com.alipay.disruptor.BlockingWaitStrategy Maven / Gradle / Ivy
/*
* Copyright 2011 LMAX Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.alipay.disruptor;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* Blocking strategy that uses a lock and condition variable for {@link EventProcessor}s waiting on a barrier.
*
* This strategy can be used when throughput and low-latency are not as important as CPU resource.
*/
public final class BlockingWaitStrategy implements WaitStrategy {
private final Lock lock = new ReentrantLock();
private final Condition processorNotifyCondition = lock.newCondition();
@Override
public long waitFor(long sequence, Sequence cursorSequence, Sequence dependentSequence,
SequenceBarrier barrier) throws AlertException, InterruptedException {
long availableSequence;
if (cursorSequence.get() < sequence) {
lock.lock();
try {
while (cursorSequence.get() < sequence) {
barrier.checkAlert();
processorNotifyCondition.await();
}
} finally {
lock.unlock();
}
}
while ((availableSequence = dependentSequence.get()) < sequence) {
barrier.checkAlert();
}
return availableSequence;
}
@Override
public void signalAllWhenBlocking() {
lock.lock();
try {
processorNotifyCondition.signalAll();
} finally {
lock.unlock();
}
}
@Override
public String toString() {
return "BlockingWaitStrategy{" + "processorNotifyCondition=" + processorNotifyCondition
+ '}';
}
}