春天-等待Rabbitmq消息监听器完成

Question

I have two message listeners, each listening to it's own message queue on same RabbitMQ server.

Now, when first listener receives a message on its queue, it has to ask other listener if he has any messages to process in it's queue, and in case he has, wait for this messages to be processed by second listener prior continuing with it's own execution.

I would need something like this:

SimpleMessageListenerContainer first;
SimpleMessageListenerContainer second;
if(second.hasReceivedMessageButItsStillNotProcessed){
  Thread.waitUntilSecondProcessesAMessage();
}

or like this

while(rabbitAdmin.getQueueProperties("qName").get("UNACKED_MSG_COUNT")>0){
  Thread.waitUntilSecondProcessesAMessage();
}

Any help appreciated.

Answer 1

If you are using spring, you can use this Queue Size in Spring AMQP Java client (second answer) to get the queue message size. You could try something like this:

Spring queues config:

<jms:listener-container 
    connection-factory="jmsFactory"  
    destination-type="queue1">
        <jms:listener destination="queue1" ref="consumer1" method="consume"/>
</jms:listener-container>
<bean id="consumer1" class="m.p.e.MessageConsumer1" scope="tenant"/>
<jms:listener-container 
    connection-factory="jmsFactory"  
    destination-type="queue2" >
        <jms:listener destination="queue2" ref="consumer2" method="consume"/>
</jms:listener-container>
<bean id="consumer2" class="m.p.e.MessageConsumer2" scope="tenant"/>

Your StatsCounter as Queue Size in Spring AMQP Java client (second answer) :

public class QueueStatsProcessor {
    @Autowired
    private RabbitAdmin admin;
    @Autowired
    private List<Queue> rabbitQueues;

    public Integer getCounts(String queueName){
        //find your queue from rabbitQueues
        //return the 
        props = admin.getQueueProperties(queue.getName());
        return Integer.parseInt(props.get("QUEUE_MESSAGE_COUNT");        
    }
}

And your second consumer that must wait until there is no messages on queue1 :

public class MessageConsumer2{
@Autowired
QueueStatsProcessor queueStatesProcesor;

public void consume(){
    while(queueStatesProcesor.getCounts("queue1")  > 0){
        Thread.sleep(1000);
    }
    //do your own work
}

}

I think this logic is a little complex to manage it "manually", I recommend you to use something like Spring Integration or Apache Camel .