org.multiverse.utils.backoff
Class ExponentialBackoffPolicy

java.lang.Object
  org.multiverse.utils.backoff.ExponentialBackoffPolicy

All Implemented Interfaces:

BackoffPolicy

public class ExponentialBackoffPolicy
extends java.lang.Object
implements BackoffPolicy

A BackoffPolicy that does an exponential backoff. So each next attempt, the delay is doubled until a configurable maximum delay has been reached.

The exponential growth of delay can be truncated by providing a maxDelay. If no max delay is provided, the maximum delay would be 10.000.000.000 seconds (292 years). So be careful with not using an acceptable maximum delay.

Author:

Peter Veentjer.

Field Summary

static ExponentialBackoffPolicy

INSTANCE_10_MS_MAX

Constructor Summary

ExponentialBackoffPolicy()
Creates an ExponentialBackoffPolicy with 100 nanoseconds as minimal delay and 10 milliseconds as maximum delay.

ExponentialBackoffPolicy(long minDelayNs, long maxDelay, java.util.concurrent.TimeUnit unit)
Creates an ExponentialBackoffPolicy with given maximum delay.

Method Summary

protected long	calcDelayNs(int attempt)
void	delay(Transaction t, int attempt) Executes the delay.
void	delayedUninterruptible(Transaction t, int attempt) Executes the delay without the possibility of being interrupted.
long	getMaxDelayNs() Returns the maximum delay in nanoseconds.
long	getMinDelayNs() Returns the minimum delay in nanoseconds.

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE_10_MS_MAX

public static final ExponentialBackoffPolicy INSTANCE_10_MS_MAX

Constructor Detail

ExponentialBackoffPolicy

public ExponentialBackoffPolicy()

Creates an ExponentialBackoffPolicy with 100 nanoseconds as minimal delay and 10 milliseconds as maximum delay.

ExponentialBackoffPolicy

public ExponentialBackoffPolicy(long minDelayNs,
                                long maxDelay,
                                java.util.concurrent.TimeUnit unit)

Creates an ExponentialBackoffPolicy with given maximum delay.

Parameters:

minDelayNs - the minimum delay in nanoseconds to wait. If a negative or zero value provided, it will be interpreted that no external minimal value is needed.

maxDelay - the maximum delay.

unit - the unit of maxDelay.

Throws:

java.lang.NullPointerException - if unit is null.

Method Detail

getMaxDelayNs

public long getMaxDelayNs()

Returns the maximum delay in nanoseconds. A negative or zero delay indicates that there is no max.

Returns:

the maximum delay in nanosecond.

getMinDelayNs

public long getMinDelayNs()

Returns the minimum delay in nanoseconds. A negative or zero value indicates that there is no minimal delay.

Returns:

the minimum delay in nanoseconds.

delay

public void delay(Transaction t,
                  int attempt)
           throws java.lang.InterruptedException

Description copied from interface: BackoffPolicy

Executes the delay. This call is interruptible.

Specified by:

delay in interface BackoffPolicy

Parameters:

t - the transaction that is going to be restarted. The transaction should never be null, but it depends on the implementation if this is checked.

attempt - indicates the number of times the transaction is tried. Attempt should always be equal or larger than 1. It depends on the implementation if this is checked.

Throws:

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

delayedUninterruptible

public void delayedUninterruptible(Transaction t,
                                   int attempt)

Description copied from interface: BackoffPolicy

Executes the delay without the possibility of being interrupted.

Specified by:

delayedUninterruptible in interface BackoffPolicy

Parameters:

t - the transaction that is going to be restarted. The transaction should never be null, but it depends on the implementation if this is checked.

attempt - indicates the number of times the transaction is tried. Attempt should always be equal or larger than 1. It depends on the implementation if this is checked.

calcDelayNs

protected long calcDelayNs(int attempt)