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ActiveMQ example source code file (ActiveMQSessionExecutor.java)

This example ActiveMQ source code file (ActiveMQSessionExecutor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

activemq, activemqmessageconsumer, activemqmessageconsumer, activemqsessionexecutor, consumerid, have, interruptedexception, interruptedexception, logger, messagedispatch, messagedispatch, received, received, taskrunner, util

The ActiveMQ ActiveMQSessionExecutor.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.activemq;

import java.util.List;
import javax.jms.JMSException;
import org.apache.activemq.command.ConsumerId;
import org.apache.activemq.command.MessageDispatch;
import org.apache.activemq.thread.Task;
import org.apache.activemq.thread.TaskRunner;
import org.apache.activemq.util.JMSExceptionSupport;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A utility class used by the Session for dispatching messages asynchronously
 * to consumers
 * 
 * 
 * @see javax.jms.Session
 */
public class ActiveMQSessionExecutor implements Task {
    private static final Logger LOG = LoggerFactory.getLogger(ActiveMQSessionExecutor.class);

    private final ActiveMQSession session;
    private final MessageDispatchChannel messageQueue;
    private boolean dispatchedBySessionPool;
    private volatile TaskRunner taskRunner;
    private boolean startedOrWarnedThatNotStarted;

    ActiveMQSessionExecutor(ActiveMQSession session) {
        this.session = session;
        if (this.session.connection != null && this.session.connection.isMessagePrioritySupported()) {
           this.messageQueue = new SimplePriorityMessageDispatchChannel();
        }else {
            this.messageQueue = new FifoMessageDispatchChannel();
        }
    }

    void setDispatchedBySessionPool(boolean value) {
        dispatchedBySessionPool = value;
        wakeup();
    }

    void execute(MessageDispatch message) throws InterruptedException {

        if (!startedOrWarnedThatNotStarted) {

            ActiveMQConnection connection = session.connection;
            long aboutUnstartedConnectionTimeout = connection.getWarnAboutUnstartedConnectionTimeout();
            if (connection.isStarted() || aboutUnstartedConnectionTimeout < 0L) {
                startedOrWarnedThatNotStarted = true;
            } else {
                long elapsedTime = System.currentTimeMillis() - connection.getTimeCreated();

                // lets only warn when a significant amount of time has passed
                // just in case its normal operation
                if (elapsedTime > aboutUnstartedConnectionTimeout) {
                    LOG.warn("Received a message on a connection which is not yet started. Have you forgotten to call Connection.start()? Connection: " + connection
                             + " Received: " + message);
                    startedOrWarnedThatNotStarted = true;
                }
            }
        }

        if (!session.isSessionAsyncDispatch() && !dispatchedBySessionPool) {
            dispatch(message);
        } else {
            messageQueue.enqueue(message);
            wakeup();
        }
    }

    public void wakeup() {
        if (!dispatchedBySessionPool) {
            if (session.isSessionAsyncDispatch()) {
                try {
                    TaskRunner taskRunner = this.taskRunner;
                    if (taskRunner == null) {
                        synchronized (this) {
                            if (this.taskRunner == null) {
                                if (!isRunning()) {
                                    // stop has been called
                                    return;
                                }
                                this.taskRunner = session.connection.getSessionTaskRunner().createTaskRunner(this,
                                        "ActiveMQ Session: " + session.getSessionId());
                            }
                            taskRunner = this.taskRunner;
                        }
                    }
                    taskRunner.wakeup();
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                }
            } else {
                while (iterate()) {
                }
            }
        }
    }

    void executeFirst(MessageDispatch message) {
        messageQueue.enqueueFirst(message);
        wakeup();
    }

    public boolean hasUncomsumedMessages() {
        return !messageQueue.isClosed() && messageQueue.isRunning() && !messageQueue.isEmpty();
    }

    void dispatch(MessageDispatch message) {

        // TODO - we should use a Map for this indexed by consumerId

        for (ActiveMQMessageConsumer consumer : this.session.consumers) {
            ConsumerId consumerId = message.getConsumerId();
            if (consumerId.equals(consumer.getConsumerId())) {
                consumer.dispatch(message);
                break;
            }
        }
    }

    synchronized void start() {
        if (!messageQueue.isRunning()) {
            messageQueue.start();
            if (hasUncomsumedMessages()) {
                wakeup();
            }
        }
    }

    void stop() throws JMSException {
        try {
            if (messageQueue.isRunning()) {
                synchronized(this) {
                    messageQueue.stop();
                    if (this.taskRunner != null) {
                        this.taskRunner.shutdown();
                        this.taskRunner = null;
                    }
                }
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw JMSExceptionSupport.create(e);
        }
    }

    boolean isRunning() {
        return messageQueue.isRunning();
    }

    void close() {
        messageQueue.close();
    }

    void clear() {
        messageQueue.clear();
    }

    MessageDispatch dequeueNoWait() {
        return messageQueue.dequeueNoWait();
    }

    protected void clearMessagesInProgress() {
        messageQueue.clear();
    }

    public boolean isEmpty() {
        return messageQueue.isEmpty();
    }

    public boolean iterate() {

        // Deliver any messages queued on the consumer to their listeners.
        for (ActiveMQMessageConsumer consumer : this.session.consumers) {
            if (consumer.iterate()) {
                return true;
            }
        }

        // No messages left queued on the listeners.. so now dispatch messages
        // queued on the session
        MessageDispatch message = messageQueue.dequeueNoWait();
        if (message == null) {
            return false;
        } else {
            dispatch(message);
            return !messageQueue.isEmpty();
        }
    }

    List getUnconsumedMessages() {
        return messageQueue.removeAll();
    }

}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ ActiveMQSessionExecutor.java source code file:

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