Don't initiate writes on setting pushes

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

@@ -91,8 +91,9 @@ static void read_action_locked(grpc_exec_ctx *exec_ctx, void *t,
 static void complete_fetch_locked(grpc_exec_ctx *exec_ctx, void *gs,
                                   grpc_error *error);
 /** Set a transport level setting, and push it to our peer */
-static void push_setting(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
-                         grpc_chttp2_setting_id id, uint32_t value);
+static void queue_setting_update(grpc_exec_ctx *exec_ctx,
+                                 grpc_chttp2_transport *t,
+                                 grpc_chttp2_setting_id id, uint32_t value);
 
 static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                            grpc_chttp2_stream *s, grpc_error *error);
@@ -342,15 +343,16 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
 
   /* configure http2 the way we like it */
   if (is_client) {
-    push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_ENABLE_PUSH, 0);
-    push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 0);
+    queue_setting_update(exec_ctx, t, GRPC_CHTTP2_SETTINGS_ENABLE_PUSH, 0);
+    queue_setting_update(exec_ctx, t,
+                         GRPC_CHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 0);
   }
-  push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE,
-               DEFAULT_WINDOW);
-  push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE,
-               DEFAULT_MAX_HEADER_LIST_SIZE);
-  push_setting(exec_ctx, t,
-               GRPC_CHTTP2_SETTINGS_GRPC_ALLOW_TRUE_BINARY_METADATA, 1);
+  queue_setting_update(exec_ctx, t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE,
+                       DEFAULT_WINDOW);
+  queue_setting_update(exec_ctx, t, GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE,
+                       DEFAULT_MAX_HEADER_LIST_SIZE);
+  queue_setting_update(exec_ctx, t,
+                       GRPC_CHTTP2_SETTINGS_GRPC_ALLOW_TRUE_BINARY_METADATA, 1);
 
   t->ping_policy = (grpc_chttp2_repeated_ping_policy){
       .max_pings_without_data = DEFAULT_MAX_PINGS_BETWEEN_DATA,
@@ -517,8 +519,8 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
               int value = grpc_channel_arg_get_integer(
                   &channel_args->args[i], settings_map[j].integer_options);
               if (value >= 0) {
-                push_setting(exec_ctx, t, settings_map[j].setting_id,
-                             (uint32_t)value);
+                queue_setting_update(exec_ctx, t, settings_map[j].setting_id,
+                                     (uint32_t)value);
               }
             }
             break;
@@ -929,8 +931,11 @@ static void write_action_end_locked(grpc_exec_ctx *exec_ctx, void *tp,
   GPR_TIMER_END("terminate_writing_with_lock", 0);
 }
 
-static void push_setting(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
-                         grpc_chttp2_setting_id id, uint32_t value) {
+// Dirties an HTTP2 setting to be sent out next time a writing path occurs.
+// If the change needs to occur immediately, manually initiate a write.
+static void queue_setting_update(grpc_exec_ctx *exec_ctx,
+                                 grpc_chttp2_transport *t,
+                                 grpc_chttp2_setting_id id, uint32_t value) {
   const grpc_chttp2_setting_parameters *sp =
       &grpc_chttp2_settings_parameters[id];
   uint32_t use_value = GPR_CLAMP(value, sp->min_value, sp->max_value);
@@ -941,7 +946,6 @@ static void push_setting(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   if (use_value != t->settings[GRPC_LOCAL_SETTINGS][id]) {
     t->settings[GRPC_LOCAL_SETTINGS][id] = use_value;
     t->dirtied_local_settings = 1;
-    grpc_chttp2_initiate_write(exec_ctx, t, "push_setting");
   }
 }
 
@@ -2107,8 +2111,8 @@ static void update_bdp(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     gpr_log(GPR_DEBUG, "%s: update initial window size to %d", t->peer_string,
             (int)bdp);
   }
-  push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE,
-               (uint32_t)bdp);
+  queue_setting_update(exec_ctx, t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE,
+                       (uint32_t)bdp);
 }
 
 static void update_frame(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
@@ -2127,8 +2131,8 @@ static void update_frame(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     gpr_log(GPR_DEBUG, "%s: update max_frame size to %d", t->peer_string,
             (int)frame_size);
   }
-  push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE,
-               (uint32_t)frame_size);
+  queue_setting_update(exec_ctx, t, GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE,
+                       (uint32_t)frame_size);
 }
 
 static grpc_error *try_http_parsing(grpc_exec_ctx *exec_ctx,