First implementation

vendor/github.com/eclipse/paho.mqtt.golang/ping.go

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2013 IBM Corp.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Seth Hoenig
+ *    Allan Stockdill-Mander
+ *    Mike Robertson
+ */
+
+package mqtt
+
+import (
+	"errors"
+	"sync/atomic"
+	"time"
+
+	"github.com/eclipse/paho.mqtt.golang/packets"
+)
+
+func keepalive(c *client) {
+	defer c.workers.Done()
+	DEBUG.Println(PNG, "keepalive starting")
+	var checkInterval int64
+	var pingSent time.Time
+
+	if c.options.KeepAlive > 10 {
+		checkInterval = 5
+	} else {
+		checkInterval = c.options.KeepAlive / 2
+	}
+
+	intervalTicker := time.NewTicker(time.Duration(checkInterval * int64(time.Second)))
+	defer intervalTicker.Stop()
+
+	for {
+		select {
+		case <-c.stop:
+			DEBUG.Println(PNG, "keepalive stopped")
+			return
+		case <-intervalTicker.C:
+			lastSent := c.lastSent.Load().(time.Time)
+			lastReceived := c.lastReceived.Load().(time.Time)
+
+			DEBUG.Println(PNG, "ping check", time.Since(lastSent).Seconds())
+			if time.Since(lastSent) >= time.Duration(c.options.KeepAlive*int64(time.Second)) || time.Since(lastReceived) >= time.Duration(c.options.KeepAlive*int64(time.Second)) {
+				if atomic.LoadInt32(&c.pingOutstanding) == 0 {
+					DEBUG.Println(PNG, "keepalive sending ping")
+					ping := packets.NewControlPacket(packets.Pingreq).(*packets.PingreqPacket)
+					//We don't want to wait behind large messages being sent, the Write call
+					//will block until it it able to send the packet.
+					atomic.StoreInt32(&c.pingOutstanding, 1)
+					ping.Write(c.conn)
+					c.lastSent.Store(time.Now())
+					pingSent = time.Now()
+				}
+			}
+			if atomic.LoadInt32(&c.pingOutstanding) > 0 && time.Now().Sub(pingSent) >= c.options.PingTimeout {
+				CRITICAL.Println(PNG, "pingresp not received, disconnecting")
+				c.errors <- errors.New("pingresp not received, disconnecting")
+				return
+			}
+		}
+	}
+}