1/* 2 * Copyright (c) 2003, 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. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24/* 25 * @bug 4530538 26 * @summary A Barrier utility class. 27 * @author Mandy Chung 28 */ 29 30public class Barrier { 31 private Object go = new Object(); 32 private int count; 33 private int waiters = 0; 34 35 public Barrier(int count) { 36 if (count <= 0) { 37 throw new IllegalArgumentException(); 38 } 39 this.count = count; 40 } 41 42 public void set(int count) { 43 if (waiters != 0) { 44 throw new IllegalArgumentException(); 45 } 46 this.count = count; 47 this.waiters = 0; 48 } 49 50 public void await() { 51 synchronized (go) { 52 waiters++; 53 while (count > 0) { 54 try { 55 go.wait(); 56 } catch (InterruptedException e) { 57 e.printStackTrace(); 58 throw new InternalError(); 59 } 60 } 61 waiters--; 62 } 63 } 64 public void signal() { 65 synchronized (go) { 66 count--; 67 go.notifyAll(); 68 } 69 } 70 71 public int getWaiterCount() { 72 synchronized (go) { 73 return waiters; 74 } 75 } 76} 77