similarset.java

pastry的java实现的2.0b版

/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

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- Redistributions of source code must retain the above copyright
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- Redistributions in binary form must reproduce the above copyright
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- Neither  the name  of Rice  University (RICE) nor  the names  of its
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This software is provided by RICE and the contributors on an "as is"
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********************************************************************************/
package rice.pastry.leafset;

import rice.pastry.*;

import java.util.*;
import java.io.*;

/**
 * A set of nodes, ordered by numerical distance of their Id from the local Id
 *
 * @version $Id: SimilarSet.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Andrew Ladd
 * @author Peter Druschel
 */

public class SimilarSet extends Observable implements NodeSetEventSource, Serializable,
  Observer {

  private NodeHandle ln;

  private boolean clockwise;

  private NodeHandle[] nodes;

  private int theSize;

  private LeafSet leafSet;

  transient ArrayList listeners = new ArrayList();

  /**
   * Numerically closest node to a given a node. Returns -1 if the local Id is
   * the most similar and returns an index otherwise.
   *
   * @param nid a node id.
   * @return -1 if the local Id is most similar, else the index of the most
   *      similar node.
   */
//  public int mostSimilar(Id nid) {
//    if (theSize == 0)
//      return -1;
//
//    Id.Distance minDist = ln.getNodeId().distance(nid);
//    int min = -1;
//
//    for (int i = 0; i < theSize; i++) {
//      Id.Distance d = nodes[i].getNodeId().distance(nid);
//      int cmp = d.compareTo(minDist);
//      if ((!clockwise && cmp < 0) || (clockwise && cmp <= 0)) {
//        minDist = d;
//        min = i;
//      }
//    }
//
//    return min;
//  }

  transient Id.Distance d1 = new Id.Distance();
  transient Id.Distance d = new Id.Distance();

  private final static long serialVersionUID = 2289610430696506873L;

  /**
   * Constructor for SimilarSet.
   *
   * @param that DESCRIBE THE PARAMETER
   * @param ls DESCRIBE THE PARAMETER
   */
  private SimilarSet(SimilarSet that, LeafSet ls) {
    this.ln = that.ln;
    this.clockwise = that.clockwise;
    this.nodes = new NodeHandle[that.nodes.length];
    System.arraycopy(that.nodes, 0, nodes, 0, nodes.length);
    this.theSize = that.theSize;
    this.leafSet = ls;
  }

  /**
   * Constructor.
   *
   * @param localNode the local node
   * @param size the size of the similar set.
   * @param cw true if this is the clockwise leafset half
   * @param leafSet DESCRIBE THE PARAMETER
   */

  public SimilarSet(LeafSet leafSet, NodeHandle localNode, int size, boolean cw) {
    this.leafSet = leafSet;
    ln = localNode;
    clockwise = cw;
    theSize = 0;
    nodes = new NodeHandle[size];
  }

  /**
   * Constructor for SimilarSet.
   *
   * @param leafSet DESCRIBE THE PARAMETER
   * @param localNode DESCRIBE THE PARAMETER
   * @param size DESCRIBE THE PARAMETER
   * @param cw DESCRIBE THE PARAMETER
   * @param handles DESCRIBE THE PARAMETER
   */
  public SimilarSet(LeafSet leafSet, NodeHandle localNode, int size, boolean cw, NodeHandle[] handles) {
    this.leafSet = leafSet;
    ln = localNode;
    clockwise = cw;
    theSize = handles.length;
    nodes = handles;
  }

  /**
   * Finds the NodeHandle associated with the Id.
   *
   * @param nid a node id.
   * @return the handle associated with that id or null if no such handle is
   *      found.
   */
  public NodeHandle get(Id nid) {
    for (int i = 0; i < theSize; i++) {
      if (nodes[i].getNodeId().equals(nid)) {
        return nodes[i];
      }
    }

    return null;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param nh DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   */
  public NodeHandle get(NodeHandle nh) {
    for (int i = 0; i < theSize; i++) {
      if (nodes[i].equals(nh)) {
        return nodes[i];
      }
    }

    return null;
  }

  /**
   * Gets the ith element in the set.
   *
   * @param i an index. i == -1 refers to the local node
   * @return the handle associated with that id or null if no such handle is
   *      found.
   */

  public NodeHandle get(int i) {
    if (i < -1 || i >= theSize) {
      return null;
    }
    if (i == -1) {
      return ln;
    }

    return nodes[i];
  }

  /**
   * Gets the index of the element with the given node id.
   *
   * @param nid the node id.
   * @return the index or -1 if the element does not exist.
   */

  public int getIndex(Id nid) {
    for (int i = 0; i < theSize; i++) {
      if (nodes[i].getNodeId().equals(nid)) {
        return i;
      }
    }

    return -1;
  }

  /**
   * Gets the Index attribute of the SimilarSet object
   *
   * @param nh DESCRIBE THE PARAMETER
   * @return The Index value
   */
  public int getIndex(NodeHandle nh) {
    for (int i = 0; i < theSize; i++) {
      if (nodes[i].equals(nh)) {
        return i;
      }
    }

    return -1;
  }

  /**
   * Finds the NodeHandle associated with the Id.
   *
   * @param id a node id.
   * @return the handle associated with that id or null if no such handle is
   *      found.
   */
  public rice.p2p.commonapi.NodeHandle getHandle(rice.p2p.commonapi.Id id) {
    return getHandle((Id) id);
  }

  /**
   * Gets the ith element in the set.
   *
   * @param i an index.
   * @return the handle associated with that id or null if no such handle is
   *      found.
   */
  public rice.p2p.commonapi.NodeHandle getHandle(int i) {
    return get(i);
  }

  /**
   * Gets the index of the element with the given node id.
   *
   * @param id the id.
   * @return the index or throws a NoSuchElementException.
   * @exception NoSuchElementException DESCRIBE THE EXCEPTION
   */
  public int getIndexHandle(rice.p2p.commonapi.Id id)
     throws NoSuchElementException {
    return getIndex((Id) id);
  }

  /**
   * This is thread safe, in that it won't throw an error if not properly
   * synchronized.
   *
   * @return
   */
  public Collection getCollection() {
    ArrayList al = new ArrayList();
    for (int i = 0; i < theSize; i++) {
      NodeHandle nh = nodes[i];
      if (nh != null) {
        al.add(nh);
      }
    }
    return al;
  }

  /**
   * swap two elements
   *
   * @param i the index of the first element
   * @param j the indes of the second element
   */

  protected void swap(int i, int j) {
    NodeHandle handle = nodes[i];
    nodes[i] = nodes[j];
    nodes[j] = handle;
  }

  /**
   * Test if a NodeHandle belongs into the set. Predicts if a put would succeed.
   *
   * @param handle the handle to test.
   * @return true if a put would succeed, false otherwise.
   */

  public boolean test(NodeHandle handle) {
    Id nid = handle.getNodeId();

    if (nid.equals(ln.getNodeId())) {
      return false;
    }

    for (int i = 0; i < theSize; i++) {
      if (nid.equals(nodes[i].getNodeId())) {
        return false;
      }
    }

    if (theSize < nodes.length) {
      return true;
    }

    if (clockwise) {
      if (!nid.isBetween(ln.getNodeId(), nodes[theSize - 1].getNodeId())) {
        return false;
      }
    } else {
      if (!nid.isBetween(nodes[theSize - 1].getNodeId(), ln.getNodeId())) {
        return false;
      }
    }

    return true;
  }

  /**
   * Puts a NodeHandle into the set.
   *
   * @param handle the handle to put.
   * @return true if the put succeeded, false otherwise.
   */

  public boolean put(NodeHandle handle) {
    Id nid = handle.getNodeId();