com.lmax.disruptor.Sequencer Maven / Gradle / Ivy
/*
* Copyright 2012 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;
/**
* Coordinates claiming sequences for access to a data structure while tracking dependent {@link Sequence}s
*/
public interface Sequencer extends Cursored, Sequenced
{
/**
* Set to -1 as sequence starting point
*/
long INITIAL_CURSOR_VALUE = -1L;
/**
* Claim a specific sequence. Only used if initialising the ring buffer to
* a specific value.
*
* @param sequence The sequence to initialise too.
*/
void claim(long sequence);
/**
* Confirms if a sequence is published and the event is available for use; non-blocking.
*
* @param sequence of the buffer to check
* @return true if the sequence is available for use, false if not
*/
boolean isAvailable(long sequence);
/**
* Add the specified gating sequences to this instance of the Disruptor. They will
* safely and atomically added to the list of gating sequences.
*
* @param gatingSequences The sequences to add.
*/
void addGatingSequences(Sequence... gatingSequences);
/**
* Remove the specified sequence from this sequencer.
*
* @param sequence to be removed.
* @return true if this sequence was found, false otherwise.
*/
boolean removeGatingSequence(Sequence sequence);
/**
* Create a new SequenceBarrier to be used by an EventProcessor to track which messages
* are available to be read from the ring buffer given a list of sequences to track.
*
* @param sequencesToTrack All of the sequences that the newly constructed barrier will wait on.
* @return A sequence barrier that will track the specified sequences.
* @see SequenceBarrier
*/
SequenceBarrier newBarrier(Sequence... sequencesToTrack);
/**
* Get the minimum sequence value from all of the gating sequences
* added to this ringBuffer.
*
* @return The minimum gating sequence or the cursor sequence if
* no sequences have been added.
*/
long getMinimumSequence();
/**
* Get the highest sequence number that can be safely read from the ring buffer. Depending
* on the implementation of the Sequencer this call may need to scan a number of values
* in the Sequencer. The scan will range from nextSequence to availableSequence. If
* there are no available values >= nextSequence the return value will be
* nextSequence - 1. To work correctly a consumer should pass a value that
* is 1 higher than the last sequence that was successfully processed.
*
* @param nextSequence The sequence to start scanning from.
* @param availableSequence The sequence to scan to.
* @return The highest value that can be safely read, will be at least nextSequence - 1.
*/
long getHighestPublishedSequence(long nextSequence, long availableSequence);
EventPoller newPoller(DataProvider provider, Sequence... gatingSequences);
}