Showing the changes to java/pkg/sun/misc/Lock.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,93 @@ | ||
| 1 | +/* | |
| 2 | + * Copyright (c) 1994, 2005, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package sun.misc; | |
| 27 | + | |
| 28 | +/** | |
| 29 | + * The Lock class provides a simple, useful interface to a lock. | |
| 30 | + * Unlike monitors which synchronize access to an object, locks | |
| 31 | + * synchronize access to an arbitrary set of resources (objects, | |
| 32 | + * methods, variables, etc.). <p> | |
| 33 | + * | |
| 34 | + * The programmer using locks must be responsible for clearly defining | |
| 35 | + * the semantics of their use and should handle deadlock avoidance in | |
| 36 | + * the face of exceptions. <p> | |
| 37 | + * | |
| 38 | + * For example, if you want to protect a set of method invocations with | |
| 39 | + * a lock, and one of the methods may throw an exception, you must be | |
| 40 | + * prepared to release the lock similarly to the following example: | |
| 41 | + * <pre> | |
| 42 | + * class SomeClass { | |
| 43 | + * Lock myLock = new Lock(); | |
| 44 | + | |
| 45 | + * void someMethod() { | |
| 46 | + * myLock.lock(); | |
| 47 | + * try { | |
| 48 | + * StartOperation(); | |
| 49 | + * ContinueOperation(); | |
| 50 | + * EndOperation(); | |
| 51 | + * } finally { | |
| 52 | + * myLock.unlock(); | |
| 53 | + * } | |
| 54 | + * } | |
| 55 | + * } | |
| 56 | + * </pre> | |
| 57 | + * | |
| 58 | + * @author Peter King | |
| 59 | + */ | |
| 60 | +public | |
| 61 | +class Lock { | |
| 62 | + private boolean locked = false; | |
| 63 | + | |
| 64 | + /** | |
| 65 | + * Create a lock, which is initially not locked. | |
| 66 | + */ | |
| 67 | + public Lock () { | |
| 68 | + } | |
| 69 | + | |
| 70 | + /** | |
| 71 | + * Acquire the lock. If someone else has the lock, wait until it | |
| 72 | + * has been freed, and then try to acquire it again. This method | |
| 73 | + * will not return until the lock has been acquired. | |
| 74 | + * | |
| 75 | + * @exception java.lang.InterruptedException if any thread has | |
| 76 | + * interrupted this thread. | |
| 77 | + */ | |
| 78 | + public final synchronized void lock() throws InterruptedException { | |
| 79 | + while (locked) { | |
| 80 | + wait(); | |
| 81 | + } | |
| 82 | + locked = true; | |
| 83 | + } | |
| 84 | + | |
| 85 | + /** | |
| 86 | + * Release the lock. If someone else is waiting for the lock, the | |
| 87 | + * will be notitified so they can try to acquire the lock again. | |
| 88 | + */ | |
| 89 | + public final synchronized void unlock() { | |
| 90 | + locked = false; | |
| 91 | + notifyAll(); | |
| 92 | + } | |
| 93 | +} | |