com.rabbitmq.jms.client.DeliveryExecutor Maven / Gradle / Ivy
/* Copyright (c) 2013 Pivotal Software, Inc. All rights reserved. */
package com.rabbitmq.jms.client;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import javax.jms.JMSException;
import javax.jms.MessageListener;
import com.rabbitmq.jms.util.RMQJMSException;
/**
* Class to deliver messages to the onMessage() callback. Handles execution on a different thread, timeout
* if execution takes too long (set on instantiation), and interrupts execution on closure or timeout. Also serialises
* calls. There is one instance of this executor per session.
*/
public class DeliveryExecutor {
private final class CallOnMessage implements Callable {
private final RMQMessage rmqMessage;
private final MessageListener messageListener;
private CallOnMessage(RMQMessage rmqMessage, MessageListener messageListener) {
this.rmqMessage = rmqMessage;
this.messageListener = messageListener;
}
public Boolean call() throws Exception {
this.messageListener.onMessage(this.rmqMessage);
return true;
}
}
/** Timeout for onMessage executions */
private final long onMessageTimeoutMs;
/** Executor allocated if/when onMessage calls are made; used to isolate us from potential hangs. */
private ExecutorService onMessageExecutorService = null;
private final Object lockOnMessageExecutorService = new Object();
public DeliveryExecutor(long onMessageTimeoutMs) {
this.onMessageTimeoutMs = onMessageTimeoutMs;
}
/**
* Method to deliver message to the client, on a separate executor thread so we can abort this if it takes too long.
* The executor service (with one thread) is allocated one per session, as and when needed, and we reserve the right
* to interrupt it if it takes too long to process the onMessage call. Within a session there should be
* only one onMessage call being executed at any one time.
*
* @param rmqMessage the message to deliver
* @param messageListener JMS message listener that will handle the delivery
* @throws JMSException if the delivery takes too long and is aborted
* @throws InterruptedException if executing thread is interrupted
*/
public void deliverMessageWithProtection(RMQMessage rmqMessage, MessageListener messageListener) throws JMSException, InterruptedException {
try {
this.getExecutorService().submit(new CallOnMessage(rmqMessage, messageListener)).get(this.onMessageTimeoutMs, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
this.closeAbruptly();
throw new RMQJMSException("onMessage took too long and was interrupted", null);
} catch (ExecutionException e) {
throw new RMQMessageListenerExecutionJMSException("onMessage threw exception", e.getCause());
}
}
public void close() {
closeExecutorService(this.takeExecutorService());
}
private void closeAbruptly() {
this.takeExecutorService().shutdownNow();
}
private void closeExecutorService(ExecutorService executorService) {
if (executorService != null) {
executorService.shutdown();
if (!this.waitForTerminatedExecutorService(executorService)) {
executorService.shutdownNow();
}
}
}
private ExecutorService takeExecutorService() {
synchronized (this.lockOnMessageExecutorService) {
ExecutorService es = this.onMessageExecutorService;
this.onMessageExecutorService = null;
return es;
}
}
private ExecutorService getExecutorService() {
synchronized (this.lockOnMessageExecutorService) {
if (this.onMessageExecutorService == null) {
this.onMessageExecutorService = Executors.newSingleThreadExecutor();
}
return this.onMessageExecutorService;
}
}
private boolean waitForTerminatedExecutorService(ExecutorService executorService) {
try {
return executorService.awaitTermination(this.onMessageTimeoutMs, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
return false;
}
}
}