Package akka.stream.scaladsl

Class RestartFlow

java.lang.Object

akka.stream.scaladsl.RestartFlow

public class RestartFlow
extends java.lang.Object

A RestartFlow wraps a Flow that gets restarted when it completes or fails.

They are useful for graphs that need to run for longer than the Flow can necessarily guarantee it will, for example, for Flow streams that depend on a remote server that may crash or become partitioned. The RestartFlow ensures that the graph can continue running while the Flow restarts.

Constructor Summary

Constructors

Constructor	Description
RestartFlow()

Method Summary

Modifier and Type	Method	Description
static <In,Out> Flow<In,Out,NotUsed>	onFailuresWithBackoff(RestartSettings settings, scala.Function0<Flow<In,Out,?>> flowFactory)	Wrap the given Flow with a Flow that will restart it when it fails using an exponential backoff.
static <In,Out> Flow<In,Out,NotUsed>	withBackoff(RestartSettings settings, scala.Function0<Flow<In,Out,?>> flowFactory)	Wrap the given Flow with a Flow that will restart it when it fails or complete using an exponential backoff.

Methods inherited from class java.lang.Object

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

Constructor Detail

RestartFlow

public RestartFlow()

Method Detail

withBackoff

public static <In,Out> Flow<In,Out,NotUsed> withBackoff(RestartSettings settings,
                                                                          scala.Function0<Flow<In,Out,?>> flowFactory)

Wrap the given Flow with a Flow that will restart it when it fails or complete using an exponential backoff.

This Flow will not cancel, complete or emit a failure, until the opposite end of it has been cancelled or completed. Any termination by the Flow before that time will be handled by restarting it as long as maxRestarts is not reached. Any termination signals sent to this Flow however will terminate the wrapped Flow, if it's running, and then the Flow will be allowed to terminate without being restarted.

The restart process is inherently lossy, since there is no coordination between cancelling and the sending of messages. A termination signal from either end of the wrapped Flow will cause the other end to be terminated, and any in transit messages will be lost. During backoff, this Flow will backpressure.

This uses the same exponential backoff algorithm as BackoffOpts.

Parameters:

settings - RestartSettings defining restart configuration

flowFactory - A factory for producing the Flow to wrap.

onFailuresWithBackoff

public static <In,Out> Flow<In,Out,NotUsed> onFailuresWithBackoff(RestartSettings settings,
                                                                                    scala.Function0<Flow<In,Out,?>> flowFactory)

Wrap the given Flow with a Flow that will restart it when it fails using an exponential backoff. Notice that this Flow will not restart on completion of the wrapped flow.

This Flow will not emit any failure The failures by the wrapped Flow will be handled by restarting the wrapping Flow as long as maxRestarts is not reached. Any termination signals sent to this Flow however will terminate the wrapped Flow, if it's running, and then the Flow will be allowed to terminate without being restarted.

The restart process is inherently lossy, since there is no coordination between cancelling and the sending of messages. A termination signal from either end of the wrapped Flow will cause the other end to be terminated, and any in transit messages will be lost. During backoff, this Flow will backpressure.

This uses the same exponential backoff algorithm as BackoffOpts.

Parameters:

settings - RestartSettings defining restart configuration

flowFactory - A factory for producing the Flow to wrap.