robocar-arduino/vendor/github.com/eclipse/paho.mqtt.golang/ping.go

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2019-12-01 21:35:19 +00:00
/*
* 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
}
}
}
}