
com.mastfrog.util.thread.MultiCountdownLatch Maven / Gradle / Ivy
/*
* The MIT License
*
* Copyright 2017 Tim Boudreau.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.mastfrog.util.thread;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
/**
* Like a CountDownLatch but with the ability to release multiple permits
* in one call.
*
* @author Tim Boudreau
*/
public class MultiCountdownLatch {
private static final class Sync extends AbstractQueuedSynchronizer {
Sync(int count) {
setState(count);
}
int getCount() {
return getState();
}
void reset(int count) {
setState(count);
}
@Override
protected int tryAcquireShared(int acquires) {
return (getState() == 0) ? 1 : -1;
}
@Override
protected boolean tryReleaseShared(int releases) {
// Decrement count; signal when transition to zero
for (;;) {
int c = getState();
if (c == 0) {
return false;
}
int nextc = c - releases;
if (compareAndSetState(c, nextc)) {
return nextc == 0;
}
}
}
}
private final Sync sync;
public MultiCountdownLatch(int count) {
this.sync = new Sync(count);
}
public void await() throws InterruptedException {
sync.acquireSharedInterruptibly(1);
}
public boolean await(long timeout, TimeUnit unit)
throws InterruptedException {
return sync.tryAcquireSharedNanos(1, unit.toNanos(timeout));
}
public void countDown() {
countDown(1);
}
public void countDown(int qty) {
sync.releaseShared(qty);
}
public long getCount() {
return sync.getCount();
}
}
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