insertmessage.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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********************************************************************************/

package rice.p2p.past.messaging;

import java.io.IOException;

import rice.*;
import rice.p2p.commonapi.*;
import rice.p2p.commonapi.rawserialization.*;
import rice.p2p.past.*;
import rice.p2p.past.rawserialization.*;

/**
 * @(#) InsertMessage.java This class represents a message which is an insert
 * request in past.
 *
 * @version $Id: InsertMessage.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 * @author Ansley Post
 * @author Peter Druschel
 */
public class InsertMessage extends ContinuationMessage {

  // the data to insert
  /**
   * DESCRIBE THE FIELD
   */
  protected RawPastContent content;
  /**
   * DESCRIBE THE FIELD
   */
  public final static short TYPE = 4;

  // serailver for bward compatibility
  final static long serialVersionUID = -7027957470028259605L;

  /**
   * Constructor which takes a unique integer Id, as well as the data to be
   * stored
   *
   * @param uid The unique id
   * @param content The content to be inserted
   * @param source The source address
   * @param dest The destination address
   */
  public InsertMessage(int uid, PastContent content, NodeHandle source, Id dest) {
    this(uid, content instanceof RawPastContent ? (RawPastContent) content : new JavaSerializedPastContent(content), source, dest);
  }

  /**
   * Constructor for InsertMessage.
   *
   * @param uid DESCRIBE THE PARAMETER
   * @param content DESCRIBE THE PARAMETER
   * @param source DESCRIBE THE PARAMETER
   * @param dest DESCRIBE THE PARAMETER
   */
  public InsertMessage(int uid, RawPastContent content, NodeHandle source, Id dest) {
    super(uid, source, dest);

    this.content = content;
  }

  /**
   * Constructor for InsertMessage.
   *
   * @param buf DESCRIBE THE PARAMETER
   * @param endpoint DESCRIBE THE PARAMETER
   * @param pcd DESCRIBE THE PARAMETER
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  protected InsertMessage(InputBuffer buf, Endpoint endpoint, PastContentDeserializer pcd) throws IOException {
    super(buf, endpoint);

    if (serType == S_SUB) {
      response = new Boolean(buf.readBoolean());
    }

    // this can be done lazilly to be more efficient, must cache remaining bits, endpoint, cd, and implement own InputBuffer
    if (buf.readBoolean()) {
      short contentType = buf.readShort();
      if (contentType == 0) {
        content = new JavaSerializedPastContent(pcd.deserializePastContent(buf, endpoint, contentType));
      } else {
        content = (RawPastContent) pcd.deserializePastContent(buf, endpoint, contentType);
      }
    }
  }

  /**
   * Method which returns the content
   *
   * @return The contained content
   */
  public PastContent getContent() {
//  if (content == null)
    if (content.getType() == 0) {
      return ((JavaSerializedPastContent) content).getContent();
    }
    return content;
  }

  /**
   * Raw Serialization **************************************
   *
   * @return The Type value
   */
  public short getType() {
    return TYPE;
  }

  /**
   * Method which builds a response for this message, using the provided object
   * as a result.
   *
   * @param o The object argument
   */
  public void receiveResult(Object o) {
    super.receiveResult(o);
    content = null;
  }

  /**
   * Method which builds a response for this message, using the provided
   * exception, which was thrown
   *
   * @param e The exception argument
   */
  public void receiveException(Exception e) {
    super.receiveException(e);
    content = null;
  }

  /**
   * Returns a string representation of this message
   *
   * @return A string representing this message
   */
  public String toString() {
    return "[InsertMessage for " + content + "]";
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param buf DESCRIBE THE PARAMETER
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public void serialize(OutputBuffer buf) throws IOException {
    buf.writeByte((byte) 0);
    // version
    serializeHelper(buf);
  }

  /**
   * So that it can be subclassed without serializing a version here
   *
   * @param buf
   * @throws IOException
   */
  protected void serializeHelper(OutputBuffer buf) throws IOException {
    if (response != null && response instanceof Boolean) {
      super.serialize(buf, false);
      buf.writeBoolean(((Boolean) response).booleanValue());
    } else {
      super.serialize(buf, true);
    }

    buf.writeBoolean(content != null);
    if (content != null) {
      buf.writeShort(content.getType());
      content.serialize(buf);
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param buf DESCRIBE THE PARAMETER
   * @param endpoint DESCRIBE THE PARAMETER
   * @param pcd DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public static InsertMessage build(InputBuffer buf, Endpoint endpoint, PastContentDeserializer pcd) throws IOException {
    byte version = buf.readByte();
    switch (version) {
      case 0:
        return new InsertMessage(buf, endpoint, pcd);
      default:
        throw new IOException("Unknown Version: " + version);
    }
  }
}