simplerandomsource.java

pastry的java实现的2.0b版

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"FreePastry" Peer-to-Peer Application Development Substrate 

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/*
 *  Created on May 26, 2005
 */
package rice.environment.random.simple;

import java.net.InetAddress;
import java.util.Random;

import rice.environment.logging.*;
import rice.environment.random.RandomSource;

/**
 * @version $Id: pretty.settings 2305 2005-03-11 20:22:33Z jeffh $
 * @author Jeff Hoye
 */
public class SimpleRandomSource implements RandomSource {
  Random rnd;

  Logger logger;

  String instance;

  /**
   * Constructor for SimpleRandomSource.
   *
   * @param seed DESCRIBE THE PARAMETER
   * @param manager DESCRIBE THE PARAMETER
   * @param instance DESCRIBE THE PARAMETER
   */
  public SimpleRandomSource(long seed, LogManager manager, String instance) {
    init(seed, manager, instance);
  }

  /**
   * Constructor for SimpleRandomSource.
   *
   * @param seed DESCRIBE THE PARAMETER
   * @param manager DESCRIBE THE PARAMETER
   */
  public SimpleRandomSource(long seed, LogManager manager) {
    this(seed, manager, null);
  }

  /**
   * Constructor for SimpleRandomSource.
   *
   * @param manager DESCRIBE THE PARAMETER
   */
  public SimpleRandomSource(LogManager manager) {
    this(manager, null);
  }

  /**
   * Constructor for SimpleRandomSource.
   *
   * @param manager DESCRIBE THE PARAMETER
   * @param instance DESCRIBE THE PARAMETER
   */
  public SimpleRandomSource(LogManager manager, String instance) {
    // NOTE: Since we are often starting up a bunch of nodes on planetlab
    // at the same time, we need this randomsource to be seeded by more
    // than just the clock, we will include the IP address
    // as amazing as this sounds, it happened in a network of 20 on 7/19/2005
    // also, if you think about it, I was starting all of the nodes at the same
    // instant, and they had synchronized clocks, if they all started within 1/10th of
    // a second, then there is only 100 different numbers to seed the generator with
    // -Jeff
    long time = System.currentTimeMillis();
    try {
      byte[] foo = InetAddress.getLocalHost().getAddress();
      for (int ctr = 0; ctr < foo.length; ctr++) {
        int i = (int) foo[ctr];
        i <<= (ctr * 8);
        time ^= i;
      }
    } catch (Exception e) {
      // if there is no NIC, screw it, this is really unlikely anyway
    }
    init(time, manager, instance);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param seed DESCRIBE THE PARAMETER
   * @param manager DESCRIBE THE PARAMETER
   * @param instance DESCRIBE THE PARAMETER
   */
  private void init(long seed, LogManager manager, String instance) {
    if (manager != null) {
      logger = manager.getLogger(SimpleRandomSource.class, instance);
    }
    if (logger != null) {
      if (logger.level <= Logger.INFO) {
        logger.log("RNG seed = " + seed);
      }
    }
    rnd = new Random(seed);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public boolean nextBoolean() {
    boolean ret = rnd.nextBoolean();
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextBoolean = " + ret);
      }
    }
    return ret;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param bytes DESCRIBE THE PARAMETER
   */
  public void nextBytes(byte[] bytes) {
    rnd.nextBytes(bytes);
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextBytes = " + bytes);
      }
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public double nextDouble() {
    double ret = rnd.nextDouble();
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextDouble = " + ret);
      }
    }
    return ret;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public float nextFloat() {
    float ret = rnd.nextFloat();
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextFloat = " + ret);
      }
    }
    return ret;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public double nextGaussian() {
    double ret = rnd.nextGaussian();
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextGaussian = " + ret);
      }
    }
    return ret;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public int nextInt() {
    int ret = rnd.nextInt();
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextInt = " + ret);
      }
    }
    return ret;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param max DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   */
  public int nextInt(int max) {
    int ret = rnd.nextInt(max);
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextInt = " + ret);
      }
    }
    return ret;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public long nextLong() {
    long ret = rnd.nextLong();
    if (logger != null) {
      if (logger.level <= Logger.FINER) {
        logger.log("nextLong = " + ret);
      }
    }
    return ret;
  }
}