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Java example source code file (ListenerCallQueueTest.java)

This example Java source code file (ListenerCallQueueTest.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

atomicinteger, callback, countdownlatch, executorservice, interruptedexception, listenercallqueue, listenercallqueuetest, object, override, runtimeexception, testcase, threading, threads, throwing_callback

The ListenerCallQueueTest.java Java example source code

/*
 * Copyright (C) 2014 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.util.concurrent.MoreExecutors.directExecutor;

import com.google.common.util.concurrent.ListenerCallQueue.Callback;

import junit.framework.TestCase;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Tests for {@link ListenerCallQueue}.
 */
public class ListenerCallQueueTest extends TestCase {

  private static final Callback<Object> THROWING_CALLBACK = new Callback("throwing()") {
    @Override public void call(Object object) {
      throw new RuntimeException();
    }
  };

  public void testAddAndExecute() {
    Object listenerInstance = new Object();
    ListenerCallQueue<Object> queue =
        new ListenerCallQueue<Object>(listenerInstance, directExecutor());

    AtomicInteger counter = new AtomicInteger();
    queue.add(incrementingCallback(counter, 1));
    queue.add(incrementingCallback(counter, 2));
    queue.add(incrementingCallback(counter, 3));
    queue.add(incrementingCallback(counter, 4));
    assertEquals(0, counter.get());
    queue.execute();
    assertEquals(4, counter.get());
  }

  public void testAddAndExecute_withExceptions() {
    Object listenerInstance = new Object();
    ListenerCallQueue<Object> queue =
        new ListenerCallQueue<Object>(listenerInstance, directExecutor());

    AtomicInteger counter = new AtomicInteger();
    queue.add(incrementingCallback(counter, 1));
    queue.add(THROWING_CALLBACK);
    queue.add(incrementingCallback(counter, 2));
    queue.add(THROWING_CALLBACK);
    queue.add(incrementingCallback(counter, 3));
    queue.add(THROWING_CALLBACK);
    queue.add(incrementingCallback(counter, 4));
    queue.add(THROWING_CALLBACK);
    assertEquals(0, counter.get());
    queue.execute();
    assertEquals(4, counter.get());
  }

  public void testAddAndExecute_multithreaded() throws InterruptedException {
    ExecutorService service = Executors.newFixedThreadPool(4);
    try {
      ListenerCallQueue<Object> queue =
          new ListenerCallQueue<Object>(new Object(), service);

      final CountDownLatch latch = new CountDownLatch(1);
      AtomicInteger counter = new AtomicInteger();
      queue.add(incrementingCallback(counter, 1));
      queue.add(incrementingCallback(counter, 2));
      queue.add(incrementingCallback(counter, 3));
      queue.add(incrementingCallback(counter, 4));
      queue.add(countDownCallback(latch));
      assertEquals(0, counter.get());
      queue.execute();
      latch.await();
      assertEquals(4, counter.get());
    } finally {
      service.shutdown();
    }
  }

  public void testAddAndExecute_multithreaded_withThrowingRunnable() throws InterruptedException {
    ExecutorService service = Executors.newFixedThreadPool(4);
    try {
      ListenerCallQueue<Object> queue =
          new ListenerCallQueue<Object>(new Object(), service);

      final CountDownLatch latch = new CountDownLatch(1);
      AtomicInteger counter = new AtomicInteger();
      queue.add(incrementingCallback(counter, 1));
      queue.add(THROWING_CALLBACK);
      queue.add(incrementingCallback(counter, 2));
      queue.add(THROWING_CALLBACK);
      queue.add(incrementingCallback(counter, 3));
      queue.add(THROWING_CALLBACK);
      queue.add(incrementingCallback(counter, 4));
      queue.add(THROWING_CALLBACK);
      queue.add(countDownCallback(latch));
      assertEquals(0, counter.get());
      queue.execute();
      latch.await();
      assertEquals(4, counter.get());
    } finally {
      service.shutdown();
    }
  }

  private Callback<Object> incrementingCallback(final AtomicInteger counter, final int expected) {
    return new Callback<Object>("incrementing") {
      @Override void call(Object listener) {
        assertEquals(expected, counter.incrementAndGet());
      }
    };
  }

  private Callback<Object> countDownCallback(final CountDownLatch latch) {
    return new Callback<Object>("countDown") {
      @Override void call(Object listener) {
        latch.countDown();
      }
    };
  }
}




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