StopWatch.java

package com.bergerkiller.bukkit.common;

/**
 * A nanosecond stop watch used to measure code execution times
 */
public class StopWatch {
	/**
	 * A global testing StopWatch that can be used when debugging
	 */
	public static final StopWatch instance = new StopWatch();

	private long prevtime;
	private long prevdur;

	/**
	 * Starts this Stop Watch
	 * 
	 * @return This Stop Watch
	 */
	public StopWatch start() {
		this.prevtime = System.nanoTime();
		return this;
	}

	/**
	 * Clears the times of this Stop Watch
	 * 
	 * @return This Stop Watch
	 */
	public StopWatch clear() {
		this.prevtime = 0;
		this.prevdur = 0;
		return this;
	}

	/**
	 * Gets the current total duration of this Stop Watch in milliseconds
	 * 
	 * @return Total time in milliseconds
	 */
	public double get() {
		return (double) prevdur / 1E6D;
	}

	/**
	 * Gets the current total duration of this Stop Watch in milliseconds
	 * 
	 * @param scale to use
	 * @return Total time in milliseconds divided by the scale
	 */
	public double get(int scale) {
		return (double) prevdur / 1E6D / (double) scale;
	}

	/**
	 * Sets a new elapsed time using a Strength to average the value
	 * 
	 * @param elapsednanotime to set to
	 * @param strength to use [0 - 1]
	 * @return This Stop Watch
	 */
	public StopWatch set(long elapsednanotime, double strength) {
		elapsednanotime += (1.0 - strength) * (this.prevdur - elapsednanotime);
		this.prevdur = elapsednanotime;
		return this;
	}

	/**
	 * Sets a new elapsed time
	 * 
	 * @param elapsednanotime to set to
	 * @return This Stop Watch
	 */
	public StopWatch set(long elapsednanotime) {
		return this.set(elapsednanotime, 1.0);
	}

	/**
	 * Performs the next measurement
	 * 
	 * @return This Stop Watch
	 */
	public StopWatch next() {
		return this.next(1.0);
	}

	/**
	 * Stops the measurement
	 * 
	 * @return This Stop Watch
	 */
	public StopWatch stop() {
		return this.stop(1.0);
	}

	/**
	 * Performs the next measurement
	 * 
	 * @return This Stop Watch
	 */
	public StopWatch next(double strength) {
		return this.set(this.prevdur - prevtime + System.nanoTime(), strength).start();
	}

	/**
	 * Stops the measurement
	 * 
	 * @return This Stop Watch
	 */
	public StopWatch stop(double strength) {
		return this.set(System.nanoTime() - this.prevtime, strength).start();
	}

	/**
	 * Logs the current duration to the server console
	 * 
	 * @param name to log for
	 * @return This Stop Watch
	 */
	public StopWatch log(final String name) {
		System.out.println(name + ": " + this.get() + " ms");
		return this;
	}
}