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Java example source code file (SupplementalMonitorTest.java)

This example Java source code file (SupplementalMonitorTest.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

atomicboolean, atomicinteger, atomicreference, flagguard, illegalmonitorstateexception, monitor, nullpointerexception, override, runnable, supplementalmonitortest, testcase, throwable

The SupplementalMonitorTest.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.GeneratedMonitorTest.startThread;
import static com.google.common.util.concurrent.Uninterruptibles.joinUninterruptibly;

import com.google.common.util.concurrent.GeneratedMonitorTest.FlagGuard;

import junit.framework.TestCase;

import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Supplemental tests for {@link Monitor}.
 *
 * <p>This test class contains various test cases that don't fit into the test case generation in
 * {@link GeneratedMonitorTest}.
 *
 * @author Justin T. Sampson
 */

public class SupplementalMonitorTest extends TestCase {

  public void testLeaveWithoutEnterThrowsIMSE() {
    Monitor monitor = new Monitor();
    try {
      monitor.leave();
      fail("expected IllegalMonitorStateException");
    } catch (IllegalMonitorStateException e) {
      // expected
    }
  }

  public void testGetWaitQueueLengthWithWrongMonitorThrowsIMSE() {
    Monitor monitor1 = new Monitor();
    Monitor monitor2 = new Monitor();
    FlagGuard guard = new FlagGuard(monitor2);
    try {
      monitor1.getWaitQueueLength(guard);
      fail("expected IllegalMonitorStateException");
    } catch (IllegalMonitorStateException e) {
      // expected
    }
  }

  public void testHasWaitersWithWrongMonitorThrowsIMSE() {
    Monitor monitor1 = new Monitor();
    Monitor monitor2 = new Monitor();
    FlagGuard guard = new FlagGuard(monitor2);
    try {
      monitor1.hasWaiters(guard);
      fail("expected IllegalMonitorStateException");
    } catch (IllegalMonitorStateException e) {
      // expected
    }
  }

  public void testNullMonitorInGuardConstructorThrowsNPE() {
    try {
      new FlagGuard(null);
      fail("expected NullPointerException");
    } catch (NullPointerException e) {
      // expected
    }
  }

  public void testIsFair() {
    assertTrue(new Monitor(true).isFair());
    assertFalse(new Monitor(false).isFair());
  }

  public void testOccupiedMethods() {
    Monitor monitor = new Monitor();
    verifyOccupiedMethodsInCurrentThread(monitor, false, false, 0);
    verifyOccupiedMethodsInAnotherThread(monitor, false, false, 0);
    monitor.enter();
    try {
      verifyOccupiedMethodsInCurrentThread(monitor, true, true, 1);
      verifyOccupiedMethodsInAnotherThread(monitor, true, false, 0);
      monitor.enter();
      try {
        verifyOccupiedMethodsInCurrentThread(monitor, true, true, 2);
        verifyOccupiedMethodsInAnotherThread(monitor, true, false, 0);
      } finally {
        monitor.leave();
      }
      verifyOccupiedMethodsInCurrentThread(monitor, true, true, 1);
      verifyOccupiedMethodsInAnotherThread(monitor, true, false, 0);
    } finally {
      monitor.leave();
    }
    verifyOccupiedMethodsInCurrentThread(monitor, false, false, 0);
    verifyOccupiedMethodsInAnotherThread(monitor, false, false, 0);
  }

  private static void verifyOccupiedMethodsInCurrentThread(Monitor monitor,
      boolean expectedIsOccupied, boolean expectedIsOccupiedByCurrentThread,
      int expectedOccupiedDepth) {
    assertEquals(expectedIsOccupied, monitor.isOccupied());
    assertEquals(expectedIsOccupiedByCurrentThread, monitor.isOccupiedByCurrentThread());
    assertEquals(expectedOccupiedDepth, monitor.getOccupiedDepth());
  }

  private static void verifyOccupiedMethodsInAnotherThread(final Monitor monitor,
      boolean expectedIsOccupied, boolean expectedIsOccupiedByCurrentThread,
      int expectedOccupiedDepth) {
    final AtomicBoolean actualIsOccupied = new AtomicBoolean();
    final AtomicBoolean actualIsOccupiedByCurrentThread = new AtomicBoolean();
    final AtomicInteger actualOccupiedDepth = new AtomicInteger();
    final AtomicReference<Throwable> thrown = new AtomicReference();
    joinUninterruptibly(startThread(new Runnable() {
      @Override public void run() {
        try {
          actualIsOccupied.set(monitor.isOccupied());
          actualIsOccupiedByCurrentThread.set(monitor.isOccupiedByCurrentThread());
          actualOccupiedDepth.set(monitor.getOccupiedDepth());
        } catch (Throwable t) {
          thrown.set(t);
        }
      }
    }));
    assertNull(thrown.get());
    assertEquals(expectedIsOccupied, actualIsOccupied.get());
    assertEquals(expectedIsOccupiedByCurrentThread, actualIsOccupiedByCurrentThread.get());
    assertEquals(expectedOccupiedDepth, actualOccupiedDepth.get());
  }

}

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