001 // This file is part of the program FRYSK.
002 //
003 // Copyright 2007, Red Hat Inc.
004 //
005 // FRYSK is free software; you can redistribute it and/or modify it
006 // under the terms of the GNU General Public License as published by
007 // the Free Software Foundation; version 2 of the License.
008 //
009 // FRYSK is distributed in the hope that it will be useful, but
010 // WITHOUT ANY WARRANTY; without even the implied warranty of
011 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 // General Public License for more details.
013 //
014 // You should have received a copy of the GNU General Public License
015 // along with FRYSK; if not, write to the Free Software Foundation,
016 // Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
017 //
018 // In addition, as a special exception, Red Hat, Inc. gives You the
019 // additional right to link the code of FRYSK with code not covered
020 // under the GNU General Public License ("Non-GPL Code") and to
021 // distribute linked combinations including the two, subject to the
022 // limitations in this paragraph. Non-GPL Code permitted under this
023 // exception must only link to the code of FRYSK through those well
024 // defined interfaces identified in the file named EXCEPTION found in
025 // the source code files (the "Approved Interfaces"). The files of
026 // Non-GPL Code may instantiate templates or use macros or inline
027 // functions from the Approved Interfaces without causing the
028 // resulting work to be covered by the GNU General Public
029 // License. Only Red Hat, Inc. may make changes or additions to the
030 // list of Approved Interfaces. You must obey the GNU General Public
031 // License in all respects for all of the FRYSK code and other code
032 // used in conjunction with FRYSK except the Non-GPL Code covered by
033 // this exception. If you modify this file, you may extend this
034 // exception to your version of the file, but you are not obligated to
035 // do so. If you do not wish to provide this exception without
036 // modification, you must delete this exception statement from your
037 // version and license this file solely under the GPL without
038 // exception.
039
040 package frysk.util;
041
042 /**
043 * Implementation of CountDownLatch from java.util.concurrent in Java
044 * 1.5
045 */
046 public class CountDownLatch {
047 private int count;
048
049 public CountDownLatch(int count)
050 throws IllegalArgumentException {
051 if (count < 0)
052 throw new IllegalArgumentException("count is less than 0");
053 this.count = count;
054 }
055
056 public synchronized void await()
057 throws InterruptedException {
058 while (count != 0) {
059 try {
060 wait();
061 }
062 catch (InterruptedException e) {
063 throw e;
064 }
065 }
066 }
067
068 public synchronized boolean await(long timeout)
069 throws InterruptedException {
070 if (count == 0)
071 return true;
072 long now = System.currentTimeMillis();
073 while (count != 0) {
074 long later = now + timeout;
075 try {
076 wait(timeout);
077 }
078 catch (InterruptedException e) {
079 throw e;
080 }
081 now = System.currentTimeMillis();
082 if (now >= later)
083 break;
084 timeout = later - now;
085 }
086 // Either the count is 0 or we timed out
087 return count == 0;
088 }
089
090 public synchronized void countDown() {
091 if (count == 0)
092 return;
093 --count;
094 if (count == 0)
095 notifyAll();
096 }
097
098 public synchronized long getCount() {
099 return count;
100 }
101
102 public String toString() {
103 return super.toString() + " [Count=" + getCount() + "]";
104 }
105 }