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/*
 * 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 com.frameworkset.commons.pool2.impl;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;

/**
 * Provides a shared idle object eviction timer for all pools.
 * 

* This class is currently implemented using {@link ScheduledThreadPoolExecutor}. This implementation may change in any * future release. This class keeps track of how many pools are using it. If no pools are using the timer, it is * cancelled. This prevents a thread being left running which, in application server environments, can lead to memory * leads and/or prevent applications from shutting down or reloading cleanly. *

*

* This class has package scope to prevent its inclusion in the pool public API. The class declaration below should * *not* be changed to public. *

*

* This class is intended to be thread-safe. *

* * @since 2.0 */ class EvictionTimer { /** Executor instance */ private static ScheduledThreadPoolExecutor executor; //@GuardedBy("EvictionTimer.class") /** Prevents instantiation */ private EvictionTimer() { // Hide the default constructor } /** * @since 2.4.3 */ @Override public String toString() { final StringBuilder builder = new StringBuilder(); builder.append("EvictionTimer []"); return builder.toString(); } /** * Adds the specified eviction task to the timer. Tasks that are added with a * call to this method *must* call {@link #()} to cancel the * task to prevent memory and/or thread leaks in application server * environments. * * @param task Task to be scheduled. * @param delay Delay in milliseconds before task is executed. * @param period Time in milliseconds between executions. */ static synchronized void schedule( final BaseGenericObjectPool.Evictor task, final long delay, final long period) { if (null == executor) { executor = new ScheduledThreadPoolExecutor(1, new EvictorThreadFactory()); executor.setRemoveOnCancelPolicy(true); } final ScheduledFuture scheduledFuture = executor.scheduleWithFixedDelay(task, delay, period, TimeUnit.MILLISECONDS); task.setScheduledFuture(scheduledFuture); } /** * Removes the specified eviction task from the timer. * * @param evictor Task to be cancelled. * @param timeout If the associated executor is no longer required, how * long should this thread wait for the executor to * terminate? * @param unit The units for the specified timeout. */ static synchronized void cancel( final BaseGenericObjectPool.Evictor evictor, final long timeout, final TimeUnit unit) { if (evictor != null) { evictor.cancel(); } if (executor != null && executor.getQueue().isEmpty()) { executor.shutdown(); try { executor.awaitTermination(timeout, unit); } catch (final InterruptedException e) { // Swallow // Significant API changes would be required to propagate this } executor.setCorePoolSize(0); executor = null; } } /** * Thread factory that creates a daemon thread, with the context class loader from this class. */ private static class EvictorThreadFactory implements ThreadFactory { @Override public Thread newThread(final Runnable runnable) { final Thread thread = new Thread(null, runnable, "commons-pool-evictor-thread"); thread.setDaemon(true); // POOL-363 - Required for applications using Runtime.addShutdownHook(). AccessController.doPrivileged(new PrivilegedAction() { @Override public Void run() { thread.setContextClassLoader(EvictorThreadFactory.class.getClassLoader()); return null; } }); return thread; } } }




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