pubsub/explorer: leave the HubRelay channels opened

There are multiple goroutines that send to HubRelay.  The WebsocketHub
is the receiver, but there are other senders.
Closing the channel is not necessary to terminate the run loops.

Also, to quit the run loops, Stop() now closes quitWSHandler instead of
sending on it.  There are NO senders, only a receiver.

explorer/websocket.go

@@ -193,10 +193,9 @@ func (wsh *WebsocketHub) pingClients() chan<- struct{} {
 // Stop kills the run() loop and unregisters all clients (connections).
 func (wsh *WebsocketHub) Stop() {
 	// End the run() loop, allowing in-progress operations to complete.
-	wsh.quitWSHandler <- struct{}{}
-	// Lastly close the hub relay channel sine the quitWSHandler signal is
-	// handled in the Run loop.
-	close(wsh.HubRelay)
+	close(wsh.quitWSHandler)
+	// Do not close HubRelay since there are multiple senders; run() is the
+	// receiver.
 }
 
 func (wsh *WebsocketHub) run() {
@@ -274,12 +273,7 @@ func (wsh *WebsocketHub) run() {
 		case c := <-wsh.Unregister:
 			wsh.unregisterClient(c)
 
-		case _, ok := <-wsh.quitWSHandler:
-			if !ok {
-				log.Error("close channel already closed. This should not happen.")
-				return
-			}
-			close(wsh.quitWSHandler)
+		case <-wsh.quitWSHandler:
 
 			// End the buffer interval send loop.
 			wsh.bufferTickerChan <- tickerSigStop

pubsub/websocket.go

@@ -283,10 +283,7 @@ func (wsh *WebsocketHub) pingClients() chan<- struct{} {
 			select {
 			case <-ticker.C:
 				wsh.HubRelay <- pstypes.HubMessage{Signal: sigPingAndUserCount}
-			case _, ok := <-stopPing:
-				if ok {
-					log.Errorf("Do not send on stopPing channel, only close it.")
-				}
+			case <-stopPing:
 				return
 			}
 		}
@@ -298,10 +295,9 @@ func (wsh *WebsocketHub) pingClients() chan<- struct{} {
 // Stop kills the run() loop and unregisters all clients (connections).
 func (wsh *WebsocketHub) Stop() {
 	// End the run() loop, allowing in progress operations to complete.
-	wsh.quitWSHandler <- struct{}{}
-	// Lastly close the hub relay channel sine the quitWSHandler signal is
-	// handled in the Run loop.
-	close(wsh.HubRelay)
+	close(wsh.quitWSHandler)
+	// Do not close HubRelay since there are multiple senders; Run() is the
+	// receiver.
 }
 
 // Run starts the main event loop, which handles the following: 1. receiving
@@ -429,13 +425,7 @@ func (wsh *WebsocketHub) Run() {
 		case c := <-wsh.Unregister:
 			wsh.unregisterClient(c)
 
-		case _, ok := <-wsh.quitWSHandler:
-			if !ok {
-				log.Error("close channel already closed. This should not happen.")
-				return
-			}
-			close(wsh.quitWSHandler)
-
+		case <-wsh.quitWSHandler:
 			// End the buffer interval send loop,
 			wsh.bufferTickerChan <- tickerSigStop