BDP based transport window

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

@@ -518,23 +518,6 @@ static void destroy_stream_locked(grpc_exec_ctx *exec_ctx, void *sp,
     }
   }
 
-  if (s->incoming_window_delta > 0) {
-    t->retract_incoming_window += s->incoming_window_delta;
-  } else if (s->incoming_window_delta < 0) {
-    int64_t give_back = -s->incoming_window_delta;
-    if (give_back > t->retract_incoming_window) {
-      give_back -= t->retract_incoming_window;
-      t->retract_incoming_window = 0;
-      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("destroy", t, announce_incoming_window,
-                                        give_back);
-      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("destroy", t, incoming_window,
-                                        give_back);
-      grpc_chttp2_initiate_write(exec_ctx, t, false, "destroy_stream");
-    } else {
-      t->retract_incoming_window -= give_back;
-    }
-  }
-
   GPR_ASSERT(s->send_initial_metadata_finished == NULL);
   GPR_ASSERT(s->fetching_send_message == NULL);
   GPR_ASSERT(s->send_trailing_metadata_finished == NULL);
@@ -1755,18 +1738,6 @@ static void update_bdp(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     return;
   }
   gpr_log(GPR_DEBUG, "%s: %d %" PRId64, t->peer_string, bdp, delta);
-  if (delta < 0) {
-    t->retract_incoming_window += -delta;
-  } else if (delta <= t->retract_incoming_window) {
-    t->retract_incoming_window -= delta;
-  } else {
-    delta -= t->retract_incoming_window;
-    t->retract_incoming_window = 0;
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("update_bdp", t, announce_incoming_window,
-                                      delta);
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("update_bdp", t, incoming_window, delta);
-    grpc_chttp2_initiate_write(exec_ctx, t, false, "update_bdp");
-  }
   push_setting(exec_ctx, t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE, bdp);
 }
 
@@ -2057,19 +2028,6 @@ static void incoming_byte_stream_update_flow_control(grpc_exec_ctx *exec_ctx,
     grpc_chttp2_become_writable(exec_ctx, t, s,
                                 new_window_write_is_covered_by_poller,
                                 "read_incoming_stream");
-    if (t->retract_incoming_window >= add_max_recv_bytes) {
-      t->retract_incoming_window -= add_max_recv_bytes;
-    } else {
-      add_max_recv_bytes -= (uint32_t)t->retract_incoming_window;
-      t->retract_incoming_window = 0;
-      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("op", t, announce_incoming_window,
-                                        add_max_recv_bytes);
-      GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("op", t, incoming_window,
-                                        add_max_recv_bytes);
-      grpc_chttp2_initiate_write(exec_ctx, t,
-                                 new_window_write_is_covered_by_poller,
-                                 "read_incoming_stream");
-    }
   }
 }
 

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

@@ -250,13 +250,6 @@ struct grpc_chttp2_transport {
   /** data to write next write */
   gpr_slice_buffer qbuf;
 
-  /** window available to announce to peer */
-  int64_t announce_incoming_window;
-  /** how many bytes have been given out as transport window that we'd now like
-      to retract? (since we can't retract incoming window, instead we just dont
-      give out any more until this amount goes to zero) */
-  int64_t retract_incoming_window;
-
   /** have we seen a goaway */
   uint8_t seen_goaway;
   /** have we sent a goaway */

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

@@ -377,6 +377,7 @@ static grpc_error *update_incoming_window(grpc_exec_ctx *exec_ctx,
 
   GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("parse", t, incoming_window,
                                    incoming_frame_size);
+  grpc_chttp2_initiate_write(exec_ctx, t, false, "flow_control");
 
   if (s != NULL) {
     if (incoming_frame_size >
@@ -398,12 +399,6 @@ static grpc_error *update_incoming_window(grpc_exec_ctx *exec_ctx,
     GRPC_CHTTP2_FLOW_DEBIT_STREAM("parse", t, s, incoming_window_delta,
                                   incoming_frame_size);
     s->received_bytes += incoming_frame_size;
-  } else {
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parse", t, announce_incoming_window,
-                                      incoming_frame_size);
-    GRPC_CHTTP2_FLOW_CREDIT_TRANSPORT("parse", t, incoming_window,
-                                      incoming_frame_size);
-    grpc_chttp2_initiate_write(exec_ctx, t, false, "destroy_stream");
   }
 
   return GRPC_ERROR_NONE;

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

@@ -222,11 +222,13 @@ bool grpc_chttp2_begin_write(grpc_exec_ctx *exec_ctx,
 
   /* 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 */
-  if (t->announce_incoming_window > 0) {
-    uint32_t announced =
-        (uint32_t)GPR_MIN(t->announce_incoming_window, UINT32_MAX);
-    GRPC_CHTTP2_FLOW_DEBIT_TRANSPORT("write", t, announce_incoming_window,
-                                     announced);
+  uint32_t target_incoming_window = GPR_MAX(
+      t->settings[GRPC_SENT_SETTINGS][GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
+      1024);
+  if (t->incoming_window < 3 * target_incoming_window / 4) {
+    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;
     gpr_slice_buffer_add(&t->outbuf, grpc_chttp2_window_update_create(
                                          0, announced, &throwaway_stats));