/*
* Copyright (C) 2013 salesforce.com, inc.
*
* Licensed 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.auraframework.impl.source.file;
import static java.nio.file.LinkOption.NOFOLLOW_LINKS;
import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.ENTRY_DELETE;
import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.log4j.Logger;
import org.auraframework.util.FileChangeEvent;
import org.auraframework.util.FileListener;
/**
* File monitor allowing to ability to add watched directory. Used to update files and clear caches on source changes
* during development
*/
public final class AuraFileMonitor implements Runnable {
private final static Logger LOG;
private static AuraFileMonitor singletonMonitor;
// keep track of directories monitored
private final Set<String> monitoredDirs;
// keep track of watch service keys for directories monitored,
// for the purpose of reporting with the same directory root as the original
private final Map<WatchKey, Path> monitoredKeys;
private WatchService watchService;
private Thread watchServiceThread;
private boolean terminateThread;
private final FileListener listener;
static {
LOG = Logger.getLogger(AuraFileMonitor.class);
singletonMonitor = new AuraFileMonitor(new FileSourceListener());
}
private AuraFileMonitor(FileListener listener)
{
this.listener = listener;
this.monitoredDirs = new HashSet<>();
this.monitoredKeys = new HashMap<>();
this.setTerminateThread(false);
try {
watchService = FileSystems.getDefault().newWatchService();
} catch (IOException e) {
LOG.error("Could not create aura WatchService. File changes will not be noticed");
}
}
@SuppressWarnings("unchecked")
static <T> WatchEvent<T> cast(WatchEvent<?> event) {
return (WatchEvent<T>) event;
}
/**
* Register a single directory with the WatchService
*/
private void register(Path dir) throws IOException {
WatchKey key = dir.register(watchService, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
monitoredKeys.put(key, dir);
monitoredDirs.add(dir.toString());
// uncomment to see every directory, rather than parent directories only.
// LOG.info("Monitoring individual directory " + dir.toString());
}
/**
* Register the given directory, and all its sub-directories, with the WatchService.
*/
private void registerAll(final Path start) throws IOException {
// register directory and sub-directories
Files.walkFileTree(start, new SimpleFileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
throws IOException
{
register(dir);
return FileVisitResult.CONTINUE;
}
});
}
@Override
public void run() {
// loop forever, waiting on monitor for watchService, unless isTerminateThread
for (;;) {
// wait for watchService to become signaled
WatchKey key;
try {
key = watchService.take();
if (isTerminateThread()) {
return;
}
} catch (InterruptedException x) {
return;
}
Path dir = monitoredKeys.get(key);
if (dir == null) {
LOG.info("did not recognize the requested WatchKey!");
continue;
}
List<WatchEvent<?>> events = key.pollEvents();
// process all events on the key
for (WatchEvent<?> event : events) {
WatchEvent.Kind<?> kind = event.kind();
if (kind == OVERFLOW) {
// TODO - perhaps notify a special event to clear all caches,
// if file changes overflow the monitor
LOG.info("WatchService for aura file changes has overflowed. Changes may have been missed.");
continue;
}
// once we have a directory event, we know the context is the file name of entry
WatchEvent<Path> pathWatchEvent = cast(event);
Path name = pathWatchEvent.context();
// ensure the path resolution (absolute, relative) matches between paths
Path child = dir.resolve(name);
// isDir is true is file exists and is directory
boolean isDir = Files.isDirectory(child, NOFOLLOW_LINKS);
// signal appropriate handlers
if (!isDir) {
try {
if (kind == ENTRY_CREATE) {
listener.fileCreated(new FileChangeEvent(child));
}
else if (kind == ENTRY_MODIFY) {
listener.fileChanged(new FileChangeEvent(child));
}
else if (kind == ENTRY_DELETE) {
listener.fileDeleted(new FileChangeEvent(child));
}
} catch (Exception ex) {
LOG.info("Unable to signal source change due to exception: " + ex.getMessage());
}
}
// recursively add any new directories created
else if (kind == ENTRY_CREATE) {
try {
registerAll(child);
} catch (IOException x) {
// if we can't monitor it for some reason, it is not an error
}
}
}
// reset key and remove from set if directory no longer accessible
boolean valid = key.reset();
if (!valid) {
monitoredKeys.remove(key);
monitoredDirs.remove(dir.toString());
// all directories are inaccessible
if (monitoredKeys.isEmpty()) {
break;
}
}
}
}
private boolean isStarted() {
return watchService != null && watchServiceThread != null && watchServiceThread.isAlive()
&& !isTerminateThread();
}
/**
* Add a root directory to monitor for changes Synchronized due to updating single static monitor. This should be
* called rarely (only on encountering a new namespace) and have no performance impact
*
* @param dirPath name of a root directory to monitor
*/
public static synchronized void addDirectory(String dirPath) {
Path dir = Paths.get(dirPath);
if (singletonMonitor == null ||
singletonMonitor.watchService == null ||
singletonMonitor.monitoredDirs.contains(dir.toString())) {
return;
}
try {
singletonMonitor.registerAll(dir);
LOG.info("Monitoring directory " + dirPath);
} catch (Exception ex) {
LOG.info("Unable to monitor directory " + dirPath + " due to exception: " + ex.getMessage());
}
}
/**
* Start monitor when aura services are ready
*/
public static synchronized void start() {
if (singletonMonitor != null && !singletonMonitor.isStarted()) {
singletonMonitor.setTerminateThread(false);
singletonMonitor.watchServiceThread = new Thread(singletonMonitor);
singletonMonitor.watchServiceThread.setDaemon(true);
singletonMonitor.watchServiceThread.start();
LOG.info("Aura file monitor started");
}
}
/**
* Stop monitor
*/
public static synchronized void stop() {
if (singletonMonitor != null && singletonMonitor.isStarted()) {
// notify thread to exit main loop, ending thread naturally
singletonMonitor.setTerminateThread(true);
singletonMonitor.watchService.notifyAll();
singletonMonitor.watchServiceThread = null;
LOG.info("Aura file monitor signaled to stop");
}
}
private boolean isTerminateThread() {
return terminateThread;
}
private void setTerminateThread(boolean terminateThread) {
this.terminateThread = terminateThread;
}
}