com.lmax.disruptor

Class PhasedBackoffWaitStrategy

java.lang.Object

com.lmax.disruptor.PhasedBackoffWaitStrategy

All Implemented Interfaces:

WaitStrategy

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

Phased wait strategy for waiting EventProcessors on a barrier.

This strategy can be used when throughput and low-latency are not as important as CPU resource. Spins, then yields, then waits using the configured fallback WaitStrategy.

Field Summary

Fields

Modifier and Type	Field and Description
private WaitStrategy	fallbackStrategy
private static int	SPIN_TRIES
private long	spinTimeoutNanos
private long	yieldTimeoutNanos

Constructor Summary

Constructors

Constructor and Description
PhasedBackoffWaitStrategy(long spinTimeout, long yieldTimeout, java.util.concurrent.TimeUnit units, WaitStrategy fallbackStrategy)

Method Summary

Modifier and Type	Method and 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.
static PhasedBackoffWaitStrategy	withLiteLock(long spinTimeout, long yieldTimeout, java.util.concurrent.TimeUnit units) Construct PhasedBackoffWaitStrategy with fallback to LiteBlockingWaitStrategy
static PhasedBackoffWaitStrategy	withLock(long spinTimeout, long yieldTimeout, java.util.concurrent.TimeUnit units) Construct PhasedBackoffWaitStrategy with fallback to BlockingWaitStrategy
static PhasedBackoffWaitStrategy	withSleep(long spinTimeout, long yieldTimeout, java.util.concurrent.TimeUnit units) Construct PhasedBackoffWaitStrategy with fallback to SleepingWaitStrategy

Methods inherited from class java.lang.Object

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

Field Detail

SPIN_TRIES

private static final int SPIN_TRIES

See Also:

Constant Field Values

spinTimeoutNanos

private final long spinTimeoutNanos

yieldTimeoutNanos

private final long yieldTimeoutNanos

fallbackStrategy

private final WaitStrategy fallbackStrategy

Constructor Detail

PhasedBackoffWaitStrategy

public PhasedBackoffWaitStrategy(long spinTimeout,
                                 long yieldTimeout,
                                 java.util.concurrent.TimeUnit units,
                                 WaitStrategy fallbackStrategy)

Method Detail

withLock

public static PhasedBackoffWaitStrategy withLock(long spinTimeout,
                                                 long yieldTimeout,
                                                 java.util.concurrent.TimeUnit units)

Construct PhasedBackoffWaitStrategy with fallback to BlockingWaitStrategy

Parameters:

spinTimeout - The maximum time in to busy spin for.

yieldTimeout - The maximum time in to yield for.

units - Time units used for the timeout values.

Returns:

The constructed wait strategy.

withLiteLock

public static PhasedBackoffWaitStrategy withLiteLock(long spinTimeout,
                                                     long yieldTimeout,
                                                     java.util.concurrent.TimeUnit units)

Construct PhasedBackoffWaitStrategy with fallback to LiteBlockingWaitStrategy

Parameters:

spinTimeout - The maximum time in to busy spin for.

yieldTimeout - The maximum time in to yield for.

units - Time units used for the timeout values.

Returns:

The constructed wait strategy.

withSleep

public static PhasedBackoffWaitStrategy withSleep(long spinTimeout,
                                                  long yieldTimeout,
                                                  java.util.concurrent.TimeUnit units)

Construct PhasedBackoffWaitStrategy with fallback to SleepingWaitStrategy

Parameters:

spinTimeout - The maximum time in to busy spin for.

yieldTimeout - The maximum time in to yield for.

units - Time units used for the timeout values.

Returns:

The constructed wait strategy.

waitFor

public long waitFor(long sequence,
                    Sequence cursor,
                    Sequence dependentSequence,
                    SequenceBarrier barrier)
             throws AlertException,
                    java.lang.InterruptedException,
                    TimeoutException

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.

java.lang.InterruptedException - if the thread is interrupted.

TimeoutException - if a timeout occurs before waiting completes (not used by some strategies)

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