hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestAutoCloseableLock.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.hadoop.util;

import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.assertEquals;

import org.junit.Test;
/**
 * A test class for AutoCloseableLock.
 */
public class TestAutoCloseableLock {

  /**
   * Test the basic lock and unlock operation.
   */
  @Test
  public void testLockAcquireRelease() {
    AutoCloseableLock lock = new AutoCloseableLock();
    AutoCloseableLock newlock = lock.acquire();
    // Ensure acquire the same lock object.
    assertEquals(newlock, lock);
    // Ensure it locked now.
    assertTrue(lock.isLocked());
    lock.release();
    // Ensure it is unlocked now.
    assertFalse(lock.isLocked());
  }

  /**
   * Test when lock is acquired, no other thread can
   * lock it.
   *
   * @throws Exception
   */
  @Test
  public void testMultipleThread() throws Exception {
    final AutoCloseableLock lock = new AutoCloseableLock();
    lock.acquire();
    assertTrue(lock.isLocked());
    Thread competingThread = new Thread() {
      @Override
      public void run() {
        assertTrue(lock.isLocked());
        assertFalse(lock.tryLock());
      }
    };
    competingThread.start();
    competingThread.join();
    assertTrue(lock.isLocked());
    lock.release();
    assertFalse(lock.isLocked());
  }

  /**
   * Test the correctness under try-with-resource syntax.
   *
   * @throws Exception
   */
  @Test
  public void testTryWithResourceSyntax() throws Exception {
    final AutoCloseableLock lock = new AutoCloseableLock();
    try(AutoCloseableLock localLock = lock.acquire()) {
      assertEquals(localLock, lock);
      assertTrue(lock.isLocked());
      Thread competingThread = new Thread() {
        @Override
        public void run() {
          assertTrue(lock.isLocked());
          assertFalse(lock.tryLock());
        }
      };
      competingThread.start();
      competingThread.join();
      assertTrue(localLock.isLocked());
    }
    assertFalse(lock.isLocked());
  }
}