From e966e944431701352adc6740ce8b8f9a0883d12f Mon Sep 17 00:00:00 2001
From: Yin Jifeng <jifeng.yin@gmail.com>
Date: Fri, 30 Sep 2016 16:18:10 +0800
Subject: [PATCH] fix server exit due to a temporary network error

---
 server.go | 39 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/server.go b/server.go
index debbd79a..5123bb60 100644
--- a/server.go
+++ b/server.go
@@ -89,10 +89,12 @@ type service struct {
 type Server struct {
 	opts options
 
-	mu    sync.Mutex // guards following
-	lis   map[net.Listener]bool
-	conns map[io.Closer]bool
-	drain bool
+	mu     sync.Mutex // guards following
+	lis    map[net.Listener]bool
+	conns  map[io.Closer]bool
+	drain  bool
+	ctx    context.Context
+	cancel context.CancelFunc
 	// A CondVar to let GracefulStop() blocks until all the pending RPCs are finished
 	// and all the transport goes away.
 	cv     *sync.Cond
@@ -203,6 +205,7 @@ func NewServer(opt ...ServerOption) *Server {
 		m:     make(map[string]*service),
 	}
 	s.cv = sync.NewCond(&s.mu)
+	s.ctx, s.cancel = context.WithCancel(context.Background())
 	if EnableTracing {
 		_, file, line, _ := runtime.Caller(1)
 		s.events = trace.NewEventLog("grpc.Server", fmt.Sprintf("%s:%d", file, line))
@@ -324,7 +327,7 @@ func (s *Server) useTransportAuthenticator(rawConn net.Conn) (net.Conn, credenti
 // Serve accepts incoming connections on the listener lis, creating a new
 // ServerTransport and service goroutine for each. The service goroutines
 // read gRPC requests and then call the registered handlers to reply to them.
-// Serve returns when lis.Accept fails. lis will be closed when
+// Serve returns when lis.Accept fails with fatal errors.  lis will be closed when
 // this method returns.
 func (s *Server) Serve(lis net.Listener) error {
 	s.mu.Lock()
@@ -344,14 +347,38 @@ func (s *Server) Serve(lis net.Listener) error {
 		}
 		s.mu.Unlock()
 	}()
+
+	var tempDelay time.Duration // how long to sleep on accept failure
+
 	for {
 		rawConn, err := lis.Accept()
 		if err != nil {
+			if ne, ok := err.(interface {
+				Temporary() bool
+			}); ok && ne.Temporary() {
+				if tempDelay == 0 {
+					tempDelay = 5 * time.Millisecond
+				} else {
+					tempDelay *= 2
+				}
+				if max := 1 * time.Second; tempDelay > max {
+					tempDelay = max
+				}
+				s.mu.Lock()
+				s.printf("Accept error: %v; retrying in %v", err, tempDelay)
+				s.mu.Unlock()
+				select {
+				case <-time.After(tempDelay):
+				case <-s.ctx.Done():
+				}
+				continue
+			}
 			s.mu.Lock()
 			s.printf("done serving; Accept = %v", err)
 			s.mu.Unlock()
 			return err
 		}
+		tempDelay = 0
 		// Start a new goroutine to deal with rawConn
 		// so we don't stall this Accept loop goroutine.
 		go s.handleRawConn(rawConn)
@@ -812,6 +839,7 @@ func (s *Server) Stop() {
 	}
 
 	s.mu.Lock()
+	s.cancel()
 	if s.events != nil {
 		s.events.Finish()
 		s.events = nil
@@ -832,6 +860,7 @@ func (s *Server) GracefulStop() {
 		lis.Close()
 	}
 	s.lis = nil
+	s.cancel()
 	for c := range s.conns {
 		c.(transport.ServerTransport).Drain()
 	}