com.hazelcast.map.impl.querycache.event.sequence

Interface PartitionSequencer

All Known Implementing Classes:

DefaultPartitionSequencer

public interface PartitionSequencer

General contract of a sequence-number provider for a partition.

Each partition has its own sequence-number on publisher-side. For every generated event, this sequence will be incremented by one and set to that event before sending it to the subscriber side.

On subscriber side, this sequence is used to keep track of published events; upon arrival of an event, there is a pre-condition check to decide whether that the arrived event has the next-expected-sequence-number for the relevant partition. If the event has next-sequence, it is applied to the query-cache.

Implementations of this interface should be thread-safe.

Method Summary

Modifier and Type	Method and Description
boolean	compareAndSetSequence(long expect, long update) Atomically sets the value of sequence number for the partition.
long	getSequence() Returns current sequence number of the partition.
long	nextSequence() Returns next number in sequence for the partition.
void	reset() Resets PartitionSequencer.
void	setSequence(long update) Sets the current sequence number for the partition.

Method Detail

nextSequence

long nextSequence()

Returns next number in sequence for the partition.

Returns:

next number in sequence.

setSequence

void setSequence(long update)

Sets the current sequence number for the partition.

Parameters:

update - new sequence number.

compareAndSetSequence

boolean compareAndSetSequence(long expect,
                              long update)

Atomically sets the value of sequence number for the partition.

Parameters:

expect - the expected sequence.

update - the new sequence.

Returns:

true if Compare-and-Set operation is successful, otherwise returns false.

getSequence

long getSequence()

Returns current sequence number of the partition.

Returns:

current sequence number.

reset

void reset()

Resets PartitionSequencer. After this call returns sequence generation will be start from zero.