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Micro Distribution of the Payara Project
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright (c) [2020-2021] Payara Foundation 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://github.com/payara/Payara/blob/master/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 glassfish/legal/LICENSE.txt.
*
* GPL Classpath Exception:
* The Payara Foundation designates this particular file as subject to the "Classpath"
* exception as provided by the Payara Foundation in the GPL Version 2 section of the License
* file that accompanied this code.
*
* Modifications:
* If applicable, add the following below the License Header, with the fields
* enclosed by brackets [] replaced by your own identifying information:
* "Portions Copyright [year] [name of copyright owner]"
*
* Contributor(s):
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
package fish.payara.nucleus.executorservice;
import static java.lang.String.format;
import static java.util.concurrent.TimeUnit.SECONDS;
import static java.util.logging.Level.WARNING;
import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.logging.Logger;
import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;
import jakarta.inject.Inject;
import org.glassfish.api.StartupRunLevel;
import org.glassfish.api.event.EventListener;
import org.glassfish.api.event.EventTypes;
import org.glassfish.api.event.Events;
import org.glassfish.hk2.runlevel.RunLevel;
import org.glassfish.internal.deployment.Deployment;
import org.jvnet.hk2.annotations.Service;
@Service(name = "payara-file-watcher")
@RunLevel(StartupRunLevel.VAL)
public class PayaraFileWatcher implements EventListener {
private static final Logger LOGGER = Logger.getLogger(PayaraFileWatcher.class.getName());
private static final Map LISTENER_MAP = new HashMap<>();
private static final Set PATHS_TO_WATCH = new HashSet<>();
private volatile boolean running;
private WatchService watcher;
@Inject
private Events events;
@Inject
private PayaraExecutorService executor;
// Lifecycle methods
@PostConstruct
protected void postConstruct() {
if (events != null) {
events.register(this);
}
initialise();
}
@PreDestroy
protected void preDestroy(){
if (events != null) {
events.unregister(this);
}
terminate();
}
@Override
public void event(Event event) {
if (event.is(Deployment.ALL_APPLICATIONS_LOADED)) {
// Embedded containers can be started and stopped multiple times.
// Thus we need to initialize anytime the server instance is started.
initialise();
} else if (event.is(EventTypes.SERVER_SHUTDOWN)) {
terminate();
}
}
// Private methods
/**
* The event loop method
*/
private void run() {
registerQueuedPaths();
try {
// Block, waiting for an event on a watched file
WatchKey key = watcher.take();
// Loop through the events
for (WatchEvent event : key.pollEvents()) {
// Find the absolute path of the modified file
final Path modifiedPath = ((Path) key.watchable()).resolve((Path) event.context());
// Loop through the watched paths to find the action associated with it
Iterator> watchIterator = LISTENER_MAP.entrySet().iterator();
while (watchIterator.hasNext()) {
Entry watchEntry = watchIterator.next();
// If this entry corresponds to the modified file
if (modifiedPath.endsWith(watchEntry.getKey())) {
// Ignore overflow events
if (event.kind() == StandardWatchEventKinds.OVERFLOW) {
continue;
}
File modifiedFile = modifiedPath.toFile();
// If it's been deleted, remove the file watcher
if (event.kind() == StandardWatchEventKinds.ENTRY_DELETE && !modifiedFile.exists()) {
LOGGER.info(format("Watched file %s was deleted; removing the file watcher", modifiedPath));
watchIterator.remove();
} else if (event.kind() == StandardWatchEventKinds.ENTRY_MODIFY && modifiedFile.length() > 0) {
// Run the associated action
LOGGER.fine(format("Watched file %s modified, running the listener", modifiedPath));
watchEntry.getValue().run();
}
}
}
}
key.reset();
} catch (InterruptedException ex) {
LOGGER.log(WARNING, "The file watcher thread was interrupted", ex);
}
}
/**
* Empty the map of file listeners, registering each one with the watch service
*/
private void registerQueuedPaths() {
if (!PATHS_TO_WATCH.isEmpty()) {
// Iterate through paths
Iterator pathIterator = PATHS_TO_WATCH.iterator();
while (pathIterator.hasNext()) {
// Get the directory of a registered path
Path path = pathIterator.next();
if (path.toFile().isFile()) {
path = path.getParent();
}
try {
path.register(watcher, StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE);
LOGGER.fine(format("Watching path: %s", path));
} catch (IOException ex) {
LOGGER.log(WARNING, format("Failed to register path %s with the watch service", path), ex);
}
pathIterator.remove();
}
}
}
private synchronized void initialise() {
if (!running && !PATHS_TO_WATCH.isEmpty()) {
try {
watcher = FileSystems.getDefault().newWatchService();
executor.scheduleWithFixedDelay(this::run, 0, 1, SECONDS);
running = true;
LOGGER.info("Initialised the file watcher service");
} catch (IOException ex) {
LOGGER.log(WARNING, "Failed to initialise the watch service", ex);
}
}
}
private synchronized void terminate() {
if (running) {
try {
watcher.close();
running = false;
LOGGER.info("Terminated the file watcher service");
} catch (IOException ex) {
LOGGER.log(WARNING, "Failed to terminate the watch service", ex);
}
}
}
// Static methods
public static void watch(Path path, Runnable runnable) {
PATHS_TO_WATCH.add(path);
LISTENER_MAP.put(path, runnable);
}
}