| /** |
| * 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 com.google.common.util.concurrent.ThreadFactoryBuilder; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.TimeoutException; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * The <code>ShutdownHookManager</code> enables running shutdownHook |
| * in a deterministic order, higher priority first. |
| * <p/> |
| * The JVM runs ShutdownHooks in a non-deterministic order or in parallel. |
| * This class registers a single JVM shutdownHook and run all the |
| * shutdownHooks registered to it (to this class) in order based on their |
| * priority. |
| */ |
| public class ShutdownHookManager { |
| |
| private static final ShutdownHookManager MGR = new ShutdownHookManager(); |
| |
| private static final Logger LOG = |
| LoggerFactory.getLogger(ShutdownHookManager.class); |
| private static final long TIMEOUT_DEFAULT = 10; |
| private static final TimeUnit TIME_UNIT_DEFAULT = TimeUnit.SECONDS; |
| |
| private static final ExecutorService EXECUTOR = |
| Executors.newSingleThreadExecutor(new ThreadFactoryBuilder() |
| .setDaemon(true).build()); |
| static { |
| try { |
| Runtime.getRuntime().addShutdownHook( |
| new Thread() { |
| @Override |
| public void run() { |
| MGR.shutdownInProgress.set(true); |
| for (HookEntry entry: MGR.getShutdownHooksInOrder()) { |
| Future<?> future = EXECUTOR.submit(entry.getHook()); |
| try { |
| future.get(entry.getTimeout(), entry.getTimeUnit()); |
| } catch (TimeoutException ex) { |
| future.cancel(true); |
| LOG.warn("ShutdownHook '" + entry.getHook().getClass(). |
| getSimpleName() + "' timeout, " + ex.toString(), ex); |
| } catch (Throwable ex) { |
| LOG.warn("ShutdownHook '" + entry.getHook().getClass(). |
| getSimpleName() + "' failed, " + ex.toString(), ex); |
| } |
| } |
| try { |
| EXECUTOR.shutdown(); |
| if (!EXECUTOR.awaitTermination(TIMEOUT_DEFAULT, |
| TIME_UNIT_DEFAULT)) { |
| LOG.error("ShutdownHookManger shutdown forcefully."); |
| EXECUTOR.shutdownNow(); |
| } |
| LOG.debug("ShutdownHookManger complete shutdown."); |
| } catch (InterruptedException ex) { |
| LOG.error("ShutdownHookManger interrupted while waiting for " + |
| "termination.", ex); |
| EXECUTOR.shutdownNow(); |
| Thread.currentThread().interrupt(); |
| } |
| } |
| } |
| ); |
| } catch (IllegalStateException ex) { |
| // JVM is being shut down. Ignore |
| LOG.warn("Failed to add the ShutdownHook", ex); |
| } |
| } |
| |
| /** |
| * Return <code>ShutdownHookManager</code> singleton. |
| * |
| * @return <code>ShutdownHookManager</code> singleton. |
| */ |
| public static ShutdownHookManager get() { |
| return MGR; |
| } |
| |
| /** |
| * Private structure to store ShutdownHook, its priority and timeout |
| * settings. |
| */ |
| static class HookEntry { |
| private final Runnable hook; |
| private final int priority; |
| private final long timeout; |
| private final TimeUnit unit; |
| |
| HookEntry(Runnable hook, int priority) { |
| this(hook, priority, TIMEOUT_DEFAULT, TIME_UNIT_DEFAULT); |
| } |
| |
| HookEntry(Runnable hook, int priority, long timeout, TimeUnit unit) { |
| this.hook = hook; |
| this.priority = priority; |
| this.timeout = timeout; |
| this.unit = unit; |
| } |
| |
| @Override |
| public int hashCode() { |
| return hook.hashCode(); |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| boolean eq = false; |
| if (obj != null) { |
| if (obj instanceof HookEntry) { |
| eq = (hook == ((HookEntry)obj).hook); |
| } |
| } |
| return eq; |
| } |
| |
| Runnable getHook() { |
| return hook; |
| } |
| |
| int getPriority() { |
| return priority; |
| } |
| |
| long getTimeout() { |
| return timeout; |
| } |
| |
| TimeUnit getTimeUnit() { |
| return unit; |
| } |
| } |
| |
| private final Set<HookEntry> hooks = |
| Collections.synchronizedSet(new HashSet<HookEntry>()); |
| |
| private AtomicBoolean shutdownInProgress = new AtomicBoolean(false); |
| |
| //private to constructor to ensure singularity |
| private ShutdownHookManager() { |
| } |
| |
| /** |
| * Returns the list of shutdownHooks in order of execution, |
| * Highest priority first. |
| * |
| * @return the list of shutdownHooks in order of execution. |
| */ |
| List<HookEntry> getShutdownHooksInOrder() { |
| List<HookEntry> list; |
| synchronized (MGR.hooks) { |
| list = new ArrayList<HookEntry>(MGR.hooks); |
| } |
| Collections.sort(list, new Comparator<HookEntry>() { |
| |
| //reversing comparison so highest priority hooks are first |
| @Override |
| public int compare(HookEntry o1, HookEntry o2) { |
| return o2.priority - o1.priority; |
| } |
| }); |
| return list; |
| } |
| |
| /** |
| * Adds a shutdownHook with a priority, the higher the priority |
| * the earlier will run. ShutdownHooks with same priority run |
| * in a non-deterministic order. |
| * |
| * @param shutdownHook shutdownHook <code>Runnable</code> |
| * @param priority priority of the shutdownHook. |
| */ |
| public void addShutdownHook(Runnable shutdownHook, int priority) { |
| if (shutdownHook == null) { |
| throw new IllegalArgumentException("shutdownHook cannot be NULL"); |
| } |
| if (shutdownInProgress.get()) { |
| throw new IllegalStateException("Shutdown in progress, cannot add a " + |
| "shutdownHook"); |
| } |
| hooks.add(new HookEntry(shutdownHook, priority)); |
| } |
| |
| /** |
| * |
| * Adds a shutdownHook with a priority and timeout the higher the priority |
| * the earlier will run. ShutdownHooks with same priority run |
| * in a non-deterministic order. The shutdown hook will be terminated if it |
| * has not been finished in the specified period of time. |
| * |
| * @param shutdownHook shutdownHook <code>Runnable</code> |
| * @param priority priority of the shutdownHook |
| * @param timeout timeout of the shutdownHook |
| * @param unit unit of the timeout <code>TimeUnit</code> |
| */ |
| public void addShutdownHook(Runnable shutdownHook, int priority, long timeout, |
| TimeUnit unit) { |
| if (shutdownHook == null) { |
| throw new IllegalArgumentException("shutdownHook cannot be NULL"); |
| } |
| if (shutdownInProgress.get()) { |
| throw new IllegalStateException("Shutdown in progress, cannot add a " + |
| "shutdownHook"); |
| } |
| hooks.add(new HookEntry(shutdownHook, priority, timeout, unit)); |
| } |
| |
| /** |
| * Removes a shutdownHook. |
| * |
| * @param shutdownHook shutdownHook to remove. |
| * @return TRUE if the shutdownHook was registered and removed, |
| * FALSE otherwise. |
| */ |
| public boolean removeShutdownHook(Runnable shutdownHook) { |
| if (shutdownInProgress.get()) { |
| throw new IllegalStateException("Shutdown in progress, cannot remove a " + |
| "shutdownHook"); |
| } |
| return hooks.remove(new HookEntry(shutdownHook, 0)); |
| } |
| |
| /** |
| * Indicates if a shutdownHook is registered or not. |
| * |
| * @param shutdownHook shutdownHook to check if registered. |
| * @return TRUE/FALSE depending if the shutdownHook is is registered. |
| */ |
| public boolean hasShutdownHook(Runnable shutdownHook) { |
| return hooks.contains(new HookEntry(shutdownHook, 0)); |
| } |
| |
| /** |
| * Indicates if shutdown is in progress or not. |
| * |
| * @return TRUE if the shutdown is in progress, otherwise FALSE. |
| */ |
| public boolean isShutdownInProgress() { |
| return shutdownInProgress.get(); |
| } |
| |
| /** |
| * clear all registered shutdownHooks. |
| */ |
| public void clearShutdownHooks() { |
| hooks.clear(); |
| } |
| } |