Performance.java

/*
 *  WPCleaner: A tool to help on Wikipedia maintenance tasks.
 *  Copyright (C) 2013  Nicolas Vervelle
 *
 *  See README.txt file for licensing information.
 */

package org.wikipediacleaner.utils;

import java.io.PrintStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;


/**
 * Utility class to measure performance.
 */
public class Performance {

  /** Stream to write performance information to */
  private final static PrintStream output = System.err;

  /** Global flag for printing */
  private static boolean print = true;

  /** Global flag for using high precision */
  private static boolean highPrecision = false;

  /** Method name */
  private final String method;

  /** Unit of time */
  private final String unit;

  /** Initial time */
  private long initialTime;

  /** Last time */
  private long lastTime;

  /** Threshold for printing duration */
  private long threshold;

  /** Map to measure parts of the execution */
  private Map<String, Long> parts;

  /** Initial time for a part of the execution */
  private long partInitialTime;

  /**
   * @param method Method name.
   */
  public Performance(String method) {
    this(method, 0);
  }

  /**
   * @param method Method name.
   * @param threshold Threshold for printing results.
   */
  public Performance(String method, long threshold) {
    this.method = method;
    this.unit = highPrecision ? "ns" : "ms";
    this.threshold = threshold;
    initialTime = currentTime();
    partInitialTime = initialTime;
    lastTime = initialTime;
  }

  /**
   * @param threshold Threshold for printing duration.
   */
  public void setThreshold(long threshold) {
    this.threshold = threshold;
  }

  /**
   * Print a message.
   * 
   * @param message Message to be printed.
   */
  private void printMessage(String message) {
    if (print) {
      output.print(method);
      if (message != null) {
        output.print(": ");
        output.print(message);
      }
      output.println();
      output.flush();
    }
  }

  /**
   * Print a message.
   * 
   * @param time Current time.
   * @param message Message to be printed.
   */
  @SuppressWarnings("unused")
  private void printTimedMessage(long time, String message) {
    if (print) {
      output.print(time);
      output.print(" - ");
      output.print(method);
      if (message != null) {
        output.print(": ");
        output.print(message);
      }
      output.println();
      output.flush();
    }
  }

  /**
   * Print a start message.
   */
  public void printStart() {
    initialTime = currentTime();
    lastTime = initialTime;
    printMessage(null);
  }

  /**
   * Print a step message.
   * 
   * @param message Message to be printed.
   */
  public void printStep(String message) {
    long time = currentTime();
    printMessage("(" + (time - lastTime) + unit + ") " + message);
    lastTime = time;
  }

  /**
   * Start measuring time for a part of the execution.
   */
  public void startPart() {
    partInitialTime = currentTime();
  }

  /**
   * Stop measuring time for a part of the execution.
   * 
   * @param part Part name.
   */
  public void stopPart(String part) {
    long time = currentTime();
    if (time <= partInitialTime) {
      return;
    }
    if (parts == null) {
      parts = new HashMap<String, Long>();
    }
    Long previousTime = parts.get(part);
    if (previousTime != null) {
      parts.put(part, Long.valueOf(time - partInitialTime + previousTime.longValue()));
    } else {
      parts.put(part, Long.valueOf(time - partInitialTime));
    }
    partInitialTime = time;
  }

  /**
   * Print an end message.
   */
  public void printEnd() {
    long time = currentTime();
    if (time > initialTime + threshold) {
      printDetail("(" + (time - initialTime) + unit + ")");
    }
  }

  /**
   * Print an end message.
   */
  public void printEnd(String message) {
    long time = currentTime();
    if (time > initialTime + threshold) {
      printDetail(message + "(" + (time - initialTime) + unit + ")");
    }
  }

  /**
   * Print an end message.
   */
  public void printEnd(String message, String message2) {
    long time = currentTime();
    if (time > initialTime + threshold) {
      printDetail(message + ":" + message2 + "(" + (time - initialTime) + unit + ")");
    }
  }

  private void printDetail(String message) {
    printMessage(message);
    if (parts != null) {
      for (Entry<String, Long> entry : parts.entrySet()) {
        printMessage("  " + entry.getKey() + "(" + entry.getValue() + unit + ")");
      }
    }
  }

  /**
   * @return Current time.
   */
  private static long currentTime() {
    if (highPrecision) {
      return System.nanoTime();
    }
    return System.currentTimeMillis();
  }
}