org.snmp4j.util

Class ThreadPool

java.lang.Object

org.snmp4j.util.ThreadPool

All Implemented Interfaces:

WorkerPool

public class ThreadPool
extends Object
implements WorkerPool

The ThreadPool provides a pool of a fixed number of threads that are capable to execute tasks that implement the Runnable interface concurrently. The ThreadPool blocks when all threads are busy with tasks and an additional task is added.

Since:

1.0.2

Version:

1.6

Author:

Frank Fock

Field Summary

Fields

Modifier and Type	Field and Description
protected String	name
protected boolean	respawnThreads
protected boolean	stop
protected Vector<org.snmp4j.util.ThreadPool.TaskManager>	taskManagers

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ThreadPool()

Method Summary

Methods

Modifier and Type	Method and Description
void	cancel() Cancels all threads non-blocking by interrupting them.
static ThreadPool	create(String name, int size) Creates a thread pool with the supplied name and size.
void	execute(WorkerTask task) Executes a task on behalf of this thread pool.
String	getName() Returns the name of the thread pool.
protected String	getTaskManagerName(String prefix, int index)
protected void	handleInterruptedExceptionOnExecute(InterruptedException interruptedException, WorkerTask task) Handle a interrupted exception on the execution attempt of WorkerTask.
void	interrupt() Interrupts all threads in the pool.
boolean	isIdle() Checks if all threads of the pool are idle.
boolean	isRespawnThreads() Tests if the threads are respawn (recreates) when they have been stopped or canceled.
void	setRespawnThreads(boolean respawnThreads) Specifies whether threads are respawned by this thread pool after they have been stopped or not.
protected void	setup(String name, int size)
void	stop() Stops all threads in this thread pool gracefully.
boolean	tryToExecute(WorkerTask task) Tries to execute a task on behalf of this thread pool.

Methods inherited from class java.lang.Object

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

Field Detail

taskManagers

protected Vector<org.snmp4j.util.ThreadPool.TaskManager> taskManagers

name

protected String name

stop

protected volatile boolean stop

respawnThreads

protected boolean respawnThreads

Constructor Detail

ThreadPool

protected ThreadPool()

Method Detail

getTaskManagerName

protected String getTaskManagerName(String prefix,
                        int index)

setup

protected void setup(String name,
         int size)

create

public static ThreadPool create(String name,
                int size)

Creates a thread pool with the supplied name and size.

Parameters:

name - the name prefix for the threads in this pool.

size - the number of threads in this pool. This number also specifies the number of concurrent tasks that can be executed with this pool.

Returns:

a ThreadPool instance.

execute

public void execute(WorkerTask task)

Executes a task on behalf of this thread pool. If all threads are currently busy, this method call blocks until a thread gets idle again which is when the call returns immediately.

Specified by:

execute in interface WorkerPool

Parameters:

task - a Runnable to execute.

handleInterruptedExceptionOnExecute

protected void handleInterruptedExceptionOnExecute(InterruptedException interruptedException,
                                       WorkerTask task)

Handle a interrupted exception on the execution attempt of WorkerTask. If the body is void, execution continues and the interrupted exception is ignored. To stop the execution, a RuntimeException has to be thrown. The default behavior is to rethrow the interrupted exception wrapped in a RuntimeException if SNMP4JSettings.forwardRuntimeExceptions is true. Otherwise, the interrupted exception is ignored.

Parameters:

interruptedException - the caught InterruptedException.

task - the task to should have been executed, but failed to execute (until now) because of a busy pool.

Since:

2.3.3

tryToExecute

public boolean tryToExecute(WorkerTask task)

Tries to execute a task on behalf of this thread pool. If all threads are currently busy, this method returns false. Otherwise the task is executed in background.

Specified by:

tryToExecute in interface WorkerPool

Parameters:

task - a Runnable to execute.

Returns:

true if the task is executing.

Since:

1.6

isRespawnThreads

public boolean isRespawnThreads()

Tests if the threads are respawn (recreates) when they have been stopped or canceled.

Returns:

true if threads are respawn.

setRespawnThreads

public void setRespawnThreads(boolean respawnThreads)

Specifies whether threads are respawned by this thread pool after they have been stopped or not. Default is no respawning.

Parameters:

respawnThreads - if true then threads will be respawn.

getName

public String getName()

Returns the name of the thread pool.

Returns:

the name of this thread pool.

stop

public void stop()

Stops all threads in this thread pool gracefully. This method will not return until all threads have been terminated and joined successfully.

Specified by:

stop in interface WorkerPool

cancel

public void cancel()

Cancels all threads non-blocking by interrupting them.

Specified by:

cancel in interface WorkerPool

interrupt

public void interrupt()

Interrupts all threads in the pool.

Since:

1.6

isIdle

public boolean isIdle()

Checks if all threads of the pool are idle.

Specified by:

isIdle in interface WorkerPool

Returns:

true if all threads are idle.

Since:

1.6