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Java example source code file (JdkFutureAdaptersTest.java)

This example Java source code file (JdkFutureAdaptersTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

assertionfailederror, countdownlatch, data1, exception, executorservice, executorspy, listenablefuture, nonlistenablesettablefuture, override, recordingrunnable, runtimeexceptionthrowingfuture, seconds, singlecalllistener, threading, threads, timeunit

The JdkFutureAdaptersTest.java Java example source code

/*
 * Copyright (C) 2009 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.base.Preconditions.checkState;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.JdkFutureAdapters.listenInPoolThread;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static java.util.concurrent.Executors.newCachedThreadPool;
import static java.util.concurrent.TimeUnit.SECONDS;

import com.google.common.testing.ClassSanityTester;
import com.google.common.util.concurrent.FuturesTest.ExecutorSpy;
import com.google.common.util.concurrent.FuturesTest.SingleCallListener;

import junit.framework.AssertionFailedError;
import junit.framework.TestCase;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * Unit tests for {@link JdkFutureAdapters}.
 *
 * @author Sven Mawson
 * @author Kurt Alfred Kluever
 */
public class JdkFutureAdaptersTest extends TestCase {
  private static final String DATA1 = "data";

  public void testListenInPoolThreadReturnsSameFuture() throws Exception {
    ListenableFuture<String> listenableFuture = immediateFuture(DATA1);
    assertSame(listenableFuture, listenInPoolThread(listenableFuture));
  }

  public void testListenInPoolThreadIgnoresExecutorWhenDelegateIsDone()
      throws Exception {
    NonListenableSettableFuture<String> abstractFuture =
        NonListenableSettableFuture.create();
    abstractFuture.set(DATA1);
    ExecutorSpy spy = new ExecutorSpy(directExecutor());
    ListenableFuture<String> listenableFuture =
        listenInPoolThread(abstractFuture, spy);

    SingleCallListener singleCallListener = new SingleCallListener();
    singleCallListener.expectCall();

    assertFalse(spy.wasExecuted);
    assertFalse(singleCallListener.wasCalled());
    assertTrue(listenableFuture.isDone()); // We call AbstractFuture#set above.

    // #addListener() will run the listener immediately because the Future is
    // already finished (we explicitly set the result of it above).
    listenableFuture.addListener(singleCallListener, directExecutor());
    assertEquals(DATA1, listenableFuture.get());

    // 'spy' should have been ignored since 'abstractFuture' was done before
    // a listener was added.
    assertFalse(spy.wasExecuted);
    assertTrue(singleCallListener.wasCalled());
    assertTrue(listenableFuture.isDone());
  }

  public void testListenInPoolThreadUsesGivenExecutor() throws Exception {
    ExecutorService executorService = newCachedThreadPool(
        new ThreadFactoryBuilder().setDaemon(true).build());
    NonListenableSettableFuture<String> abstractFuture =
        NonListenableSettableFuture.create();
    ExecutorSpy spy = new ExecutorSpy(executorService);
    ListenableFuture<String> listenableFuture =
        listenInPoolThread(abstractFuture, spy);

    SingleCallListener singleCallListener = new SingleCallListener();
    singleCallListener.expectCall();

    assertFalse(spy.wasExecuted);
    assertFalse(singleCallListener.wasCalled());
    assertFalse(listenableFuture.isDone());

    listenableFuture.addListener(singleCallListener, executorService);
    abstractFuture.set(DATA1);
    assertEquals(DATA1, listenableFuture.get());
    singleCallListener.waitForCall();

    assertTrue(spy.wasExecuted);
    assertTrue(singleCallListener.wasCalled());
    assertTrue(listenableFuture.isDone());
  }

  public void testListenInPoolThreadCustomExecutorInterrupted()
      throws Exception {
    final CountDownLatch submitSuccessful = new CountDownLatch(1);
    ExecutorService executorService = new ThreadPoolExecutor(
        0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS,
        new SynchronousQueue<Runnable>(),
        new ThreadFactoryBuilder().setDaemon(true).build()) {
      @Override
      protected void beforeExecute(Thread t, Runnable r) {
        submitSuccessful.countDown();
      }
    };
    NonListenableSettableFuture<String> abstractFuture =
        NonListenableSettableFuture.create();
    ListenableFuture<String> listenableFuture =
        listenInPoolThread(abstractFuture, executorService);

    SingleCallListener singleCallListener = new SingleCallListener();
    singleCallListener.expectCall();

    assertFalse(singleCallListener.wasCalled());
    assertFalse(listenableFuture.isDone());

    listenableFuture.addListener(singleCallListener, directExecutor());
    /*
     * Don't shut down until the listenInPoolThread task has been accepted to
     * run. We want to see what happens when it's interrupted, not when it's
     * rejected.
     */
    submitSuccessful.await();
    executorService.shutdownNow();
    abstractFuture.set(DATA1);
    assertEquals(DATA1, listenableFuture.get());
    singleCallListener.waitForCall();

    assertTrue(singleCallListener.wasCalled());
    assertTrue(listenableFuture.isDone());
  }

  /**
   * A Future that doesn't implement ListenableFuture, useful for testing
   * listenInPoolThread.
   */
  private static final class NonListenableSettableFuture<V>
      extends ForwardingFuture<V> {
    static <V> NonListenableSettableFuture create() {
      return new NonListenableSettableFuture<V>();
    }

    final SettableFuture<V> delegate = SettableFuture.create();

    @Override protected Future<V> delegate() {
      return delegate;
    }

    void set(V value) {
      delegate.set(value);
    }
  }

  private static final class RuntimeExceptionThrowingFuture<V>
      implements Future<V> {
    final CountDownLatch allowGetToComplete = new CountDownLatch(1);

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
      throw new AssertionFailedError();
    }

    @Override
    public V get() throws InterruptedException {
      /*
       * Wait a little to give us time to call addListener before the future's
       * value is set in addition to the call we'll make after then.
       */
      allowGetToComplete.await(1, SECONDS);
      throw new RuntimeException("expected, should be caught");
    }

    @Override
    public V get(long timeout, TimeUnit unit) {
      throw new AssertionFailedError();
    }

    @Override
    public boolean isCancelled() {
      throw new AssertionFailedError();
    }

    @Override
    public boolean isDone() {
      /*
       * If isDone is true during the call to listenInPoolThread,
       * listenInPoolThread doesn't start a thread. Make sure it's false the
       * first time through (and forever after, since no one else cares about
       * it).
       */
      return false;
    }
  }

  private static final class RecordingRunnable implements Runnable {
    final CountDownLatch wasRun = new CountDownLatch(1);

    // synchronized so that checkState works as expected.
    @Override
    public synchronized void run() {
      checkState(wasRun.getCount() > 0);
      wasRun.countDown();
    }
  }

  public void testListenInPoolThreadRunsListenerAfterRuntimeException()
      throws Exception {
    RuntimeExceptionThrowingFuture<String> input =
        new RuntimeExceptionThrowingFuture<String>();
    /*
     * The compiler recognizes that "input instanceof ListenableFuture" is
     * impossible. We want the test, though, in case that changes in the future,
     * so we use isInstance instead.
     */
    assertFalse("Can't test the main listenInPoolThread path "
        + "if the input is already a ListenableFuture",
        ListenableFuture.class.isInstance(input));
    ListenableFuture<String> listenable = listenInPoolThread(input);
    /*
     * This will occur before the waiting get() in the
     * listenInPoolThread-spawned thread completes:
     */
    RecordingRunnable earlyListener = new RecordingRunnable();
    listenable.addListener(earlyListener, directExecutor());

    input.allowGetToComplete.countDown();
    // Now give the get() thread time to finish:
    assertTrue(earlyListener.wasRun.await(1, SECONDS));

    // Now test an additional addListener call, which will be run in-thread:
    RecordingRunnable lateListener = new RecordingRunnable();
    listenable.addListener(lateListener, directExecutor());
    assertTrue(lateListener.wasRun.await(1, SECONDS));
  }

  public void testAdapters_nullChecks() throws Exception {
    new ClassSanityTester()
        .forAllPublicStaticMethods(JdkFutureAdapters.class)
        .thatReturn(Future.class)
        .testNulls();
  }
}

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