| /* |
| * Copyright 1999-2007 Sun Microsystems, Inc. All Rights Reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Sun designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Sun in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| */ |
| |
| package com.sun.jmx.mbeanserver; |
| |
| import java.lang.ref.WeakReference; |
| import java.util.concurrent.ThreadPoolExecutor; |
| |
| /** |
| * <p>A factory for ThreadPoolExecutor objects that allows the same object to |
| * be shared by all users of the factory that are in the same ThreadGroup.</p> |
| */ |
| // We return a ThreadPoolExecutor rather than the more general ExecutorService |
| // because we need to be able to call allowCoreThreadTimeout so that threads in |
| // the pool will eventually be destroyed when the pool is no longer in use. |
| // Otherwise these threads would keep the ThreadGroup alive forever. |
| public class PerThreadGroupPool<T extends ThreadPoolExecutor> { |
| private final WeakIdentityHashMap<ThreadGroup, WeakReference<T>> map = |
| WeakIdentityHashMap.make(); |
| |
| public static interface Create<T extends ThreadPoolExecutor> { |
| public T createThreadPool(ThreadGroup group); |
| } |
| |
| private PerThreadGroupPool() {} |
| |
| public static <T extends ThreadPoolExecutor> PerThreadGroupPool<T> make() { |
| return new PerThreadGroupPool<T>(); |
| } |
| |
| public synchronized T getThreadPoolExecutor(Create<T> create) { |
| // Find out if there's already an existing executor for the calling |
| // thread and reuse it. Otherwise, create a new one and store it in |
| // the executors map. If there is a SecurityManager, the group of |
| // System.getSecurityManager() is used, else the group of the calling |
| // thread. |
| SecurityManager s = System.getSecurityManager(); |
| ThreadGroup group = (s != null) ? s.getThreadGroup() : |
| Thread.currentThread().getThreadGroup(); |
| WeakReference<T> wr = map.get(group); |
| T executor = (wr == null) ? null : wr.get(); |
| if (executor == null) { |
| executor = create.createThreadPool(group); |
| executor.allowCoreThreadTimeOut(true); |
| map.put(group, new WeakReference<T>(executor)); |
| } |
| return executor; |
| } |
| } |