/*
* Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 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
* <http://www.gnu.org/licenses/> or <http://www.apache.org/licenses/LICENSE-2.0>.
*
* 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.nutsnbolts.io;
import java.io.File;
import java.io.FileFilter;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
public class FileProcessorQueue {
private static enum State {
STARTED, STOPPED
}
private ReentrantLock exclusiveLock;
private Condition emptyCondition;
private FileProcessorGopher fileProcessorGopher;
private LinkedList<File> waitingQueue;
private HashSet<File> waitingSet;
private HashSet<File> processingSet;
private File directory;
private FileFilter fileFilter;
private TimeUnit timeUnit;
private AtomicReference<State> atomicState = new AtomicReference<State>(State.STOPPED);
private boolean removeEmptyDirectories = false;
private long pulse;
public FileProcessorQueue () {
waitingQueue = new LinkedList<File>();
waitingSet = new HashSet<File>();
processingSet = new LinkedHashSet<File>();
exclusiveLock = new ReentrantLock();
emptyCondition = exclusiveLock.newCondition();
}
public FileProcessorQueue (File directory, long pulse, TimeUnit timeUnit) {
this(directory, null, false, pulse, timeUnit);
}
public FileProcessorQueue (File directory, boolean removeEmptyDirectories, long pulse, TimeUnit timeUnit) {
this(directory, null, removeEmptyDirectories, pulse, timeUnit);
}
public FileProcessorQueue (File directory, FileFilter fileFilter, long pulse, TimeUnit timeUnit) {
this(directory, fileFilter, false, pulse, timeUnit);
}
public FileProcessorQueue (File directory, FileFilter fileFilter, boolean removeEmptyDirectories, long pulse, TimeUnit timeUnit) {
this();
this.directory = directory;
this.fileFilter = fileFilter;
this.removeEmptyDirectories = removeEmptyDirectories;
this.pulse = pulse;
this.timeUnit = timeUnit;
}
public void setDirectory (File directory) {
this.directory = directory;
}
public File getDirectory () {
return directory;
}
public void setFileFilter (FileFilter fileFilter) {
this.fileFilter = fileFilter;
}
public void setRemoveEmptyDirectories (boolean removeEmptyDirectories) {
this.removeEmptyDirectories = removeEmptyDirectories;
}
public void setPulse (long pulse) {
this.pulse = pulse;
}
public void setTimeUnit (TimeUnit timeUnit) {
this.timeUnit = timeUnit;
}
public void push (File file) {
push(file, false);
}
public void push (File file, boolean forced) {
exclusiveLock.lock();
try {
if ((forced || atomicState.get().equals(State.STARTED)) && file.exists()) {
if (!(waitingSet.contains(file) || processingSet.contains(file))) {
waitingQueue.addLast(file);
waitingSet.add(file);
emptyCondition.signal();
}
}
}
finally {
exclusiveLock.unlock();
}
}
public File poll ()
throws InterruptedException {
return poll(0, TimeUnit.MILLISECONDS);
}
public File poll (long timeout, TimeUnit timeUnit)
throws InterruptedException {
File file;
boolean unexpired = true;
exclusiveLock.lock();
try {
while (unexpired && atomicState.get().equals(State.STARTED) && waitingQueue.isEmpty()) {
unexpired = emptyCondition.await(timeout, timeUnit);
}
if (unexpired && atomicState.get().equals(State.STARTED)) {
waitingSet.remove(file = waitingQueue.removeFirst());
processingSet.add(file);
return file;
}
return null;
}
finally {
exclusiveLock.unlock();
}
}
public void delete (File file)
throws FileProcessingException {
exclusiveLock.lock();
try {
if (!processingSet.contains(file)) {
throw new FileProcessingException("File(%s) is not currently marked for processing", file.getAbsolutePath());
}
processingSet.remove(file);
if (!file.delete()) {
throw new FileProcessingException("Unable to delete the file(%s)", file.getAbsolutePath());
}
if (removeEmptyDirectories && (file.getParentFile().list().length == 0)) {
if (!file.getParentFile().delete()) {
throw new FileProcessingException("Unable to delete the empty directory(%s)", file.getParentFile().getAbsolutePath());
}
}
}
finally {
exclusiveLock.unlock();
}
}
public void start () {
if (atomicState.compareAndSet(State.STOPPED, State.STARTED)) {
new Thread(fileProcessorGopher = new FileProcessorGopher(this, directory, fileFilter, pulse, timeUnit)).start();
}
}
public void stop ()
throws InterruptedException {
if (atomicState.compareAndSet(State.STARTED, State.STOPPED)) {
fileProcessorGopher.finish();
}
}
}