Package akka.pattern

Interface RetrySupport

All Known Implementing Classes:

RetrySupport$

public interface RetrySupport

This trait provides the retry utility function

Method Summary

Modifier and Type	Method	Description
<T> scala.concurrent.Future<T>	retry(scala.Function0<scala.concurrent.Future<T>> attempt, int attempts, scala.concurrent.duration.FiniteDuration minBackoff, scala.concurrent.duration.FiniteDuration maxBackoff, double randomFactor, scala.concurrent.ExecutionContext ec, Scheduler scheduler)	Given a function from Unit to Future, returns an internally retrying Future.
<T> scala.concurrent.Future<T>	retry(scala.Function0<scala.concurrent.Future<T>> attempt, int attempts, scala.concurrent.duration.FiniteDuration delay, scala.concurrent.ExecutionContext ec, Scheduler scheduler)	Given a function from Unit to Future, returns an internally retrying Future.
<T> scala.concurrent.Future<T>	retry(scala.Function0<scala.concurrent.Future<T>> attempt, int attempts, scala.concurrent.ExecutionContext ec)	Given a function from Unit to Future, returns an internally retrying Future.
<T> scala.concurrent.Future<T>	retry(scala.Function0<scala.concurrent.Future<T>> attempt, int attempts, scala.Function1<java.lang.Object,scala.Option<scala.concurrent.duration.FiniteDuration>> delayFunction, scala.concurrent.ExecutionContext ec, Scheduler scheduler)	Given a function from Unit to Future, returns an internally retrying Future.

Method Detail

retry

<T> scala.concurrent.Future<T> retry(scala.Function0<scala.concurrent.Future<T>> attempt,
                                     int attempts,
                                     scala.concurrent.ExecutionContext ec)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made immediately if the previous attempt failed.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

 def possiblyFailing(): Future[Something] = ???
 val withRetry: Future[Something] = retry(attempt = possiblyFailing, attempts = 10)
 

retry

<T> scala.concurrent.Future<T> retry(scala.Function0<scala.concurrent.Future<T>> attempt,
                                     int attempts,
                                     scala.concurrent.duration.FiniteDuration minBackoff,
                                     scala.concurrent.duration.FiniteDuration maxBackoff,
                                     double randomFactor,
                                     scala.concurrent.ExecutionContext ec,
                                     Scheduler scheduler)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made with a backoff time, if the previous attempt failed.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

 protected val sendAndReceive: HttpRequest => Future[HttpResponse]
 private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
   attempt = () => sendAndReceive(req),
   attempts = 10,
   minBackoff = 1.seconds,
   maxBackoff = 2.seconds,
   randomFactor = 0.5
 )
 

Parameters:

minBackoff - minimum (initial) duration until the child actor will started again, if it is terminated

maxBackoff - the exponential back-off is capped to this duration

randomFactor - after calculation of the exponential back-off an additional random delay based on this factor is added, e.g. 0.2 adds up to 20% delay. In order to skip this additional delay pass in 0.

retry

<T> scala.concurrent.Future<T> retry(scala.Function0<scala.concurrent.Future<T>> attempt,
                                     int attempts,
                                     scala.concurrent.duration.FiniteDuration delay,
                                     scala.concurrent.ExecutionContext ec,
                                     Scheduler scheduler)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made after 'delay'. A scheduler (eg context.system.scheduler) must be provided to delay each retry.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

 protected val sendAndReceive: HttpRequest => Future[HttpResponse]
 private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
   attempt = () => sendAndReceive(req),
   attempts = 10,
   delay = 2.seconds
 )
 

retry

<T> scala.concurrent.Future<T> retry(scala.Function0<scala.concurrent.Future<T>> attempt,
                                     int attempts,
                                     scala.Function1<java.lang.Object,scala.Option<scala.concurrent.duration.FiniteDuration>> delayFunction,
                                     scala.concurrent.ExecutionContext ec,
                                     Scheduler scheduler)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made after the 'delay' return by delayFunction(the input next attempt count start from 1). Returns None for no delay. A scheduler (eg context.system.scheduler) must be provided to delay each retry. You could provide a function to generate the next delay duration after first attempt, this function should never return null, otherwise an IllegalArgumentException will be through.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

//retry with back off

 protected val sendAndReceive: HttpRequest => Future[HttpResponse]
 private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
   attempt = () => sendAndReceive(req),
   attempts = 10,
   delayFunction = attempted => Option(2.seconds * attempted)
 )