org.apache.activemq.artemis.utils

Class ReusableLatch

java.lang.Object

org.apache.activemq.artemis.utils.ReusableLatch

public class ReusableLatch
extends Object

This class will use the framework provided to by AbstractQueuedSynchronizer.

AbstractQueuedSynchronizer is the framework for any sort of concurrent synchronization, such as Semaphores, events, etc, based on AtomicIntegers.

This class works just like CountDownLatch, with the difference you can also increase the counter

It could be used for sync points when one process is feeding the latch while another will wait when everything is done. (e.g. waiting IO completions to finish)

On ActiveMQ Artemis we have the requirement of increment and decrement a counter until the user fires a ready event (commit). At that point we just act as a regular countDown.

Note: This latch is reusable. Once it reaches zero, you can call up again, and reuse it on further waits.

For example: prepareTransaction will wait for the current completions, and further adds will be called on the latch. Later on when commit is called you can reuse the same latch.

Constructor Summary

Constructors

Constructor and Description
ReusableLatch()
ReusableLatch(int count)

Method Summary

Modifier and Type	Method and Description
void	await()
boolean	await(long milliseconds)
boolean	await(long timeWait, TimeUnit timeUnit)
void	countDown()
void	countDown(int count)
void	countUp()
int	getCount()
void	setCount(int count)

Methods inherited from class java.lang.Object

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

Constructor Detail

ReusableLatch

public ReusableLatch()

ReusableLatch

public ReusableLatch(int count)

Method Detail

getCount

public int getCount()

setCount

public void setCount(int count)

countUp

public void countUp()

countDown

public void countDown()

countDown

public void countDown(int count)

await

public void await()
           throws InterruptedException

Throws:

InterruptedException

await

public boolean await(long milliseconds)
              throws InterruptedException

Throws:

InterruptedException

await

public boolean await(long timeWait,
                     TimeUnit timeUnit)
              throws InterruptedException

Throws:

InterruptedException