From a900d1521e890ba65f2b936fd55115b1ecf5e447 Mon Sep 17 00:00:00 2001
From: Kane York <rikingcoding@gmail.com>
Date: Fri, 27 Oct 2017 13:13:39 -0700
Subject: [PATCH] Optimize pings to reduce timer percolation

---
 socketserver/server/handlecore.go | 25 +++++++++++++------------
 socketserver/server/types.go      |  4 ----
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/socketserver/server/handlecore.go b/socketserver/server/handlecore.go
index fe62c927..bba45d62 100644
--- a/socketserver/server/handlecore.go
+++ b/socketserver/server/handlecore.go
@@ -375,11 +375,7 @@ func RunSocketConnection(conn *websocket.Conn) {
 	// report.RemoteAddr = client.RemoteAddr
 
 	conn.SetPongHandler(func(pongBody string) error {
-		client.Mutex.Lock()
-		if client.HelloOK { // do not accept PONGs until hello sent
-			client.pingCount = 0
-		}
-		client.Mutex.Unlock()
+		_clientChan <- ClientMessage{Command: "__ping"}
 		return nil
 	})
 
@@ -467,6 +463,10 @@ func runSocketReader(conn *websocket.Conn, client *ClientInfo, errorChan chan<-
 }
 
 func runSocketWriter(conn *websocket.Conn, client *ClientInfo, errorChan <-chan error, clientChan <-chan ClientMessage, serverMessageChan <-chan ClientMessage) websocket.CloseError {
+	pingTicker := time.NewTicker(1*time.Minute)
+	defer pingTicker.Stop()
+	lastPacket := time.Now()
+
 	for {
 		select {
 		case err := <-errorChan:
@@ -488,6 +488,10 @@ func runSocketWriter(conn *websocket.Conn, client *ClientInfo, errorChan <-chan
 			if !client.HelloOK && msg.Command != HelloCommand {
 				return CloseFirstMessageNotHello
 			}
+			lastPacket = time.Now()
+			if msg.Command == "__ping" {
+				continue // generated by server, not by client
+			}
 
 			for _, char := range msg.Command {
 				if char == utf8.RuneError {
@@ -506,14 +510,11 @@ func runSocketWriter(conn *websocket.Conn, client *ClientInfo, errorChan <-chan
 			}
 			SendMessage(conn, msg)
 
-		case <-time.After(1 * time.Minute):
-			client.Mutex.Lock()
-			client.pingCount++
-			tooManyPings := client.pingCount == 5
-			client.Mutex.Unlock()
-			if tooManyPings {
+		case <-pingTicker.C:
+			now := time.Now()
+			if lastPacket.Add(5*time.Minute).Before(now) {
 				return CloseTimedOut
-			} else {
+			} else if lastPacket.Add(1*time.Minute).Before(now) {
 				conn.WriteControl(websocket.PingMessage, []byte(strconv.FormatInt(time.Now().Unix(), 10)), getDeadline())
 			}
 
diff --git a/socketserver/server/types.go b/socketserver/server/types.go
index 3face4c4..e5b464d9 100644
--- a/socketserver/server/types.go
+++ b/socketserver/server/types.go
@@ -141,10 +141,6 @@ type ClientInfo struct {
 
 	// Take out an Add() on this during a command if you need to use the MessageChannel later.
 	MsgChannelKeepalive sync.WaitGroup
-
-	// The number of pings sent without a response.
-	// Protected by Mutex
-	pingCount int
 }
 
 func VersionFromString(v string) ClientVersion {