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A log library that embraces the kiss principle.

There is a newer version: 2.1.2

package org.mentalog.util;

public class Benchmarker {

	private final static Benchmarker instance = new Benchmarker();

	private static final int DEFAULT_WARMUP = 0;

	private long time;
	private long count = 0;
	private long totalTime = 0;
	private long minTime = Long.MAX_VALUE;
	private long maxTime = Long.MIN_VALUE;

	private final int warmup;

	public Benchmarker(final int warmup) {
		this.warmup = warmup;
		try {
			// initialize it here so when you measure for the first time gargage is not created...
			Class.forName("java.lang.Math");
		}
		catch (final Exception e) {
			e.printStackTrace();
		}
	}

	public Benchmarker() {
		this(DEFAULT_WARMUP);
	}

	public final static Benchmarker instance() {
		return instance;
	}

	public void reset() {
		time = 0;
		count = 0;
		totalTime = 0;
		minTime = Long.MAX_VALUE;
		maxTime = Long.MIN_VALUE;
	}

	public void mark() {
		time = System.nanoTime();
	}

	public long measure() {
		if (time > 0) {
			final long lastTime = System.nanoTime() - time;
			final boolean counted = measure(lastTime);
			if (counted) {
				return lastTime;
			}
		}
		return -1;
	}

	public boolean measure(final long lastTime) {
		if (++count > warmup) {
			totalTime += lastTime;
			minTime = Math.min(minTime, lastTime);
			maxTime = Math.max(maxTime, lastTime);
			return true;
		}
		return false;
	}

	private final double avg() {
		final long realCount = count - warmup;
		if (realCount <= 0) {
			return 0;
		}
		final double avg = ((double) totalTime / (double) realCount);
		final double rounded = Math.round(avg * 100D) / 100D;
		return rounded;
	}

	public String results() {
		final StringBuilder sb = new StringBuilder(128);
		final long realCount = count - warmup;
		sb.append("Iterations: ").append(realCount);
		sb.append(" | Avg Time: ").append(String.valueOf(avg())).append(" nanos");
		if (realCount > 0) {
			sb.append(" | Min Time: ").append(minTime);
			sb.append(" nanos | Max Time: ").append(maxTime);
			sb.append(" nanos");
		}

		return sb.toString();
	}
}