Method handleGoAway

internal/transport/http2_client.go:1361–1436

(f *http2.GoAwayFrame)

}

func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) error {
	t.mu.Lock()
	if t.state == closing {
		t.mu.Unlock()
		return nil
	}
	if f.ErrCode == http2.ErrCodeEnhanceYourCalm && string(f.DebugData()) == "too_many_pings" {
		// When a client receives a GOAWAY with error code ENHANCE_YOUR_CALM and debug
		// data equal to ASCII "too_many_pings", it should log the occurrence at a log level that is
		// enabled by default and double the configure KEEPALIVE_TIME used for new connections
		// on that channel.
		logger.Errorf("Client received GoAway with error code ENHANCE_YOUR_CALM and debug data equal to ASCII \"too_many_pings\".")
	}
	id := f.LastStreamID
	if id > 0 && id%2 == 0 {
		t.mu.Unlock()
		return connectionErrorf(true, nil, "received goaway with non-zero even-numbered stream id: %v", id)
	}
	// A client can receive multiple GoAways from the server (see
	// https://github.com/grpc/grpc-go/issues/1387).  The idea is that the first
	// GoAway will be sent with an ID of MaxInt32 and the second GoAway will be
	// sent after an RTT delay with the ID of the last stream the server will
	// process.
	//
	// Therefore, when we get the first GoAway we don't necessarily close any
	// streams. While in case of second GoAway we close all streams created after
	// the GoAwayId. This way streams that were in-flight while the GoAway from
	// server was being sent don't get killed.
	select {
	case <-t.goAway: // t.goAway has been closed (i.e.,multiple GoAways).
		// If there are multiple GoAways the first one should always have an ID greater than the following ones.
		if id > t.prevGoAwayID {
			t.mu.Unlock()
			return connectionErrorf(true, nil, "received goaway with stream id: %v, which exceeds stream id of previous goaway: %v", id, t.prevGoAwayID)
		}
	default:
		t.setGoAwayReason(f)
		close(t.goAway)
		defer t.controlBuf.put(&incomingGoAway{}) // Defer as t.mu is currently held.
		// Notify the clientconn about the GOAWAY before we set the state to
		// draining, to allow the client to stop attempting to create streams
		// before disallowing new streams on this connection.
		if t.state != draining {
			t.onClose(GoAwayInfo{Reason: t.goAwayReason, GoAwayCode: t.goAwayCode})
			t.state = draining
		}
	}
	// All streams with IDs greater than the GoAwayId
	// and smaller than the previous GoAway ID should be killed.
	upperLimit := t.prevGoAwayID
	if upperLimit == 0 { // This is the first GoAway Frame.
		upperLimit = math.MaxUint32 // Kill all streams after the GoAway ID.
	}

	t.prevGoAwayID = id
	if len(t.activeStreams) == 0 {
		t.mu.Unlock()
		return connectionErrorf(true, nil, "received goaway and there are no active streams")