vendor github.com/cloudflare/cloudflare-go

1 files changed, 64 insertions, 2 deletions

diff --git a/vendor/golang.org/x/net/http2/server.go b/vendor/golang.org/x/net/http2/server.go
index de60fa88f1..02c88b6b3e 100644
--- a/vendor/golang.org/x/net/http2/server.go
+++ b/vendor/golang.org/x/net/http2/server.go
@@ -581,9 +581,11 @@ type serverConn struct {
 	advMaxStreams               uint32 // our SETTINGS_MAX_CONCURRENT_STREAMS advertised the client
 	curClientStreams            uint32 // number of open streams initiated by the client
 	curPushedStreams            uint32 // number of open streams initiated by server push
+	curHandlers                 uint32 // number of running handler goroutines
 	maxClientStreamID           uint32 // max ever seen from client (odd), or 0 if there have been no client requests
 	maxPushPromiseID            uint32 // ID of the last push promise (even), or 0 if there have been no pushes
 	streams                     map[uint32]*stream
+	unstartedHandlers           []unstartedHandler
 	initialStreamSendWindowSize int32
 	maxFrameSize                int32
 	peerMaxHeaderListSize       uint32            // zero means unknown (default)
@@ -981,6 +983,8 @@ func (sc *serverConn) serve() {
 					return
 				case gracefulShutdownMsg:
 					sc.startGracefulShutdownInternal()
+				case handlerDoneMsg:
+					sc.handlerDone()
 				default:
 					panic("unknown timer")
 				}
@@ -1020,6 +1024,7 @@ var (
 	idleTimerMsg        = new(serverMessage)
 	shutdownTimerMsg    = new(serverMessage)
 	gracefulShutdownMsg = new(serverMessage)
+	handlerDoneMsg      = new(serverMessage)
 )
 
 func (sc *serverConn) onSettingsTimer() { sc.sendServeMsg(settingsTimerMsg) }
@@ -2017,8 +2022,7 @@ func (sc *serverConn) processHeaders(f *MetaHeadersFrame) error {
 		st.readDeadline = time.AfterFunc(sc.hs.ReadTimeout, st.onReadTimeout)
 	}
 
-	go sc.runHandler(rw, req, handler)
-	return nil
+	return sc.scheduleHandler(id, rw, req, handler)
 }
 
 func (sc *serverConn) upgradeRequest(req *http.Request) {
@@ -2038,6 +2042,10 @@ func (sc *serverConn) upgradeRequest(req *http.Request) {
 		sc.conn.SetReadDeadline(time.Time{})
 	}
 
+	// This is the first request on the connection,
+	// so start the handler directly rather than going
+	// through scheduleHandler.
+	sc.curHandlers++
 	go sc.runHandler(rw, req, sc.handler.ServeHTTP)
 }
 
@@ -2278,8 +2286,62 @@ func (sc *serverConn) newResponseWriter(st *stream, req *http.Request) *response
 	return &responseWriter{rws: rws}
 }
 
+type unstartedHandler struct {
+	streamID uint32
+	rw       *responseWriter
+	req      *http.Request
+	handler  func(http.ResponseWriter, *http.Request)
+}
+
+// scheduleHandler starts a handler goroutine,
+// or schedules one to start as soon as an existing handler finishes.
+func (sc *serverConn) scheduleHandler(streamID uint32, rw *responseWriter, req *http.Request, handler func(http.ResponseWriter, *http.Request)) error {
+	sc.serveG.check()
+	maxHandlers := sc.advMaxStreams
+	if sc.curHandlers < maxHandlers {
+		sc.curHandlers++
+		go sc.runHandler(rw, req, handler)
+		return nil
+	}
+	if len(sc.unstartedHandlers) > int(4*sc.advMaxStreams) {
+		return sc.countError("too_many_early_resets", ConnectionError(ErrCodeEnhanceYourCalm))
+	}
+	sc.unstartedHandlers = append(sc.unstartedHandlers, unstartedHandler{
+		streamID: streamID,
+		rw:       rw,
+		req:      req,
+		handler:  handler,
+	})
+	return nil
+}
+
+func (sc *serverConn) handlerDone() {
+	sc.serveG.check()
+	sc.curHandlers--
+	i := 0
+	maxHandlers := sc.advMaxStreams
+	for ; i < len(sc.unstartedHandlers); i++ {
+		u := sc.unstartedHandlers[i]
+		if sc.streams[u.streamID] == nil {
+			// This stream was reset before its goroutine had a chance to start.
+			continue
+		}
+		if sc.curHandlers >= maxHandlers {
+			break
+		}
+		sc.curHandlers++
+		go sc.runHandler(u.rw, u.req, u.handler)
+		sc.unstartedHandlers[i] = unstartedHandler{} // don't retain references
+	}
+	sc.unstartedHandlers = sc.unstartedHandlers[i:]
+	if len(sc.unstartedHandlers) == 0 {
+		sc.unstartedHandlers = nil
+	}
+}
+
 // Run on its own goroutine.
 func (sc *serverConn) runHandler(rw *responseWriter, req *http.Request, handler func(http.ResponseWriter, *http.Request)) {
+	defer sc.sendServeMsg(handlerDoneMsg)
 	didPanic := true
 	defer func() {
 		rw.rws.stream.cancelCtx()