MQTT paho - 发布消息失败时没有错误

Question

我正在使用 paho.mqtt.golang 库连接到代理并发布消息。

除了发布失败时没有出现错误外，一切正常。

我做的测试如下：

我启动代理
我运行我的代码连接到代理。连接后代码等待输入继续发布
我杀了经纪人
我按回车键继续发布消息

我预计发布函数 if token.Error() != nil {...} 返回的令牌会出错，但我得到了 none。

发布函数的代码如下：

func (handle Handler) Pub(ctx context.Context, topic, payload string, qos int, retained bool) error {
    token := handle.client.Publish(topic, byte(qos), retained, payload)
    go func(ctx context.Context) {
        log := logger.NewLogFromCtx(ctx)
        log.Debug("waiting for transaction to complete...")
        _ = token.Done()
        log.Debug("transaction Done!", zap.Any("token.Error()", token.Error()))
        if token.Error() != nil {
            log.Error("failed to publish MQTT message", zap.Error(token.Error()))
        }
    }(ctx)
    log := logger.NewLogFromCtx(ctx)
    log.Debug("Msg sent !")
    return nil
}

这是日志：

Thu 27 May 17:40:25 CEST        INFO    logger/logging.go:32    logger initialized in development mode
[DEBUG][client]   Connect()
[DEBUG][store]    memorystore initialized
[DEBUG][client]   about to write new connect msg
[DEBUG][client]   socket connected to broker
[DEBUG][client]   Using MQTT 3.1.1 protocol
[DEBUG][net]      connect started
[DEBUG][net]      received connack
[DEBUG][client]   startCommsWorkers called
[DEBUG][client]   client is connected/reconnected
[DEBUG][net]      incoming started
[DEBUG][net]      startIncomingComms started
[DEBUG][net]      outgoing started
[DEBUG][net]      startComms started
[DEBUG][client]   startCommsWorkers done
[WARN][store]    memorystore wiped
[DEBUG][client]   exit startClient
Thu 27 May 17:40:25 CEST        INFO    mqtt_/client.go:68      successfully connected to MQTT broker   {"url": "tcp://127.0.0.1:1883", "in": "41.843622ms"}
press enter to publish...

此时我已连接到代理，代码正在等待输入；我杀经纪人：

[ERROR][client]   Connect comms goroutine - error triggered EOF
[DEBUG][client]   internalConnLost called
[DEBUG][client]   stopCommsWorkers called
[DEBUG][router]   matchAndDispatch exiting
[DEBUG][pinger]   keepalive stopped
[DEBUG][client]   startCommsWorkers output redirector finished
[DEBUG][net]      outgoing waiting for an outbound message
[DEBUG][net]      outgoing waiting for an outbound message
[DEBUG][net]      outgoing comms stopping
[DEBUG][net]      startComms closing outError
[DEBUG][client]   incoming comms goroutine done
[DEBUG][client]   stopCommsWorkers waiting for workers
[DEBUG][client]   stopCommsWorkers waiting for comms
[DEBUG][client]   stopCommsWorkers done
[DEBUG][client]   internalConnLost waiting on workers
[DEBUG][client]   internalConnLost workers stopped
[DEBUG][client]   internalConnLost complete
[DEBUG]Connection lost: EOF
[DEBUG][client]   enter reconnect
[DEBUG][client]   about to write new connect msg
[DEBUG][client]   socket connected to broker
[DEBUG][client]   Using MQTT 3.1.1 protocol
[DEBUG][net]      connect started
[ERROR][net]      connect got error EOF
[ERROR][client]   Connecting to tcp://127.0.0.1:1883 CONNACK was not CONN_ACCEPTED, but rather Connection Error
[DEBUG][client]   Reconnect failed, sleeping for 1 seconds: network Error : EOF

连接确实丢失了。我按回车继续发布：

[DEBUG][client]   enter Publish
[DEBUG][client]   storing publish message (reconnecting), topic: just/for/test
Thu 27 May 17:40:42 CEST        DEBUG   mqtt_/client.go:84      Msg sent !
Thu 27 May 17:40:42 CEST        DEBUG   mqtt_/client.go:76      waiting for transaction to complete...
Thu 27 May 17:40:42 CEST        DEBUG   mqtt_/client.go:78      transaction Done!       {"token.Error()": null}

token.Error() 中没有任何内容。如何检查发布是否成功？

如果您需要更多详细信息，这是我的完整代码。

连接并发布到代理：

type Handler struct {
    client MQTT.Client
    conf   config.Configuration
}

func InitMQTT() {
    MQTT.DEBUG = lg.New(os.Stdout, "[DEBUG]", 0)
    MQTT.WARN = lg.New(os.Stdout, "[WARN]", 0)
    MQTT.CRITICAL = lg.New(os.Stdout, "[CRIT]", 0)
    MQTT.ERROR = lg.New(os.Stdout, "[ERROR]", 0)
}

func NewClient(ctx context.Context, conf config.Configuration) (Handler, error) {
    start := time.Now()
    log := logger.NewLogFromCtx(ctx)
    brokerUrl := fmt.Sprintf("tcp://%s:%s", conf.GW_MQTT_BROKER_HOST_IP, conf.GW_MQTT_BROKER_PORT)
    hostname, _ := os.Hostname()
    clientId := hostname + strconv.Itoa(time.Now().Second())
    connOpts := MQTT.NewClientOptions()
    connOpts.AddBroker(brokerUrl)
    connOpts.SetClientID(clientId)
    connOpts.SetCleanSession(true)
    handler := Handler{conf: conf}
    handler.client = MQTT.NewClient(connOpts)
    if token := handler.client.Connect(); token.Wait() && token.Error() != nil {
        log.Error("failed to connect to MQTT broker", zap.Error(token.Error()))
        return Handler{}, token.Error()
    }
    log.Info("successfully connected to MQTT broker", zap.String("url", brokerUrl), zap.Duration("in", time.Since(start)))
    return handler, nil
}

func (handle Handler) Pub(ctx context.Context, topic, payload string, qos int, retained bool) error {
    token := handle.client.Publish(topic, byte(qos), retained, payload)
    go func(ctx context.Context) {
        log := logger.NewLogFromCtx(ctx)
        log.Debug("waiting for transaction to complete...")
        _ = token.Done()
        log.Debug("transaction Done!", zap.Any("token.Error", token.Error()))
        if token.Error() != nil {
            log.Error("failed to publish MQTT message", zap.Error(token.Error()))
        }
    }(ctx)
    log := logger.NewLogFromCtx(ctx)
    log.Debug("Msg sent !")
    return nil
}

这是主要内容：

func main() {
    conf := config.GetConfig()
    err := logger.SetupLogging(conf.IS_DEV_ENV)
    if err != nil {
        panic(err)
    }
    ctx := context.Background()
    log := logger.NewLogFromCtx(ctx)

    mqtt.InitMQTT()
    mqttClient, _ := mqtt.NewClient(ctx, conf)

    reader := bufio.NewReader(os.Stdin)
    fmt.Print("press enter to publish...")
    text, _ := reader.ReadString('\n')
    mqttClient.Pub(ctx, "just/for/test", "test", 2, false)
}

Answer 1

来自the docs：

// Wait will wait indefinitely for the Token to complete, ie the Publish
// to be sent and confirmed receipt from the broker.
Wait() bool

// Done is provided for use in select statements. Simple use cases may
// use Wait or WaitTimeout.
Done() <-chan struct{}

所以_ = token.Done()真的什么都不做；最简单的等待就是使用token.Wait()。如果你想使用 token.Done() 你需要等待返回的通道；例如<- token.Done()。 Done() 存在的原因是为了在您等待多个事件时使事情变得更简单（例如等待 context 或 mqtt 操作完成）。

MQTT paho - 发布消息失败时没有错误

MQTT paho - no error when failed to publish message

go

mqtt

paho