anycastmessage.java

p2p仿真器。开发者可以工作在覆盖层中进行创造和测试逻辑算法或者创建和测试新的服务。PlanetSim还可以将仿真代码平稳转换为在Internet上的实验代码

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"Free Pastry" Peer-to-Peer Application Development Substrate

Copyright 2002, Rice University. All rights reserved.

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package planet.scribe.messaging;

import java.util.*;

import planet.commonapi.*;
import planet.scribe.*;

/**
 * @version $Id: AnycastMessage.java,v 1.6 2003/10/22 03:16:42 amislove Exp $
 * @author Alan Mislove
 */
public class AnycastMessage extends ScribeMessage {

  /**
   * the content of this message
   */
  protected ScribeContent content;

  /**
   * the list of nodes which we have visited
   */
  protected Vector visited;

  /**
   * the list of nodes which we are going to visit
   */
  protected LinkedList toVisit;

  /**
   * @param source The source address
   * @param topic The topic
   * @param content The content
   */
  public AnycastMessage(NodeHandle source, Topic topic, ScribeContent content) {
    super(source, topic);

    this.content = content;
    this.visited = new Vector();
    this.toVisit = new LinkedList();

    addVisited(source);
  }

  /**
   * Returns the content
   *
   * @return The content
   */
  public ScribeContent getContent() {
    return content;
  }

  /**
   * Sets the content
   *
   * @param content The content
   */
  public void setContent(ScribeContent content) {
    this.content = content;
  }

  /**
   * Returns the next handle to visit
   *
   * @return The next handle to visit
   */
  public NodeHandle peekNext() {
    if (toVisit.size() == 0) {
      return null;
    }

    return (NodeHandle) toVisit.getFirst();
  }

  /**
   * Returns the next handle to visit and removes the
   * node from the list.
   *
   * @return The next handle to visit
   */
  public NodeHandle getNext() {
    if (toVisit.size() == 0) {
      return null;
    }
    
    return (NodeHandle) toVisit.removeFirst();
  }

  /**
   * Adds a node to the visited list
   *
   * @param handle The node to add
   */
  public void addVisited(NodeHandle handle) {
    if (handle == null) {
      return;
    }

    if (!visited.contains(handle)) {
      visited.add(handle);
    }

    while (toVisit.remove(handle)) {
      toVisit.remove(handle);
    }
  }

  /**
   * Adds a node the the front of the to-visit list
   *
   * @param handle The handle to add
   */
  public void addFirst(NodeHandle handle) {
    if (handle == null) {
      return;
    }

    if ((!toVisit.contains(handle)) && (!visited.contains(handle))) {
      toVisit.addFirst(handle);
    }
  }

  /**
   * Adds a node the the end of the to-visit list
   *
   * @param handle The handle to add
   */
  public void addLast(NodeHandle handle) {
    if (handle == null) {
      return;
    }

    if ((!toVisit.contains(handle)) && (!visited.contains(handle))) {
      toVisit.addLast(handle);
    }
  }

  /**
   * Removes the node handle from the to visit and visited lists
   *
   * @param handle The handle to remove
   */
  public void remove(NodeHandle handle) {
    if (handle == null) {
      return;
    }

    toVisit.remove(handle);
    visited.remove(handle);
  }
}