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 /** 37 * Interfaces and classes providing a framework for locking and waiting 38 * for conditions that is distinct from built-in synchronization and 39 * monitors. The framework permits much greater flexibility in the use of 40 * locks and conditions, at the expense of more awkward syntax. 41 * 42 * <p>The {@link java.util.concurrent.locks.Lock} interface supports 43 * locking disciplines that differ in semantics (reentrant, fair, etc), 44 * and that can be used in non-block-structured contexts including 45 * hand-over-hand and lock reordering algorithms. The main implementation 46 * is {@link java.util.concurrent.locks.ReentrantLock}. 47 * 48 * <p>The {@link java.util.concurrent.locks.ReadWriteLock} interface 49 * similarly defines locks that may be shared among readers but are 50 * exclusive to writers. Only a single implementation, {@link 51 * java.util.concurrent.locks.ReentrantReadWriteLock}, is provided, since 52 * it covers most standard usage contexts. But programmers may create 53 * their own implementations to cover nonstandard requirements. 54 * 55 * <p>The {@link java.util.concurrent.locks.Condition} interface 56 * describes condition variables that may be associated with Locks. 57 * These are similar in usage to the implicit monitors accessed using 58 * {@code Object.wait}, but offer extended capabilities. 59 * In particular, multiple {@code Condition} objects may be associated 60 * with a single {@code Lock}. To avoid compatibility issues, the 61 * names of {@code Condition} methods are different from the 62 * corresponding {@code Object} versions. 63 * 64 * <p>The {@link java.util.concurrent.locks.AbstractQueuedSynchronizer} 65 * class serves as a useful superclass for defining locks and other 66 * synchronizers that rely on queuing blocked threads. The {@link 67 * java.util.concurrent.locks.AbstractQueuedLongSynchronizer} class 68 * provides the same functionality but extends support to 64 bits of 69 * synchronization state. Both extend class {@link 70 * java.util.concurrent.locks.AbstractOwnableSynchronizer}, a simple 71 * class that helps record the thread currently holding exclusive 72 * synchronization. The {@link java.util.concurrent.locks.LockSupport} 73 * class provides lower-level blocking and unblocking support that is 74 * useful for those developers implementing their own customized lock 75 * classes. 76 * 77 * @since 1.5 78 */ 79 package java.util.concurrent.locks; 80