stream: fix the map of streams leak

In a connection, streams are added only, but not deleted.
When replying to the last data, delete the stream from map.

And delete operations require concurrency.

Signed-off-by: wllenyj <wllenyj@linux.alibaba.com>

server.go

@@ -318,6 +318,7 @@ func (c *serverConn) run(sctx context.Context) {
 		responses              = make(chan response)
 		recvErr                = make(chan error, 1)
 		done                   = make(chan struct{})
+		streams                = sync.Map{}
 		active       int32
 		lastStreamID uint32
 	)
@@ -347,7 +348,6 @@ func (c *serverConn) run(sctx context.Context) {
 
 	go func(recvErr chan error) {
 		defer close(recvErr)
-		streams := map[uint32]*streamHandler{}
 		for {
 			select {
 			case <-c.shutdown:
@@ -383,12 +383,13 @@ func (c *serverConn) run(sctx context.Context) {
 			}
 
 			if mh.Type == messageTypeData {
-				sh, ok := streams[mh.StreamID]
+				i, ok := streams.Load(mh.StreamID)
 				if !ok {
 					if !sendStatus(mh.StreamID, status.Newf(codes.InvalidArgument, "StreamID is no longer active")) {
 						return
 					}
 				}
+				sh := i.(*streamHandler)
 				if mh.Flags&flagNoData != flagNoData {
 					unmarshal := func(obj interface{}) error {
 						err := protoUnmarshal(p, obj)
@@ -458,7 +459,7 @@ func (c *serverConn) run(sctx context.Context) {
 					continue
 				}
 
-				streams[id] = sh
+				streams.Store(id, sh)
 				atomic.AddInt32(&active, 1)
 			}
 			// TODO: else we must ignore this for future compat. log this?
@@ -518,6 +519,7 @@ func (c *serverConn) run(sctx context.Context) {
 				// The ttrpc protocol currently does not support the case where
 				// the server is localClosed but not remoteClosed. Once the server
 				// is closing, the whole stream may be considered finished
+				streams.Delete(response.id)
 				atomic.AddInt32(&active, -1)
 			}
 		case err := <-recvErr: