1 /* 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /* 26 * This file is available under and governed by the GNU General Public 27 * License version 2 only, as published by the Free Software Foundation. 28 * However, the following notice accompanied the original version of this 29 * file: 30 * 31 * Written by Doug Lea with assistance from members of JCP JSR-166 32 * Expert Group and released to the public domain, as explained at 33 * http://creativecommons.org/publicdomain/zero/1.0/ 34 */ 35 36 package java.util.concurrent.locks; 37 38 /** 39 * A synchronizer that may be exclusively owned by a thread. This 40 * class provides a basis for creating locks and related synchronizers 41 * that may entail a notion of ownership. The 42 * {@code AbstractOwnableSynchronizer} class itself does not manage or 43 * use this information. However, subclasses and tools may use 44 * appropriately maintained values to help control and monitor access 45 * and provide diagnostics. 46 * 47 * @since 1.6 48 * @author Doug Lea 49 */ 50 public abstract class AbstractOwnableSynchronizer 51 implements java.io.Serializable { 52 53 /** Use serial ID even though all fields transient. */ 54 private static final long serialVersionUID = 3737899427754241961L; 55 56 /** 57 * Empty constructor for use by subclasses. 58 */ 59 protected AbstractOwnableSynchronizer() { } 60 61 /** 62 * The current owner of exclusive mode synchronization. 63 */ 64 private transient Thread exclusiveOwnerThread; 65 66 /** 67 * Sets the thread that currently owns exclusive access. 68 * A {@code null} argument indicates that no thread owns access. 69 * This method does not otherwise impose any synchronization or 70 * {@code volatile} field accesses. 71 * @param thread the owner thread 72 */ 73 protected final void setExclusiveOwnerThread(Thread thread) { 74 exclusiveOwnerThread = thread; 75 } 76 77 /** 78 * Returns the thread last set by {@code setExclusiveOwnerThread}, 79 * or {@code null} if never set. This method does not otherwise 80 * impose any synchronization or {@code volatile} field accesses. 81 * @return the owner thread 82 */ 83 protected final Thread getExclusiveOwnerThread() { 84 return exclusiveOwnerThread; 85 } 86 } 87
