SlowCountDownLatch.java

// Awful CountDownLatch implementation - busy-waits incessantly!
package org.effectivejava.examples.chapter10.item72;

public class SlowCountDownLatch {
	private int count;

	public SlowCountDownLatch(int count) {
		if (count < 0)
			throw new IllegalArgumentException(count + " < 0");
		this.count = count;
	}

	public void await() {
		while (true) {
			synchronized (this) {
				if (count == 0)
					return;
			}
		}
	}

	public synchronized void countDown() {
		if (count != 0)
			count--;
	}
}