001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.util;
019
020import static org.junit.jupiter.api.Assertions.assertFalse;
021import static org.junit.jupiter.api.Assertions.assertNotEquals;
022import static org.junit.jupiter.api.Assertions.assertTrue;
023
024import java.util.concurrent.locks.ReentrantLock;
025import org.apache.hadoop.hbase.testclassification.MiscTests;
026import org.apache.hadoop.hbase.testclassification.SmallTests;
027import org.junit.jupiter.api.Tag;
028import org.junit.jupiter.api.Test;
029
030@Tag(MiscTests.TAG)
031@Tag(SmallTests.TAG)
032public class TestKeyLocker {
033
034  @Test
035  public void testLocker() {
036    KeyLocker<String> locker = new KeyLocker<>();
037    ReentrantLock lock1 = locker.acquireLock("l1");
038    assertTrue(lock1.isHeldByCurrentThread());
039
040    ReentrantLock lock2 = locker.acquireLock("l2");
041    assertTrue(lock2.isHeldByCurrentThread());
042    assertTrue(lock1 != lock2);
043
044    // same key = same lock
045    ReentrantLock lock20 = locker.acquireLock("l2");
046    assertTrue(lock20 == lock2);
047    assertTrue(lock2.isHeldByCurrentThread());
048    assertTrue(lock20.isHeldByCurrentThread());
049
050    // Locks are still reentrant; so with 2 acquires we want two unlocks
051    lock20.unlock();
052    assertTrue(lock20.isHeldByCurrentThread());
053
054    lock2.unlock();
055    assertFalse(lock20.isHeldByCurrentThread());
056
057    // The lock object will be garbage-collected
058    // if you free its reference for a long time,
059    // and you will get a new one at the next time.
060    int lock2Hash = System.identityHashCode(lock2);
061    lock2 = null;
062    lock20 = null;
063
064    System.gc();
065    System.gc();
066    System.gc();
067
068    ReentrantLock lock200 = locker.acquireLock("l2");
069    assertNotEquals(lock2Hash, System.identityHashCode(lock200));
070    lock200.unlock();
071    assertFalse(lock200.isHeldByCurrentThread());
072
073    // first lock is still there
074    assertTrue(lock1.isHeldByCurrentThread());
075    lock1.unlock();
076    assertFalse(lock1.isHeldByCurrentThread());
077  }
078}