package tryAny.effectiveJava;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
public class CountDownLatchTest {
public static void main(String[] args) throws InterruptedException {
Executor e = Executors.newFixedThreadPool(3); //If the argument here is less than the value of the second argument of time, the process will not end.
System.out.println(time(e, 3, () -> System.out.println("a")));
}
// Simple framework for timing concurrent execution
public static long time(Executor executor, int concurrency, Runnable action) throws InterruptedException {
CountDownLatch ready = new CountDownLatch(concurrency);
CountDownLatch start = new CountDownLatch(1);
CountDownLatch done = new CountDownLatch(concurrency);
for (int i = 0; i < concurrency; i++) {
executor.execute(() -> {
ready.countDown(); // Tell timer we're ready
try {
start.await(); // Wait till peers are ready
action.run();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} finally {
done.countDown(); // Tell timer we're done
}
});
}
ready.await(); // Wait for all workers to be ready
long startNanos = System.nanoTime();
start.countDown(); // And they're off!
done.await(); // Wait for all workers to finish
return System.nanoTime() - startNanos;
}
}
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