addrConn: not reset backoff if update address in TransientFailure (#2740

)

clientconn.go

@@ -735,7 +735,6 @@ func (ac *addrConn) connect() error {
 		ac.mu.Unlock()
 		return nil
 	}
-	ac.updateConnectivityState(connectivity.Connecting)
 	ac.mu.Unlock()
 
 	// Start a goroutine connecting to the server asynchronously.
@@ -745,25 +744,35 @@ func (ac *addrConn) connect() error {
 
 // tryUpdateAddrs tries to update ac.addrs with the new addresses list.
 //
-// It checks whether current connected address of ac is in the new addrs list.
+// If ac is Connecting, it returns false. The caller should tear down the ac and
+// create a new one. Note that the backoff will be reset when this happens.
+//
+// If ac is TransientFailure, it updates ac.addrs and returns true. The updated
+// addresses will be picked up by retry in the next iteration after backoff.
+//
+// If ac is Shutdown or Idle, it updates ac.addrs and returns true.
+//
+// If ac is Ready, it checks whether current connected address of ac is in the
+// new addrs list.
 //  - If true, it updates ac.addrs and returns true. The ac will keep using
 //    the existing connection.
 //  - If false, it does nothing and returns false.
 func (ac *addrConn) tryUpdateAddrs(addrs []resolver.Address) bool {
 	ac.mu.Lock()
 	defer ac.mu.Unlock()
 	grpclog.Infof("addrConn: tryUpdateAddrs curAddr: %v, addrs: %v", ac.curAddr, addrs)
-	if ac.state == connectivity.Shutdown {
+	if ac.state == connectivity.Shutdown ||
+		ac.state == connectivity.TransientFailure ||
+		ac.state == connectivity.Idle {
 		ac.addrs = addrs
 		return true
 	}
 
-	// Unless we're busy reconnecting already, let's reconnect from the top of
-	// the list.
-	if ac.state != connectivity.Ready {
+	if ac.state == connectivity.Connecting {
 		return false
 	}
 
+	// ac.state is Ready, try to find the connected address.
 	var curAddrFound bool
 	for _, a := range addrs {
 		if reflect.DeepEqual(ac.curAddr, a) {
@@ -1012,6 +1021,9 @@ func (ac *addrConn) resetTransport() {
 		// The spec doesn't mention what should be done for multiple addresses.
 		// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md#proposed-backoff-algorithm
 		connectDeadline := time.Now().Add(dialDuration)
+
+		ac.updateConnectivityState(connectivity.Connecting)
+		ac.transport = nil
 		ac.mu.Unlock()
 
 		newTr, addr, reconnect, err := ac.tryAllAddrs(addrs, connectDeadline)
@@ -1108,8 +1120,6 @@ func (ac *addrConn) tryAllAddrs(addrs []resolver.Address, connectDeadline time.T
 			ac.mu.Unlock()
 			return nil, resolver.Address{}, nil, errConnClosing
 		}
-		ac.updateConnectivityState(connectivity.Connecting)
-		ac.transport = nil
 
 		ac.cc.mu.RLock()
 		ac.dopts.copts.KeepaliveParams = ac.cc.mkp