package net.jcip.examples;
import static java.util.concurrent.TimeUnit.SECONDS;
import java.math.BigInteger;
import java.util.*;
import java.util.concurrent.*;
import net.jcip.annotations.*;
/**
* PrimeGenerator
* <p/>
* Using a volatile field to hold cancellation state
*
* @author Brian Goetz and Tim Peierls
*/
@ThreadSafe
public class PrimeGenerator implements Runnable {
private static ExecutorService exec = Executors.newCachedThreadPool();
@GuardedBy("this") private final List<BigInteger> primes
= new ArrayList<BigInteger>();
private volatile boolean cancelled;
public void run() {
BigInteger p = BigInteger.ONE;
while (!cancelled) {
p = p.nextProbablePrime();
synchronized (this) {
primes.add(p);
}
}
}
public void cancel() {
cancelled = true;
}
public synchronized List<BigInteger> get() {
return new ArrayList<BigInteger>(primes);
}
static List<BigInteger> aSecondOfPrimes() throws InterruptedException {
PrimeGenerator generator = new PrimeGenerator();
exec.execute(generator);
try {
SECONDS.sleep(1);
} finally {
generator.cancel();
}
return generator.get();
}
}