/*
 * This file is part of ELKI:
 * Environment for Developing KDD-Applications Supported by Index-Structures
 *
 * Copyright (C) 2017
 * ELKI Development Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package de.lmu.ifi.dbs.elki.logging.statistics;

/**
 * Class that tracks the runtime of a task with {@code System.nanoTime()}
 * 
 * @author Erich Schubert
 * @since 0.5.0
 */
public class NanoDuration extends AbstractStatistic implements Duration {
  /**
   * Tracking variables.
   */
  long begin = -1, end = -2;

  /**
   * Constructor.
   * 
   * @param key Key
   */
  public NanoDuration(String key) {
    super(key);
  }

  @Override
  public NanoDuration begin() {
    begin = System.nanoTime();
    return this;
  }

  @Override
  public NanoDuration end() {
    end = System.nanoTime();
    return this;
  }

  @Override
  public long getBegin() {
    return begin;
  }

  @Override
  public long getEnd() {
    return end;
  }

  @Override
  public long getDuration() {
    return (end - begin);
  }

  @Override
  public String formatValue() {
    return getDuration() + " ns";
  }
}