rpcclient: fix #3135 wsclient hangs on making request

* Rename c.done channel to c.readerDone
* Introduce c.writerDone channel that is closed if the wsWriter's loop
  is done
* Make the error returned by makeWsRequests verbose

Signed-off-by: Ayrtat <amper.meter1775@gmail.com>

pkg/rpcclient/local.go

@@ -29,7 +29,8 @@ func NewInternal(ctx context.Context, register InternalHook) (*Internal, error)
 			Client: Client{},
 
 			shutdown:      make(chan struct{}),
-			done:          make(chan struct{}),
+			readerDone:    make(chan struct{}),
+			writerDone:    make(chan struct{}),
 			subscriptions: make(map[string]notificationReceiver),
 			receivers:     make(map[any][]string),
 		},
@@ -63,7 +64,7 @@ eventloop:
 			c.notifySubscribers(ntf)
 		}
 	}
-	close(c.done)
+	close(c.readerDone)
 	c.ctxCancel()
 	// ctx is cancelled, server is notified and will finish soon.
 drainloop:

pkg/rpcclient/wsclient.go

@@ -58,7 +58,8 @@ type WSClient struct {
 
 	ws          *websocket.Conn
 	wsOpts      WSOptions
-	done        chan struct{}
+	readerDone  chan struct{}
+	writerDone  chan struct{}
 	requests    chan *neorpc.Request
 	shutdown    chan struct{}
 	closeCalled atomic.Bool
@@ -425,7 +426,8 @@ func NewWS(ctx context.Context, endpoint string, opts WSOptions) (*WSClient, err
 		ws:            ws,
 		wsOpts:        opts,
 		shutdown:      make(chan struct{}),
-		done:          make(chan struct{}),
+		readerDone:    make(chan struct{}),
+		writerDone:    make(chan struct{}),
 		respChannels:  make(map[uint64]chan *neorpc.Response),
 		requests:      make(chan *neorpc.Request),
 		subscriptions: make(map[string]notificationReceiver),
@@ -457,7 +459,7 @@ func (c *WSClient) Close() {
 		// Call to cancel will send signal to all users of Context().
 		c.Client.ctxCancel()
 	}
-	<-c.done
+	<-c.readerDone
 }
 
 func (c *WSClient) wsReader() {
@@ -551,7 +553,7 @@ readloop:
 	if connCloseErr != nil {
 		c.setCloseErr(connCloseErr)
 	}
-	close(c.done)
+	close(c.readerDone)
 	c.respLock.Lock()
 	for _, ch := range c.respChannels {
 		close(ch)
@@ -583,13 +585,14 @@ func (c *WSClient) wsWriter() {
 	pingTicker := time.NewTicker(wsPingPeriod)
 	defer c.ws.Close()
 	defer pingTicker.Stop()
+	defer close(c.writerDone)
 	var connCloseErr error
 writeloop:
 	for {
 		select {
 		case <-c.shutdown:
 			return
-		case <-c.done:
+		case <-c.readerDone:
 			return
 		case req, ok := <-c.requests:
 			if !ok {
@@ -660,28 +663,42 @@ func (c *WSClient) getResponseChannel(id uint64) chan *neorpc.Response {
 	return c.respChannels[id]
 }
 
+// closeErrOrConnLost returns the error that may occur either in wsReader or wsWriter.
+// If wsReader or wsWriter do not set the error, it returns ErrWSConnLost.
+func (c *WSClient) closeErrOrConnLost() (err error) {
+	err = ErrWSConnLost
+	if closeErr := c.GetError(); closeErr != nil {
+		err = closeErr
+	}
+	return
+}
+
 func (c *WSClient) makeWsRequest(r *neorpc.Request) (*neorpc.Response, error) {
 	ch := make(chan *neorpc.Response)
 	c.respLock.Lock()
 	select {
-	case <-c.done:
+	case <-c.readerDone:
 		c.respLock.Unlock()
-		return nil, fmt.Errorf("%w: before registering response channel", ErrWSConnLost)
+		return nil, fmt.Errorf("%w: before registering response channel", c.closeErrOrConnLost())
 	default:
 		c.respChannels[r.ID] = ch
 		c.respLock.Unlock()
 	}
 	select {
-	case <-c.done:
-		return nil, fmt.Errorf("%w: before sending the request", ErrWSConnLost)
+	case <-c.readerDone:
+		return nil, fmt.Errorf("%w: before sending the request", c.closeErrOrConnLost())
+	case <-c.writerDone:
+		return nil, fmt.Errorf("%w: before sending the request", c.closeErrOrConnLost())
 	case c.requests <- r:
 	}
 	select {
-	case <-c.done:
-		return nil, fmt.Errorf("%w: while waiting for the response", ErrWSConnLost)
+	case <-c.readerDone:
+		return nil, fmt.Errorf("%w: while waiting for the response", c.closeErrOrConnLost())
+	case <-c.writerDone:
+		return nil, fmt.Errorf("%w: while waiting for the response", c.closeErrOrConnLost())
 	case resp, ok := <-ch:
 		if !ok {
-			return nil, fmt.Errorf("%w: while waiting for the response", ErrWSConnLost)
+			return nil, fmt.Errorf("%w: while waiting for the response", c.closeErrOrConnLost())
 		}
 		c.unregisterRespChannel(r.ID)
 		return resp, nil