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.hdfs.util;
019
020/** Read-write lock interface. */
021public interface RwLock {
022  /** Acquire read lock. */
023  public void readLock();
024
025  /** Acquire read lock, unless interrupted while waiting  */
026  void readLockInterruptibly() throws InterruptedException;
027
028  /** Release read lock. */
029  public void readUnlock();
030
031  /** Check if the current thread holds read lock. */
032  public boolean hasReadLock();
033
034  /** Acquire write lock. */
035  public void writeLock();
036  
037  /** Acquire write lock, unless interrupted while waiting  */
038  void writeLockInterruptibly() throws InterruptedException;
039
040  /** Release write lock. */
041  public void writeUnlock();
042
043  /** Check if the current thread holds write lock. */
044  public boolean hasWriteLock();
045}