Introduced a registry for LB policies.

BUILD

@@ -158,6 +158,8 @@ cc_library(
     "src/core/client_config/connector.h",
     "src/core/client_config/lb_policies/pick_first.h",
     "src/core/client_config/lb_policy.h",
+    "src/core/client_config/lb_policy_factory.h",
+    "src/core/client_config/lb_policy_registry.h",
     "src/core/client_config/resolver.h",
     "src/core/client_config/resolver_factory.h",
     "src/core/client_config/resolver_registry.h",
@@ -283,6 +285,8 @@ cc_library(
     "src/core/client_config/connector.c",
     "src/core/client_config/lb_policies/pick_first.c",
     "src/core/client_config/lb_policy.c",
+    "src/core/client_config/lb_policy_factory.c",
+    "src/core/client_config/lb_policy_registry.c",
     "src/core/client_config/resolver.c",
     "src/core/client_config/resolver_factory.c",
     "src/core/client_config/resolver_registry.c",
@@ -428,6 +432,8 @@ cc_library(
     "src/core/client_config/connector.h",
     "src/core/client_config/lb_policies/pick_first.h",
     "src/core/client_config/lb_policy.h",
+    "src/core/client_config/lb_policy_factory.h",
+    "src/core/client_config/lb_policy_registry.h",
     "src/core/client_config/resolver.h",
     "src/core/client_config/resolver_factory.h",
     "src/core/client_config/resolver_registry.h",
@@ -533,6 +539,8 @@ cc_library(
     "src/core/client_config/connector.c",
     "src/core/client_config/lb_policies/pick_first.c",
     "src/core/client_config/lb_policy.c",
+    "src/core/client_config/lb_policy_factory.c",
+    "src/core/client_config/lb_policy_registry.c",
     "src/core/client_config/resolver.c",
     "src/core/client_config/resolver_factory.c",
     "src/core/client_config/resolver_registry.c",
@@ -1047,6 +1055,8 @@ objc_library(
     "src/core/client_config/connector.c",
     "src/core/client_config/lb_policies/pick_first.c",
     "src/core/client_config/lb_policy.c",
+    "src/core/client_config/lb_policy_factory.c",
+    "src/core/client_config/lb_policy_registry.c",
     "src/core/client_config/resolver.c",
     "src/core/client_config/resolver_factory.c",
     "src/core/client_config/resolver_registry.c",
@@ -1189,6 +1199,8 @@ objc_library(
     "src/core/client_config/connector.h",
     "src/core/client_config/lb_policies/pick_first.h",
     "src/core/client_config/lb_policy.h",
+    "src/core/client_config/lb_policy_factory.h",
+    "src/core/client_config/lb_policy_registry.h",
     "src/core/client_config/resolver.h",
     "src/core/client_config/resolver_factory.h",
     "src/core/client_config/resolver_registry.h",

Makefile

@@ -4045,6 +4045,8 @@ LIBGRPC_SRC = \
     src/core/client_config/connector.c \
     src/core/client_config/lb_policies/pick_first.c \
     src/core/client_config/lb_policy.c \
+    src/core/client_config/lb_policy_factory.c \
+    src/core/client_config/lb_policy_registry.c \
     src/core/client_config/resolver.c \
     src/core/client_config/resolver_factory.c \
     src/core/client_config/resolver_registry.c \
@@ -4320,6 +4322,8 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/client_config/connector.c \
     src/core/client_config/lb_policies/pick_first.c \
     src/core/client_config/lb_policy.c \
+    src/core/client_config/lb_policy_factory.c \
+    src/core/client_config/lb_policy_registry.c \
     src/core/client_config/resolver.c \
     src/core/client_config/resolver_factory.c \
     src/core/client_config/resolver_registry.c \

build.yaml

@@ -46,6 +46,7 @@ filegroups:
     src/core/channel/context.h, src/core/channel/http_client_filter.h, src/core/channel/http_server_filter.h,
     src/core/channel/noop_filter.h, src/core/client_config/client_config.h, src/core/client_config/connector.h,
     src/core/client_config/lb_policies/pick_first.h, src/core/client_config/lb_policy.h,
+    src/core/client_config/lb_policy_factory.h, src/core/client_config/lb_policy_registry.h,
     src/core/client_config/resolver.h, src/core/client_config/resolver_factory.h,
     src/core/client_config/resolver_registry.h, src/core/client_config/resolvers/dns_resolver.h,
     src/core/client_config/resolvers/sockaddr_resolver.h, src/core/client_config/subchannel.h,
@@ -85,6 +86,7 @@ filegroups:
     src/core/channel/connected_channel.c, src/core/channel/http_client_filter.c, src/core/channel/http_server_filter.c,
     src/core/channel/noop_filter.c, src/core/client_config/client_config.c, src/core/client_config/connector.c,
     src/core/client_config/lb_policies/pick_first.c, src/core/client_config/lb_policy.c,
+    src/core/client_config/lb_policy_factory.c, src/core/client_config/lb_policy_registry.c,
     src/core/client_config/resolver.c, src/core/client_config/resolver_factory.c,
     src/core/client_config/resolver_registry.c, src/core/client_config/resolvers/dns_resolver.c,
     src/core/client_config/resolvers/sockaddr_resolver.c, src/core/client_config/subchannel.c,

gRPC.podspec

@@ -160,6 +160,8 @@ Pod::Spec.new do |s|
                       'src/core/client_config/connector.h',
                       'src/core/client_config/lb_policies/pick_first.h',
                       'src/core/client_config/lb_policy.h',
+                      'src/core/client_config/lb_policy_factory.h',
+                      'src/core/client_config/lb_policy_registry.h',
                       'src/core/client_config/resolver.h',
                       'src/core/client_config/resolver_factory.h',
                       'src/core/client_config/resolver_registry.h',
@@ -292,6 +294,8 @@ Pod::Spec.new do |s|
                       'src/core/client_config/connector.c',
                       'src/core/client_config/lb_policies/pick_first.c',
                       'src/core/client_config/lb_policy.c',
+                      'src/core/client_config/lb_policy_factory.c',
+                      'src/core/client_config/lb_policy_registry.c',
                       'src/core/client_config/resolver.c',
                       'src/core/client_config/resolver_factory.c',
                       'src/core/client_config/resolver_registry.c',
@@ -434,6 +438,8 @@ Pod::Spec.new do |s|
                               'src/core/client_config/connector.h',
                               'src/core/client_config/lb_policies/pick_first.h',
                               'src/core/client_config/lb_policy.h',
+                              'src/core/client_config/lb_policy_factory.h',
+                              'src/core/client_config/lb_policy_registry.h',
                               'src/core/client_config/resolver.h',
                               'src/core/client_config/resolver_factory.h',
                               'src/core/client_config/resolver_registry.h',

src/core/client_config/lb_policies/pick_first.c

@@ -31,6 +31,7 @@
  *
  */
 
+#include "src/core/client_config/lb_policy_factory.h"
 #include "src/core/client_config/lb_policies/pick_first.h"
 
 #include <string.h>
@@ -314,8 +315,13 @@ static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = {
     pf_check_connectivity,
     pf_notify_on_state_change};
 
-grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
-                                                 size_t num_subchannels) {
+static void pick_first_factory_ref(grpc_lb_policy_factory *factory) {}
+
+static void pick_first_factory_unref(grpc_lb_policy_factory *factory) {}
+
+static grpc_lb_policy *create_pick_first(grpc_lb_policy_factory *factory,
+                                         grpc_subchannel **subchannels,
+                                         size_t num_subchannels) {
   pick_first_lb_policy *p = gpr_malloc(sizeof(*p));
   GPR_ASSERT(num_subchannels);
   memset(p, 0, sizeof(*p));
@@ -330,3 +336,14 @@ grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
   gpr_mu_init(&p->mu);
   return &p->base;
 }
+
+static const grpc_lb_policy_factory_vtable pick_first_factory_vtable = {
+    pick_first_factory_ref, pick_first_factory_unref, create_pick_first,
+    "pick_first"};
+
+static grpc_lb_policy_factory pick_first_lb_policy_factory = {
+    &pick_first_factory_vtable};
+
+grpc_lb_policy_factory *grpc_pick_first_lb_factory_create() {
+  return &pick_first_lb_policy_factory;
+}

src/core/client_config/lb_policies/pick_first.h

@@ -34,11 +34,10 @@
 #ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_PICK_FIRST_H
 #define GRPC_INTERNAL_CORE_CLIENT_CONFIG_PICK_FIRST_H
 
-#include "src/core/client_config/lb_policy.h"
+#include "src/core/client_config/lb_policy_factory.h"
 
-/** Returns a load balancing policy instance that picks up the first subchannel
- *  from \a subchannels to succesfully connect */
-grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
-                                                 size_t num_subchannels);
+/** Returns a load balancing factory for the pick first policy, which picks up
+ * the first subchannel from \a subchannels to succesfully connect */
+grpc_lb_policy_factory *grpc_pick_first_lb_factory_create();
 
 #endif

src/core/client_config/lb_policy_factory.c

@@ -0,0 +1,49 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/client_config/lb_policy_factory.h"
+
+void grpc_lb_policy_factory_ref(grpc_lb_policy_factory *factory) {
+  factory->vtable->ref(factory);
+}
+void grpc_lb_policy_factory_unref(grpc_lb_policy_factory *factory) {
+  factory->vtable->unref(factory);
+}
+
+grpc_lb_policy *grpc_lb_policy_factory_create_lb_policy(
+    grpc_lb_policy_factory *factory, grpc_subchannel **subchannels,
+    size_t num_subchannels) {
+  if (factory == NULL) return NULL;
+  return factory->vtable->create_lb_policy(factory, subchannels,
+                                           num_subchannels);
+}

src/core/client_config/lb_policy_factory.h

@@ -0,0 +1,70 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_FACTORY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_FACTORY_H
+
+#include "src/core/client_config/lb_policy.h"
+#include "src/core/client_config/subchannel.h"
+
+typedef struct grpc_lb_policy_factory grpc_lb_policy_factory;
+typedef struct grpc_lb_policy_factory_vtable grpc_lb_policy_factory_vtable;
+
+/** grpc_lb_policy provides grpc_client_config objects to grpc_channel
+    objects */
+struct grpc_lb_policy_factory {
+  const grpc_lb_policy_factory_vtable *vtable;
+};
+
+struct grpc_lb_policy_factory_vtable {
+  void (*ref)(grpc_lb_policy_factory *factory);
+  void (*unref)(grpc_lb_policy_factory *factory);
+
+  /** Implementation of grpc_lb_policy_factory_create_lb_policy */
+  grpc_lb_policy *(*create_lb_policy)(grpc_lb_policy_factory *factory,
+                                      grpc_subchannel **subchannels,
+                                      size_t num_subchannels);
+
+  /** Name for the LB policy this factory implements */
+  const char *name;
+};
+
+void grpc_lb_policy_factory_ref(grpc_lb_policy_factory *factory);
+void grpc_lb_policy_factory_unref(grpc_lb_policy_factory *factory);
+
+/** Create a lb_policy instance. */
+grpc_lb_policy *grpc_lb_policy_factory_create_lb_policy(
+    grpc_lb_policy_factory *factory, grpc_subchannel **subchannels,
+    size_t num_subchannels);
+
+#endif /* GRPC_INTERNAL_CORE_CONFIG_LB_POLICY_FACTORY_H */

src/core/client_config/lb_policy_registry.c

@@ -0,0 +1,89 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/client_config/lb_policy_registry.h"
+
+#include <string.h>
+
+#define MAX_POLICIES 10
+
+static grpc_lb_policy_factory *g_all_of_the_lb_policies[MAX_POLICIES];
+static int g_number_of_lb_policies = 0;
+
+static grpc_lb_policy_factory *g_default_lb_policy_factory;
+
+void grpc_lb_policy_registry_init(grpc_lb_policy_factory *default_factory) {
+  g_number_of_lb_policies = 0;
+  g_default_lb_policy_factory = default_factory;
+}
+
+void grpc_lb_policy_registry_shutdown(void) {
+  int i;
+  for (i = 0; i < g_number_of_lb_policies; i++) {
+    grpc_lb_policy_factory_unref(g_all_of_the_lb_policies[i]);
+  }
+}
+
+void grpc_register_lb_policy(grpc_lb_policy_factory *factory) {
+  int i;
+  for (i = 0; i < g_number_of_lb_policies; i++) {
+    GPR_ASSERT(0 != strcmp(factory->vtable->name,
+                           g_all_of_the_lb_policies[i]->vtable->name));
+  }
+  GPR_ASSERT(g_number_of_lb_policies != MAX_POLICIES);
+  grpc_lb_policy_factory_ref(factory);
+  g_all_of_the_lb_policies[g_number_of_lb_policies++] = factory;
+}
+
+static grpc_lb_policy_factory *lookup_factory(const char* name) {
+  int i;
+
+  if (name == NULL) return NULL;
+
+  for (i = 0; i < g_number_of_lb_policies; i++) {
+    if (0 == strcmp(name, g_all_of_the_lb_policies[i]->vtable->name)) {
+      return g_all_of_the_lb_policies[i];
+    }
+  }
+
+  return NULL;
+}
+
+grpc_lb_policy *grpc_lb_policy_create(const char *name,
+                                      grpc_subchannel **subchannels,
+                                      size_t num_subchannels) {
+  grpc_lb_policy_factory *factory = lookup_factory(name);
+  grpc_lb_policy *lb_policy = grpc_lb_policy_factory_create_lb_policy(
+      factory, subchannels, num_subchannels);
+  return lb_policy;
+}

src/core/client_config/lb_policy_registry.h

@@ -0,0 +1,55 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_REGISTRY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_REGISTRY_H
+
+#include "src/core/client_config/lb_policy_factory.h"
+
+/** Initialize the registry and set \a default_factory as the factory to be
+ * returned when no name is provided in a lookup */
+void grpc_lb_policy_registry_init(grpc_lb_policy_factory *default_factory);
+void grpc_lb_policy_registry_shutdown(void);
+
+/** Register a LB policy factory. */
+void grpc_register_lb_policy(grpc_lb_policy_factory *factory);
+
+/** Create a \a grpc_lb_policy instance.
+ *
+ * If \a name is NULL, the default factory from \a grpc_lb_policy_registry_init
+ * will be returned. */
+grpc_lb_policy *grpc_lb_policy_create(const char *name,
+                                      grpc_subchannel **subchannels,
+                                      size_t num_subchannels);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_REGISTRY_H */

src/core/client_config/resolvers/dns_resolver.c

@@ -39,7 +39,7 @@
 #include <grpc/support/host_port.h>
 #include <grpc/support/string_util.h>
 
-#include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/client_config/lb_policy_registry.h"
 #include "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h"
 #include "src/core/iomgr/resolve_address.h"
 #include "src/core/support/string.h"
@@ -55,9 +55,8 @@ typedef struct {
   char *default_port;
   /** subchannel factory */
   grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy factory */
-  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                       size_t num_subchannels);
+  /** load balancing policy name */
+  char *lb_policy_name;
 
   /** mutex guarding the rest of the state */
   gpr_mu mu;
@@ -144,7 +143,8 @@ static void dns_on_resolved(void *arg, grpc_resolved_addresses *addresses) {
       subchannels[i] = grpc_subchannel_factory_create_subchannel(
           r->subchannel_factory, &args);
     }
-    lb_policy = r->lb_policy_factory(subchannels, addresses->naddrs);
+    lb_policy = grpc_lb_policy_create(r->lb_policy_name, subchannels,
+                                      addresses->naddrs);
     grpc_client_config_set_lb_policy(config, lb_policy);
     GRPC_LB_POLICY_UNREF(lb_policy, "construction");
     grpc_resolved_addresses_destroy(addresses);
@@ -193,13 +193,13 @@ static void dns_destroy(grpc_resolver *gr) {
   grpc_subchannel_factory_unref(r->subchannel_factory);
   gpr_free(r->name);
   gpr_free(r->default_port);
+  gpr_free(r->lb_policy_name);
   gpr_free(r);
 }
 
 static grpc_resolver *dns_create(
     grpc_uri *uri, const char *default_port,
-    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                         size_t num_subchannels),
+    const char* lb_policy_name,
     grpc_subchannel_factory *subchannel_factory) {
   dns_resolver *r;
   const char *path = uri->path;
@@ -220,7 +220,7 @@ static grpc_resolver *dns_create(
   r->default_port = gpr_strdup(default_port);
   r->subchannel_factory = subchannel_factory;
   grpc_subchannel_factory_ref(subchannel_factory);
-  r->lb_policy_factory = lb_policy_factory;
+  r->lb_policy_name = gpr_strdup(lb_policy_name);
   return &r->base;
 }
 
@@ -235,8 +235,7 @@ static void dns_factory_unref(grpc_resolver_factory *factory) {}
 static grpc_resolver *dns_factory_create_resolver(
     grpc_resolver_factory *factory, grpc_uri *uri,
     grpc_subchannel_factory *subchannel_factory) {
-  return dns_create(uri, "https", grpc_create_pick_first_lb_policy,
-                    subchannel_factory);
+  return dns_create(uri, "https", "pick_first", subchannel_factory);
 }
 
 char *dns_factory_get_default_host_name(grpc_resolver_factory *factory,

src/core/client_config/resolvers/sockaddr_resolver.c

@@ -45,7 +45,7 @@
 #include <grpc/support/host_port.h>
 #include <grpc/support/string_util.h>
 
-#include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/client_config/lb_policy_registry.h"
 #include "src/core/iomgr/resolve_address.h"
 #include "src/core/support/string.h"
 
@@ -56,9 +56,8 @@ typedef struct {
   gpr_refcount refs;
   /** subchannel factory */
   grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy factory */
-  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                       size_t num_subchannels);
+  /** load balancing policy name */
+  char *lb_policy_name;
 
   /** the addresses that we've 'resolved' */
   struct sockaddr_storage *addrs;
@@ -136,7 +135,8 @@ static void sockaddr_maybe_finish_next_locked(sockaddr_resolver *r) {
       subchannels[i] = grpc_subchannel_factory_create_subchannel(
           r->subchannel_factory, &args);
     }
-    lb_policy = r->lb_policy_factory(subchannels, r->num_addrs);
+    lb_policy =
+        grpc_lb_policy_create(r->lb_policy_name, subchannels, r->num_addrs);
     gpr_free(subchannels);
     grpc_client_config_set_lb_policy(cfg, lb_policy);
     GRPC_LB_POLICY_UNREF(lb_policy, "unix");
@@ -153,6 +153,7 @@ static void sockaddr_destroy(grpc_resolver *gr) {
   grpc_subchannel_factory_unref(r->subchannel_factory);
   gpr_free(r->addrs);
   gpr_free(r->addrs_len);
+  gpr_free(r->lb_policy_name);
   gpr_free(r);
 }
 
@@ -271,9 +272,7 @@ done:
 
 static void do_nothing(void *ignored) {}
 static grpc_resolver *sockaddr_create(
-    grpc_uri *uri,
-    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                         size_t num_subchannels),
+    grpc_uri *uri, const char *lb_policy_name,
     grpc_subchannel_factory *subchannel_factory,
     int parse(grpc_uri *uri, struct sockaddr_storage *dst, int *len)) {
   size_t i;
@@ -320,7 +319,7 @@ static grpc_resolver *sockaddr_create(
   gpr_mu_init(&r->mu);
   grpc_resolver_init(&r->base, &sockaddr_resolver_vtable);
   r->subchannel_factory = subchannel_factory;
-  r->lb_policy_factory = lb_policy_factory;
+  r->lb_policy_name = gpr_strdup(lb_policy_name);
 
   grpc_subchannel_factory_ref(subchannel_factory);
   return &r->base;
@@ -338,7 +337,7 @@ static void sockaddr_factory_unref(grpc_resolver_factory *factory) {}
   static grpc_resolver *name##_factory_create_resolver(                     \
       grpc_resolver_factory *factory, grpc_uri *uri,                        \
       grpc_subchannel_factory *subchannel_factory) {                        \
-    return sockaddr_create(uri, grpc_create_pick_first_lb_policy,           \
+    return sockaddr_create(uri, "pick_first",                               \
                            subchannel_factory, parse_##name);               \
   }                                                                         \
   static const grpc_resolver_factory_vtable name##_factory_vtable = {       \

src/core/client_config/resolvers/zookeeper_resolver.c

@@ -41,7 +41,7 @@
 #include <grpc/grpc_zookeeper.h>
 #include <zookeeper/zookeeper.h>
 
-#include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/client_config/lb_policy_registry.h"
 #include "src/core/client_config/resolver_registry.h"
 #include "src/core/iomgr/resolve_address.h"
 #include "src/core/support/string.h"
@@ -59,9 +59,8 @@ typedef struct {
   char *name;
   /** subchannel factory */
   grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy factory */
-  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                       size_t num_subchannels);
+  /** load balancing policy name */
+  char *lb_policy_name;
 
   /** mutex guarding the rest of the state */
   gpr_mu mu;
@@ -192,7 +191,8 @@ static void zookeeper_on_resolved(void *arg,
       subchannels[i] = grpc_subchannel_factory_create_subchannel(
           r->subchannel_factory, &args);
     }
-    lb_policy = r->lb_policy_factory(subchannels, addresses->naddrs);
+    lb_policy =
+        grpc_lb_policy_create(r->lb_policy_name, subchannels, addresses->naddrs);
     grpc_client_config_set_lb_policy(config, lb_policy);
     GRPC_LB_POLICY_UNREF(lb_policy, "construction");
     grpc_resolved_addresses_destroy(addresses);
@@ -420,13 +420,12 @@ static void zookeeper_destroy(grpc_resolver *gr) {
   }
   grpc_subchannel_factory_unref(r->subchannel_factory);
   gpr_free(r->name);
+  gpr_free(r->lb_policy_name);
   gpr_free(r);
 }
 
 static grpc_resolver *zookeeper_create(
-    grpc_uri *uri,
-    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
-                                         size_t num_subchannels),
+    grpc_uri *uri, const char *lb_policy_name,
     grpc_subchannel_factory *subchannel_factory) {
   zookeeper_resolver *r;
   size_t length;
@@ -451,7 +450,7 @@ static grpc_resolver *zookeeper_create(
   r->name = gpr_strdup(path);
 
   r->subchannel_factory = subchannel_factory;
-  r->lb_policy_factory = lb_policy_factory;
+  r->lb_policy_name = gpr_strdup(lb_policy_name);
   grpc_subchannel_factory_ref(subchannel_factory);
 
   /** Initializes zookeeper client */
@@ -490,8 +489,7 @@ static char *zookeeper_factory_get_default_hostname(
 static grpc_resolver *zookeeper_factory_create_resolver(
     grpc_resolver_factory *factory, grpc_uri *uri,
     grpc_subchannel_factory *subchannel_factory) {
-  return zookeeper_create(uri, grpc_create_pick_first_lb_policy,
-                          subchannel_factory);
+  return zookeeper_create(uri, "pick_first", subchannel_factory);
 }
 
 static const grpc_resolver_factory_vtable zookeeper_factory_vtable = {

src/core/surface/init.c

@@ -40,6 +40,8 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/time.h>
 #include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/lb_policy_registry.h"
+#include "src/core/client_config/lb_policies/pick_first.h"
 #include "src/core/client_config/resolver_registry.h"
 #include "src/core/client_config/resolvers/dns_resolver.h"
 #include "src/core/client_config/resolvers/sockaddr_resolver.h"
@@ -85,6 +87,8 @@ void grpc_init(void) {
   gpr_mu_lock(&g_init_mu);
   if (++g_initializations == 1) {
     gpr_time_init();
+    grpc_lb_policy_registry_init(grpc_pick_first_lb_factory_create());
+    grpc_register_lb_policy(grpc_pick_first_lb_factory_create());
     grpc_resolver_registry_init("dns:///");
     grpc_register_resolver_type(grpc_dns_resolver_factory_create());
     grpc_register_resolver_type(grpc_ipv4_resolver_factory_create());

tools/doxygen/Doxyfile.core.internal

@@ -794,6 +794,8 @@ src/core/client_config/client_config.h \
 src/core/client_config/connector.h \
 src/core/client_config/lb_policies/pick_first.h \
 src/core/client_config/lb_policy.h \
+src/core/client_config/lb_policy_factory.h \
+src/core/client_config/lb_policy_registry.h \
 src/core/client_config/resolver.h \
 src/core/client_config/resolver_factory.h \
 src/core/client_config/resolver_registry.h \
@@ -919,6 +921,8 @@ src/core/client_config/client_config.c \
 src/core/client_config/connector.c \
 src/core/client_config/lb_policies/pick_first.c \
 src/core/client_config/lb_policy.c \
+src/core/client_config/lb_policy_factory.c \
+src/core/client_config/lb_policy_registry.c \
 src/core/client_config/resolver.c \
 src/core/client_config/resolver_factory.c \
 src/core/client_config/resolver_registry.c \

tools/run_tests/sources_and_headers.json

@@ -12246,6 +12246,8 @@
       "src/core/client_config/connector.h", 
       "src/core/client_config/lb_policies/pick_first.h", 
       "src/core/client_config/lb_policy.h", 
+      "src/core/client_config/lb_policy_factory.h", 
+      "src/core/client_config/lb_policy_registry.h", 
       "src/core/client_config/resolver.h", 
       "src/core/client_config/resolver_factory.h", 
       "src/core/client_config/resolver_registry.h", 
@@ -12392,6 +12394,10 @@
       "src/core/client_config/lb_policies/pick_first.h", 
       "src/core/client_config/lb_policy.c", 
       "src/core/client_config/lb_policy.h", 
+      "src/core/client_config/lb_policy_factory.c", 
+      "src/core/client_config/lb_policy_factory.h", 
+      "src/core/client_config/lb_policy_registry.c", 
+      "src/core/client_config/lb_policy_registry.h", 
       "src/core/client_config/resolver.c", 
       "src/core/client_config/resolver.h", 
       "src/core/client_config/resolver_factory.c", 
@@ -12726,6 +12732,8 @@
       "src/core/client_config/connector.h", 
       "src/core/client_config/lb_policies/pick_first.h", 
       "src/core/client_config/lb_policy.h", 
+      "src/core/client_config/lb_policy_factory.h", 
+      "src/core/client_config/lb_policy_registry.h", 
       "src/core/client_config/resolver.h", 
       "src/core/client_config/resolver_factory.h", 
       "src/core/client_config/resolver_registry.h", 
@@ -12858,6 +12866,10 @@
       "src/core/client_config/lb_policies/pick_first.h", 
       "src/core/client_config/lb_policy.c", 
       "src/core/client_config/lb_policy.h", 
+      "src/core/client_config/lb_policy_factory.c", 
+      "src/core/client_config/lb_policy_factory.h", 
+      "src/core/client_config/lb_policy_registry.c", 
+      "src/core/client_config/lb_policy_registry.h", 
       "src/core/client_config/resolver.c", 
       "src/core/client_config/resolver.h", 
       "src/core/client_config/resolver_factory.c", 

vsprojects/vcxproj/grpc/grpc.vcxproj

@@ -256,6 +256,8 @@
     <ClInclude Include="..\..\..\src\core\client_config\connector.h" />
     <ClInclude Include="..\..\..\src\core\client_config\lb_policies\pick_first.h" />
     <ClInclude Include="..\..\..\src\core\client_config\lb_policy.h" />
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_factory.h" />
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_registry.h" />
     <ClInclude Include="..\..\..\src\core\client_config\resolver.h" />
     <ClInclude Include="..\..\..\src\core\client_config\resolver_factory.h" />
     <ClInclude Include="..\..\..\src\core\client_config\resolver_registry.h" />
@@ -418,6 +420,10 @@
     </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\lb_policy.c">
     </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_factory.c">
+    </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_registry.c">
+    </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\resolver.c">
     </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\resolver_factory.c">

vsprojects/vcxproj/grpc/grpc.vcxproj.filters

@@ -106,6 +106,12 @@
     <ClCompile Include="..\..\..\src\core\client_config\lb_policy.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_factory.c">
+      <Filter>src\core\client_config</Filter>
+    </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_registry.c">
+      <Filter>src\core\client_config</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\resolver.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
@@ -530,6 +536,12 @@
     <ClInclude Include="..\..\..\src\core\client_config\lb_policy.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_factory.h">
+      <Filter>src\core\client_config</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_registry.h">
+      <Filter>src\core\client_config</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\..\src\core\client_config\resolver.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>

vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj

@@ -235,6 +235,8 @@
     <ClInclude Include="..\..\..\src\core\client_config\connector.h" />
     <ClInclude Include="..\..\..\src\core\client_config\lb_policies\pick_first.h" />
     <ClInclude Include="..\..\..\src\core\client_config\lb_policy.h" />
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_factory.h" />
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_registry.h" />
     <ClInclude Include="..\..\..\src\core\client_config\resolver.h" />
     <ClInclude Include="..\..\..\src\core\client_config\resolver_factory.h" />
     <ClInclude Include="..\..\..\src\core\client_config\resolver_registry.h" />
@@ -357,6 +359,10 @@
     </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\lb_policy.c">
     </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_factory.c">
+    </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_registry.c">
+    </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\resolver.c">
     </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\resolver_factory.c">

vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters

@@ -46,6 +46,12 @@
     <ClCompile Include="..\..\..\src\core\client_config\lb_policy.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_factory.c">
+      <Filter>src\core\client_config</Filter>
+    </ClCompile>
+    <ClCompile Include="..\..\..\src\core\client_config\lb_policy_registry.c">
+      <Filter>src\core\client_config</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\src\core\client_config\resolver.c">
       <Filter>src\core\client_config</Filter>
     </ClCompile>
@@ -428,6 +434,12 @@
     <ClInclude Include="..\..\..\src\core\client_config\lb_policy.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_factory.h">
+      <Filter>src\core\client_config</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\..\src\core\client_config\lb_policy_registry.h">
+      <Filter>src\core\client_config</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\..\src\core\client_config\resolver.h">
       <Filter>src\core\client_config</Filter>
     </ClInclude>