org.smallmind.file.ephemeral.watch.EphemeralWatchService Maven / Gradle / Ivy
/*
* Copyright (c) 2007 through 2024 David Berkman
*
* This file is part of the SmallMind Code Project.
*
* The SmallMind Code Project is free software, you can redistribute
* it and/or modify it under either, at your discretion...
*
* 1) The terms of GNU Affero General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at
* your option) any later version.
*
* ...or...
*
* 2) The terms of the Apache License, Version 2.0.
*
* The SmallMind Code Project is distributed in the hope that it will
* be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License or Apache License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* and the Apache License along with the SmallMind Code Project. If not, see
* .
*
* Additional permission under the GNU Affero GPL version 3 section 7
* ------------------------------------------------------------------
* If you modify this Program, or any covered work, by linking or
* combining it with other code, such other code is not for that reason
* alone subject to any of the requirements of the GNU Affero GPL
* version 3.
*/
package org.smallmind.file.ephemeral.watch;
import java.nio.file.ClosedWatchServiceException;
import java.nio.file.NoSuchFileException;
import java.nio.file.NotDirectoryException;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import org.smallmind.file.ephemeral.EphemeralFileStore;
import org.smallmind.file.ephemeral.EphemeralPath;
import org.smallmind.file.ephemeral.heap.HeapEventListener;
public class EphemeralWatchService implements WatchService {
private final EphemeralFileStore ephemeralFileStore;
private final HeapEventListener heapEventListener;
private final HashMap> watchKeyMap = new HashMap<>();
private final LinkedBlockingQueue watchKeyQueue = new LinkedBlockingQueue<>();
private volatile boolean closed = false;
public EphemeralWatchService (EphemeralFileStore ephemeralFileStore) {
this.ephemeralFileStore = ephemeralFileStore;
heapEventListener = new EphemeralHeapEventListener(this);
}
public boolean isClosed () {
return closed;
}
@Override
public synchronized void close () {
if (!closed) {
closed = true;
for (LinkedList watchKeyList : watchKeyMap.values()) {
for (EphemeralWatchKey watchKey : watchKeyList) {
watchKey.cancel(false);
}
}
}
}
public synchronized void register (EphemeralWatchKey ephemeralWatchKey)
throws NoSuchFileException, NotDirectoryException {
if (closed) {
throw new ClosedWatchServiceException();
} else {
LinkedList watchKeyList;
if ((watchKeyList = watchKeyMap.get(ephemeralWatchKey.getPath())) == null) {
watchKeyMap.put(ephemeralWatchKey.getPath(), watchKeyList = new LinkedList<>());
ephemeralFileStore.registerHeapListener(ephemeralWatchKey.getPath(), heapEventListener);
}
watchKeyList.add(ephemeralWatchKey);
}
}
public synchronized void unregister (EphemeralWatchKey ephemeralWatchKey)
throws NoSuchFileException {
LinkedList watchKeyList;
if ((watchKeyList = watchKeyMap.get(ephemeralWatchKey.getPath())) != null) {
if (watchKeyList.remove(ephemeralWatchKey)) {
if (watchKeyList.isEmpty()) {
watchKeyMap.remove(ephemeralWatchKey.getPath());
ephemeralFileStore.unregisterHeapListener(ephemeralWatchKey.getPath(), heapEventListener);
}
watchKeyQueue.remove(ephemeralWatchKey);
}
}
}
public synchronized void fire (EphemeralPath path, WatchEvent.Kind event) {
if (!closed) {
LinkedList watchKeyList;
if ((watchKeyList = watchKeyMap.get(path)) != null) {
for (EphemeralWatchKey watchKey : watchKeyList) {
if (watchKey.fire(event)) {
watchKeyQueue.add(watchKey);
}
}
}
}
}
public synchronized void requeue (EphemeralWatchKey watchKey) {
if (!closed) {
watchKeyQueue.add(watchKey);
}
}
@Override
public WatchKey poll () {
if (closed) {
throw new ClosedWatchServiceException();
} else {
return watchKeyQueue.poll();
}
}
@Override
public WatchKey poll (long timeout, TimeUnit unit)
throws InterruptedException {
if (closed) {
throw new ClosedWatchServiceException();
} else {
long wait;
if ((wait = unit.toMillis(timeout)) < 500) {
return watchKeyQueue.poll(timeout, unit);
} else {
long started = System.currentTimeMillis();
do {
WatchKey watchKey;
if ((watchKey = watchKeyQueue.poll(500, TimeUnit.MILLISECONDS)) != null) {
return watchKey;
}
} while ((!closed) && (System.currentTimeMillis() - started < wait));
if (closed) {
throw new ClosedWatchServiceException();
} else {
return null;
}
}
}
}
@Override
public WatchKey take ()
throws InterruptedException {
if (closed) {
throw new ClosedWatchServiceException();
} else {
do {
WatchKey watchKey;
if ((watchKey = watchKeyQueue.poll(500, TimeUnit.MILLISECONDS)) != null) {
return watchKey;
}
} while (!closed);
throw new ClosedWatchServiceException();
}
}
}