Module com.lmax.disruptor

Package com.lmax.disruptor

Class SleepingWaitStrategy

java.lang.Object

com.lmax.disruptor.SleepingWaitStrategy

All Implemented Interfaces:

WaitStrategy

public final class SleepingWaitStrategy
extends java.lang.Object
implements WaitStrategy

Sleeping strategy that initially spins, then uses a Thread.yield(), and eventually sleep (LockSupport.parkNanos(n)) for the minimum number of nanos the OS and JVM will allow while the EventProcessors are waiting on a barrier.

This strategy is a good compromise between performance and CPU resource. Latency spikes can occur after quiet periods. It will also reduce the impact on the producing thread as it will not need signal any conditional variables to wake up the event handling thread.

Constructor Summary

Constructors

Constructor	Description
SleepingWaitStrategy()	Provides a sleeping wait strategy with the default retry and sleep settings
SleepingWaitStrategy(int retries)
SleepingWaitStrategy(int retries, long sleepTimeNs)

Method Summary

Modifier and Type	Method	Description
void	signalAllWhenBlocking()	Implementations should signal the waiting EventProcessors that the cursor has advanced.
long	waitFor(long sequence, Sequence cursor, Sequence dependentSequence, SequenceBarrier barrier)	Wait for the given sequence to be available.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SleepingWaitStrategy

public SleepingWaitStrategy()

Provides a sleeping wait strategy with the default retry and sleep settings

SleepingWaitStrategy

public SleepingWaitStrategy(int retries)

Parameters:

retries - How many times the strategy should retry before sleeping

SleepingWaitStrategy

public SleepingWaitStrategy(int retries,
                            long sleepTimeNs)

Parameters:

retries - How many times the strategy should retry before sleeping

sleepTimeNs - How long the strategy should sleep, in nanoseconds

Method Detail

waitFor

public long waitFor(long sequence,
                    Sequence cursor,
                    Sequence dependentSequence,
                    SequenceBarrier barrier)
             throws AlertException

Description copied from interface: WaitStrategy

Wait for the given sequence to be available. It is possible for this method to return a value less than the sequence number supplied depending on the implementation of the WaitStrategy. A common use for this is to signal a timeout. Any EventProcessor that is using a WaitStrategy to get notifications about message becoming available should remember to handle this case. The BatchEventProcessor explicitly handles this case and will signal a timeout if required.

Specified by:

waitFor in interface WaitStrategy

Parameters:

sequence - to be waited on.

cursor - the main sequence from ringbuffer. Wait/notify strategies will need this as it's the only sequence that is also notified upon update.

dependentSequence - on which to wait.

barrier - the processor is waiting on.

Returns:

the sequence that is available which may be greater than the requested sequence.

Throws:

AlertException - if the status of the Disruptor has changed.

signalAllWhenBlocking

public void signalAllWhenBlocking()

Description copied from interface: WaitStrategy

Implementations should signal the waiting EventProcessors that the cursor has advanced.

Specified by:

signalAllWhenBlocking in interface WaitStrategy