org.apache.lens.server.api.retry

Interface BackOffRetryHandler<FC extends FailureContext>

All Superinterfaces:

Serializable

All Known Implementing Classes:

FibonacciExponentialBackOffRetryHandler, ImmediateRetryHandler, NoRetryHandler

public interface BackOffRetryHandler<FC extends FailureContext>
extends Serializable

A backoff retry handler. This allows a backoff on any call, so provides methods whether we can try the operation now, whats next time when operation can be performed and whether operation has exhausted all retries. Callers of this can do the following : if (handler.canTryOpNow(FailureContext)) { try { tryCallerOperation(); FailureContext.clear(); } catch (any Transient Exception) { FailureContext.updateFailure(); if (!handler.hasExhaustedRetries(FailureContext)) { // will be tried later again } throw exception; } } Note that this is only one of the possible use cases, other complex use cases are in retry framework.

Method Summary

Modifier and Type	Method and Description
boolean	canTryOpNow(FC failContext) To know whether operation can be done now.
long	getOperationNextTime(FC failContext) Get the time when the operation can be done next.
boolean	hasExhaustedRetries(FC failContext) Has the operation exhausted all its retries

Method Detail

canTryOpNow

boolean canTryOpNow(FC failContext)

To know whether operation can be done now.

Parameters:

failContext - FailureContext holding failures till now.

Returns:

true if operation can be done now, false otherwise.

getOperationNextTime

long getOperationNextTime(FC failContext)

Get the time when the operation can be done next.

Parameters:

failContext - FC holding failures till now.

Returns:

Next operation time in millis since epoch

hasExhaustedRetries

boolean hasExhaustedRetries(FC failContext)

Has the operation exhausted all its retries

Parameters:

failContext - FC holding failures till now.

Returns:

true if all retries have exhausted, false otherwise.