com.lmax.disruptor.AbstractSequencer 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.Arrays;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import com.lmax.disruptor.util.Util;
/**
* Base class for the various sequencer types (single/multi). Provides
* common functionality like the management of gating sequences (add/remove) and
* ownership of the current cursor.
*/
public abstract class AbstractSequencer implements Sequencer
{
private static final AtomicReferenceFieldUpdater SEQUENCE_UPDATER =
AtomicReferenceFieldUpdater.newUpdater(AbstractSequencer.class, Sequence[].class, "gatingSequences");
protected final int bufferSize;
protected final WaitStrategy waitStrategy;
protected final Sequence cursor = new Sequence(Sequencer.INITIAL_CURSOR_VALUE);
protected volatile Sequence[] gatingSequences = new Sequence[0];
/**
* Create with the specified buffer size and wait strategy.
*
* @param bufferSize The total number of entries, must be a positive power of 2.
* @param waitStrategy The wait strategy used by this sequencer
*/
public AbstractSequencer(int bufferSize, WaitStrategy waitStrategy)
{
if (bufferSize < 1)
{
throw new IllegalArgumentException("bufferSize must not be less than 1");
}
if (Integer.bitCount(bufferSize) != 1)
{
throw new IllegalArgumentException("bufferSize must be a power of 2");
}
this.bufferSize = bufferSize;
this.waitStrategy = waitStrategy;
}
/**
* @see Sequencer#getCursor()
*/
@Override
public final long getCursor()
{
return cursor.get();
}
/**
* @see Sequencer#getBufferSize()
*/
@Override
public final int getBufferSize()
{
return bufferSize;
}
/**
* @see Sequencer#addGatingSequences(Sequence...)
*/
@Override
public final void addGatingSequences(Sequence... gatingSequences)
{
SequenceGroups.addSequences(this, SEQUENCE_UPDATER, this, gatingSequences);
}
/**
* @see Sequencer#removeGatingSequence(Sequence)
*/
@Override
public boolean removeGatingSequence(Sequence sequence)
{
return SequenceGroups.removeSequence(this, SEQUENCE_UPDATER, sequence);
}
/**
* @see Sequencer#getMinimumSequence()
*/
@Override
public long getMinimumSequence()
{
return Util.getMinimumSequence(gatingSequences, cursor.get());
}
/**
* @see Sequencer#newBarrier(Sequence...)
*/
@Override
public SequenceBarrier newBarrier(Sequence... sequencesToTrack)
{
return new ProcessingSequenceBarrier(this, waitStrategy, cursor, sequencesToTrack);
}
/**
* Creates an event poller for this sequence that will use the supplied data provider and
* gating sequences.
*
* @param dataProvider The data source for users of this event poller
* @param gatingSequences Sequence to be gated on.
* @return A poller that will gate on this ring buffer and the supplied sequences.
*/
@Override
public EventPoller newPoller(DataProvider dataProvider, Sequence... gatingSequences)
{
return EventPoller.newInstance(dataProvider, this, new Sequence(), cursor, gatingSequences);
}
@Override
public String toString()
{
return "AbstractSequencer{" +
"waitStrategy=" + waitStrategy +
", cursor=" + cursor +
", gatingSequences=" + Arrays.toString(gatingSequences) +
'}';
}
}