Glassfish example source code file (DynamicReloadService.java)

This example Glassfish source code file (DynamicReloadService.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 - Glassfish tags/keywords

bean, dasconfig, dynamicreloader, dynamicreloader, exception, inject, inject, javabean, list, log, logging, reloader, reloader, string, string, timer, timertask, unprocessedchangeevents, util

The Glassfish DynamicReloadService.java source code

/*
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 *
 * Copyright (c) 2008-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
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package com.sun.enterprise.v3.server;

import com.sun.enterprise.config.serverbeans.Applications;
import com.sun.enterprise.config.serverbeans.DasConfig;
import java.beans.PropertyChangeEvent;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.api.Async;
import org.glassfish.api.Startup;
import org.glassfish.internal.api.*;
import org.jvnet.hk2.annotations.Inject;
import org.jvnet.hk2.annotations.Scoped;
import org.jvnet.hk2.annotations.Service;
import org.jvnet.hk2.component.Habitat;
import org.jvnet.hk2.component.PostConstruct;
import org.jvnet.hk2.component.PreDestroy;
import org.jvnet.hk2.component.Singleton;
import org.jvnet.hk2.config.ConfigListener;
import org.jvnet.hk2.config.UnprocessedChangeEvent;
import org.jvnet.hk2.config.UnprocessedChangeEvents;

/**
 * A service wrapper around the dynamic reload processor.
 * <p>
 * The module system will start this service during GlassFish start-up.  In turn
 * it will start the actual reload logic to run periodically.
 * <p>
 * 
 * @author tjquinn
 */
@Service
@Scoped(Singleton.class)
public class DynamicReloadService implements ConfigListener, PostStartup, PostConstruct, PreDestroy {

    @Inject
    DasConfig activeDasConfig;

    @Inject
    Applications applications;
    
    @Inject
    Habitat habitat;
    
    private Logger logger;
    
    private Timer timer;
    
    private TimerTask timerTask;
    
    private DynamicReloader reloader;
    
    private static final String DEFAULT_POLL_INTERVAL_IN_SECONDS = "2";
    
    private static final List<String> configPropertyNames = Arrays.asList(
            "dynamic-reload-enabled", "dynamic-reload-poll-interval-in-seconds"
            );

    public DynamicReloadService() {
    }

    public void postConstruct() {
        logger = Logger.getLogger(DynamicReloadService.class.getName());
        /*
         * Create the dynamic reloader right away, even if its use is disabled 
         * currently.  This way any initialization errors will appear early 
         * in the log rather than later if and when the reloader is 
         * enabled.
         */
        try {
            logger.fine("[Reloader] ReloaderService starting");
            reloader = new DynamicReloader(
                    applications,
                    habitat
                    );
            
             /*
             * Also create the timer and the timer task, reusing them as needed as
             * we need to stop and restart the task.
             */
            timer = new Timer("DynamicReloader", true);

            if (isEnabled(activeDasConfig)) {
                start(getPollIntervalInSeconds(activeDasConfig));
            } else {
                logger.fine("[Reloader] Reloader is configured as disabled, so NOT starting the periodic task");
            }
            logger.fine("[Reloader] Service start-up complete");
        } catch (Exception e) {
            logger.log(Level.SEVERE, e.getLocalizedMessage(), e); 
        }

    }

    public void preDestroy() {
        stop();
    }

    static String getValue(String value, String defaultValue) {
        return (value == null || value.equals("")) ? defaultValue : value;
    }
    
    private boolean isEnabled(DasConfig config) {
        return Boolean.parseBoolean(config.getDynamicReloadEnabled());
    }
    
    private int getPollIntervalInSeconds(DasConfig config) {
        int result;
        try {
            result = Integer.parseInt(config.getDynamicReloadPollIntervalInSeconds());
        } catch (NumberFormatException e) {
            result = Integer.parseInt(DEFAULT_POLL_INTERVAL_IN_SECONDS);
        }
        return result;
    }
    
    private void start(int pollIntervalInSeconds) {
        long pollIntervalInMS = pollIntervalInSeconds * 1000L;
        timer.schedule(
                timerTask = new TimerTask() {
                    @Override
                    public void run() {
                        try {
                            reloader.run();
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        }
                    }
                }, 
                pollIntervalInMS, 
                pollIntervalInMS);
        logger.fine("[Reloader] Started, monitoring every " +
                    pollIntervalInSeconds + " seconds"
                    );
    }

    private void stop() {
        /*
         * Tell the running autodeployer to stop, then cancel the timer task 
         * and the timer.
         */
        logger.fine("[Reloader] Stopping");
        reloader.cancel();
        if(timerTask != null) {
            timerTask.cancel();
        }
    }
    
    /**
     * Reschedules the autodeployer because a configuration change has altered
     * the frequency.
     */
    private void reschedule(int pollIntervalInSeconds) {
        logger.fine("[Reloader] Restarting...");
        stop();
        try {
            reloader.waitUntilIdle();
        } catch (InterruptedException e) {
            // XXX OK to glide through here?
        }
        start(pollIntervalInSeconds);
    }

    public synchronized UnprocessedChangeEvents changed(PropertyChangeEvent[] events) {
        /*
         * Deal with any changes to the DasConfig that might affect whether
         * the reloader should be stopped or started or rescheduled with a
         * different frequency.  Those change are handled here, by this
         * class.
         */
       
        /* Record any events we tried to process but could not. */
        List<UnprocessedChangeEvent> unprocessedEvents = new ArrayList();

        Boolean newEnabled = null;
        Integer newPollIntervalInSeconds = null;
        
        for (PropertyChangeEvent event : events) {
            String propName = event.getPropertyName();
            if (event.getSource() instanceof DasConfig) {
                if (configPropertyNames.contains(propName) && (event.getOldValue().equals(event.getNewValue()))) {
                    logger.fine("[DynamicReload] Ignoring reconfig of " + propName + 
                            " from " + event.getOldValue() + " to " + event.getNewValue());
                    continue;
                }
                if (propName.equals("dynamic-reload-enabled")) {
                    /*
                     * Either start the currently stopped reloader or stop the
                     * currently running one.
                     */
                    newEnabled = Boolean.valueOf((String) event.getNewValue());
                } else if (propName.equals("dynamic-reload-poll-interval-in-seconds")) {
                    try {
                        newPollIntervalInSeconds = new Integer((String) event.getNewValue());
                    } catch (NumberFormatException ex) {
                        String reason = ex.getClass().getName() + " " + ex.getLocalizedMessage();
                        logger.log(Level.WARNING, reason);
                    }
                }
            }
        }
        if (newEnabled != null) {
            if (newEnabled) {
                start(newPollIntervalInSeconds == null ? getPollIntervalInSeconds(activeDasConfig) : newPollIntervalInSeconds);
            } else {
                stop();
            }
        } else {
            if (newPollIntervalInSeconds != null && isEnabled(activeDasConfig)) {
                /*
                 * There is no change in whether the reloader should be running, only
                 * in how often it should run.  If it is not running now don't
                 * start it.  If it is running now, restart it to use the new
                 * polling interval.
                 */
                reschedule(newPollIntervalInSeconds);
            }
        }
        return (unprocessedEvents.size() > 0) ? new UnprocessedChangeEvents(unprocessedEvents) : null;
    }
}