visad.util

Class ThreadPool

java.lang.Object

visad.util.ThreadPool

public class ThreadPool
extends Object

A pool of threads which can be used to execute any Runnable tasks. Internally this class uses a java.util.concurrent.ThreadPoolExecutor, but originally it did not because the original class predates java.util.concurrent. As the internals of this class have evolved, an effort has been made to preserve the original API. Note that a java.util.concurrent.ThreadPoolExecutor does not support the notion of minimum and maximum threads so minimum threads is ignored, and maximum threads is simply the size of the thread pool.

Constructor Summary

Constructors

Constructor and Description
ThreadPool() Build a thread pool with the default thread name prefix and the default minimum and maximum numbers of threads.
ThreadPool(int max) Build a thread pool with the specified maximum number of threads, and the default thread name prefix and minimum number of threads
ThreadPool(int min, int max) Build a thread pool with the specified minimum and maximum numbers of threads, and the default thread name prefix.
ThreadPool(String prefix) Build a thread pool with the specified thread name prefix, and the default minimum and maximum numbers of threads
ThreadPool(String prefix, int min, int max) Build a thread pool with the specified thread name prefix and minimum and maximum numbers of threads

Method Summary

Methods

Modifier and Type	Method and Description
int	getTaskCount() Return the number of tasks in the queue that are running.
boolean	isTerminated() Has the thread pool been closed?
void	printPool() Utility method to print out the tasks
void	queue(Runnable r) Add a task to the queue; tasks are executed as soon as a thread is available, in the order in which they are submitted
void	remove(Runnable r) Remove this task from the tread pool.
void	setThreadMaximum(int num) Set the maximum number of pooled threads
void	stopThreads() Shut down this thread pool.
boolean	waitForTasks() Wait for currently-running tasks to finish.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ThreadPool

public ThreadPool()
           throws Exception

Build a thread pool with the default thread name prefix and the default minimum and maximum numbers of threads.

Throws:

Exception

ThreadPool

public ThreadPool(String prefix)
           throws Exception

Build a thread pool with the specified thread name prefix, and the default minimum and maximum numbers of threads

Parameters:

prefix -

Throws:

Exception

ThreadPool

public ThreadPool(int max)
           throws Exception

Build a thread pool with the specified maximum number of threads, and the default thread name prefix and minimum number of threads

Parameters:

max -

Throws:

Exception

ThreadPool

public ThreadPool(int min,
          int max)
           throws Exception

Build a thread pool with the specified minimum and maximum numbers of threads, and the default thread name prefix.

Parameters:

min -

max -

Throws:

Exception

ThreadPool

public ThreadPool(String prefix,
          int min,
          int max)
           throws Exception

Build a thread pool with the specified thread name prefix and minimum and maximum numbers of threads

Parameters:

prefix -

min -

max -

Throws:

Exception

Method Detail

getTaskCount

public int getTaskCount()

Return the number of tasks in the queue that are running. Note this number is constantly changing so check than act is not really recommended.

Returns:

a rough number of queued and active tasks

remove

public void remove(Runnable r)

Remove this task from the tread pool.

Parameters:

r - the runnable to remove from the queue

isTerminated

public boolean isTerminated()

Has the thread pool been closed?

Returns:

true if the pool has been terminated.

printPool

public void printPool()

Utility method to print out the tasks

queue

public void queue(Runnable r)

Add a task to the queue; tasks are executed as soon as a thread is available, in the order in which they are submitted

Parameters:

r - the runnable that will be executed by this thread pool.

waitForTasks

public boolean waitForTasks()

Wait for currently-running tasks to finish. Blocks while the internal queue of tasks is completed.

Returns:

true

setThreadMaximum

public void setThreadMaximum(int num)
                      throws Exception

Set the maximum number of pooled threads

Parameters:

num - the number of threads

Throws:

Exception

stopThreads

public void stopThreads()

Shut down this thread pool.