com.lmax.disruptor.NoOpEventProcessor 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;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* No operation version of a {@link EventProcessor} that simply tracks a {@link Sequence}.
*
* This is useful in tests or for pre-filling a {@link RingBuffer} from a publisher.
*/
public final class NoOpEventProcessor implements EventProcessor
{
private final SequencerFollowingSequence sequence;
private final AtomicBoolean running = new AtomicBoolean(false);
/**
* Construct a {@link EventProcessor} that simply tracks a {@link Sequence} object.
*
* @param sequencer to track.
*/
public NoOpEventProcessor(final RingBuffer sequencer)
{
sequence = new SequencerFollowingSequence(sequencer);
}
@Override
public Sequence getSequence()
{
return sequence;
}
@Override
public void halt()
{
running.set(false);
}
@Override
public boolean isRunning()
{
return running.get();
}
@Override
public void run()
{
if (!running.compareAndSet(false, true))
{
throw new IllegalStateException("Thread is already running");
}
}
/**
* Sequence that follows (by wrapping) another sequence
*/
private static final class SequencerFollowingSequence extends Sequence
{
private final RingBuffer sequencer;
private SequencerFollowingSequence(final RingBuffer sequencer)
{
super(Sequencer.INITIAL_CURSOR_VALUE);
this.sequencer = sequencer;
}
@Override
public long get()
{
return sequencer.getCursor();
}
}
}