| /* |
| * [The "BSD license"] |
| * Copyright (c) 2010 Terence Parr |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| package org.antlr.misc; |
| |
| /**A very simple barrier wait. Once a thread has requested a |
| * wait on the barrier with waitForRelease, it cannot fool the |
| * barrier into releasing by "hitting" the barrier multiple times-- |
| * the thread is blocked on the wait(). |
| */ |
| public class Barrier { |
| protected int threshold; |
| protected int count = 0; |
| |
| public Barrier(int t) { |
| threshold = t; |
| } |
| |
| public synchronized void waitForRelease() |
| throws InterruptedException |
| { |
| count++; |
| // The final thread to reach barrier resets barrier and |
| // releases all threads |
| if ( count==threshold ) { |
| // notify blocked threads that threshold has been reached |
| action(); // perform the requested operation |
| notifyAll(); |
| } |
| else while ( count<threshold ) { |
| wait(); |
| } |
| } |
| |
| /** What to do when everyone reaches barrier */ |
| public void action() { |
| } |
| } |