Doc onFailureWithBackoff (#28356)
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Christopher Batey
GitHub
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3 changed files with 238 additions and 5 deletions
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/*
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* Copyright (C) 2019-2020 Lightbend Inc. <https://www.lightbend.com>
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*/
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package jdocs.stream.operators.source;
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import akka.NotUsed;
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import akka.actor.Cancellable;
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import akka.japi.Creator;
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import akka.stream.KillSwitches;
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import akka.stream.UniqueKillSwitch;
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import akka.stream.javadsl.Keep;
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import akka.stream.javadsl.RestartSource;
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import akka.stream.javadsl.Sink;
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import akka.stream.javadsl.Source;
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import java.time.Duration;
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import java.util.Arrays;
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public class Restart {
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static akka.actor.ActorSystem system = akka.actor.ActorSystem.create();
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public static void onRestartWithBackoffInnerFailure() {
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// #restart-failure-inner-failure
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// could throw if for example it used a database connection to get rows
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Source<Creator<Integer>, NotUsed> flakySource =
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Source.from(
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Arrays.<Creator<Integer>>asList(
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() -> 1,
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() -> 2,
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() -> 3,
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() -> {
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throw new RuntimeException("darn");
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}));
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Source<Creator<Integer>, NotUsed> forever =
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RestartSource.onFailuresWithBackoff(
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Duration.ofSeconds(1), Duration.ofSeconds(10), 0.1, () -> flakySource);
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forever.runWith(
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Sink.foreach((Creator<Integer> nr) -> system.log().info("{}", nr.create())), system);
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// logs
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// [INFO] [12/10/2019 13:51:58.300] [default-akka.test.stream-dispatcher-7]
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// [akka.actor.ActorSystemImpl(default)] 1
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// [INFO] [12/10/2019 13:51:58.301] [default-akka.test.stream-dispatcher-7]
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// [akka.actor.ActorSystemImpl(default)] 2
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// [INFO] [12/10/2019 13:51:58.302] [default-akka.test.stream-dispatcher-7]
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// [akka.actor.ActorSystemImpl(default)] 3
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// [WARN] [12/10/2019 13:51:58.310] [default-akka.test.stream-dispatcher-7]
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// [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace:
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// (RuntimeException: darn)
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// --> 1 second gap
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// [INFO] [12/10/2019 13:51:59.379] [default-akka.test.stream-dispatcher-8]
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// [akka.actor.ActorSystemImpl(default)] 1
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// [INFO] [12/10/2019 13:51:59.382] [default-akka.test.stream-dispatcher-8]
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// [akka.actor.ActorSystemImpl(default)] 2
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// [INFO] [12/10/2019 13:51:59.383] [default-akka.test.stream-dispatcher-8]
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// [akka.actor.ActorSystemImpl(default)] 3
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// [WARN] [12/10/2019 13:51:59.386] [default-akka.test.stream-dispatcher-8]
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// [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace:
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// (RuntimeException: darn)
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// --> 2 second gap
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// [INFO] [12/10/2019 13:52:01.594] [default-akka.test.stream-dispatcher-8]
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// [akka.actor.ActorSystemImpl(default)] 1
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// [INFO] [12/10/2019 13:52:01.595] [default-akka.test.stream-dispatcher-8]
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// [akka.actor.ActorSystemImpl(default)] 2
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// [INFO] [12/10/2019 13:52:01.595] [default-akka.test.stream-dispatcher-8]
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// [akka.actor.ActorSystemImpl(default)] 3
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// [WARN] [12/10/2019 13:52:01.596] [default-akka.test.stream-dispatcher-8]
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// [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace:
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// (RuntimeException: darn)
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// #restart-failure-inner-failure
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}
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public static void onRestartWithBackoffInnerComplete() {
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// #restart-failure-inner-complete
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Source<String, Cancellable> finiteSource =
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Source.tick(Duration.ofSeconds(1), Duration.ofSeconds(1), "tick").take(3);
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Source<String, NotUsed> forever =
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RestartSource.onFailuresWithBackoff(
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Duration.ofSeconds(1), Duration.ofSeconds(10), 0.1, () -> finiteSource);
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forever.runWith(Sink.foreach(System.out::println), system);
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// prints
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// tick
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// tick
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// tick
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// #restart-failure-inner-complete
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}
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public static void onRestartWitFailureKillSwitch() {
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// #restart-failure-inner-complete-kill-switch
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Source<Creator<Integer>, NotUsed> flakySource =
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Source.from(
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Arrays.<Creator<Integer>>asList(
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() -> 1,
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() -> 2,
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() -> 3,
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() -> {
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throw new RuntimeException("darn");
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}));
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UniqueKillSwitch stopRestarting =
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RestartSource.onFailuresWithBackoff(
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Duration.ofSeconds(1), Duration.ofSeconds(10), 0.1, () -> flakySource)
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.viaMat(KillSwitches.single(), Keep.right())
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.toMat(Sink.foreach(nr -> System.out.println("nr " + nr.create())), Keep.left())
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.run(system);
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// ... from some where else
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// stop the source from restarting
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stopRestarting.shutdown();
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// #restart-failure-inner-complete-kill-switch
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}
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}
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@ -0,0 +1,83 @@
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/*
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* Copyright (C) 2009-2020 Lightbend Inc. <https://www.lightbend.com>
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*/
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package docs.stream.operators.source
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import akka.NotUsed
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import akka.actor.ActorSystem
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import akka.stream.KillSwitches
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import akka.stream.UniqueKillSwitch
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import akka.stream.scaladsl.Keep
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import akka.stream.scaladsl.RestartSource
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import akka.stream.scaladsl.Sink
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import scala.concurrent.duration._
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import scala.util.control.NoStackTrace
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// #imports
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import akka.stream.scaladsl.Source
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// #imports
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object Restart extends App {
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implicit val system: ActorSystem = ActorSystem()
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onRestartWitFailureKillSwitch()
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case class CantConnectToDatabase(msg: String) extends RuntimeException(msg) with NoStackTrace
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def onRestartWithBackoffInnerFailure(): Unit = {
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//#restart-failure-inner-failure
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// could throw if for example it used a database connection to get rows
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val flakySource: Source[() => Int, NotUsed] =
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Source(List(() => 1, () => 2, () => 3, () => throw CantConnectToDatabase("darn")))
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val forever =
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RestartSource.onFailuresWithBackoff(minBackoff = 1.second, maxBackoff = 10.seconds, 0.1)(() => flakySource)
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forever.runWith(Sink.foreach(nr => system.log.info("{}", nr())))
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// logs
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//[INFO] [12/10/2019 13:51:58.300] [default-akka.test.stream-dispatcher-7] [akka.actor.ActorSystemImpl(default)] 1
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//[INFO] [12/10/2019 13:51:58.301] [default-akka.test.stream-dispatcher-7] [akka.actor.ActorSystemImpl(default)] 2
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//[INFO] [12/10/2019 13:51:58.302] [default-akka.test.stream-dispatcher-7] [akka.actor.ActorSystemImpl(default)] 3
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//[WARN] [12/10/2019 13:51:58.310] [default-akka.test.stream-dispatcher-7] [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace: (docs.stream.operators.source.Restart$CantConnectToDatabase: darn)
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// --> 1 second gap
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//[INFO] [12/10/2019 13:51:59.379] [default-akka.test.stream-dispatcher-8] [akka.actor.ActorSystemImpl(default)] 1
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//[INFO] [12/10/2019 13:51:59.382] [default-akka.test.stream-dispatcher-8] [akka.actor.ActorSystemImpl(default)] 2
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//[INFO] [12/10/2019 13:51:59.383] [default-akka.test.stream-dispatcher-8] [akka.actor.ActorSystemImpl(default)] 3
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//[WARN] [12/10/2019 13:51:59.386] [default-akka.test.stream-dispatcher-8] [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace: (docs.stream.operators.source.Restart$CantConnectToDatabase: darn)
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//--> 2 second gap
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//[INFO] [12/10/2019 13:52:01.594] [default-akka.test.stream-dispatcher-8] [akka.actor.ActorSystemImpl(default)] 1
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//[INFO] [12/10/2019 13:52:01.595] [default-akka.test.stream-dispatcher-8] [akka.actor.ActorSystemImpl(default)] 2
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//[INFO] [12/10/2019 13:52:01.595] [default-akka.test.stream-dispatcher-8] [akka.actor.ActorSystemImpl(default)] 3
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//[WARN] [12/10/2019 13:52:01.596] [default-akka.test.stream-dispatcher-8] [RestartWithBackoffSource(akka://default)] Restarting graph due to failure. stack_trace: (docs.stream.operators.source.Restart$CantConnectToDatabase: darn)
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//#restart-failure-inner-failure
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}
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def onRestartWithBackoffInnerComplete() {
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//#restart-failure-inner-complete
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val finiteSource = Source.tick(1.second, 1.second, "tick").take(3)
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val forever = RestartSource.onFailuresWithBackoff(1.second, 10.seconds, 0.1)(() => finiteSource)
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forever.runWith(Sink.foreach(println))
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// prints
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// tick
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// tick
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// tick
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//#restart-failure-inner-complete
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}
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def onRestartWitFailureKillSwitch(): Unit = {
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//#restart-failure-inner-complete-kill-switch
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val flakySource: Source[() => Int, NotUsed] =
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Source(List(() => 1, () => 2, () => 3, () => throw CantConnectToDatabase("darn")))
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val stopRestarting: UniqueKillSwitch =
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RestartSource
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.onFailuresWithBackoff(1.second, 10.seconds, 0.1)(() => flakySource)
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.viaMat(KillSwitches.single)(Keep.right)
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.toMat(Sink.foreach(nr => println(s"Nr ${nr()}")))(Keep.left)
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.run()
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//... from some where else
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// stop the source from restarting
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stopRestarting.shutdown()
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//#restart-failure-inner-complete-kill-switch
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}
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}
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