com.lmax.disruptor.YieldingWaitStrategy 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.lmax.disruptor;
/**
* Yielding strategy that uses a Thread.yield() for {@link com.lmax.disruptor.EventProcessor}s waiting on a barrier
* after an initially spinning.
*
* This strategy will use 100% CPU, but will more readily give up the CPU than a busy spin strategy if other threads
* require CPU resource.
*/
public final class YieldingWaitStrategy implements WaitStrategy
{
private static final int SPIN_TRIES = 100;
@Override
public long waitFor(
final long sequence, Sequence cursor, final Sequence dependentSequence, final SequenceBarrier barrier)
throws AlertException, InterruptedException
{
long availableSequence;
int counter = SPIN_TRIES;
while ((availableSequence = dependentSequence.get()) < sequence)
{
counter = applyWaitMethod(barrier, counter);
}
return availableSequence;
}
@Override
public void signalAllWhenBlocking()
{
}
private int applyWaitMethod(final SequenceBarrier barrier, int counter)
throws AlertException
{
barrier.checkAlert();
if (0 == counter)
{
Thread.yield();
}
else
{
--counter;
}
return counter;
}
}