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 * ConditionLock is a Lock with a built in state variable. This class 30 * provides the ability to wait for the state variable to be set to a 31 * desired value and then acquire the lock.<p> 32 * 33 * The lockWhen() and unlockWith() methods can be safely intermixed 34 * with the lock() and unlock() methods. However if there is a thread 35 * waiting for the state variable to become a particular value and you 36 * simply call Unlock(), that thread will not be able to acquire the 37 * lock until the state variable equals its desired value. <p> 38 * 39 * @author Peter King 40 */ 41 public final 42 class ConditionLock extends Lock { 43 private int state = 0; 44 45 /** 46 * Creates a ConditionLock. 47 */ 48 public ConditionLock () { 49 } 50 51 /** 52 * Creates a ConditionLock in an initialState. 53 */ 54 public ConditionLock (int initialState) { 55 state = initialState; 56 } 57 58 /** 59 * Acquires the lock when the state variable equals the desired state. 60 * 61 * @param desiredState the desired state 62 * @exception java.lang.InterruptedException if any thread has 63 * interrupted this thread. 64 */ 65 public synchronized void lockWhen(int desiredState) 66 throws InterruptedException 67 { 68 while (state != desiredState) { 69 wait(); 70 } 71 lock(); 72 } 73 74 /** 75 * Releases the lock, and sets the state to a new value. 76 * @param newState the new state 77 */ 78 public synchronized void unlockWith(int newState) { 79 state = newState; 80 unlock(); 81 } 82 }