Stopwatch.java

package LOG320.labo3.helpers;

import java.util.Collections;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;

/**
 * Forked from https://gist.github.com/juanmf/4147a9b7010c7b04c003
 */
public class Stopwatch {

    private static final Map<String, Stopwatch> RUNNING = new TreeMap<>();
    private long startedAt;
    private long endedAt;

    public static Map<String, Stopwatch> getRunning() {
        return Collections.unmodifiableMap(RUNNING);
    }

    public static void start(String name) {
        RUNNING.put(name, new Stopwatch().start());
    }

    public static long end(String name) {
        Stopwatch task = RUNNING.get(name);
        if (task == null) {
            throw new IllegalArgumentException("no task after name: " + name);
        }
        task.end();

        long elapsedTime = task.getElapsedTime();
        System.out.println(name + " ended after : " + elapsedTime + " ms");
        RUNNING.remove(name);

        return elapsedTime;
    }

    public static long getElapsedTime(String name) {
        Stopwatch task = RUNNING.get(name);
        if (task == null) {
            throw new IllegalArgumentException("no task after name: " + name);
        }
        return task.getElapsedTime();
    }

    private Stopwatch start() {
        startedAt = System.nanoTime();
        return this;
    }

    private Stopwatch end() {
        endedAt = System.nanoTime();
        return this;
    }

    private long getElapsedTime() {
        if (startedAt == 0) {
            throw new IllegalStateException("startedAt is not set.");
        }

        long end = endedAt != 0 ? endedAt : System.nanoTime();
        return TimeUnit.MILLISECONDS.convert(end - startedAt, TimeUnit.NANOSECONDS);
    }
}