intermediate change

transport/http2_client.go

@@ -1075,12 +1075,16 @@ func (t *http2Client) controller() {
 	}
 	isPingSent := false
 	keepalivePing := &ping{data: [8]byte{}}
+	cchan := t.controlBuf.get()
+	wchan := nil
 	for {
 		select {
-		case i := <-t.controlBuf.get():
+		case i := <-cchan:
 			t.controlBuf.load()
-			select {
+			wchan = t.writableChan
-			case <-t.writableChan:
+			cchan = nil
+			continue
+		case <-wchan:
 			switch i := i.(type) {
 			case *windowUpdate:
 				t.framer.writeWindowUpdate(true, i.streamID, i.increment)
@@ -1100,11 +1104,10 @@ func (t *http2Client) controller() {
 			default:
 				grpclog.Printf("transport: http2Client.controller got unexpected item type %v\n", i)
 			}
-				t.writableChan <- 0
+			wchan <- 0
+			wchan = nil
+			cchan = t.controlBuf.get()
 			continue
-			case <-t.shutdownChan:
-				return
-			}
 		case <-timer.C:
 			t.mu.Lock()
 			ns := len(t.activeStreams)