        python37_config,
+                    )
                 else:
                     return (
                         python27_config,
+                        python35_config,
                         python36_config,
                         python37_config,
                     )

tools/run_tests/run_xds_tests.py

@@ -86,12 +86,17 @@ argp.add_argument(
     type=parse_test_cases,
     help='Comma-separated list of test cases to run, or \'all\' to run every '
     'test. Available tests: %s' % ' '.join(_TEST_CASES))
+argp.add_argument(
+    '--bootstrap_file',
+    default='',
+    help='File to reference via GRPC_XDS_BOOTSTRAP. Disables built-in '
+    'bootstrap generation')
 argp.add_argument(
     '--client_cmd',
     default=None,
-    help='Command to launch xDS test client. This script will fill in '
-    '{server_uri}, {stats_port} and {qps} parameters using str.format(), and '
-    'generate the GRPC_XDS_BOOTSTRAP file.')
+    help='Command to launch xDS test client. {server_uri}, {stats_port} and '
+    '{qps} references will be replaced using str.format(). GRPC_XDS_BOOTSTRAP '
+    'will be set for the command')
 argp.add_argument('--zone', default='us-central1-a')
 argp.add_argument('--secondary_zone',
                   default='us-west1-b',
@@ -117,20 +122,22 @@ argp.add_argument(
     help=
     'If provided, uses this file instead of retrieving via the GCP discovery '
     'API')
+argp.add_argument(
+    '--alpha_compute_discovery_document',
+    default=None,
+    type=str,
+    help='If provided, uses this file instead of retrieving via the alpha GCP '
+    'discovery API')
 argp.add_argument('--network',
                   default='global/networks/default',
                   help='GCP network to use')
 argp.add_argument('--service_port_range',
-                  default='80',
+                  default='8080:8110',
                   type=parse_port_range,
                   help='Listening port for created gRPC backends. Specified as '
                   'either a single int or as a range in the format min:max, in '
                   'which case an available port p will be chosen s.t. min <= p '
                   '<= max')
-argp.add_argument('--forwarding_rule_ip_prefix',
-                  default='172.16.0.',
-                  help='If set, an available IP with this prefix followed by '
-                  '0-255 will be used for the generated forwarding rule.')
 argp.add_argument(
     '--stats_port',
     default=8079,
@@ -142,6 +149,11 @@ argp.add_argument('--xds_server',
 argp.add_argument('--source_image',
                   default='projects/debian-cloud/global/images/family/debian-9',
                   help='Source image for VMs created during the test')
+argp.add_argument('--path_to_server_binary',
+                  default=None,
+                  type=str,
+                  help='If set, the server binary must already be pre-built on '
+                  'the specified source image')
 argp.add_argument('--machine_type',
                   default='e2-standard-2',
                   help='Machine type for VMs created during the test')
@@ -164,6 +176,12 @@ argp.add_argument('--verbose',
                   help='verbose log output',
                   default=False,
                   action='store_true')
+# TODO(ericgribkoff) Remove this param once the sponge-formatted log files are
+# visible in all test environments.
+argp.add_argument('--log_client_output',
+                  help='Log captured client output',
+                  default=False,
+                  action='store_true')
 args = argp.parse_args()
 
 if args.verbose:
@@ -322,9 +340,9 @@ def test_change_backend_service(gcp, original_backend_service, instance_group,
                                              _WAIT_FOR_STATS_SEC)
     try:
         patch_url_map_backend_service(gcp, alternate_backend_service)
-        stats = get_client_stats(_NUM_TEST_RPCS, _WAIT_FOR_STATS_SEC)
-        if stats.num_failures > 0:
-            raise Exception('Unexpected failure: %s', stats)
+        # TODO(ericgribkoff) Verify no RPCs fail during backend switch.
+        # Currently TD may briefly send an update with no localities if adding
+        # the MIG to the backend service above races with the URL map patch.
         wait_until_all_rpcs_go_to_given_backends(alternate_backend_instances,
                                                  _WAIT_FOR_URL_MAP_PATCH_SEC)
     finally:
@@ -473,7 +491,27 @@ def test_secondary_locality_gets_requests_on_primary_failure(
         patch_backend_instances(gcp, backend_service, [primary_instance_group])
 
 
-def create_instance_template(gcp, name, network, source_image, machine_type):
+def get_startup_script(path_to_server_binary, service_port):
+    if path_to_server_binary:
+        return "nohup %s --port=%d 1>/dev/null &" % (path_to_server_binary,
+                                                     service_port)
+    else:
+        return """#!/bin/bash
+sudo apt update
+sudo apt install -y git default-jdk
+mkdir java_server
+pushd java_server
+git clone https://github.com/grpc/grpc-java.git
+pushd grpc-java
+pushd interop-testing
+../gradlew installDist -x test -PskipCodegen=true -PskipAndroid=true
+
+nohup build/install/grpc-interop-testing/bin/xds-test-server \
+    --port=%d 1>/dev/null &""" % service_port
+
+
+def create_instance_template(gcp, name, network, source_image, machine_type,
+                             startup_script):
     config = {
         'name': name,
         'properties': {
@@ -499,21 +537,8 @@ def create_instance_template(gcp, name, network, source_image, machine_type):
             }],
             'metadata': {
                 'items': [{
-                    'key':
-                        'startup-script',
-                    'value':
-                        """#!/bin/bash
-sudo apt update
-sudo apt install -y git default-jdk
-mkdir java_server
-pushd java_server
-git clone https://github.com/grpc/grpc-java.git
-pushd grpc-java
-pushd interop-testing
-../gradlew installDist -x test -PskipCodegen=true -PskipAndroid=true
-
-nohup build/install/grpc-interop-testing/bin/xds-test-server --port=%d 1>/dev/null &"""
-                        % gcp.service_port
+                    'key': 'startup-script',
+                    'value': startup_script
                 }]
             }
         }
@@ -554,14 +579,14 @@ def add_instance_group(gcp, zone, name, size):
 def create_health_check(gcp, name):
     config = {
         'name': name,
-        'type': 'TCP',
-        'tcpHealthCheck': {
-            'portName': 'grpc'
+        'type': 'GRPC',
+        'grpcHealthCheck': {
+            'portSpecification': 'USE_SERVING_PORT'
         }
     }
     logger.debug('Sending GCP request with body=%s', config)
-    result = gcp.compute.healthChecks().insert(project=gcp.project,
-                                               body=config).execute()
+    result = gcp.alpha_compute.healthChecks().insert(project=gcp.project,
+                                                     body=config).execute()
     wait_for_global_operation(gcp, result['name'])
     gcp.health_check = GcpResource(config['name'], result['targetLink'])
 
@@ -590,11 +615,11 @@ def add_backend_service(gcp, name):
         'loadBalancingScheme': 'INTERNAL_SELF_MANAGED',
         'healthChecks': [gcp.health_check.url],
         'portName': 'grpc',
-        'protocol': 'HTTP2'
+        'protocol': 'GRPC'
     }
     logger.debug('Sending GCP request with body=%s', config)
-    result = gcp.compute.backendServices().insert(project=gcp.project,
-                                                  body=config).execute()
+    result = gcp.alpha_compute.backendServices().insert(project=gcp.project,
+                                                        body=config).execute()
     wait_for_global_operation(gcp, result['name'])
     backend_service = GcpResource(config['name'], result['targetLink'])
     gcp.backend_services.append(backend_service)
@@ -621,33 +646,56 @@ def create_url_map(gcp, name, backend_service, host_name):
     gcp.url_map = GcpResource(config['name'], result['targetLink'])
 
 
-def create_target_http_proxy(gcp, name):
+def patch_url_map_host_rule(gcp, name, backend_service, host_name):
     config = {
-        'name': name,
-        'url_map': gcp.url_map.url,
+        'hostRules': [{
+            'hosts': ['%s:%d' % (host_name, gcp.service_port)],
+            'pathMatcher': _PATH_MATCHER_NAME
+        }]
     }
     logger.debug('Sending GCP request with body=%s', config)
-    result = gcp.compute.targetHttpProxies().insert(project=gcp.project,
-                                                    body=config).execute()
+    result = gcp.compute.urlMaps().patch(project=gcp.project,
+                                         urlMap=name,
+                                         body=config).execute()
     wait_for_global_operation(gcp, result['name'])
-    gcp.target_http_proxy = GcpResource(config['name'], result['targetLink'])
 
 
-def create_global_forwarding_rule(gcp, name, ip, port):
+def create_target_grpc_proxy(gcp, name):
     config = {
         'name': name,
-        'loadBalancingScheme': 'INTERNAL_SELF_MANAGED',
-        'portRange': str(port),
-        'IPAddress': ip,
-        'network': args.network,
-        'target': gcp.target_http_proxy.url,
+        'url_map': gcp.url_map.url,
+        'validate_for_proxyless': True,
     }
     logger.debug('Sending GCP request with body=%s', config)
-    result = gcp.compute.globalForwardingRules().insert(project=gcp.project,
-                                                        body=config).execute()
+    result = gcp.alpha_compute.targetGrpcProxies().insert(
+        project=gcp.project, body=config).execute()
     wait_for_global_operation(gcp, result['name'])
-    gcp.global_forwarding_rule = GcpResource(config['name'],
-                                             result['targetLink'])
+    gcp.target_grpc_proxy = GcpResource(config['name'], result['targetLink'])
+
+
+def create_global_forwarding_rule(gcp, name, potential_ports):
+    for port in potential_ports:
+        try:
+            config = {
+                'name': name,
+                'loadBalancingScheme': 'INTERNAL_SELF_MANAGED',
+                'portRange': str(port),
+                'IPAddress': '0.0.0.0',
+                'network': args.network,
+                'target': gcp.target_grpc_proxy.url,
+            }
+            logger.debug('Sending GCP request with body=%s', config)
+            result = gcp.alpha_compute.globalForwardingRules().insert(
+                project=gcp.project, body=config).execute()
+            wait_for_global_operation(gcp, result['name'])
+            gcp.global_forwarding_rule = GcpResource(config['name'],
+                                                     result['targetLink'])
+            gcp.service_port = port
+            return
+        except googleapiclient.errors.HttpError as http_error:
+            logger.warning(
+                'Got error %s when attempting to create forwarding rule to '
+                '0.0.0.0:%d. Retrying with another port.' % (http_error, port))
 
 
 def delete_global_forwarding_rule(gcp):
@@ -660,11 +708,11 @@ def delete_global_forwarding_rule(gcp):
         logger.info('Delete failed: %s', http_error)
 
 
-def delete_target_http_proxy(gcp):
+def delete_target_grpc_proxy(gcp):
     try:
-        result = gcp.compute.targetHttpProxies().delete(
+        result = gcp.alpha_compute.targetGrpcProxies().delete(
             project=gcp.project,
-            targetHttpProxy=gcp.target_http_proxy.name).execute()
+            targetGrpcProxy=gcp.target_grpc_proxy.name).execute()
         wait_for_global_operation(gcp, result['name'])
     except googleapiclient.errors.HttpError as http_error:
         logger.info('Delete failed: %s', http_error)
@@ -746,7 +794,7 @@ def patch_backend_instances(gcp,
         } for instance_group in instance_groups],
     }
     logger.debug('Sending GCP request with body=%s', config)
-    result = gcp.compute.backendServices().patch(
+    result = gcp.alpha_compute.backendServices().patch(
         project=gcp.project, backendService=backend_service.name,
         body=config).execute()
     wait_for_global_operation(gcp, result['name'])
@@ -869,26 +917,11 @@ def get_instance_names(gcp, instance_group):
     return instance_names
 
 
-def start_xds_client(cmd):
-    bootstrap_path = None
-    with tempfile.NamedTemporaryFile(delete=False) as bootstrap_file:
-        bootstrap_file.write(
-            _BOOTSTRAP_TEMPLATE.format(
-                node_id=socket.gethostname()).encode('utf-8'))
-        bootstrap_path = bootstrap_file.name
-
-    client_process = subprocess.Popen(shlex.split(cmd),
-                                      env=dict(
-                                          os.environ,
-                                          GRPC_XDS_BOOTSTRAP=bootstrap_path))
-    return client_process
-
-
 def clean_up(gcp):
     if gcp.global_forwarding_rule:
         delete_global_forwarding_rule(gcp)
-    if gcp.target_http_proxy:
-        delete_target_http_proxy(gcp)
+    if gcp.target_grpc_proxy:
+        delete_target_grpc_proxy(gcp)
     if gcp.url_map:
         delete_url_map(gcp)
     delete_backend_services(gcp)
@@ -918,14 +951,15 @@ class GcpResource(object):
 
 class GcpState(object):
 
-    def __init__(self, compute, project):
+    def __init__(self, compute, alpha_compute, project):
         self.compute = compute
+        self.alpha_compute = alpha_compute
         self.project = project
         self.health_check = None
         self.health_check_firewall_rule = None
         self.backend_services = []
         self.url_map = None
-        self.target_http_proxy = None
+        self.target_grpc_proxy = None
         self.global_forwarding_rule = None
         self.service_port = None
         self.instance_template = None
@@ -936,20 +970,24 @@ if args.compute_discovery_document:
     with open(args.compute_discovery_document, 'r') as discovery_doc:
         compute = googleapiclient.discovery.build_from_document(
             discovery_doc.read())
+    with open(args.alpha_compute_discovery_document, 'r') as discovery_doc:
+        alpha_compute = googleapiclient.discovery.build_from_document(
+            discovery_doc.read())
 else:
     compute = googleapiclient.discovery.build('compute', 'v1')
+    alpha_compute = googleapiclient.discovery.build('compute', 'alpha')
 
 try:
-    gcp = GcpState(compute, args.project_id)
+    gcp = GcpState(compute, alpha_compute, args.project_id)
     health_check_name = _BASE_HEALTH_CHECK_NAME + args.gcp_suffix
     firewall_name = _BASE_FIREWALL_RULE_NAME + args.gcp_suffix
     backend_service_name = _BASE_BACKEND_SERVICE_NAME + args.gcp_suffix
     alternate_backend_service_name = _BASE_BACKEND_SERVICE_NAME + '-alternate' + args.gcp_suffix
     url_map_name = _BASE_URL_MAP_NAME + args.gcp_suffix
     service_host_name = _BASE_SERVICE_HOST + args.gcp_suffix
-    target_http_proxy_name = _BASE_TARGET_PROXY_NAME + args.gcp_suffix
+    target_grpc_proxy_name = _BASE_TARGET_PROXY_NAME + args.gcp_suffix
     forwarding_rule_name = _BASE_FORWARDING_RULE_NAME + args.gcp_suffix
-    template_name = _BASE_TARGET_PROXY_NAME + args.gcp_suffix
+    template_name = _BASE_TEMPLATE_NAME + args.gcp_suffix
     instance_group_name = _BASE_INSTANCE_GROUP_NAME + args.gcp_suffix
     same_zone_instance_group_name = _BASE_INSTANCE_GROUP_NAME + '-same-zone' + args.gcp_suffix
     if _USE_SECONDARY_IG:
@@ -961,33 +999,21 @@ try:
         alternate_backend_service = add_backend_service(
             gcp, alternate_backend_service_name)
         create_url_map(gcp, url_map_name, backend_service, service_host_name)
-        create_target_http_proxy(gcp, target_http_proxy_name)
+        create_target_grpc_proxy(gcp, target_grpc_proxy_name)
         potential_service_ports = list(args.service_port_range)
         random.shuffle(potential_service_ports)
-        if args.forwarding_rule_ip_prefix == '':
-            potential_ips = ['0.0.0.0']
-        else:
-            potential_ips = [
-                args.forwarding_rule_ip_prefix + str(x) for x in range(256)
-            ]
-        random.shuffle(potential_ips)
-        for port in potential_service_ports:
-            for ip in potential_ips:
-                try:
-                    create_global_forwarding_rule(gcp, forwarding_rule_name, ip,
-                                                  port)
-                    gcp.service_port = port
-                    break
-                except googleapiclient.errors.HttpError as http_error:
-                    logger.warning(
-                        'Got error %s when attempting to create forwarding rule to '
-                        '%s:%d. Retrying with another ip:port.' %
-                        (http_error, ip, port))
+        create_global_forwarding_rule(gcp, forwarding_rule_name,
+                                      potential_service_ports)
         if not gcp.service_port:
             raise Exception(
                 'Failed to find a valid ip:port for the forwarding rule')
+        patch_url_map_host_rule(gcp, url_map_name, backend_service,
+                                service_host_name)
+        startup_script = get_startup_script(args.path_to_server_binary,
+                                            gcp.service_port)
         create_instance_template(gcp, template_name, args.network,
-                                 args.source_image, args.machine_type)
+                                 args.source_image, args.machine_type,
+                                 startup_script)
         instance_group = add_instance_group(gcp, args.zone, instance_group_name,
                                             _INSTANCE_GROUP_SIZE)
         patch_backend_instances(gcp, backend_service, [instance_group])
@@ -1070,11 +1096,14 @@ try:
         server_uri = service_host_name
     else:
         server_uri = service_host_name + ':' + str(gcp.service_port)
-    with tempfile.NamedTemporaryFile(delete=False) as bootstrap_file:
-        bootstrap_file.write(
-            _BOOTSTRAP_TEMPLATE.format(
-                node_id=socket.gethostname()).encode('utf-8'))
-        bootstrap_path = bootstrap_file.name
+    if args.bootstrap_file:
+        bootstrap_path = os.path.abspath(args.bootstrap_file)
+    else:
+        with tempfile.NamedTemporaryFile(delete=False) as bootstrap_file:
+            bootstrap_file.write(
+                _BOOTSTRAP_TEMPLATE.format(
+                    node_id=socket.gethostname()).encode('utf-8'))
+            bootstrap_path = bootstrap_file.name
     client_env = dict(os.environ, GRPC_XDS_BOOTSTRAP=bootstrap_path)
     client_cmd = shlex.split(
         args.client_cmd.format(server_uri=server_uri,
@@ -1088,7 +1117,8 @@ try:
         log_dir = os.path.join(_TEST_LOG_BASE_DIR, test_case)
         if not os.path.exists(log_dir):
             os.makedirs(log_dir)
-        test_log_file = open(os.path.join(log_dir, _SPONGE_LOG_NAME), 'w+')
+        test_log_filename = os.path.join(log_dir, _SPONGE_LOG_NAME)
+        test_log_file = open(test_log_filename, 'w+')
         client_process = None
         try:
             client_process = subprocess.Popen(client_cmd,
@@ -1134,10 +1164,15 @@ try:
         finally:
             if client_process:
                 client_process.terminate()
+            test_log_file.close()
             # Workaround for Python 3, as report_utils will invoke decode() on
             # result.message, which has a default value of ''.
             result.message = result.message.encode('UTF-8')
             test_results[test_case] = [result]
+            if args.log_client_output:
+                logger.info('Client output:')
+                with open(test_log_filename, 'r') as client_output:
+                    logger.info(client_output.read())
     if not os.path.exists(_TEST_LOG_BASE_DIR):
         os.makedirs(_TEST_LOG_BASE_DIR)
     report_utils.render_junit_xml_report(test_results,