86 lines
2.5 KiB
Java
86 lines
2.5 KiB
Java
/*
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* Copyright (C) 2015-2022 Lightbend Inc. <https://www.lightbend.com>
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*/
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package jdocs.stream.javadsl.cookbook;
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import org.apache.pekko.NotUsed;
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import org.apache.pekko.actor.ActorSystem;
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import org.apache.pekko.stream.javadsl.Sink;
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import org.apache.pekko.stream.javadsl.Source;
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import org.apache.pekko.testkit.javadsl.TestKit;
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import org.junit.AfterClass;
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import org.junit.BeforeClass;
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import org.junit.Test;
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import java.util.Arrays;
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import java.util.List;
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import java.util.concurrent.CompletionStage;
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import java.util.concurrent.TimeUnit;
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public class RecipeSeq extends RecipeTest {
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static ActorSystem system;
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@BeforeClass
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public static void setup() {
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system = ActorSystem.create("RecipeLoggingElements");
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}
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@AfterClass
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public static void tearDown() {
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TestKit.shutdownActorSystem(system);
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system = null;
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}
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@Test
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public void drainSourceToList() throws Exception {
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new TestKit(system) {
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{
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final Source<String, NotUsed> mySource = Source.from(Arrays.asList("1", "2", "3"));
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// #draining-to-list-unsafe
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// Dangerous: might produce a collection with 2 billion elements!
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final CompletionStage<List<String>> strings = mySource.runWith(Sink.seq(), system);
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// #draining-to-list-unsafe
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strings.toCompletableFuture().get(3, TimeUnit.SECONDS);
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}
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};
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}
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@Test
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public void drainSourceToListWithLimit() throws Exception {
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new TestKit(system) {
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{
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final Source<String, NotUsed> mySource = Source.from(Arrays.asList("1", "2", "3"));
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// #draining-to-list-safe
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final int MAX_ALLOWED_SIZE = 100;
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// OK. Future will fail with a `StreamLimitReachedException`
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// if the number of incoming elements is larger than max
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final CompletionStage<List<String>> strings =
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mySource.limit(MAX_ALLOWED_SIZE).runWith(Sink.seq(), system);
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// #draining-to-list-safe
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strings.toCompletableFuture().get(1, TimeUnit.SECONDS);
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}
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};
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}
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public void drainSourceToListWithTake() throws Exception {
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new TestKit(system) {
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{
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final Source<String, NotUsed> mySource = Source.from(Arrays.asList("1", "2", "3"));
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final int MAX_ALLOWED_SIZE = 100;
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// #draining-to-list-safe
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// OK. Collect up until max-th elements only, then cancel upstream
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final CompletionStage<List<String>> strings =
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mySource.take(MAX_ALLOWED_SIZE).runWith(Sink.seq(), system);
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// #draining-to-list-safe
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strings.toCompletableFuture().get(1, TimeUnit.SECONDS);
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}
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};
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}
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}
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