Golang Channel.ExchangeDeclare方法代碼示例

// A simplified way to declare and subscribe to an AMQP queue
func amqpSubscribe(ch *amqp.Channel, name string, log *blog.AuditLogger) (msgs <-chan amqp.Delivery, err error) {
	err = ch.ExchangeDeclare(
		AmqpExchange,
		AmqpExchangeType,
		AmqpDurable,
		AmqpDeleteUnused,
		AmqpInternal,
		AmqpNoWait,
		nil)
	if err != nil {
		log.Crit(fmt.Sprintf("Could not declare exchange: %s", err))
		return
	}

	q, err := ch.QueueDeclare(
		name,
		AmqpDurable,
		AmqpDeleteUnused,
		AmqpExclusive,
		AmqpNoWait,
		nil)
	if err != nil {
		log.Crit(fmt.Sprintf("Could not declare queue: %s", err))
		return
	}

	err = ch.QueueBind(
		name,
		name,
		AmqpExchange,
		false,
		nil)
	if err != nil {
		log.Crit(fmt.Sprintf("Could not bind queue: %s", err))
		return
	}

	msgs, err = ch.Consume(
		q.Name,
		"",
		AmqpAutoAck,
		AmqpExclusive,
		AmqpNoLocal,
		AmqpNoWait,
		nil)
	if err != nil {
		log.Crit(fmt.Sprintf("Could not subscribe to queue: %s", err))
		return
	}

	return
}

// AMQPDeclareExchange attempts to declare the configured AMQP exchange,
// returning silently if already declared, erroring if nonexistant and
// unable to create.
func amqpDeclareExchange(conn *amqp.Connection) error {
	var err error
	var ch *amqp.Channel
	log := blog.GetAuditLogger()

	ch, err = conn.Channel()
	if err != nil {
		log.Crit(fmt.Sprintf("Could not connect Channel: %s", err))
		return err
	}

	err = ch.ExchangeDeclarePassive(
		AmqpExchange,
		AmqpExchangeType,
		AmqpDurable,
		AmqpDeleteUnused,
		AmqpInternal,
		AmqpNoWait,
		nil)
	if err != nil {
		log.Info(fmt.Sprintf("Exchange %s does not exist on AMQP server, creating.", AmqpExchange))

		// Channel is invalid at this point, so recreate
		ch.Close()
		ch, err = conn.Channel()
		if err != nil {
			log.Crit(fmt.Sprintf("Could not connect Channel: %s", err))
			return err
		}

		err = ch.ExchangeDeclare(
			AmqpExchange,
			AmqpExchangeType,
			AmqpDurable,
			AmqpDeleteUnused,
			AmqpInternal,
			AmqpNoWait,
			nil)
		if err != nil {
			log.Crit(fmt.Sprintf("Could not declare exchange: %s", err))
			ch.Close()
			return err
		}
		log.Info(fmt.Sprintf("Created exchange %s.", AmqpExchange))
	}

	ch.Close()
	return err
}

func startMonitor(rpcCh *amqp.Channel, logger *blog.AuditLogger, stats statsd.Statter) {
	ae := analysisengine.NewLoggingAnalysisEngine()

	// For convenience at the broker, identifiy ourselves by hostname
	consumerTag, err := os.Hostname()
	if err != nil {
		cmd.FailOnError(err, "Could not determine hostname")
	}

	err = rpcCh.ExchangeDeclare(
		AmqpExchange,
		AmqpExchangeType,
		AmqpDurable,
		AmqpDeleteUnused,
		AmqpInternal,
		AmqpNoWait,
		nil)
	if err != nil {
		cmd.FailOnError(err, "Could not declare exchange")
	}

	_, err = rpcCh.QueueDeclare(
		QueueName,
		AmqpDurable,
		AmqpDeleteUnused,
		AmqpExclusive,
		AmqpNoWait,
		nil)
	if err != nil {
		cmd.FailOnError(err, "Could not declare queue")
	}

	err = rpcCh.QueueBind(
		QueueName,
		"#", //wildcard
		AmqpExchange,
		false,
		nil)
	if err != nil {
		cmd.FailOnError(err, "Could not bind queue")
	}

	deliveries, err := rpcCh.Consume(
		QueueName,
		consumerTag,
		AmqpAutoAck,
		AmqpExclusive,
		AmqpNoLocal,
		AmqpNoWait,
		nil)
	if err != nil {
		cmd.FailOnError(err, "Could not subscribe to queue")
	}

	deliveryTimings := make(map[string]time.Time)

	// Run forever.
	for d := range deliveries {
		go timeDelivery(d, stats, deliveryTimings)

		// Pass each message to the Analysis Engine
		err = ae.ProcessMessage(d)
		if err != nil {
			logger.Alert(fmt.Sprintf("Could not process message: %s", err))
		} else {
			// Only ack the delivery we actually handled (ackMultiple=false)
			const ackMultiple = false
			d.Ack(ackMultiple)
		}
	}
}