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Merge pull request #29356 from ignasi35/monitor-operator-sample-code

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Ignasi Marimon-Clos 2020-07-13 19:33:36 +02:00 • committed by GitHub
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akka-docs/src/test/java/jdocs/stream/operators/sourceorflow/Monitor.java Normal file
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/*
* Copyright (C) 2020 Lightbend Inc. <https://www.lightbend.com>
*/
package jdocs.stream.operators.sourceorflow;
import akka.Done;
import akka.NotUsed;
import akka.actor.ActorSystem;
import akka.japi.Pair;
import akka.stream.FlowMonitor;
import akka.stream.FlowMonitorState;
import akka.stream.javadsl.Keep;
import akka.stream.javadsl.Sink;
import akka.stream.javadsl.Source;
import java.time.Duration;
import java.util.Arrays;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/** */
public class Monitor {
// #monitor
private static <T> void printMonitorState(FlowMonitorState.StreamState<T> state) {
if (state == FlowMonitorState.finished()) {
System.out.println("Stream is initialized but hasn't processed any element");
} else if (state instanceof FlowMonitorState.Received) {
FlowMonitorState.Received msg = (FlowMonitorState.Received) state;
System.out.println("Last message received: " + msg.msg());
} else if (state instanceof FlowMonitorState.Failed) {
Throwable cause = ((FlowMonitorState.Failed) state).cause();
System.out.println("Stream failed with cause: " + cause.getMessage());
} else {
System.out.println("Stream completed already");
}
}
// #monitor
public static void main(String[] args)
throws InterruptedException, TimeoutException, ExecutionException {
ActorSystem actorSystem = ActorSystem.create("25fps-stream");
// #monitor
Source<Integer, FlowMonitor<Integer>> monitoredSource =
Source.fromIterator(() -> Arrays.asList(0, 1, 2, 3, 4, 5).iterator())
.throttle(5, Duration.ofSeconds(1))
.monitorMat(Keep.right());
Pair<FlowMonitor<Integer>, CompletionStage<Done>> run =
monitoredSource.toMat(Sink.foreach(System.out::println), Keep.both()).run(actorSystem);
FlowMonitor<Integer> monitor = run.first();
// If we peek in the monitor too early, it's possible it was not initialized yet.
printMonitorState(monitor.state());
// Periodically check the monitor
Source.tick(Duration.ofMillis(200), Duration.ofMillis(400), "")
.runForeach(__ -> printMonitorState(monitor.state()), actorSystem);
// #monitor
run.second().toCompletableFuture().whenComplete((x, t) -> actorSystem.terminate());
}
}