Restart Flow/Source/Sink #19950

akka-docs/src/test/java/jdocs/stream/RestartDocTest.java

@@ -0,0 +1,86 @@
+/**
+ * Copyright (C) 2015-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+package jdocs.stream;
+
+import akka.NotUsed;
+import akka.actor.ActorSystem;
+import akka.stream.KillSwitch;
+import akka.stream.KillSwitches;
+import akka.stream.Materializer;
+import akka.stream.javadsl.*;
+import scala.concurrent.duration.Duration;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.TimeUnit;
+
+public class RestartDocTest {
+
+  static ActorSystem system;
+  static Materializer materializer;
+
+  // Mocking akka-http
+  public static class Http {
+    public static Http get(ActorSystem system) {
+      return new Http();
+    }
+    public CompletionStage<Http> singleRequest(String uri) {
+      return new CompletableFuture<>();
+    }
+    public NotUsed entity() {
+      return NotUsed.getInstance();
+    }
+  }
+  public static class HttpRequest {
+    public static String create(String uri) {
+      return uri;
+    }
+  }
+  public static class ServerSentEvent {}
+  public static class EventStreamUnmarshalling {
+    public static EventStreamUnmarshalling fromEventStream() {
+      return new EventStreamUnmarshalling();
+    }
+    public CompletionStage<Source<ServerSentEvent, NotUsed>> unmarshall(Http http, Materializer mat) {
+      return new CompletableFuture<>();
+    }
+  }
+  public void doSomethingElse() {
+
+  }
+
+  public void recoverWithBackoffSource() {
+    //#restart-with-backoff-source
+    Source<ServerSentEvent, NotUsed> eventStream = RestartSource.withBackoff(
+        Duration.apply(3, TimeUnit.SECONDS), // min backoff
+        Duration.apply(30, TimeUnit.SECONDS), // max backoff
+        0.2, // adds 20% "noise" to vary the intervals slightly
+
+        () ->
+            // Create a source from a future of a source
+            Source.fromSourceCompletionStage(
+                // Issue a GET request on the event stream
+                Http.get(system).singleRequest(HttpRequest.create("http://example.com/eventstream"))
+                    .thenCompose(response ->
+                        // Unmarshall it to a stream of ServerSentEvents
+                        EventStreamUnmarshalling.fromEventStream()
+                            .unmarshall(response, materializer)
+                    )
+            )
+    );
+    //#restart-with-backoff-source
+
+    //#with-kill-switch
+    KillSwitch killSwitch = eventStream
+        .viaMat(KillSwitches.single(), Keep.right())
+        .toMat(Sink.foreach(event -> System.out.println("Got event: " + event)), Keep.left())
+        .run(materializer);
+
+    doSomethingElse();
+
+    killSwitch.shutdown();
+    //#with-kill-switch
+
+  }
+}