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/*
* [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() {
}
}
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