// lowlevel/MutexEvenProducer.java

// (c)2017 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// Preventing thread collisions with mutexes

import java.util.concurrent.locks.*;

import onjava.Nap;

public class MutexEvenProducer extends IntGenerator {

private int currentEvenValue = 0;

private Lock lock = new ReentrantLock();

@Override

public int next() {

lock.lock();

try {

++currentEvenValue;

new Nap(0.01); // Cause failure faster

++currentEvenValue;

return currentEvenValue;

} finally {

lock.unlock();

}

}

public static void main(String[] args) {

EvenChecker.test(new MutexEvenProducer());

}

}

/*

No odd numbers discovered

*/