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/*
* Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistribution of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
* INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
* MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
* ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
* DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
* DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
* ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
* SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed or intended for use
* in the design, construction, operation or maintenance of any nuclear
* facility.
*/
package demos.util;
import java.util.*;
public class TaskManager {
private ThreadGroup threadGroup;
private volatile boolean shouldStop = false;
private TaskWorker taskWorker = null;
private Object taskWorkerLock = new Object();
private ArrayList tasks = new ArrayList();
private String name;
public TaskManager(String name) {
threadGroup = new ThreadGroup(name);
this.name=name;
}
public String getName() { return name; }
public ThreadGroup getThreadGroup() { return threadGroup; }
public void start() {
synchronized(taskWorkerLock) {
if(null==taskWorker) {
taskWorker = new TaskWorker(name);
}
if(!taskWorker.isRunning()) {
taskWorker.start();
}
taskWorkerLock.notifyAll();
}
}
public void stop() {
synchronized(taskWorkerLock) {
if(null!=taskWorker && taskWorker.isRunning()) {
shouldStop = true;
}
taskWorkerLock.notifyAll();
}
}
public void addTask(Runnable task) {
if(task == null) {
return;
}
synchronized(taskWorkerLock) {
tasks.add(task);
taskWorkerLock.notifyAll();
}
}
public void removeTask(Runnable task) {
if (task == null) {
return;
}
synchronized(taskWorkerLock) {
tasks.remove(task);
taskWorkerLock.notifyAll();
}
}
public Runnable[] getTasks() {
Runnable[] res;
synchronized(taskWorkerLock) {
res = (Runnable[]) tasks.toArray();
}
return res;
}
public void waitUntilStopped() {
synchronized(taskWorkerLock) {
while(null!=taskWorker && taskWorker.isRunning()) {
try {
taskWorkerLock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
class TaskWorker extends Thread {
volatile boolean isRunning = false;
public TaskWorker(String name) {
super(threadGroup, name);
}
public synchronized boolean isRunning() {
return isRunning;
}
public void run() {
synchronized(this) {
isRunning = true;
}
while(!shouldStop) {
try {
// prolog - lock stuff you may wanne do ..
// wait for something todo ..
synchronized(taskWorkerLock) {
while(!shouldStop && tasks.size()==0) {
try {
taskWorkerLock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
// do it for all tasks,
// first make a safe clone of the list
// since it may change while working on it
ArrayList clonedTasks = (ArrayList) tasks.clone();
for(Iterator i = clonedTasks.iterator(); i.hasNext(); ) {
Runnable task = (Runnable) i.next();
task.run();
}
} catch (Throwable t) {
// handle errors ..
t.printStackTrace();
} finally {
// epilog - unlock locked stuff
}
}
synchronized(this) {
isRunning = false;
}
shouldStop=false;
synchronized(taskWorkerLock) {
taskWorkerLock.notifyAll();
}
}
}
}
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