CODEWITHSUNDEEP
gorabbitmqgo-micro
Vladimir Hraban
Vladimir Hraban

Reputation: 3581

Go-micro rabbit mq plugin - publish message with priority

Since RabbitMQ version 3.5.0 priority queues are supported - https://www.rabbitmq.com/priority.html

The queue can be declared if x-max-priority argument is passed during the queue creation.

I can successfully declare a queue with priority support

brkrSub := broker.NewSubscribeOptions(
        broker.DisableAutoAck(),
        rabbitmq.QueueArguments(map[string]interface{}{"x-max-priority": 10}),
    )

    service.Server().Subscribe(
        service.Server().NewSubscriber(
            "mytopic",
            h.Handle,
            server.SubscriberQueue("mytopic.hello"),
            server.SubscriberContext(brkrSub.Context),
        ),
    )

But how do I publish a message specifying a priority?

    body := &message.MyTestMessage{
        Message: fmt.Sprintf("Message number %d", counter),
    }

    msg := client.NewMessage(
        topic,
        body,
        // TODO: Priority
    )
    if err := client.Publish(ctx, msg); err != nil {
        fmt.Printf("Cannot publish message: ", err.Error())
        return
    }

I could not find a direct way of passing Priority as either MessageOption or PublishOption, however, it seems there is a way to specify additional options in client.Publish context. Am I looking into the correct direction, and if so can you help me a little here?

Edit: I was able to do the following without causing any compile time errors. Priority is still ignored though and messages coming in the usual fasion


func setPriority(ctx context.Context, priority int) client.PublishOption {
    return func(o *client.PublishOptions) {
        o.Context = context.WithValue(ctx, "priority", priority)
    }
}

func publish(ctx context.Context, priority int, counter int) {
    //body := fmt.Sprintf("hello, I am a message %d", counter)
    body := &message.MyTestMessage{
        Message: fmt.Sprintf("Message number %d", counter),
    }

    msg := client.NewMessage(
        topic,
        body,
    )
    if err := client.Publish(ctx, msg, setPriority(ctx, priority)); err != nil {
        fmt.Printf("Cannot publish message: ", err.Error())
        return
    }

    fmt.Printf("Published message %d to %s \n", counter, topic)
}

Upvotes: 1

Views: 517

Answers (2)

Shytik
Shytik

Reputation: 11

var brokerOpts broker.PublishOptions
rabbitmq.Priority(uint8(10))(&brokerOpts)

event.Publish(ctx, payload, client.PublishContext(brokerOpts.Context))

Upvotes: 0

J-Jacques M
J-Jacques M

Reputation: 1118

Try something like that:

func publishMessageToChan(queue *amqp.Queue, channel *amqp.Channel, messageToQueue string) error {
    return channel.Publish(
        "<exchange>", // exchange
        "<queue>",    // routing key
        false,        // mandatory
        false,        // immediate
        amqp.Publishing{
            Timestamp:   time.Now(),
            ContentType: "text/plain",
            Body:        []byte(messageToQueue),
            Priority:    0, // <-- Priority here < 0 to 9>
        })
}

With library "github.com/streadway/amqp"

Upvotes: 0

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