Package org.camunda.bpm.client.backoff

Class ExponentialErrorBackoffStrategy

java.lang.Object

org.camunda.bpm.client.backoff.ExponentialErrorBackoffStrategy

All Implemented Interfaces:

BackoffStrategy, ErrorAwareBackoffStrategy

public class ExponentialErrorBackoffStrategy
extends Object
implements ErrorAwareBackoffStrategy

Provides an exponential backoff strategy when an error occurs fetching external tasks.

Note this strategy does not provide any backoff when no external tasks are received. It should therefore only be used with long polling (asyncResponseTimeout) to ensure appropriate throttling of requests.

Field Summary

Fields

Modifier and Type	Field	Description
protected float	factor
protected long	initTime
protected int	level
protected long	maxTime

Constructor Summary

Constructors

Constructor	Description
ExponentialErrorBackoffStrategy()
ExponentialErrorBackoffStrategy(long initTime, float factor, long maxTime)

Method Summary

Modifier and Type	Method	Description
long	calculateBackoffTime()	Calculates the back off time and is invoked after ErrorAwareBackoffStrategy.reconfigure(List, ExternalTaskClientException).
void	reconfigure(List<ExternalTask> externalTasks, ExternalTaskClientException error)	Reconfigures the back off strategy based on the fetched external tasks and any error that might have occurred.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.camunda.bpm.client.backoff.ErrorAwareBackoffStrategy

reconfigure

Field Detail

initTime

protected long initTime

factor

protected float factor

level

protected int level

maxTime

protected long maxTime

Constructor Detail

ExponentialErrorBackoffStrategy

public ExponentialErrorBackoffStrategy()

ExponentialErrorBackoffStrategy

public ExponentialErrorBackoffStrategy(long initTime,
                                       float factor,
                                       long maxTime)

Parameters:

initTime - in milliseconds for which the client is suspended after the first request

factor - is the base of the power by which the waiting time increases

maxTime - in milliseconds for which the client can be suspended

Method Detail

reconfigure

public void reconfigure(List<ExternalTask> externalTasks,
                        ExternalTaskClientException error)

Description copied from interface: ErrorAwareBackoffStrategy

Reconfigures the back off strategy based on the fetched external tasks and any error that might have occurred. It is invoked before ErrorAwareBackoffStrategy.calculateBackoffTime().

The implementation might count the amount of invocations and realize a strategy reset.

Specified by:

reconfigure in interface ErrorAwareBackoffStrategy

Parameters:

externalTasks - which have been fetched

error - can be of the following types:

• EngineException if something went wrong during the engine execution (e.g., a persistence exception occurred).
• BadRequestException if an illegal operation was performed or the given data is invalid.
• ConnectionLostException if the connection could not be established.
• UnknownHttpErrorException if the HTTP status code is not known by the client.

calculateBackoffTime

public long calculateBackoffTime()

Description copied from interface: ErrorAwareBackoffStrategy

Calculates the back off time and is invoked after ErrorAwareBackoffStrategy.reconfigure(List, ExternalTaskClientException).

Specified by:

calculateBackoffTime in interface BackoffStrategy

Specified by:

calculateBackoffTime in interface ErrorAwareBackoffStrategy

Returns:

the back off time between fetch and lock requests in milliseconds