org.transitime.utils.threading

Class BoundedExecutor

java.lang.Object

org.transitime.utils.threading.BoundedExecutor

public class BoundedExecutor
extends java.lang.Object

An Executor but limits how many tasks can be queued. If queue is full and attempt to execute an additional task then execute() will block.

Based on code from the book "Java Concurrency in Practice" by Brian Goetz

Author:

SkiBu Smith

Constructor Summary

Constructors

Constructor and Description
BoundedExecutor(java.util.concurrent.Executor exec, int allowableNumberBeforeBlocking) Constructs an Executor that allows Runnables to be executed using multiple threads.

Method Summary

Modifier and Type	Method and Description
void	execute(java.lang.Runnable command) Executes the task by running the Runnable.run() method.
int	spaceInQueue() Returns how many items can still be added to the executor's queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

BoundedExecutor

public BoundedExecutor(java.util.concurrent.Executor exec,
                       int allowableNumberBeforeBlocking)

Constructs an Executor that allows Runnables to be executed using multiple threads. If try to execute more Runnables than there are available threads then those are queued up. If queue fills up then adding an additional Runnable will block.

Parameters:

exec - The executor. Recommend using Executors.newFixedThreadPool() to get a fixed thread pool.

allowableNumberBeforeBlocking - How many items that can be queued before execute() will block if another Runnable is added. Includes both Runnables that are currently running plus ones that have already been submitted but are still queued up. The value needs to be at least as large as the number of threads allowed by the Executor in order for all threads to be usable simultaneously.

Method Detail

spaceInQueue

public int spaceInQueue()

Returns how many items can still be added to the executor's queue.

Returns:

How many items can add to queue

execute

public void execute(java.lang.Runnable command)
             throws java.lang.InterruptedException

Executes the task by running the Runnable.run() method. Blocks if queue is already full. The queue includes tasks already being executed so if Executor can use 5 threads and all 5 threads are executing a task and allowableNumberBeforeBlocking is 8 then can only have 3 items queued up and not yet started execution before this method will block.

Parameters:

command - For which run() is to be called

Throws:

java.lang.InterruptedException - if this task cannot be accepted for execution.