WindowedTimeThrottler.java

package backtype.storm.utils;

public class WindowedTimeThrottler {
	long _windowMillis;
	int _maxAmt;
	long _windowStartTime;
	int _windowEvents = 0;

	public WindowedTimeThrottler(Number windowMillis, Number maxAmt) {
		_windowMillis = windowMillis.longValue();
		_maxAmt = maxAmt.intValue();
		_windowStartTime = System.currentTimeMillis();
	}

	public boolean isThrottled() {
		resetIfNecessary();
		return _windowEvents >= _maxAmt;
	}

	// returns void if the event should continue, false if the event should not
	// be done
	public void markEvent() {
		resetIfNecessary();
		_windowEvents++;

	}

	private void resetIfNecessary() {
		long now = System.currentTimeMillis();
		if (now - _windowStartTime >= _windowMillis) {
			_windowStartTime = now;
			_windowEvents = 0;
		}
	}
}