01: /*BEGIN_COPYRIGHT_BLOCK
02: *
03: * Copyright (c) 2001-2007, JavaPLT group at Rice University (javaplt@rice.edu)
04: * All rights reserved.
05: *
06: * Redistribution and use in source and binary forms, with or without
07: * modification, are permitted provided that the following conditions are met:
08: * * Redistributions of source code must retain the above copyright
09: * notice, this list of conditions and the following disclaimer.
10: * * Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * * Neither the names of DrJava, the JavaPLT group, Rice University, nor the
14: * names of its contributors may be used to endorse or promote products
15: * derived from this software without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
21: * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
22: * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
23: * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
24: * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25: * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26: * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27: * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28: *
29: * This software is Open Source Initiative approved Open Source Software.
30: * Open Source Initative Approved is a trademark of the Open Source Initiative.
31: *
32: * This file is part of DrJava. Download the current version of this project
33: * from http://www.drjava.org/ or http://sourceforge.net/projects/drjava/
34: *
35: * END_COPYRIGHT_BLOCK*/
36:
37: package edu.rice.cs.util;
38:
39: /** Enables threads to communicate with each other by signaling. Typically, this communication concerns a
40: * task which one thread must complete before other threads can proceed.
41: */
42: public class CompletionMonitor {
43: private boolean _flag;
44:
45: public CompletionMonitor(boolean flag) {
46: _flag = flag;
47: }
48:
49: public CompletionMonitor() {
50: this (false);
51: }
52:
53: /** Returns whether the flag is currently set */
54: public synchronized boolean isFlag() {
55: return _flag;
56: }
57:
58: /** Sets the state to signaled, indicating that waiting threads can continue */
59: public synchronized void set() {
60: _flag = true;
61: this .notifyAll();
62: }
63:
64: /** Sets the state to unsignaled */
65: public synchronized void reset() {
66: _flag = false;
67: }
68:
69: /** Causes the calling thread to wait for the signal to be set before continuing
70: * If the signal is already set, it returns immediately
71: * @return returns true, unless the waiting thread was interrupted */
72: public synchronized boolean waitOne() {
73: while (!_flag) {
74: try {
75: this .wait();
76: } catch (InterruptedException e) {
77: return false;
78: }
79: }
80: return true;
81: }
82: }
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