feat: count graceful HTTP2 goaways

transport/http2/server.go

@@ -57,6 +57,7 @@ type Server struct {
 	rejectedConns  atomic.Uint64
 	rejectedReqs   atomic.Uint64
 	protocolErrors atomic.Uint64
+	goAwaySent     atomic.Uint64
 	activeConns    atomic.Int64
 	activeRequests atomic.Int64
 	wg             sync.WaitGroup
@@ -69,6 +70,7 @@ type Stats struct {
 	RejectedConnections uint64 `json:"rejectedConnections"`
 	RejectedRequests    uint64 `json:"rejectedRequests"`
 	ProtocolErrors      uint64 `json:"protocolErrors"`
+	GoAwaySent          uint64 `json:"goAwaySent"`
 	ActiveConnections   int64  `json:"activeConnections"`
 	ActiveRequests      int64  `json:"activeRequests"`
 }
@@ -93,6 +95,7 @@ func (s *Server) Stats() Stats {
 		RejectedConnections: s.rejectedConns.Load(),
 		RejectedRequests:    s.rejectedReqs.Load(),
 		ProtocolErrors:      s.protocolErrors.Load(),
+		GoAwaySent:          s.goAwaySent.Load(),
 		ActiveConnections:   s.activeConns.Load(),
 		ActiveRequests:      s.activeRequests.Load(),
 	}
@@ -374,6 +377,7 @@ func (s *Server) Shutdown(ctx context.Context) error {
 		s.mu.Unlock()
 		return nil
 	}
+	alreadyClosing := s.closing
 	s.closing = true
 	listener := s.listener
 	shutdownConfig := s.shutdownConfig
@@ -389,7 +393,8 @@ func (s *Server) Shutdown(ctx context.Context) error {
 	// x/net/http2's configured shutdown callback sends GOAWAY and lets active
 	// streams finish. The base request context remains live until the timeout
 	// path below, where connections are forcibly closed.
-	if shutdownConfig != nil {
+	if shutdownConfig != nil && !alreadyClosing {
+		s.goAwaySent.Add(uint64(len(connections)))
 		_ = shutdownConfig.Shutdown(context.Background())
 	}