com.lmax.disruptor

Interface Sequencer

All Superinterfaces:

Cursored, Sequenced

All Known Implementing Classes:

AbstractSequencer, MultiProducerSequencer, SingleProducerSequencer

public interface Sequencer
extends Cursored, Sequenced

Coordinates claiming sequences for access to a data structure while tracking dependent Sequences

Field Summary

Fields

Modifier and Type	Field and Description
static long	INITIAL_CURSOR_VALUE Set to -1 as sequence starting point

Method Summary

Modifier and Type	Method and Description
void	addGatingSequences(Sequence... gatingSequences) Add the specified gating sequences to this instance of the Disruptor.
void	claim(long sequence) Claim a specific sequence.
long	getHighestPublishedSequence(long nextSequence, long availableSequence) Get the highest sequence number that can be safely read from the ring buffer.
long	getMinimumSequence() Get the minimum sequence value from all of the gating sequences added to this ringBuffer.
boolean	isAvailable(long sequence) Confirms if a sequence is published and the event is available for use; non-blocking.
SequenceBarrier	newBarrier(Sequence... sequencesToTrack) 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.
<T> EventPoller<T>	newPoller(DataProvider<T> provider, Sequence... gatingSequences)
boolean	removeGatingSequence(Sequence sequence) Remove the specified sequence from this sequencer.

Methods inherited from interface com.lmax.disruptor.Cursored

getCursor

Methods inherited from interface com.lmax.disruptor.Sequenced

getBufferSize, hasAvailableCapacity, next, next, publish, publish, remainingCapacity, tryNext, tryNext

Field Detail

INITIAL_CURSOR_VALUE

static final long INITIAL_CURSOR_VALUE

Set to -1 as sequence starting point

See Also:

Constant Field Values

Method Detail

claim

void claim(long sequence)

Claim a specific sequence. Only used if initialising the ring buffer to a specific value.

Parameters:

sequence - The sequence to initialise too.

isAvailable

boolean isAvailable(long sequence)

Confirms if a sequence is published and the event is available for use; non-blocking.

Parameters:

sequence - of the buffer to check

Returns:

true if the sequence is available for use, false if not

addGatingSequences

void addGatingSequences(Sequence... gatingSequences)

Add the specified gating sequences to this instance of the Disruptor. They will safely and atomically added to the list of gating sequences.

Parameters:

gatingSequences - The sequences to add.

removeGatingSequence

boolean removeGatingSequence(Sequence sequence)

Remove the specified sequence from this sequencer.

Parameters:

sequence - to be removed.

Returns:

true if this sequence was found, false otherwise.

newBarrier

SequenceBarrier newBarrier(Sequence... sequencesToTrack)

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.

Parameters:

sequencesToTrack - All of the sequences that the newly constructed barrier will wait on.

Returns:

A sequence barrier that will track the specified sequences.

See Also:

SequenceBarrier

getMinimumSequence

long getMinimumSequence()

Get the minimum sequence value from all of the gating sequences added to this ringBuffer.

Returns:

The minimum gating sequence or the cursor sequence if no sequences have been added.

getHighestPublishedSequence

long getHighestPublishedSequence(long nextSequence,
                                 long availableSequence)

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.

Parameters:

nextSequence - The sequence to start scanning from.

availableSequence - The sequence to scan to.

Returns:

The highest value that can be safely read, will be at least nextSequence - 1.

newPoller

<T> EventPoller<T> newPoller(DataProvider<T> provider,
                             Sequence... gatingSequences)