JMSAppender.java

/**
 * 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.servicemix.logging.jms;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.DeliveryMode;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.ops4j.pax.logging.spi.PaxAppender;
import org.ops4j.pax.logging.spi.PaxLoggingEvent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class JMSAppender implements PaxAppender {
    private static final String PACKAGE = JMSAppender.class.getPackage().getName();
    private static final transient Logger LOG = LoggerFactory.getLogger(JMSAppender.class);

    private static final String DEFAULT_EVENT_FORMAT = "default";
    private static final String LOGSTASH_EVENT_FORMAT = "logstash";

    private ConnectionFactory jmsConnectionFactory;
    private Connection connection;
    private Session session;
    private MessageProducer producer;
    private String destinationName;

    private LoggingEventFormat format = new DefaultLoggingEventFormat();

    private  ExecutorService executor = Executors.newSingleThreadExecutor();

    public void close() {
        closeJMSResources();
    }

    public void onBind(ConnectionFactory service){
        closeJMSResources();
        jmsConnectionFactory = service;
        // Connect early to fail fast in case of config errors
        executor.execute(new Runnable() {
            
            @Override
            public void run() {
                try {
                    getOrCreateConnection();
                } catch (JMSException e) {
                    LOG.warn("Exception connecting to broker - reinitializing JMS resources to recover",e);
                    closeJMSResources();
                }
            }
        });
    }

    public void onUnbind(ConnectionFactory service){
        closeJMSResources();
    }

    public void doAppend(final PaxLoggingEvent paxLoggingEvent) {
        if (exclude(paxLoggingEvent) || jmsConnectionFactory == null) {
            return;
        }
        Runnable worker = new Runnable() {
            public void run() {
                try {
                    // Send message to the destination
                    TextMessage message = getOrCreateSession().createTextMessage();
                    message.setText(format.toString(paxLoggingEvent));
                    MessageProducer producer = getOrCreatePublisher();
                    producer.send(message);
                } catch (JMSException e) {
                    LOG.warn("Exception caught while sending log event - reinitializing JMS resources to recover",e);
                    closeJMSResources();
                }
            }
        };
        executor.execute(worker);
    }

    private static boolean exclude(PaxLoggingEvent event) {
        return startsWith(event.getLoggerName(), PACKAGE);
    }

    private static boolean startsWith(String string, String start) {
        return string != null && string.startsWith(start);
    }

    public void setJmsConnectionFactory(ConnectionFactory jmsConnectionFactory) {
        this.jmsConnectionFactory = jmsConnectionFactory;
    }

    public void setDestinationName(String destinationName) {
        this.destinationName = destinationName;
    }

    public void setFormat(String name) {
        if (LOGSTASH_EVENT_FORMAT.equals(name)) {
            format = new LogstashEventFormat();
        } else {
            format = new DefaultLoggingEventFormat();
        }
    }
    
    protected Connection getOrCreateConnection() throws JMSException {
        if (connection == null) {
            connection = jmsConnectionFactory.createConnection();
            connection.start();
        }
        return connection;
    }

    protected Session getOrCreateSession() throws JMSException {
        if (session == null) {
            session = getOrCreateConnection().createSession(false, Session.AUTO_ACKNOWLEDGE);
        }
        return session;
    }

    protected MessageProducer getOrCreatePublisher() throws JMSException {
        if (producer == null) {
            Destination topic = session.createTopic(destinationName);
            producer = session.createProducer(topic);
            producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
        }

        return producer;
    }

    private void closeJMSResources() {
        close(producer);
        close(session);
        close(connection);
        producer = null;
        session = null;
        connection = null;
    }
    
    private static void close(Object obj) {
        if (obj == null) {
            return;
        }
        try {
            if (obj instanceof MessageProducer) {
                ((MessageProducer)obj).close();
            } else if (obj instanceof Session) {
                ((Session)obj).close();
            } else if (obj instanceof Connection) {
                ((Connection)obj).close();
            }
        } catch (JMSException e) {
            LOG.debug("Exception caught while closing JMS resources", e);
        }
    }
}