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Doc onFailureWithBackoff (#28356)

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Christopher Batey 2020-03-03 09:18:34 +00:00 • committed by GitHub
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akka-docs/src/test/java/jdocs/stream/operators/source/Restart.java Normal file
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/*
* Copyright (C) 2019-2020 Lightbend Inc. <https://www.lightbend.com>
*/
package jdocs.stream.operators.source;
import akka.NotUsed;
import akka.actor.Cancellable;
import akka.japi.Creator;
import akka.stream.KillSwitches;
import akka.stream.UniqueKillSwitch;
import akka.stream.javadsl.Keep;
import akka.stream.javadsl.RestartSource;
import akka.stream.javadsl.Sink;
import akka.stream.javadsl.Source;
import java.time.Duration;
import java.util.Arrays;
public class Restart {
static akka.actor.ActorSystem system = akka.actor.ActorSystem.create();
public static void onRestartWithBackoffInnerFailure() {
// #restart-failure-inner-failure
// could throw if for example it used a database connection to get rows
Source<Creator<Integer>, NotUsed> flakySource =
Source.from(
Arrays.<Creator<Integer>>asList(
() -> 1,
() -> 2,
() -> 3,
() -> {
throw new RuntimeException("darn");
}));
Source<Creator<Integer>, NotUsed> forever =
RestartSource.onFailuresWithBackoff(
Duration.ofSeconds(1), Duration.ofSeconds(10), 0.1, () -> flakySource);
forever.runWith(
Sink.foreach((Creator<Integer> nr) -> system.log().info("{}", nr.create())), system);
// logs
// [INFO] [12/10/2019 13:51:58.300] [default-akka.test.stream-dispatcher-7]
// [akka.actor.ActorSystemImpl(default)] 1
// [INFO] [12/10/2019 13:51:58.301] [default-akka.test.stream-dispatcher-7]
// [akka.actor.ActorSystemImpl(default)] 2
// [INFO] [12/10/2019 13:51:58.302] [default-akka.test.stream-dispatcher-7]
// [akka.actor.ActorSystemImpl(default)] 3
// [WARN] [12/10/2019 13:51:58.310] [default-akka.test.stream-dispatcher-7]
// [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace:
// (RuntimeException: darn)
// --> 1 second gap
// [INFO] [12/10/2019 13:51:59.379] [default-akka.test.stream-dispatcher-8]
// [akka.actor.ActorSystemImpl(default)] 1
// [INFO] [12/10/2019 13:51:59.382] [default-akka.test.stream-dispatcher-8]
// [akka.actor.ActorSystemImpl(default)] 2
// [INFO] [12/10/2019 13:51:59.383] [default-akka.test.stream-dispatcher-8]
// [akka.actor.ActorSystemImpl(default)] 3
// [WARN] [12/10/2019 13:51:59.386] [default-akka.test.stream-dispatcher-8]
// [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace:
// (RuntimeException: darn)
// --> 2 second gap
// [INFO] [12/10/2019 13:52:01.594] [default-akka.test.stream-dispatcher-8]
// [akka.actor.ActorSystemImpl(default)] 1
// [INFO] [12/10/2019 13:52:01.595] [default-akka.test.stream-dispatcher-8]
// [akka.actor.ActorSystemImpl(default)] 2
// [INFO] [12/10/2019 13:52:01.595] [default-akka.test.stream-dispatcher-8]
// [akka.actor.ActorSystemImpl(default)] 3
// [WARN] [12/10/2019 13:52:01.596] [default-akka.test.stream-dispatcher-8]
// [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace:
// (RuntimeException: darn)
// #restart-failure-inner-failure
}
public static void onRestartWithBackoffInnerComplete() {
// #restart-failure-inner-complete
Source<String, Cancellable> finiteSource =
Source.tick(Duration.ofSeconds(1), Duration.ofSeconds(1), "tick").take(3);
Source<String, NotUsed> forever =
RestartSource.onFailuresWithBackoff(
Duration.ofSeconds(1), Duration.ofSeconds(10), 0.1, () -> finiteSource);
forever.runWith(Sink.foreach(System.out::println), system);
// prints
// tick
// tick
// tick
// #restart-failure-inner-complete
}
public static void onRestartWitFailureKillSwitch() {
// #restart-failure-inner-complete-kill-switch
Source<Creator<Integer>, NotUsed> flakySource =
Source.from(
Arrays.<Creator<Integer>>asList(
() -> 1,
() -> 2,
() -> 3,
() -> {
throw new RuntimeException("darn");
}));
UniqueKillSwitch stopRestarting =
RestartSource.onFailuresWithBackoff(
Duration.ofSeconds(1), Duration.ofSeconds(10), 0.1, () -> flakySource)
.viaMat(KillSwitches.single(), Keep.right())
.toMat(Sink.foreach(nr -> System.out.println("nr " + nr.create())), Keep.left())
.run(system);
// ... from some where else
// stop the source from restarting
stopRestarting.shutdown();
// #restart-failure-inner-complete-kill-switch
}
}