Fix deadlock bug in websocket client impl

benchmarks/simu/counter.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/gorilla/websocket"
+	. "github.com/tendermint/go-common"
+	"github.com/tendermint/go-wire"
+	"github.com/tendermint/tendermint/rpc/client"
+	// ctypes "github.com/tendermint/tendermint/rpc/core/types"
+	"github.com/tendermint/tendermint/rpc/types"
+)
+
+func main() {
+	ws := rpcclient.NewWSClient("ws://127.0.0.1:46657/websocket")
+	// ws := rpcclient.NewWSClient("ws://104.236.69.128:46657/websocket")
+	_, err := ws.Start()
+	if err != nil {
+		Exit(err.Error())
+	}
+
+	// Read a bunch of responses
+	go func() {
+		for {
+			res, ok := <-ws.ResultsCh
+			if !ok {
+				break
+			}
+			fmt.Println("Received response", res)
+		}
+	}()
+
+	// Make a bunch of requests
+	request := rpctypes.NewRPCRequest("fakeid", "status", nil)
+	for i := 0; ; i++ {
+		reqBytes := wire.JSONBytes(request)
+		err := ws.WriteMessage(websocket.TextMessage, reqBytes)
+		if err != nil {
+			Exit(err.Error())
+		}
+	}
+
+	ws.Stop()
+}

rpc/client/log.go

@@ -1,4 +1,3 @@
-
 package rpcclient
 
 import (

rpc/client/ws_client.go

@@ -0,0 +1,126 @@
+package rpcclient
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/gorilla/websocket"
+	. "github.com/tendermint/go-common"
+	"github.com/tendermint/go-wire"
+	ctypes "github.com/tendermint/tendermint/rpc/core/types"
+	"github.com/tendermint/tendermint/rpc/types"
+)
+
+const (
+	wsEventsChannelCapacity  = 10
+	wsResultsChannelCapacity = 10
+	wsWriteTimeoutSeconds    = 10
+)
+
+type WSClient struct {
+	QuitService
+	Address string
+	*websocket.Conn
+	EventsCh  chan ctypes.ResultEvent // closes upon WSClient.Stop()
+	ResultsCh chan ctypes.Result      // closes upon WSClient.Stop()
+}
+
+// create a new connection
+func NewWSClient(addr string) *WSClient {
+	wsClient := &WSClient{
+		Address:   addr,
+		Conn:      nil,
+		EventsCh:  make(chan ctypes.ResultEvent, wsEventsChannelCapacity),
+		ResultsCh: make(chan ctypes.Result, wsResultsChannelCapacity),
+	}
+	wsClient.QuitService = *NewQuitService(log, "WSClient", wsClient)
+	return wsClient
+}
+
+func (wsc *WSClient) OnStart() error {
+	wsc.QuitService.OnStart()
+	err := wsc.dial()
+	if err != nil {
+		return err
+	}
+	go wsc.receiveEventsRoutine()
+	return nil
+}
+
+func (wsc *WSClient) dial() error {
+	// Dial
+	dialer := websocket.DefaultDialer
+	rHeader := http.Header{}
+	con, _, err := dialer.Dial(wsc.Address, rHeader)
+	if err != nil {
+		return err
+	}
+	// Set the ping/pong handlers
+	con.SetPingHandler(func(m string) error {
+		// NOTE: https://github.com/gorilla/websocket/issues/97
+		go con.WriteControl(websocket.PongMessage, []byte(m), time.Now().Add(time.Second*wsWriteTimeoutSeconds))
+		return nil
+	})
+	con.SetPongHandler(func(m string) error {
+		// NOTE: https://github.com/gorilla/websocket/issues/97
+		return nil
+	})
+	wsc.Conn = con
+	return nil
+}
+
+func (wsc *WSClient) OnStop() {
+	wsc.QuitService.OnStop()
+	// EventsCh and ResultsCh are closed in receiveEventsRoutine.
+}
+
+func (wsc *WSClient) receiveEventsRoutine() {
+	for {
+		_, data, err := wsc.ReadMessage()
+		if err != nil {
+			log.Info("WSClient failed to read message", "error", err, "data", string(data))
+			wsc.Stop()
+			break
+		} else {
+			var response ctypes.Response
+			wire.ReadJSON(&response, data, &err)
+			if err != nil {
+				log.Info("WSClient failed to parse message", "error", err)
+				wsc.Stop()
+				break
+			}
+			if strings.HasSuffix(response.ID, "#event") {
+				wsc.EventsCh <- *response.Result.(*ctypes.ResultEvent)
+			} else {
+				wsc.ResultsCh <- response.Result
+			}
+		}
+	}
+
+	// Cleanup
+	close(wsc.EventsCh)
+	close(wsc.ResultsCh)
+}
+
+// subscribe to an event
+func (wsc *WSClient) Subscribe(eventid string) error {
+	err := wsc.WriteJSON(rpctypes.RPCRequest{
+		JSONRPC: "2.0",
+		ID:      "",
+		Method:  "subscribe",
+		Params:  []interface{}{eventid},
+	})
+	return err
+}
+
+// unsubscribe from an event
+func (wsc *WSClient) Unsubscribe(eventid string) error {
+	err := wsc.WriteJSON(rpctypes.RPCRequest{
+		JSONRPC: "2.0",
+		ID:      "",
+		Method:  "unsubscribe",
+		Params:  []interface{}{eventid},
+	})
+	return err
+}

rpc/server/handlers.go

@@ -252,11 +252,13 @@ func (wsc *WSConnection) OnStart() error {
 	wsc.readTimeout = time.NewTimer(time.Second * wsReadTimeoutSeconds)
 	wsc.pingTicker = time.NewTicker(time.Second * wsPingTickerSeconds)
 	wsc.baseConn.SetPingHandler(func(m string) error {
-		wsc.baseConn.WriteControl(websocket.PongMessage, []byte(m), time.Now().Add(time.Second*wsWriteTimeoutSeconds))
+		// NOTE: https://github.com/gorilla/websocket/issues/97
+		go wsc.baseConn.WriteControl(websocket.PongMessage, []byte(m), time.Now().Add(time.Second*wsWriteTimeoutSeconds))
 		wsc.readTimeout.Reset(time.Second * wsReadTimeoutSeconds)
 		return nil
 	})
 	wsc.baseConn.SetPongHandler(func(m string) error {
+		// NOTE: https://github.com/gorilla/websocket/issues/97
 		wsc.readTimeout.Reset(time.Second * wsReadTimeoutSeconds)
 		return nil
 	})
@@ -287,13 +289,12 @@ func (wsc *WSConnection) readTimeoutRoutine() {
 	}
 }
 
-// Attempt to write response to writeChan and record failures
+// Block trying to write to writeChan until service stops.
 func (wsc *WSConnection) writeRPCResponse(resp RPCResponse) {
 	select {
+	case <-wsc.Quit:
+		return
 	case wsc.writeChan <- resp:
-	default:
-		log.Notice("Stopping connection due to writeChan overflow", "id", wsc.id)
-		wsc.Stop() // writeChan capacity exceeded, error.
 	}
 }
 
@@ -412,7 +413,8 @@ func (wsc *WSConnection) writeRoutine() {
 				log.Error("Failed to marshal RPCResponse to JSON", "error", err)
 			} else {
 				wsc.baseConn.SetWriteDeadline(time.Now().Add(time.Second * wsWriteTimeoutSeconds))
-				if err = wsc.baseConn.WriteMessage(websocket.TextMessage, buf.Bytes()); err != nil {
+				bufBytes := buf.Bytes()
+				if err = wsc.baseConn.WriteMessage(websocket.TextMessage, bufBytes); err != nil {
 					log.Warn("Failed to write response on websocket", "error", err)
 					wsc.Stop()
 					return

rpc/types/types.go

@@ -7,6 +7,15 @@ type RPCRequest struct {
 	Params  []interface{} `json:"params"`
 }
 
+func NewRPCRequest(id string, method string, params []interface{}) RPCRequest {
+	return RPCRequest{
+		JSONRPC: "2.0",
+		ID:      id,
+		Method:  method,
+		Params:  params,
+	}
+}
+
 type RPCResponse struct {
 	JSONRPC string      `json:"jsonrpc"`
 	ID      string      `json:"id"`