Pull flow control into one module

BUILD

@@ -1212,6 +1212,7 @@ grpc_cc_library(
         "src/core/ext/transport/chttp2/transport/bin_encoder.c",
         "src/core/ext/transport/chttp2/transport/chttp2_plugin.c",
         "src/core/ext/transport/chttp2/transport/chttp2_transport.c",
+        "src/core/ext/transport/chttp2/transport/flow_control.c",
         "src/core/ext/transport/chttp2/transport/frame_data.c",
         "src/core/ext/transport/chttp2/transport/frame_goaway.c",
         "src/core/ext/transport/chttp2/transport/frame_ping.c",

CMakeLists.txt

@@ -1078,6 +1078,7 @@ add_library(grpc
   src/core/ext/transport/chttp2/transport/bin_encoder.c
   src/core/ext/transport/chttp2/transport/chttp2_plugin.c
   src/core/ext/transport/chttp2/transport/chttp2_transport.c
+  src/core/ext/transport/chttp2/transport/flow_control.c
   src/core/ext/transport/chttp2/transport/frame_data.c
   src/core/ext/transport/chttp2/transport/frame_goaway.c
   src/core/ext/transport/chttp2/transport/frame_ping.c
@@ -1424,6 +1425,7 @@ add_library(grpc_cronet
   src/core/ext/transport/chttp2/transport/bin_encoder.c
   src/core/ext/transport/chttp2/transport/chttp2_plugin.c
   src/core/ext/transport/chttp2/transport/chttp2_transport.c
+  src/core/ext/transport/chttp2/transport/flow_control.c
   src/core/ext/transport/chttp2/transport/frame_data.c
   src/core/ext/transport/chttp2/transport/frame_goaway.c
   src/core/ext/transport/chttp2/transport/frame_ping.c
@@ -2006,6 +2008,7 @@ add_library(grpc_unsecure
   src/core/ext/transport/chttp2/transport/bin_encoder.c
   src/core/ext/transport/chttp2/transport/chttp2_plugin.c
   src/core/ext/transport/chttp2/transport/chttp2_transport.c
+  src/core/ext/transport/chttp2/transport/flow_control.c
   src/core/ext/transport/chttp2/transport/frame_data.c
   src/core/ext/transport/chttp2/transport/frame_goaway.c
   src/core/ext/transport/chttp2/transport/frame_ping.c
@@ -2516,6 +2519,7 @@ add_library(grpc++_cronet
   src/core/ext/transport/chttp2/transport/bin_encoder.c
   src/core/ext/transport/chttp2/transport/chttp2_plugin.c
   src/core/ext/transport/chttp2/transport/chttp2_transport.c
+  src/core/ext/transport/chttp2/transport/flow_control.c
   src/core/ext/transport/chttp2/transport/frame_data.c
   src/core/ext/transport/chttp2/transport/frame_goaway.c
   src/core/ext/transport/chttp2/transport/frame_ping.c

Makefile

@@ -3022,6 +3022,7 @@ LIBGRPC_SRC = \
     src/core/ext/transport/chttp2/transport/bin_encoder.c \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.c \
     src/core/ext/transport/chttp2/transport/chttp2_transport.c \
+    src/core/ext/transport/chttp2/transport/flow_control.c \
     src/core/ext/transport/chttp2/transport/frame_data.c \
     src/core/ext/transport/chttp2/transport/frame_goaway.c \
     src/core/ext/transport/chttp2/transport/frame_ping.c \
@@ -3366,6 +3367,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/ext/transport/chttp2/transport/bin_encoder.c \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.c \
     src/core/ext/transport/chttp2/transport/chttp2_transport.c \
+    src/core/ext/transport/chttp2/transport/flow_control.c \
     src/core/ext/transport/chttp2/transport/frame_data.c \
     src/core/ext/transport/chttp2/transport/frame_goaway.c \
     src/core/ext/transport/chttp2/transport/frame_ping.c \
@@ -3917,6 +3919,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/transport/chttp2/transport/bin_encoder.c \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.c \
     src/core/ext/transport/chttp2/transport/chttp2_transport.c \
+    src/core/ext/transport/chttp2/transport/flow_control.c \
     src/core/ext/transport/chttp2/transport/frame_data.c \
     src/core/ext/transport/chttp2/transport/frame_goaway.c \
     src/core/ext/transport/chttp2/transport/frame_ping.c \
@@ -4411,6 +4414,7 @@ LIBGRPC++_CRONET_SRC = \
     src/core/ext/transport/chttp2/transport/bin_encoder.c \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.c \
     src/core/ext/transport/chttp2/transport/chttp2_transport.c \
+    src/core/ext/transport/chttp2/transport/flow_control.c \
     src/core/ext/transport/chttp2/transport/frame_data.c \
     src/core/ext/transport/chttp2/transport/frame_goaway.c \
     src/core/ext/transport/chttp2/transport/frame_ping.c \

binding.gyp

@@ -767,6 +767,7 @@
         'src/core/ext/transport/chttp2/transport/bin_encoder.c',
         'src/core/ext/transport/chttp2/transport/chttp2_plugin.c',
         'src/core/ext/transport/chttp2/transport/chttp2_transport.c',
+        'src/core/ext/transport/chttp2/transport/flow_control.c',
         'src/core/ext/transport/chttp2/transport/frame_data.c',
         'src/core/ext/transport/chttp2/transport/frame_goaway.c',
         'src/core/ext/transport/chttp2/transport/frame_ping.c',

build.yaml

@@ -749,6 +749,7 @@ filegroups:
   - src/core/ext/transport/chttp2/transport/bin_encoder.c
   - src/core/ext/transport/chttp2/transport/chttp2_plugin.c
   - src/core/ext/transport/chttp2/transport/chttp2_transport.c
+  - src/core/ext/transport/chttp2/transport/flow_control.c
   - src/core/ext/transport/chttp2/transport/frame_data.c
   - src/core/ext/transport/chttp2/transport/frame_goaway.c
   - src/core/ext/transport/chttp2/transport/frame_ping.c

config.m4

@@ -217,6 +217,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/transport/chttp2/transport/bin_encoder.c \
     src/core/ext/transport/chttp2/transport/chttp2_plugin.c \
     src/core/ext/transport/chttp2/transport/chttp2_transport.c \
+    src/core/ext/transport/chttp2/transport/flow_control.c \
     src/core/ext/transport/chttp2/transport/frame_data.c \
     src/core/ext/transport/chttp2/transport/frame_goaway.c \
     src/core/ext/transport/chttp2/transport/frame_ping.c \

config.w32

@@ -194,6 +194,7 @@ if (PHP_GRPC != "no") {
     "src\\core\\ext\\transport\\chttp2\\transport\\bin_encoder.c " +
     "src\\core\\ext\\transport\\chttp2\\transport\\chttp2_plugin.c " +
     "src\\core\\ext\\transport\\chttp2\\transport\\chttp2_transport.c " +
+    "src\\core\\ext\\transport\\chttp2\\transport\\flow_control.c " +
     "src\\core\\ext\\transport\\chttp2\\transport\\frame_data.c " +
     "src\\core\\ext\\transport\\chttp2\\transport\\frame_goaway.c " +
     "src\\core\\ext\\transport\\chttp2\\transport\\frame_ping.c " +

gRPC-Core.podspec

@@ -591,6 +591,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/transport/chttp2/transport/bin_encoder.c',
                       'src/core/ext/transport/chttp2/transport/chttp2_plugin.c',
                       'src/core/ext/transport/chttp2/transport/chttp2_transport.c',
+                      'src/core/ext/transport/chttp2/transport/flow_control.c',
                       'src/core/ext/transport/chttp2/transport/frame_data.c',
                       'src/core/ext/transport/chttp2/transport/frame_goaway.c',
                       'src/core/ext/transport/chttp2/transport/frame_ping.c',

grpc.gemspec

@@ -527,6 +527,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/transport/chttp2/transport/bin_encoder.c )
   s.files += %w( src/core/ext/transport/chttp2/transport/chttp2_plugin.c )
   s.files += %w( src/core/ext/transport/chttp2/transport/chttp2_transport.c )
+  s.files += %w( src/core/ext/transport/chttp2/transport/flow_control.c )
   s.files += %w( src/core/ext/transport/chttp2/transport/frame_data.c )
   s.files += %w( src/core/ext/transport/chttp2/transport/frame_goaway.c )
   s.files += %w( src/core/ext/transport/chttp2/transport/frame_ping.c )

package.xml

@@ -541,6 +541,7 @@
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/bin_encoder.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/chttp2_plugin.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/chttp2_transport.c" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/flow_control.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/frame_data.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/frame_goaway.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/transport/chttp2/transport/frame_ping.c" role="src" />

src/core/ext/transport/chttp2/transport/chttp2_transport.c

@@ -114,11 +114,6 @@ static void connectivity_state_set(grpc_exec_ctx *exec_ctx,
                                    grpc_connectivity_state state,
                                    grpc_error *error, const char *reason);
 
-static void incoming_byte_stream_update_flow_control(grpc_exec_ctx *exec_ctx,
-                                                     grpc_chttp2_transport *t,
-                                                     grpc_chttp2_stream *s,
-                                                     size_t max_size_hint,
-                                                     size_t have_already);
 static void incoming_byte_stream_destroy_locked(grpc_exec_ctx *exec_ctx,
                                                 void *byte_stream,
                                                 grpc_error *error_ignored);
@@ -270,8 +265,9 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   t->endpoint_reading = 1;
   t->next_stream_id = is_client ? 1 : 2;
   t->is_client = is_client;
-  t->outgoing_window = DEFAULT_WINDOW;
-  t->incoming_window = DEFAULT_WINDOW;
+  t->local_window = DEFAULT_WINDOW;
+  t->remote_window = DEFAULT_WINDOW;
+  t->announced_window = DEFAULT_WINDOW;
   t->deframe_state = is_client ? GRPC_DTS_FH_0 : GRPC_DTS_CLIENT_PREFIX_0;
   t->is_first_frame = true;
   grpc_connectivity_state_init(
@@ -758,13 +754,7 @@ static void destroy_stream_locked(grpc_exec_ctx *exec_ctx, void *sp,
   GRPC_ERROR_UNREF(s->write_closed_error);
   GRPC_ERROR_UNREF(s->byte_stream_error);
 
-  if (s->incoming_window_delta > 0) {
-    GRPC_CHTTP2_FLOW_DEBIT_STREAM_INCOMING_WINDOW_DELTA(
-        "destroy", t, s, s->incoming_window_delta);
-  } else if (s->incoming_window_delta < 0) {
-    GRPC_CHTTP2_FLOW_CREDIT_STREAM_INCOMING_WINDOW_DELTA(
-        "destroy", t, s, -s->incoming_window_delta);
-  }
+  grpc_chttp2_flowctl_destroy_stream(s);
 
   GRPC_CHTTP2_UNREF_TRANSPORT(exec_ctx, t, "stream");
 
@@ -1460,7 +1450,7 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
         already_received = s->frame_storage.length +
                            s->unprocessed_incoming_frames_buffer.length;
       }
-      incoming_byte_stream_update_flow_control(exec_ctx, t, s, 5,
+      grpc_chttp2_flowctl_incoming_bs_update(exec_ctx, t, s, 5,
                                                already_received);
     }
     grpc_chttp2_maybe_complete_recv_message(exec_ctx, t, s);
@@ -2159,9 +2149,10 @@ static void update_bdp(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   if (delta == 0 || (delta > -bdp / 10 && delta < bdp / 10)) {
     return;
   }
-  if (GRPC_TRACER_ON(grpc_bdp_estimator_trace)) {
-    gpr_log(GPR_DEBUG, "%s: update initial window size to %d", t->peer_string,
-            (int)bdp);
+  if (GRPC_TRACER_ON(grpc_bdp_estimator_trace) ||
+      GRPC_TRACER_ON(grpc_flowctl_trace)) {
+    gpr_log(GPR_DEBUG, "%s | %p[%s] | update initial window size to %d",
+            t->peer_string, t, t->is_client ? "cli" : "svr", (int)bdp);
   }
   queue_setting_update(exec_ctx, t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE,
                        (uint32_t)bdp);
@@ -2544,54 +2535,6 @@ static void incoming_byte_stream_unref(grpc_exec_ctx *exec_ctx,
   }
 }
 
-static void incoming_byte_stream_update_flow_control(grpc_exec_ctx *exec_ctx,
-                                                     grpc_chttp2_transport *t,
-                                                     grpc_chttp2_stream *s,
-                                                     size_t max_size_hint,
-                                                     size_t have_already) {
-  uint32_t max_recv_bytes;
-  uint32_t initial_window_size =
-      t->settings[GRPC_SENT_SETTINGS][GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
-
-  /* clamp max recv hint to an allowable size */
-  if (max_size_hint >= UINT32_MAX - initial_window_size) {
-    max_recv_bytes = UINT32_MAX - initial_window_size;
-  } else {
-    max_recv_bytes = (uint32_t)max_size_hint;
-  }
-
-  /* account for bytes already received but unknown to higher layers */
-  if (max_recv_bytes >= have_already) {
-    max_recv_bytes -= (uint32_t)have_already;
-  } else {
-    max_recv_bytes = 0;
-  }
-
-  /* add some small lookahead to keep pipelines flowing */
-  GPR_ASSERT(max_recv_bytes <= UINT32_MAX - initial_window_size);
-  if (s->incoming_window_delta < max_recv_bytes && !s->read_closed) {
-    uint32_t add_max_recv_bytes =
-        (uint32_t)(max_recv_bytes - s->incoming_window_delta);
-    grpc_chttp2_stream_write_type write_type =
-        GRPC_CHTTP2_STREAM_WRITE_INITIATE_UNCOVERED;
-    if (s->incoming_window_delta + initial_window_size <
-        (int64_t)have_already) {
-      write_type = GRPC_CHTTP2_STREAM_WRITE_INITIATE_COVERED;
-    }
-    GRPC_CHTTP2_FLOW_CREDIT_STREAM_INCOMING_WINDOW_DELTA("op", t, s,
-                                                         add_max_recv_bytes);
-    GRPC_CHTTP2_FLOW_CREDIT_STREAM("op", t, s, announce_window,
-                                   add_max_recv_bytes);
-    if ((int64_t)s->incoming_window_delta + (int64_t)initial_window_size -
-            (int64_t)s->announce_window >
-        (int64_t)initial_window_size / 2) {
-      write_type = GRPC_CHTTP2_STREAM_WRITE_PIGGYBACK;
-    }
-    grpc_chttp2_become_writable(exec_ctx, t, s, write_type,
-                                "read_incoming_stream");
-  }
-}
-
 static void incoming_byte_stream_next_locked(grpc_exec_ctx *exec_ctx,
                                              void *argp,
                                              grpc_error *error_ignored) {
@@ -2600,7 +2543,7 @@ static void incoming_byte_stream_next_locked(grpc_exec_ctx *exec_ctx,
   grpc_chttp2_stream *s = bs->stream;
 
   size_t cur_length = s->frame_storage.length;
-  incoming_byte_stream_update_flow_control(
+  grpc_chttp2_flowctl_incoming_bs_update(
       exec_ctx, t, s, bs->next_action.max_size_hint, cur_length);
 
   GPR_ASSERT(s->unprocessed_incoming_frames_buffer.length == 0);
@@ -2874,83 +2817,6 @@ static void destructive_reclaimer_locked(grpc_exec_ctx *exec_ctx, void *arg,
   GRPC_CHTTP2_UNREF_TRANSPORT(exec_ctx, t, "destructive_reclaimer");
 }
 
-/*******************************************************************************
- * TRACING
- */
-
-static char *format_flowctl_context_var(const char *context, const char *var,
-                                        int64_t val, uint32_t id) {
-  char *name;
-  if (context == NULL) {
-    name = gpr_strdup(var);
-  } else if (0 == strcmp(context, "t")) {
-    GPR_ASSERT(id == 0);
-    gpr_asprintf(&name, "TRANSPORT:%s", var);
-  } else if (0 == strcmp(context, "s")) {
-    GPR_ASSERT(id != 0);
-    gpr_asprintf(&name, "STREAM[%d]:%s", id, var);
-  } else {
-    gpr_asprintf(&name, "BAD_CONTEXT[%s][%d]:%s", context, id, var);
-  }
-  char *name_fld = gpr_leftpad(name, ' ', 64);
-  char *value;
-  gpr_asprintf(&value, "%" PRId64, val);
-  char *value_fld = gpr_leftpad(value, ' ', 8);
-  char *result;
-  gpr_asprintf(&result, "%s %s", name_fld, value_fld);
-  gpr_free(name);
-  gpr_free(name_fld);
-  gpr_free(value);
-  gpr_free(value_fld);
-  return result;
-}
-
-void grpc_chttp2_flowctl_trace(const char *file, int line, const char *phase,
-                               grpc_chttp2_flowctl_op op, const char *context1,
-                               const char *var1, const char *context2,
-                               const char *var2, int is_client,
-                               uint32_t stream_id, int64_t val1, int64_t val2) {
-  char *tmp_phase;
-  char *label1 = format_flowctl_context_var(context1, var1, val1, stream_id);
-  char *label2 = format_flowctl_context_var(context2, var2, val2, stream_id);
-  char *clisvr = is_client ? "client" : "server";
-  char *prefix;
-
-  tmp_phase = gpr_leftpad(phase, ' ', 8);
-  gpr_asprintf(&prefix, "FLOW %s: %s ", tmp_phase, clisvr);
-  gpr_free(tmp_phase);
-
-  switch (op) {
-    case GRPC_CHTTP2_FLOWCTL_MOVE:
-      if (val2 != 0) {
-        gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
-                "%sMOVE   %s <- %s giving %" PRId64, prefix, label1, label2,
-                val1 + val2);
-      }
-      break;
-    case GRPC_CHTTP2_FLOWCTL_CREDIT:
-      GPR_ASSERT(val2 >= 0);
-      if (val2 != 0) {
-        gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
-                "%sCREDIT %s by %s giving %" PRId64, prefix, label1, label2,
-                val1 + val2);
-      }
-      break;
-    case GRPC_CHTTP2_FLOWCTL_DEBIT:
-      GPR_ASSERT(val2 >= 0);
-      if (val2 != 0) {
-        gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
-                "%sDEBIT  %s by %s giving %" PRId64, prefix, label1, label2,
-                val1 - val2);
-      }
-      break;
-  }
-
-  gpr_free(label1);
-  gpr_free(label2);
-  gpr_free(prefix);
-}
-
 /*******************************************************************************
  * INTEGRATION GLUE
  */

src/core/ext/transport/chttp2/transport/flow_control.c

@@ -0,0 +1,364 @@
+/*
+ *
+ * Copyright 2017 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 "src/core/ext/transport/chttp2/transport/internal.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/support/string.h"
+
+#ifndef NDEBUG
+
+typedef struct {
+  int64_t remote_window;
+  int64_t local_window;
+  int64_t announced_window;
+  int64_t remote_window_delta;
+  int64_t local_window_delta;
+  int64_t announced_window_delta;
+} shadow_flow_control;
+
+static void pretrace(shadow_flow_control* sfc, grpc_chttp2_transport* t,
+                     grpc_chttp2_stream* s) {
+  sfc->remote_window = t->remote_window;
+  sfc->local_window = t->local_window;
+  sfc->announced_window = t->announced_window;
+  if (s != NULL) {
+    sfc->remote_window_delta = s->remote_window_delta;
+    sfc->local_window_delta = s->local_window_delta;
+    sfc->announced_window_delta = s->announced_window_delta;
+  }
+}
+
+static char* fmt_str(int64_t old, int64_t new) {
+  char* str;
+  if (old != new) {
+    gpr_asprintf(&str, "%" PRId64 " -> %" PRId64 "", old, new);
+  } else {
+    gpr_asprintf(&str, "%" PRId64 "", old);
+  }
+  char* str_lp = gpr_leftpad(str, ' ', 30);
+  gpr_free(str);
+  return str_lp;
+}
+
+static void posttrace(shadow_flow_control* sfc, grpc_chttp2_transport* t,
+                      grpc_chttp2_stream* s, char* reason) {
+  uint32_t acked_local_window =
+      t->settings[GRPC_SENT_SETTINGS][GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
+  uint32_t remote_window =
+      t->settings[GRPC_PEER_SETTINGS][GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
+  char* trw_str = fmt_str(sfc->remote_window, t->remote_window);
+  char* tlw_str = fmt_str(sfc->local_window, t->local_window);
+  char* taw_str = fmt_str(sfc->announced_window, t->announced_window);
+  char* srw_str;
+  char* slw_str;
+  char* saw_str;
+  if (s != NULL) {
+    srw_str = fmt_str(sfc->remote_window_delta + remote_window,
+                      s->remote_window_delta + remote_window);
+    slw_str = fmt_str(sfc->local_window_delta + acked_local_window,
+                      s->local_window_delta + acked_local_window);
+    saw_str = fmt_str(sfc->announced_window_delta + acked_local_window,
+                      s->announced_window_delta + acked_local_window);
+  } else {
+    srw_str = gpr_leftpad("", ' ', 30);
+    slw_str = gpr_leftpad("", ' ', 30);
+    saw_str = gpr_leftpad("", ' ', 30);
+  }
+  gpr_log(GPR_DEBUG,
+          "%p[%u][%s] | %s | trw:%s, tlw:%s, taw:%s, srw:%s, slw:%s, saw:%s", t,
+          s != NULL ? s->id : 0, t->is_client ? "cli" : "svr", reason, trw_str,
+          tlw_str, taw_str, srw_str, slw_str, saw_str);
+  gpr_free(trw_str);
+  gpr_free(tlw_str);
+  gpr_free(taw_str);
+  gpr_free(srw_str);
+  gpr_free(slw_str);
+  gpr_free(saw_str);
+}
+
+#define PRETRACE(t, s)     \
+  shadow_flow_control sfc; \
+  GRPC_FLOW_CONTROL_IF_TRACING(pretrace(&sfc, t, s))
+#define POSTTRACE(t, s, reason) \
+  GRPC_FLOW_CONTROL_IF_TRACING(posttrace(&sfc, t, s, reason))
+#else
+#define PRETRACE(t, s)
+#define POSTTRACE(t, s, reason) ;
+#endif
+
+/* How many bytes of incoming flow control would we like to advertise */
+static uint32_t grpc_chttp2_target_announced_window(grpc_chttp2_transport* t) {
+  return (uint32_t)GPR_MIN(
+      (int64_t)((1u << 31) - 1),
+      t->announced_stream_total_over_incoming_window +
+          t->settings[GRPC_ACKED_SETTINGS]
+                     [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
+}
+
+// we have sent data on the wire, we must track this in our bookkeeping for the
+// remote peer's flow control.
+void grpc_chttp2_flowctl_sent_data(grpc_chttp2_transport* t,
+                                   grpc_chttp2_stream* s, int64_t size) {
+  PRETRACE(t, s);
+  t->remote_window -= size;
+  s->remote_window_delta -= size;
+  POSTTRACE(t, s, "  data sent");
+}
+
+static void announced_window_delta_preupdate(grpc_chttp2_transport* t,
+                                             grpc_chttp2_stream* s) {
+  if (s->announced_window_delta > 0) {
+    t->announced_stream_total_over_incoming_window -= s->announced_window_delta;
+  } else {
+    t->announced_stream_total_under_incoming_window +=
+        -s->announced_window_delta;
+  }
+}
+
+static void announced_window_delta_postupdate(grpc_chttp2_transport* t,
+                                              grpc_chttp2_stream* s) {
+  if (s->announced_window_delta > 0) {
+    t->announced_stream_total_over_incoming_window += s->announced_window_delta;
+  } else {
+    t->announced_stream_total_under_incoming_window -=
+        -s->announced_window_delta;
+  }
+}
+
+// We have received data from the wire. We must track this in our own flow
+// control bookkeeping.
+// Returns an error if the incoming frame violates our flow control.
+grpc_error* grpc_chttp2_flowctl_recv_data(grpc_exec_ctx* exec_ctx,
+                                          grpc_chttp2_transport* t,
+                                          grpc_chttp2_stream* s,
+                                          int64_t incoming_frame_size) {
+  PRETRACE(t, s);
+  if (incoming_frame_size > t->local_window) {
+    char* msg;
+    gpr_asprintf(&msg, "frame of size %d overflows local window of %" PRId64,
+                 t->incoming_frame_size, t->local_window);
+    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
+    gpr_free(msg);
+    return err;
+  }
+
+  // TODO(ncteisen): can this ever be null? ANSWER: only when incoming frame
+  // size is zero?
+  if (s != NULL) {
+    int64_t acked_stream_window =
+        s->announced_window_delta +
+        t->settings[GRPC_ACKED_SETTINGS]
+                   [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
+    int64_t sent_stream_window =
+        s->announced_window_delta +
+        t->settings[GRPC_SENT_SETTINGS]
+                   [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
+    if (incoming_frame_size > acked_stream_window) {
+      if (incoming_frame_size <= sent_stream_window) {
+        gpr_log(
+            GPR_ERROR,
+            "Incoming frame of size %d exceeds local window size of %" PRId64
+            ".\n"
+            "The (un-acked, future) window size would be %" PRId64
+            " which is not exceeded.\n"
+            "This would usually cause a disconnection, but allowing it due to"
+            "broken HTTP2 implementations in the wild.\n"
+            "See (for example) https://github.com/netty/netty/issues/6520.",
+            t->incoming_frame_size, acked_stream_window, sent_stream_window);
+      } else {
+        char* msg;
+        gpr_asprintf(&msg,
+                     "frame of size %d overflows local window of %" PRId64,
+                     t->incoming_frame_size, acked_stream_window);
+        grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
+        gpr_free(msg);
+        return err;
+      }
+    }
+
+    announced_window_delta_preupdate(t, s);
+    s->announced_window_delta -= incoming_frame_size;
+    announced_window_delta_postupdate(t, s);
+    s->local_window_delta -= incoming_frame_size;
+    s->received_bytes += incoming_frame_size;
+
+    if (s->announced_window_delta > 0) {
+      t->announced_stream_total_over_incoming_window +=
+          s->announced_window_delta;
+    } else {
+      t->announced_stream_total_under_incoming_window -=
+          -s->announced_window_delta;
+    }
+
+    // TODO(control bit)
+    if ((int64_t)s->local_window_delta > (int64_t)s->announced_window_delta && (int64_t)s->announced_window_delta <=
+        (int64_t)t->settings[GRPC_SENT_SETTINGS]
+                            [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE] /
+            2) {
+      grpc_chttp2_become_writable(exec_ctx, t, s,
+                                  GRPC_CHTTP2_STREAM_WRITE_INITIATE_UNCOVERED,
+                                  "window-update-required");
+    }
+  }
+
+  t->announced_window -= incoming_frame_size;
+  t->local_window -= incoming_frame_size;
+
+  // TODO(control bit)
+  uint32_t target_announced_window = grpc_chttp2_target_announced_window(t);
+  if (t->announced_window <= target_announced_window / 2) {
+    grpc_chttp2_initiate_write(exec_ctx, t, "flow_control");
+  }
+
+  POSTTRACE(t, s, "  data recv");
+  return GRPC_ERROR_NONE;
+}
+
+// Returns a non zero announce integer if we should send a transport window
+// update
+uint32_t grpc_chttp2_flowctl_maybe_send_transport_update(
+    grpc_chttp2_transport* t) {
+  PRETRACE(t, NULL);
+  uint32_t target_announced_window = grpc_chttp2_target_announced_window(t);
+  uint32_t threshold_to_send_transport_window_update =
+      t->outbuf.count > 0 ? 3 * target_announced_window / 4
+                          : target_announced_window / 2;
+  if (t->announced_window < t->local_window &&
+      t->announced_window <= threshold_to_send_transport_window_update &&
+      t->announced_window != target_announced_window) {
+    uint32_t announce = (uint32_t)GPR_CLAMP(
+        target_announced_window - t->announced_window, 0, UINT32_MAX);
+    t->announced_window += announce;
+    t->local_window =
+        t->announced_window;  // announced should never be higher than local.
+    POSTTRACE(t, NULL, "t updt sent");
+    return announce;
+  }
+
+  // uint32_t announce = 0;
+  // if (t->local_window > t->announced_window) {
+  //   announce = (uint32_t)GPR_CLAMP(
+  //       t->local_window - t->announced_window, 0, UINT32_MAX);
+  //   t->announced_window += announce;
+  //   POSTTRACE(t, NULL, "t updt sent");
+  // }
+  GRPC_FLOW_CONTROL_IF_TRACING(
+      gpr_log(GPR_DEBUG, "%p[0][%s] will not to send transport update", t,
+              t->is_client ? "cli" : "svr"));
+  return 0;
+}
+
+// Returns a non zero announce integer if we should send a stream window update
+uint32_t grpc_chttp2_flowctl_maybe_send_stream_update(grpc_chttp2_stream* s) {
+  PRETRACE(s->t, s);
+  if (s->local_window_delta > s->announced_window_delta) {
+    uint32_t announce = (uint32_t)GPR_CLAMP(
+        s->local_window_delta - s->announced_window_delta, 0, UINT32_MAX);
+    announced_window_delta_preupdate(s->t, s);
+    s->announced_window_delta += announce;
+    announced_window_delta_postupdate(s->t, s);
+    POSTTRACE(s->t, s, "s updt sent");
+    return announce;
+  }
+  GRPC_FLOW_CONTROL_IF_TRACING(
+      gpr_log(GPR_DEBUG, "%p[%u][%s] will not to send stream update", s->t,
+              s->id, s->t->is_client ? "cli" : "svr"));
+  return 0;
+}
+
+// we have received a WINDOW_UPDATE frame for a transport
+void grpc_chttp2_flowctl_recv_transport_update(grpc_chttp2_transport* t,
+                                               uint32_t size) {
+  PRETRACE(t, NULL);
+  t->remote_window += size;
+  POSTTRACE(t, NULL, "t updt recv");
+}
+
+// we have received a WINDOW_UPDATE frame for a stream
+void grpc_chttp2_flowctl_recv_stream_update(grpc_chttp2_stream* s,
+                                            uint32_t size) {
+  PRETRACE(s->t, s);
+  s->remote_window_delta += size;
+  POSTTRACE(s->t, s, "s updt recv");
+}
+
+void grpc_chttp2_flowctl_incoming_bs_update(grpc_exec_ctx *exec_ctx,
+                                                     grpc_chttp2_transport *t,
+                                                     grpc_chttp2_stream *s,
+                                                     size_t max_size_hint,
+                                                     size_t have_already) {
+  PRETRACE(t, s);
+  uint32_t max_recv_bytes;
+  uint32_t initial_window_size =
+      t->settings[GRPC_SENT_SETTINGS][GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
+
+  /* clamp max recv hint to an allowable size */
+  if (max_size_hint >= UINT32_MAX - initial_window_size) {
+    max_recv_bytes = UINT32_MAX - initial_window_size;
+  } else {
+    max_recv_bytes = (uint32_t)max_size_hint;
+  }
+
+  /* account for bytes already received but unknown to higher layers */
+  if (max_recv_bytes >= have_already) {
+    max_recv_bytes -= (uint32_t)have_already;
+  } else {
+    max_recv_bytes = 0;
+  }
+
+  /* add some small lookahead to keep pipelines flowing */
+  GPR_ASSERT(max_recv_bytes <= UINT32_MAX - initial_window_size);
+  if (s->local_window_delta < max_recv_bytes && !s->read_closed) {
+    uint32_t add_max_recv_bytes =
+        (uint32_t)(max_recv_bytes - s->local_window_delta);
+    grpc_chttp2_stream_write_type write_type =
+        GRPC_CHTTP2_STREAM_WRITE_INITIATE_UNCOVERED;
+    s->local_window_delta += add_max_recv_bytes;
+    s->t->local_window += add_max_recv_bytes;
+    // TODO(control bits)
+    if ((int64_t)initial_window_size + (int64_t)s->announced_window_delta >
+            (int64_t)initial_window_size / 2 &&
+        t->announced_window > (int64_t)initial_window_size / 2) {
+      write_type = GRPC_CHTTP2_STREAM_WRITE_PIGGYBACK;  // TODO(contol bits)
+    }
+    GRPC_FLOW_CONTROL_IF_TRACING(gpr_log(
+        GPR_DEBUG, "%p[%u][%s] becoming writable, %sinitiating read", t, s->id,
+        t->is_client ? "cli" : "svr",
+        write_type == GRPC_CHTTP2_STREAM_WRITE_PIGGYBACK ? "not " : ""));
+    grpc_chttp2_become_writable(exec_ctx, t, s, write_type,
+                                "read_incoming_stream");
+  }
+  POSTTRACE(t, s, "app st recv");
+}
+
+void grpc_chttp2_flowctl_destroy_stream(grpc_chttp2_stream* s) {
+  if (s->announced_window_delta > 0) {
+    s->t->announced_stream_total_over_incoming_window -=
+        s->announced_window_delta;
+  } else {
+    s->t->announced_stream_total_under_incoming_window +=
+        -s->announced_window_delta;
+  }
+}

src/core/ext/transport/chttp2/transport/frame_settings.c

@@ -203,8 +203,10 @@ grpc_error *grpc_chttp2_settings_parser_parse(grpc_exec_ctx *exec_ctx, void *p,
               parser->incoming_settings[id] != parser->value) {
             t->initial_window_update +=
                 (int64_t)parser->value - parser->incoming_settings[id];
-            if (GRPC_TRACER_ON(grpc_http_trace)) {
-              gpr_log(GPR_DEBUG, "adding %d for initial_window change",
+            if (GRPC_TRACER_ON(grpc_http_trace) ||
+                GRPC_TRACER_ON(grpc_flowctl_trace)) {
+              gpr_log(GPR_DEBUG, "%p[%s] adding %d for initial_window change",
+                      t, t->is_client ? "cli" : "svr",
                       (int)t->initial_window_update);
             }
           }

src/core/ext/transport/chttp2/transport/frame_window_update.c

@@ -95,8 +95,8 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
 
     if (t->incoming_stream_id != 0) {
       if (s != NULL) {
-        GRPC_CHTTP2_FLOW_CREDIT_STREAM("parse", t, s, outgoing_window_delta,
-                                       received_update);
+        grpc_chttp2_flowctl_recv_stream_update(s, received_update);
+        // TODO(control bits)
         if (grpc_chttp2_list_remove_stalled_by_stream(t, s)) {
           grpc_chttp2_become_writable(
               exec_ctx, t, s, GRPC_CHTTP2_STREAM_WRITE_INITIATE_UNCOVERED,
@@ -104,10 +104,10 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
         }
       }
     } else {
-      bool was_zero = t->outgoing_window <= 0;
-      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parse", t, outgoing_window,
-                                        received_update);
-      bool is_zero = t->outgoing_window <= 0;
+      bool was_zero = t->remote_window <= 0;
+      grpc_chttp2_flowctl_recv_transport_update(t, received_update);
+      // TODO(control bits)
+      bool is_zero = t->remote_window <= 0;
       if (was_zero && !is_zero) {
         grpc_chttp2_initiate_write(exec_ctx, t, "new_global_flow_control");
       }

src/core/ext/transport/chttp2/transport/internal.h

@@ -271,7 +271,6 @@ struct grpc_chttp2_transport {
   grpc_slice_buffer outbuf;
   /** hpack encoding */
   grpc_chttp2_hpack_compressor hpack_compressor;
-  int64_t outgoing_window;
   /** is this a client? */
   uint8_t is_client;
 
@@ -328,11 +327,26 @@ struct grpc_chttp2_transport {
   /** parser for goaway frames */
   grpc_chttp2_goaway_parser goaway_parser;
 
-  /** initial window change */
+  /*********** Flow Control **************/
+
+  /** initial window change. This is tracked as we parse settings frames from
+   * the remote peer. If there is a positive delta, then we will make all
+   * streams readable since they may have become unstalled */
   int64_t initial_window_update;
 
-  /** window available for peer to send to us */
-  int64_t incoming_window;
+  /** Our bookkeeping for the remote peer's available window */
+  int64_t remote_window;
+
+  /** Our bookkeeping for our window. Essentially this tracks available buffer
+   * space to hold data that peer sends to us. This is our local view of the
+   * window. It does not reflect how the remote peer sees it. */
+  int64_t local_window;
+
+  /** This is out window according to what we have sent to our remote peer. The
+   * difference between this and local_window is what we use to decide when
+   * to send WINDOW_UPDATE frames. */
+  int64_t announced_window;
+
   /** calculating what we should give for incoming window:
       we track the total amount of flow control over initial window size
       across all streams: this is data that we want to receive right now (it
@@ -341,8 +355,17 @@ struct grpc_chttp2_transport {
       streams: this is data we've read early
       we want to adjust incoming_window such that:
       incoming_window = total_over - max(bdp - total_under, 0) */
-  int64_t stream_total_over_incoming_window;
-  int64_t stream_total_under_incoming_window;
+  int64_t announced_stream_total_over_incoming_window;
+  int64_t announced_stream_total_under_incoming_window;
+
+  /* bdp estimation */
+  grpc_bdp_estimator bdp_estimator;
+
+  /* pid controller */
+  grpc_pid_controller pid_controller;
+  gpr_timespec last_pid_update;
+
+  /*********** End of Flow Control **************/
 
   /* deframing */
   grpc_chttp2_deframe_transport_state deframe_state;
@@ -369,11 +392,8 @@ struct grpc_chttp2_transport {
   grpc_chttp2_write_cb *write_cb_pool;
 
   /* bdp estimator */
-  grpc_bdp_estimator bdp_estimator;
-  grpc_pid_controller pid_controller;
   grpc_closure start_bdp_ping_locked;
   grpc_closure finish_bdp_ping_locked;
-  gpr_timespec last_pid_update;
 
   /* if non-NULL, close the transport with this error when writes are finished
    */
@@ -435,10 +455,6 @@ struct grpc_chttp2_stream {
   /** HTTP2 stream id for this stream, or zero if one has not been assigned */
   uint32_t id;
 
-  /** window available for us to send to peer, over or under the initial window
-   * size of the transport... ie:
-   * outgoing_window = outgoing_window_delta + transport.initial_window_size */
-  int64_t outgoing_window_delta;
   /** things the upper layers would like to send */
   grpc_metadata_batch *send_initial_metadata;
   grpc_closure *send_initial_metadata_finished;
@@ -505,10 +521,6 @@ struct grpc_chttp2_stream {
   grpc_error *forced_close_error;
   /** how many header frames have we received? */
   uint8_t header_frames_received;
-  /** window available for peer to send to us (as a delta on
-   * transport.initial_window_size)
-   * incoming_window = incoming_window_delta + transport.initial_window_size */
-  int64_t incoming_window_delta;
   /** parsing state for data frames */
   /* Accessed only by transport thread when stream->pending_byte_stream == false
    * Accessed only by application thread when stream->pending_byte_stream ==
@@ -519,8 +531,25 @@ struct grpc_chttp2_stream {
 
   bool sent_initial_metadata;
   bool sent_trailing_metadata;
-  /** how much window should we announce? */
-  uint32_t announce_window;
+
+  /*********** Flow Control ***********/
+
+  /** window available for us to send to peer, over or under the initial window
+   * size of the transport... ie:
+   * remote_window = remote_window_delta + transport.initial_window_size */
+  int64_t remote_window_delta;
+
+  /** window available for peer to send to us (as a delta on
+   * transport.initial_window_size)
+   * local_window = local_window_delta + transport.initial_window_size */
+  int64_t local_window_delta;
+
+  /** window available for peer to send to us over this stream that we have
+   * announced to the peer */
+  int64_t announced_window_delta;
+
+  /*********** End of Flow Control ***********/
+
   grpc_slice_buffer flow_controlled_buffer;
 
   grpc_chttp2_write_cb *on_write_finished_cbs;
@@ -601,6 +630,42 @@ bool grpc_chttp2_list_pop_stalled_by_stream(grpc_chttp2_transport *t,
 bool grpc_chttp2_list_remove_stalled_by_stream(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream *s);
 
+/********* Flow Control ***************/
+
+// we have sent data on the wire
+void grpc_chttp2_flowctl_sent_data(grpc_chttp2_transport *t,
+                                   grpc_chttp2_stream *s, int64_t size);
+
+// we have received data from the wire
+grpc_error *grpc_chttp2_flowctl_recv_data(grpc_exec_ctx *exec_ctx,
+                                          grpc_chttp2_transport *t,
+                                          grpc_chttp2_stream *s,
+                                          int64_t incoming_frame_size);
+
+uint32_t grpc_chttp2_flowctl_maybe_send_transport_update(
+    grpc_chttp2_transport *t);
+
+uint32_t grpc_chttp2_flowctl_maybe_send_stream_update(grpc_chttp2_stream *s);
+
+// we have received a WINDOW_UPDATE frame for a transport
+void grpc_chttp2_flowctl_recv_transport_update(grpc_chttp2_transport *t,
+                                               uint32_t size);
+
+// we have received a WINDOW_UPDATE frame for a stream
+void grpc_chttp2_flowctl_recv_stream_update(grpc_chttp2_stream *s,
+                                            uint32_t size);
+
+// the application is asking for a certain amount of bytes
+void grpc_chttp2_flowctl_incoming_bs_update(grpc_exec_ctx *exec_ctx,
+                                                     grpc_chttp2_transport *t,
+                                                     grpc_chttp2_stream *s,
+                                                     size_t max_size_hint,
+                                                     size_t have_already);
+
+void grpc_chttp2_flowctl_destroy_stream(grpc_chttp2_stream *s);
+
+/********* End of Flow Control ***************/
+
 grpc_chttp2_stream *grpc_chttp2_parsing_lookup_stream(grpc_chttp2_transport *t,
                                                       uint32_t id);
 grpc_chttp2_stream *grpc_chttp2_parsing_accept_stream(grpc_exec_ctx *exec_ctx,
@@ -628,126 +693,22 @@ void grpc_chttp2_complete_closure_step(grpc_exec_ctx *exec_ctx,
 extern grpc_tracer_flag grpc_http_trace;
 extern grpc_tracer_flag grpc_flowctl_trace;
 
+#ifndef NDEBUG
+#define GRPC_FLOW_CONTROL_IF_TRACING(stmt)   \
+  if (!(GRPC_TRACER_ON(grpc_flowctl_trace))) \
+    ;                                        \
+  else                                       \
+  stmt
+#else
+#define GRPC_FLOW_CONTROL_IF_TRACING(stmt)
+#endif
+
 #define GRPC_CHTTP2_IF_TRACING(stmt)      \
   if (!(GRPC_TRACER_ON(grpc_http_trace))) \
     ;                                     \
   else                                    \
   stmt
 
-typedef enum {
-  GRPC_CHTTP2_FLOWCTL_MOVE,
-  GRPC_CHTTP2_FLOWCTL_CREDIT,
-  GRPC_CHTTP2_FLOWCTL_DEBIT
-} grpc_chttp2_flowctl_op;
-
-#define GRPC_CHTTP2_FLOW_MOVE_COMMON(phase, transport, id1, id2, dst_context, \
-                                     dst_var, src_context, src_var)           \
-  do {                                                                        \
-    assert(id1 == id2);                                                       \
-    if (GRPC_TRACER_ON(grpc_flowctl_trace)) {                                 \
-      grpc_chttp2_flowctl_trace(                                              \
-          __FILE__, __LINE__, phase, GRPC_CHTTP2_FLOWCTL_MOVE, #dst_context,  \
-          #dst_var, #src_context, #src_var, transport->is_client, id1,        \
-          dst_context->dst_var, src_context->src_var);                        \
-    }                                                                         \
-    dst_context->dst_var += src_context->src_var;                             \
-    src_context->src_var = 0;                                                 \
-  } while (0)
-
-#define GRPC_CHTTP2_FLOW_MOVE_STREAM(phase, transport, dst_context, dst_var, \
-                                     src_context, src_var)                   \
-  GRPC_CHTTP2_FLOW_MOVE_COMMON(phase, transport, dst_context->id,            \
-                               src_context->id, dst_context, dst_var,        \
-                               src_context, src_var)
-#define GRPC_CHTTP2_FLOW_MOVE_TRANSPORT(phase, dst_context, dst_var,           \
-                                        src_context, src_var)                  \
-  GRPC_CHTTP2_FLOW_MOVE_COMMON(phase, dst_context, 0, 0, dst_context, dst_var, \
-                               src_context, src_var)
-
-#define GRPC_CHTTP2_FLOW_CREDIT_COMMON(phase, transport, id, dst_context,      \
-                                       dst_var, amount)                        \
-  do {                                                                         \
-    if (GRPC_TRACER_ON(grpc_flowctl_trace)) {                                  \
-      grpc_chttp2_flowctl_trace(__FILE__, __LINE__, phase,                     \
-                                GRPC_CHTTP2_FLOWCTL_CREDIT, #dst_context,      \
-                                #dst_var, NULL, #amount, transport->is_client, \
-                                id, dst_context->dst_var, amount);             \
-    }                                                                          \
-    dst_context->dst_var += amount;                                            \
-  } while (0)
-
-#define GRPC_CHTTP2_FLOW_CREDIT_STREAM(phase, transport, dst_context, dst_var, \
-                                       amount)                                 \
-  GRPC_CHTTP2_FLOW_CREDIT_COMMON(phase, transport, dst_context->id,            \
-                                 dst_context, dst_var, amount)
-#define GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT(phase, dst_context, dst_var, amount) \
-  GRPC_CHTTP2_FLOW_CREDIT_COMMON(phase, dst_context, 0, dst_context, dst_var,  \
-                                 amount)
-
-#define GRPC_CHTTP2_FLOW_STREAM_INCOMING_WINDOW_DELTA_PREUPDATE( \
-    phase, transport, dst_context)                               \
-  if (dst_context->incoming_window_delta < 0) {                  \
-    transport->stream_total_under_incoming_window +=             \
-        dst_context->incoming_window_delta;                      \
-  } else if (dst_context->incoming_window_delta > 0) {           \
-    transport->stream_total_over_incoming_window -=              \
-        dst_context->incoming_window_delta;                      \
-  }
-
-#define GRPC_CHTTP2_FLOW_STREAM_INCOMING_WINDOW_DELTA_POSTUPDATE( \
-    phase, transport, dst_context)                                \
-  if (dst_context->incoming_window_delta < 0) {                   \
-    transport->stream_total_under_incoming_window -=              \
-        dst_context->incoming_window_delta;                       \
-  } else if (dst_context->incoming_window_delta > 0) {            \
-    transport->stream_total_over_incoming_window +=               \
-        dst_context->incoming_window_delta;                       \
-  }
-
-#define GRPC_CHTTP2_FLOW_DEBIT_STREAM_INCOMING_WINDOW_DELTA(                 \
-    phase, transport, dst_context, amount)                                   \
-  GRPC_CHTTP2_FLOW_STREAM_INCOMING_WINDOW_DELTA_PREUPDATE(phase, transport,  \
-                                                          dst_context);      \
-  GRPC_CHTTP2_FLOW_DEBIT_STREAM(phase, transport, dst_context,               \
-                                incoming_window_delta, amount);              \
-  GRPC_CHTTP2_FLOW_STREAM_INCOMING_WINDOW_DELTA_POSTUPDATE(phase, transport, \
-                                                           dst_context);
-
-#define GRPC_CHTTP2_FLOW_CREDIT_STREAM_INCOMING_WINDOW_DELTA(                \
-    phase, transport, dst_context, amount)                                   \
-  GRPC_CHTTP2_FLOW_STREAM_INCOMING_WINDOW_DELTA_PREUPDATE(phase, transport,  \
-                                                          dst_context);      \
-  GRPC_CHTTP2_FLOW_CREDIT_STREAM(phase, transport, dst_context,              \
-                                 incoming_window_delta, amount);             \
-  GRPC_CHTTP2_FLOW_STREAM_INCOMING_WINDOW_DELTA_POSTUPDATE(phase, transport, \
-                                                           dst_context);
-
-#define GRPC_CHTTP2_FLOW_DEBIT_COMMON(phase, transport, id, dst_context,       \
-                                      dst_var, amount)                         \
-  do {                                                                         \
-    if (GRPC_TRACER_ON(grpc_flowctl_trace)) {                                  \
-      grpc_chttp2_flowctl_trace(__FILE__, __LINE__, phase,                     \
-                                GRPC_CHTTP2_FLOWCTL_DEBIT, #dst_context,       \
-                                #dst_var, NULL, #amount, transport->is_client, \
-                                id, dst_context->dst_var, amount);             \
-    }                                                                          \
-    dst_context->dst_var -= amount;                                            \
-  } while (0)
-
-#define GRPC_CHTTP2_FLOW_DEBIT_STREAM(phase, transport, dst_context, dst_var, \
-                                      amount)                                 \
-  GRPC_CHTTP2_FLOW_DEBIT_COMMON(phase, transport, dst_context->id,            \
-                                dst_context, dst_var, amount)
-#define GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT(phase, dst_context, dst_var, amount) \
-  GRPC_CHTTP2_FLOW_DEBIT_COMMON(phase, dst_context, 0, dst_context, dst_var,  \
-                                amount)
-
-void grpc_chttp2_flowctl_trace(const char *file, int line, const char *phase,
-                               grpc_chttp2_flowctl_op op, const char *context1,
-                               const char *var1, const char *context2,
-                               const char *var2, int is_client,
-                               uint32_t stream_id, int64_t val1, int64_t val2);
-
 void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                              grpc_chttp2_stream *stream, grpc_error *error);
 void grpc_chttp2_mark_stream_closed(grpc_exec_ctx *exec_ctx,
@@ -849,8 +810,6 @@ void grpc_chttp2_fail_pending_writes(grpc_exec_ctx *exec_ctx,
                                      grpc_chttp2_transport *t,
                                      grpc_chttp2_stream *s, grpc_error *error);
 
-uint32_t grpc_chttp2_target_incoming_window(grpc_chttp2_transport *t);
-
 /** Set the default keepalive configurations, must only be called at
     initialization */
 void grpc_chttp2_config_default_keepalive_args(grpc_channel_args *args,

src/core/ext/transport/chttp2/transport/parsing.c

@@ -349,87 +349,12 @@ void grpc_chttp2_parsing_become_skip_parser(grpc_exec_ctx *exec_ctx,
                          t->parser == grpc_chttp2_header_parser_parse);
 }
 
-static grpc_error *update_incoming_window(grpc_exec_ctx *exec_ctx,
-                                          grpc_chttp2_transport *t,
-                                          grpc_chttp2_stream *s) {
-  uint32_t incoming_frame_size = t->incoming_frame_size;
-  if (incoming_frame_size > t->incoming_window) {
-    char *msg;
-    gpr_asprintf(&msg, "frame of size %d overflows incoming window of %" PRId64,
-                 t->incoming_frame_size, t->incoming_window);
-    grpc_error *err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
-  }
-
-  if (s != NULL) {
-    if (incoming_frame_size >
-        s->incoming_window_delta +
-            t->settings[GRPC_ACKED_SETTINGS]
-                       [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]) {
-      if (incoming_frame_size <=
-          s->incoming_window_delta +
-              t->settings[GRPC_SENT_SETTINGS]
-                         [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]) {
-        gpr_log(
-            GPR_ERROR,
-            "Incoming frame of size %d exceeds incoming window size of %" PRId64
-            ".\n"
-            "The (un-acked, future) window size would be %" PRId64
-            " which is not exceeded.\n"
-            "This would usually cause a disconnection, but allowing it due to "
-            "broken HTTP2 implementations in the wild.\n"
-            "See (for example) https://github.com/netty/netty/issues/6520.",
-            t->incoming_frame_size,
-            s->incoming_window_delta +
-                t->settings[GRPC_ACKED_SETTINGS]
-                           [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
-            s->incoming_window_delta +
-                t->settings[GRPC_SENT_SETTINGS]
-                           [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
-      } else {
-        char *msg;
-        gpr_asprintf(&msg,
-                     "frame of size %d overflows incoming window of %" PRId64,
-                     t->incoming_frame_size,
-                     s->incoming_window_delta +
-                         t->settings[GRPC_ACKED_SETTINGS]
-                                    [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
-        grpc_error *err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-        gpr_free(msg);
-        return err;
-      }
-    }
-
-    GRPC_CHTTP2_FLOW_DEBIT_STREAM_INCOMING_WINDOW_DELTA("parse", t, s,
-                                                        incoming_frame_size);
-    if ((int64_t)s->incoming_window_delta - (int64_t)s->announce_window <=
-        -(int64_t)t->settings[GRPC_SENT_SETTINGS]
-                             [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE] /
-            2) {
-      grpc_chttp2_become_writable(exec_ctx, t, s,
-                                  GRPC_CHTTP2_STREAM_WRITE_INITIATE_UNCOVERED,
-                                  "window-update-required");
-    }
-    s->received_bytes += incoming_frame_size;
-  }
-
-  uint32_t target_incoming_window = grpc_chttp2_target_incoming_window(t);
-  GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("parse", t, incoming_window,
-                                   incoming_frame_size);
-  if (t->incoming_window <= target_incoming_window / 2) {
-    grpc_chttp2_initiate_write(exec_ctx, t, "flow_control");
-  }
-
-  return GRPC_ERROR_NONE;
-}
-
 static grpc_error *init_data_frame_parser(grpc_exec_ctx *exec_ctx,
                                           grpc_chttp2_transport *t) {
   grpc_chttp2_stream *s =
       grpc_chttp2_parsing_lookup_stream(t, t->incoming_stream_id);
   grpc_error *err = GRPC_ERROR_NONE;
-  err = update_incoming_window(exec_ctx, t, s);
+  err = grpc_chttp2_flowctl_recv_data(exec_ctx, t, s, t->incoming_frame_size);
   if (err != GRPC_ERROR_NONE) {
     goto error_handler;
   }

src/core/ext/transport/chttp2/transport/stream_lists.c

@@ -150,12 +150,17 @@ void grpc_chttp2_list_remove_waiting_for_concurrency(grpc_chttp2_transport *t,
 
 void grpc_chttp2_list_add_stalled_by_transport(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream *s) {
+  GRPC_FLOW_CONTROL_IF_TRACING(
+      gpr_log(GPR_DEBUG, "stream %u stalled by transport", s->id));
   stream_list_add(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
 }
 
 bool grpc_chttp2_list_pop_stalled_by_transport(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream **s) {
-  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
+  bool ret = stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT);
+  GRPC_FLOW_CONTROL_IF_TRACING(if (ret) gpr_log(
+      GPR_DEBUG, "stream %u un-stalled by transport", (*s)->id));
+  return ret;
 }
 
 void grpc_chttp2_list_remove_stalled_by_transport(grpc_chttp2_transport *t,
@@ -165,15 +170,23 @@ void grpc_chttp2_list_remove_stalled_by_transport(grpc_chttp2_transport *t,
 
 void grpc_chttp2_list_add_stalled_by_stream(grpc_chttp2_transport *t,
                                             grpc_chttp2_stream *s) {
+  GRPC_FLOW_CONTROL_IF_TRACING(
+      gpr_log(GPR_DEBUG, "stream %u stalled by stream", s->id));
   stream_list_add(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
 }
 
 bool grpc_chttp2_list_pop_stalled_by_stream(grpc_chttp2_transport *t,
                                             grpc_chttp2_stream **s) {
-  return stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
+  bool ret = stream_list_pop(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
+  GRPC_FLOW_CONTROL_IF_TRACING(
+      if (ret) gpr_log(GPR_DEBUG, "stream %u un-stalled by stream", (*s)->id));
+  return ret;
 }
 
 bool grpc_chttp2_list_remove_stalled_by_stream(grpc_chttp2_transport *t,
                                                grpc_chttp2_stream *s) {
-  return stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
+  bool ret = stream_list_maybe_remove(t, s, GRPC_CHTTP2_LIST_STALLED_BY_STREAM);
+  GRPC_FLOW_CONTROL_IF_TRACING(
+      if (ret) gpr_log(GPR_DEBUG, "stream %u un-stalled by stream", s->id));
+  return ret;
 }

src/core/ext/transport/chttp2/transport/writing.c

@@ -148,15 +148,6 @@ static bool stream_ref_if_not_destroyed(gpr_refcount *r) {
   return true;
 }
 
-/* How many bytes of incoming flow control would we like to advertise */
-uint32_t grpc_chttp2_target_incoming_window(grpc_chttp2_transport *t) {
-  return (uint32_t)GPR_MIN(
-      (int64_t)((1u << 31) - 1),
-      t->stream_total_over_incoming_window +
-          t->settings[GRPC_SENT_SETTINGS]
-                     [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
-}
-
 /* How many bytes would we like to put on the wire during a single syscall */
 static uint32_t target_write_size(grpc_chttp2_transport *t) {
   return 1024 * 1024;
@@ -201,7 +192,7 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
       &t->hpack_compressor,
       t->settings[GRPC_PEER_SETTINGS][GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
 
-  if (t->outgoing_window > 0) {
+  if (t->remote_window > 0) {
     while (grpc_chttp2_list_pop_stalled_by_transport(t, &s)) {
       if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s) &&
           stream_ref_if_not_destroyed(&s->refcount->refs)) {
@@ -227,10 +218,11 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
     bool sent_initial_metadata = s->sent_initial_metadata;
     bool now_writing = false;
 
-    GRPC_CHTTP2_IF_TRACING(gpr_log(
-        GPR_DEBUG, "W:%p %s[%d] im-(sent,send)=(%d,%d) announce=%d", t,
-        t->is_client ? "CLIENT" : "SERVER", s->id, sent_initial_metadata,
-        s->send_initial_metadata != NULL, s->announce_window));
+    GRPC_CHTTP2_IF_TRACING(
+        gpr_log(GPR_DEBUG, "W:%p %s[%d] im-(sent,send)=(%d,%d) announce=%d", t,
+                t->is_client ? "CLIENT" : "SERVER", s->id,
+                sent_initial_metadata, s->send_initial_metadata != NULL,
+                (int)(s->local_window_delta - s->announced_window_delta)));
 
     grpc_mdelem *extra_headers_for_trailing_metadata[2];
     size_t num_extra_headers_for_trailing_metadata = 0;
@@ -287,11 +279,11 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
       sent_initial_metadata = true;
     }
     /* send any window updates */
-    if (s->announce_window > 0) {
-      uint32_t announce = s->announce_window;
-      grpc_slice_buffer_add(&t->outbuf,
-                            grpc_chttp2_window_update_create(
-                                s->id, s->announce_window, &s->stats.outgoing));
+    uint32_t stream_announce = grpc_chttp2_flowctl_maybe_send_stream_update(s);
+    if (stream_announce > 0) {
+      grpc_slice_buffer_add(
+          &t->outbuf, grpc_chttp2_window_update_create(s->id, stream_announce,
+                                                       &s->stats.outgoing));
       t->ping_state.pings_before_data_required =
           t->ping_policy.max_pings_without_data;
       if (!t->is_client) {
@@ -299,20 +291,19 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
             gpr_inf_past(GPR_CLOCK_MONOTONIC);
         t->ping_recv_state.ping_strikes = 0;
       }
-      GRPC_CHTTP2_FLOW_DEBIT_STREAM("write", t, s, announce_window, announce);
     }
     if (sent_initial_metadata) {
       /* send any body bytes, if allowed by flow control */
       if (s->flow_controlled_buffer.length > 0) {
-        uint32_t stream_outgoing_window = (uint32_t)GPR_MAX(
+        uint32_t stream_remote_window = (uint32_t)GPR_MAX(
             0,
-            s->outgoing_window_delta +
+            s->remote_window_delta +
                 (int64_t)t->settings[GRPC_PEER_SETTINGS]
                                     [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]);
-        uint32_t max_outgoing = (uint32_t)GPR_MIN(
-            t->settings[GRPC_PEER_SETTINGS]
-                       [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
-            GPR_MIN(stream_outgoing_window, t->outgoing_window));
+        uint32_t max_outgoing =
+            (uint32_t)GPR_MIN(t->settings[GRPC_PEER_SETTINGS]
+                                         [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE],
+                              GPR_MIN(stream_remote_window, t->remote_window));
         if (max_outgoing > 0) {
           uint32_t send_bytes =
               (uint32_t)GPR_MIN(max_outgoing, s->flow_controlled_buffer.length);
@@ -325,10 +316,7 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
           grpc_chttp2_encode_data(s->id, &s->flow_controlled_buffer, send_bytes,
                                   is_last_frame, &s->stats.outgoing,
                                   &t->outbuf);
-          GRPC_CHTTP2_FLOW_DEBIT_STREAM("write", t, s, outgoing_window_delta,
-                                        send_bytes);
-          GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("write", t, outgoing_window,
-                                           send_bytes);
+          grpc_chttp2_flowctl_sent_data(t, s, send_bytes);
           t->ping_state.pings_before_data_required =
               t->ping_policy.max_pings_without_data;
           if (!t->is_client) {
@@ -351,10 +339,10 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
             GRPC_CHTTP2_STREAM_REF(s, "chttp2_writing:fork");
             grpc_chttp2_list_add_writable_stream(t, s);
           }
-        } else if (t->outgoing_window == 0) {
+        } else if (t->remote_window == 0) {
           grpc_chttp2_list_add_stalled_by_transport(t, s);
           now_writing = true;
-        } else if (stream_outgoing_window == 0) {
+        } else if (stream_remote_window == 0) {
           grpc_chttp2_list_add_stalled_by_stream(t, s);
           now_writing = true;
         }
@@ -406,22 +394,15 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
     }
   }
 
-  /* if the grpc_chttp2_transport is ready to send a window update, do so here
-     also; 3/4 is a magic number that will likely get tuned soon */
-  uint32_t target_incoming_window = grpc_chttp2_target_incoming_window(t);
-  uint32_t threshold_to_send_transport_window_update =
-      t->outbuf.count > 0 ? 3 * target_incoming_window / 4
-                          : target_incoming_window / 2;
-  if (t->incoming_window <= threshold_to_send_transport_window_update &&
-      t->incoming_window != target_incoming_window) {
+  uint32_t transport_announce =
+      grpc_chttp2_flowctl_maybe_send_transport_update(t);
+  if (transport_announce) {
     maybe_initiate_ping(exec_ctx, t,
                         GRPC_CHTTP2_PING_BEFORE_TRANSPORT_WINDOW_UPDATE);
-    uint32_t announced = (uint32_t)GPR_CLAMP(
-        target_incoming_window - t->incoming_window, 0, UINT32_MAX);
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("write", t, incoming_window, announced);
     grpc_transport_one_way_stats throwaway_stats;
-    grpc_slice_buffer_add(&t->outbuf, grpc_chttp2_window_update_create(
-                                          0, announced, &throwaway_stats));
+    grpc_slice_buffer_add(
+        &t->outbuf, grpc_chttp2_window_update_create(0, transport_announce,
+                                                     &throwaway_stats));
     t->ping_state.pings_before_data_required =
         t->ping_policy.max_pings_without_data;
     if (!t->is_client) {

src/python/grpcio/grpc_core_dependencies.py

@@ -193,6 +193,7 @@ CORE_SOURCE_FILES = [
   'src/core/ext/transport/chttp2/transport/bin_encoder.c',
   'src/core/ext/transport/chttp2/transport/chttp2_plugin.c',
   'src/core/ext/transport/chttp2/transport/chttp2_transport.c',
+  'src/core/ext/transport/chttp2/transport/flow_control.c',
   'src/core/ext/transport/chttp2/transport/frame_data.c',
   'src/core/ext/transport/chttp2/transport/frame_goaway.c',
   'src/core/ext/transport/chttp2/transport/frame_ping.c',

test/cpp/microbenchmarks/bm_chttp2_transport.cc

@@ -391,8 +391,8 @@ static void BM_TransportStreamSend(benchmark::State &state) {
       MakeClosure([&](grpc_exec_ctx *exec_ctx, grpc_error *error) {
         if (!state.KeepRunning()) return;
         // force outgoing window to be yuge
-        s.chttp2_stream()->outgoing_window_delta = 1024 * 1024 * 1024;
-        f.chttp2_transport()->outgoing_window = 1024 * 1024 * 1024;
+        s.chttp2_stream()->remote_window_delta = 1024 * 1024 * 1024;
+        f.chttp2_transport()->remote_window = 1024 * 1024 * 1024;
         grpc_slice_buffer_stream_init(&send_stream, &send_buffer, 0);
         reset_op();
         op.on_complete = c.get();
@@ -521,8 +521,10 @@ static void BM_TransportStreamRecv(benchmark::State &state) {
       MakeClosure([&](grpc_exec_ctx *exec_ctx, grpc_error *error) {
         if (!state.KeepRunning()) return;
         // force outgoing window to be yuge
-        s.chttp2_stream()->incoming_window_delta = 1024 * 1024 * 1024;
-        f.chttp2_transport()->incoming_window = 1024 * 1024 * 1024;
+        s.chttp2_stream()->local_window_delta = 1024 * 1024 * 1024;
+        f.chttp2_transport()->local_window = 1024 * 1024 * 1024;
+        s.chttp2_stream()->announced_window_delta = 1024 * 1024 * 1024;
+        f.chttp2_transport()->announced_window = 1024 * 1024 * 1024;
         received = 0;
         reset_op();
         op.on_complete = do_nothing.get();

test/cpp/microbenchmarks/bm_fullstack_trickle.cc

@@ -73,11 +73,12 @@ class TrickledCHTTP2 : public EndpointPairFixture {
       log_.reset(new std::ofstream(fn.str().c_str()));
       write_csv(log_.get(), "t", "iteration", "client_backlog",
                 "server_backlog", "client_t_stall", "client_s_stall",
-                "server_t_stall", "server_s_stall", "client_t_outgoing",
-                "server_t_outgoing", "client_t_incoming", "server_t_incoming",
-                "client_s_outgoing_delta", "server_s_outgoing_delta",
-                "client_s_incoming_delta", "server_s_incoming_delta",
-                "client_s_announce_window", "server_s_announce_window",
+                "server_t_stall", "server_s_stall", "client_t_remote",
+                "server_t_remote", "client_t_local", "server_t_local",
+                "client_t_announced", "server_t_announced",
+                "client_s_remote_delta", "server_s_remote_delta",
+                "client_s_local_delta", "server_s_local_delta",
+                "client_s_announced_delta", "server_s_announced_delta",
                 "client_peer_iws", "client_local_iws", "client_sent_iws",
                 "client_acked_iws", "server_peer_iws", "server_local_iws",
                 "server_sent_iws", "server_acked_iws", "client_queued_bytes",
@@ -127,14 +128,15 @@ class TrickledCHTTP2 : public EndpointPairFixture {
         client->lists[GRPC_CHTTP2_LIST_STALLED_BY_STREAM].head != nullptr,
         server->lists[GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT].head != nullptr,
         server->lists[GRPC_CHTTP2_LIST_STALLED_BY_STREAM].head != nullptr,
-        client->outgoing_window, server->outgoing_window,
-        client->incoming_window, server->incoming_window,
-        client_stream ? client_stream->outgoing_window_delta : -1,
-        server_stream ? server_stream->outgoing_window_delta : -1,
-        client_stream ? client_stream->incoming_window_delta : -1,
-        server_stream ? server_stream->incoming_window_delta : -1,
-        client_stream ? client_stream->announce_window : -1,
-        server_stream ? server_stream->announce_window : -1,
+        client->remote_window, server->remote_window, client->local_window,
+        server->local_window, client->announced_window,
+        server->announced_window,
+        client_stream ? client_stream->remote_window_delta : -1,
+        server_stream ? server_stream->remote_window_delta : -1,
+        client_stream ? client_stream->local_window_delta : -1,
+        server_stream ? server_stream->local_window_delta : -1,
+        client_stream ? client_stream->announced_window_delta : -1,
+        server_stream ? server_stream->announced_window_delta : -1,
         client->settings[GRPC_PEER_SETTINGS]
                         [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
         client->settings[GRPC_LOCAL_SETTINGS]

tools/doxygen/Doxyfile.core.internal

@@ -1014,6 +1014,7 @@ src/core/ext/transport/chttp2/transport/bin_encoder.h \
 src/core/ext/transport/chttp2/transport/chttp2_plugin.c \
 src/core/ext/transport/chttp2/transport/chttp2_transport.c \
 src/core/ext/transport/chttp2/transport/chttp2_transport.h \
+src/core/ext/transport/chttp2/transport/flow_control.c \
 src/core/ext/transport/chttp2/transport/frame.h \
 src/core/ext/transport/chttp2/transport/frame_data.c \
 src/core/ext/transport/chttp2/transport/frame_data.h \

tools/run_tests/generated/sources_and_headers.json

@@ -8667,6 +8667,7 @@
       "src/core/ext/transport/chttp2/transport/chttp2_plugin.c", 
       "src/core/ext/transport/chttp2/transport/chttp2_transport.c", 
       "src/core/ext/transport/chttp2/transport/chttp2_transport.h", 
+      "src/core/ext/transport/chttp2/transport/flow_control.c", 
       "src/core/ext/transport/chttp2/transport/frame.h", 
       "src/core/ext/transport/chttp2/transport/frame_data.c", 
       "src/core/ext/transport/chttp2/transport/frame_data.h", 

vsprojects/vcxproj/grpc/grpc.vcxproj

@@ -786,6 +786,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\chttp2_transport.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\flow_control.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\frame_data.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\frame_goaway.c">

vsprojects/vcxproj/grpc/grpc.vcxproj.filters

@@ -397,6 +397,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\chttp2_transport.c">
       <Filter>src\core\ext\transport\chttp2\transport</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\flow_control.c">
+      <Filter>src\core\ext\transport\chttp2\transport</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\frame_data.c">
       <Filter>src\core\ext\transport\chttp2\transport</Filter>
     </ClCompile>

vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj

@@ -754,6 +754,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\chttp2_transport.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\flow_control.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\frame_data.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\frame_goaway.c">

vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters

@@ -403,6 +403,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\chttp2_transport.c">
       <Filter>src\core\ext\transport\chttp2\transport</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\flow_control.c">
+      <Filter>src\core\ext\transport\chttp2\transport</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\transport\chttp2\transport\frame_data.c">
       <Filter>src\core\ext\transport\chttp2\transport</Filter>
     </ClCompile>