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/*
* Copyright 2009 - 2010 JogAmp Community. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are
* permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation are those of the
* authors and should not be interpreted as representing official policies, either expressed
* or implied, of JogAmp Community.
*/
package com.jogamp.opencl.util;
import com.jogamp.opencl.CLCommandQueue;
import com.jogamp.opencl.CLEventList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
/**
* An utility for synchronizing multiple concurrent {@link CLCommandQueue}s.
* This Barrier can be reused after it has been broken.
* @author Michael Bien
*/
public class MultiQueueBarrier {
private CountDownLatch latch;
private final Set<CLCommandQueue> queues;
private final int count;
/**
* Creates a new MultiQueueBarrier with the given queueCount.
* It is recommented to use {@link #MultiQueueBarrier(CLCommandQueue... allowedQueues)} if possible
* which restricts the set of allowed queues for the barrier.
*/
public MultiQueueBarrier(int queueCount) {
if(queueCount == 0) {
throw new IllegalArgumentException("queueCount was 0");
}
this.latch = new CountDownLatch(queueCount);
this.queues = null;
this.count = queueCount;
}
/**
* Creates a new MultiQueueBarrier for the given queues.
*/
public MultiQueueBarrier(CLCommandQueue... allowedQueues) {
if(allowedQueues.length == 0) {
throw new IllegalArgumentException("allowedQueues was empty");
}
this.latch = new CountDownLatch(allowedQueues.length);
this.count = allowedQueues.length;
HashSet<CLCommandQueue> set = new HashSet<CLCommandQueue>(allowedQueues.length);
for (CLCommandQueue queue : allowedQueues) {
set.add(queue);
}
this.queues = Collections.unmodifiableSet(set);
}
/**
* Blocks the current Thread until all commands on the {@link CLCommandQueue} finished excecution.
* This method may be invoked concurrently without synchronization on the MultiQueueBarrier object
* as long each Thread passes a distinct CLCommandQueue as parameter to this method.
*/
public MultiQueueBarrier waitFor(CLCommandQueue queue) {
checkQueue(queue);
queue.putBarrier();
synchronized(this) {
latch.countDown();
}
return this;
}
/**
* Blocks the current Thread until the given events on the {@link CLCommandQueue} occurred.
* This method may be invoked concurrently without synchronization on the MultiQueueBarrier object
* as long each Thread passes a distinct CLCommandQueue as parameter to this method.
*/
public MultiQueueBarrier waitFor(CLCommandQueue queue, CLEventList events) {
checkQueue(queue);
queue.putWaitForEvents(events, true);
synchronized(this) {
latch.countDown();
}
return this;
}
/**
* Blocks until all Threads which called {@link #waitFor}
* continue execution.
* This method blocks only once, all subsequent calls are ignored.
*/
public MultiQueueBarrier await() throws InterruptedException {
latch.await();
rebuildBarrierIfBroken();
return this;
}
/**
* @see #await()
* @param timeout the maximum time to wait
* @param unit the time unit of the {@code timeout} argument
*/
public boolean await(long timeout, TimeUnit unit) throws InterruptedException {
boolean ret = latch.await(timeout, unit);
rebuildBarrierIfBroken();
return ret;
}
/**
* Resets this barrier and unblocks all waiting threads.
*/
public void resetBarrier() {
synchronized(this) {
while(latch.getCount() > 0) {
latch.countDown();
}
// thats OK. Another Thread can not rebuild the barrier since we have the lock.
// we have to rebuid it here in case there was no thread waiting.
latch = new CountDownLatch(count);
}
}
private void rebuildBarrierIfBroken() {
synchronized (this) {
if (latch.getCount() == 0) {
latch = new CountDownLatch(count);
}
}
}
/**
* Returns the current number of events which must occure before this barrier unblocks the waiting threads.
* This method is typically used for debugging and testing purposes.
*/
public long getCount() {
return latch.getCount();
}
private void checkQueue(CLCommandQueue queue) throws IllegalArgumentException {
if (queues != null && !queues.contains(queue)) {
throw new IllegalArgumentException(queue + " is not in the allowedQueues Set: " + queues);
}
}
}
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