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 org.apache.yetus.audience.InterfaceAudience;
021
022/**
023 * This class provides ShutdownHookManager shims for HBase to interact with the Hadoop 1.0.x and the
024 * Hadoop 2.0+ series.
025 *
026 * NOTE: No testing done against 0.22.x, or 0.21.x.
027 */
028@InterfaceAudience.Private
029abstract public class ShutdownHookManager {
030  private static ShutdownHookManager instance;
031
032  static Class shutdownHookManagerClass = null;
033  static {
034    try {
035      // This class exists in hadoop 2.0+ but not in Hadoop 20.x/1.x
036      shutdownHookManagerClass = Class.forName("org.apache.hadoop.util.ShutdownHookManager");
037      instance = new ShutdownHookManagerV2();
038    } catch (Exception e) {
039      instance = new ShutdownHookManagerV1();
040    }
041  }
042
043  abstract public void addShutdownHook(Thread shutdownHook, int priority);
044
045  abstract public boolean removeShutdownHook(Runnable shutdownHook);
046
047  public static void affixShutdownHook(Thread shutdownHook, int priority) {
048    instance.addShutdownHook(shutdownHook, priority);
049  }
050
051  public static boolean deleteShutdownHook(Runnable shutdownHook) {
052    return instance.removeShutdownHook(shutdownHook);
053  }
054
055  private static class ShutdownHookManagerV1 extends ShutdownHookManager {
056    // priority is ignored in hadoop versions earlier than 2.0
057    @Override
058    public void addShutdownHook(Thread shutdownHookThread, int priority) {
059      Runtime.getRuntime().addShutdownHook(shutdownHookThread);
060    }
061
062    @Override
063    public boolean removeShutdownHook(Runnable shutdownHook) {
064      Thread shutdownHookThread = null;
065      if (!(shutdownHook instanceof Thread)) {
066        shutdownHookThread = new Thread(shutdownHook);
067      } else shutdownHookThread = (Thread) shutdownHook;
068
069      return Runtime.getRuntime().removeShutdownHook(shutdownHookThread);
070    }
071  }
072
073  private static class ShutdownHookManagerV2 extends ShutdownHookManager {
074    @Override
075    public void addShutdownHook(Thread shutdownHookThread, int priority) {
076      try {
077        Methods.call(shutdownHookManagerClass,
078            Methods.call(shutdownHookManagerClass, null, "get", null, null),
079            "addShutdownHook",
080            new Class[] { Runnable.class, int.class },
081            new Object[] { shutdownHookThread, priority });
082      } catch (Exception ex) {
083        throw new RuntimeException("we could not use ShutdownHookManager.addShutdownHook", ex);
084      }
085    }
086
087    @Override
088    public boolean removeShutdownHook(Runnable shutdownHook) {
089      try {
090        return (Boolean)
091        Methods.call(shutdownHookManagerClass,
092            Methods.call(shutdownHookManagerClass, null, "get", null, null),
093            "removeShutdownHook",
094            new Class[] { Runnable.class },
095            new Object[] { shutdownHook });
096      } catch (Exception ex) {
097        throw new RuntimeException("we could not use ShutdownHookManager", ex);
098      }
099    }
100  }
101}