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World Wind is a collection of components that interactively display 3D geographic information within Java applications or applets.
/*
* Copyright (C) 2012 United States Government as represented by the Administrator of the
* National Aeronautics and Space Administration.
* All Rights Reserved.
*/
package gov.nasa.worldwind.util;
import gov.nasa.worldwind.*;
import gov.nasa.worldwind.avlist.AVKey;
import java.util.concurrent.*;
/**
* A service to execute tasks periodically, or after a delay.
*
* @author pabercrombie
* @version $Id: BasicScheduledTaskService.java 1171 2013-02-11 21:45:02Z dcollins $
*/
public class BasicScheduledTaskService extends WWObjectImpl
implements ScheduledTaskService, Thread.UncaughtExceptionHandler
{
/** Default thread pool size. */
protected static final int DEFAULT_POOL_SIZE = 1;
/** Name assigned to active threads. */
protected static final String RUNNING_THREAD_NAME_PREFIX = Logging.getMessage(
"ThreadedTaskService.RunningThreadNamePrefix");
/** Name assigned to idle threads. */
protected static final String IDLE_THREAD_NAME_PREFIX = Logging.getMessage(
"ThreadedTaskService.IdleThreadNamePrefix");
/** Tasks currently running. */
protected ConcurrentLinkedQueue activeTasks;
/** Executor for running tasks. */
protected ScheduledTaskExecutor executor;
/**
* Create a new scheduled task service. The thread pool size is from the WorldWind configuration file property
* {@link AVKey#TASK_POOL_SIZE}.
*/
public BasicScheduledTaskService()
{
Integer poolSize = Configuration.getIntegerValue(AVKey.TASK_POOL_SIZE, DEFAULT_POOL_SIZE);
// this.executor runs the tasks, each in their own thread
this.executor = new ScheduledTaskExecutor(poolSize);
// this.activeTasks holds the list of currently executing tasks
this.activeTasks = new ConcurrentLinkedQueue();
}
public void shutdown(boolean immediately)
{
if (immediately)
this.executor.shutdownNow();
else
this.executor.shutdown();
this.activeTasks.clear();
}
public void uncaughtException(Thread thread, Throwable throwable)
{
String message = Logging.getMessage("ThreadedTaskService.UncaughtExceptionDuringTask", thread.getName());
Logging.logger().fine(message);
Thread.currentThread().getThreadGroup().uncaughtException(thread, throwable);
}
/** Custom executor to run tasks. */
protected class ScheduledTaskExecutor extends ScheduledThreadPoolExecutor
{
protected ScheduledTaskExecutor(int poolSize)
{
super(poolSize,
new ThreadFactory()
{
public Thread newThread(Runnable runnable)
{
Thread thread = new Thread(runnable);
thread.setDaemon(true);
thread.setPriority(Thread.MIN_PRIORITY);
thread.setUncaughtExceptionHandler(BasicScheduledTaskService.this);
return thread;
}
},
new DiscardPolicy()
{
public void rejectedExecution(Runnable runnable, ScheduledThreadPoolExecutor threadPoolExecutor)
{
// Interposes logging for rejected execution
String message = Logging.getMessage("ThreadedTaskService.ResourceRejected", runnable);
Logging.logger().fine(message);
super.rejectedExecution(runnable, threadPoolExecutor);
}
});
}
@Override
protected void beforeExecute(Thread thread, Runnable runnable)
{
if (thread == null)
{
String msg = Logging.getMessage("nullValue.ThreadIsNull");
Logging.logger().fine(msg);
throw new IllegalArgumentException(msg);
}
if (runnable == null)
{
String msg = Logging.getMessage("nullValue.RunnableIsNull");
Logging.logger().fine(msg);
throw new IllegalArgumentException(msg);
}
if (BasicScheduledTaskService.this.activeTasks.contains(runnable))
{
// Duplicate requests are simply interrupted here. The task itself must check the thread's isInterrupted
// flag and actually terminate the task.
String message = Logging.getMessage("ThreadedTaskService.CancellingDuplicateTask", runnable);
Logging.logger().finer(message);
thread.interrupt();
return;
}
BasicScheduledTaskService.this.activeTasks.add(runnable);
if (RUNNING_THREAD_NAME_PREFIX != null)
thread.setName(RUNNING_THREAD_NAME_PREFIX + runnable);
thread.setPriority(Thread.MIN_PRIORITY);
thread.setUncaughtExceptionHandler(BasicScheduledTaskService.this);
super.beforeExecute(thread, runnable);
}
@Override
protected void afterExecute(Runnable runnable, Throwable throwable)
{
if (runnable == null)
{
String msg = Logging.getMessage("nullValue.RunnableIsNull");
Logging.logger().fine(msg);
throw new IllegalArgumentException(msg);
}
super.afterExecute(runnable, throwable);
BasicScheduledTaskService.this.activeTasks.remove(runnable);
if (throwable == null && IDLE_THREAD_NAME_PREFIX != null)
Thread.currentThread().setName(IDLE_THREAD_NAME_PREFIX);
}
}
/** {@inheritDoc} */
public synchronized void addTask(Runnable runnable)
{
if (runnable == null)
{
String message = Logging.getMessage("nullValue.RunnableIsNull");
Logging.logger().fine(message);
throw new IllegalArgumentException(message);
}
// Do not queue duplicates.
if (this.activeTasks.contains(runnable) || this.executor.getQueue().contains(runnable))
return;
this.executor.execute(runnable);
}
/** {@inheritDoc} */
public synchronized ScheduledFuture addScheduledTask(Runnable runnable, long delay, TimeUnit timeunit)
{
if (runnable == null)
{
String message = Logging.getMessage("nullValue.RunnableIsNull");
Logging.logger().fine(message);
throw new IllegalArgumentException(message);
}
// Do not queue duplicates.
if (this.activeTasks.contains(runnable) || this.executor.getQueue().contains(runnable))
return null;
return this.executor.schedule(runnable, delay, timeunit);
}
/** {@inheritDoc} */
public synchronized ScheduledFuture addRepeatingTask(Runnable runnable, long initialDelay, long period,
TimeUnit timeunit)
{
if (runnable == null)
{
String message = Logging.getMessage("nullValue.RunnableIsNull");
Logging.logger().fine(message);
throw new IllegalArgumentException(message);
}
// Do not queue duplicates.
if (this.activeTasks.contains(runnable) || this.executor.getQueue().contains(runnable))
return null;
return this.executor.scheduleAtFixedRate(runnable, initialDelay, period, timeunit);
}
}