gcpastmetadata.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.gc;

import java.io.*;

import rice.p2p.past.*;

/**
 * @(#) GCPastMetadata.java Class which is used as the metadata storage for the
 * GC past implementation. Basically wraps the long timestamp.
 *
 * @version $Id: GCPastMetadata.java 2302 2005-03-11 00:58:26Z jeffh $
 * @author Peter Druschel
 */
public class GCPastMetadata implements Serializable, Comparable {

  // the expiration time
  /**
   * DESCRIBE THE FIELD
   */
  protected long expiration;

  // serialver for backwards compatibility
  private final static long serialVersionUID = -2432306227012003387L;

  /**
   * Constructor.
   *
   * @param expiration DESCRIBE THE PARAMETER
   */
  public GCPastMetadata(long expiration) {
    this.expiration = expiration;
  }

  /**
   * Method which returns the expiration time
   *
   * @return The contained expiration time
   */
  public long getExpiration() {
    return expiration;
  }

  /**
   * Method which sets the expiration time
   *
   * @param expiration The new Expiration value
   * @return DESCRIBE THE RETURN VALUE
   */
  public GCPastMetadata setExpiration(long expiration) {
    return new GCPastMetadata(expiration);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param o DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   */
  public boolean equals(Object o) {
    return ((GCPastMetadata) o).expiration == expiration;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public int hashCode() {
    return (int) expiration;
  }

  /**
   * Comparable, returns -1 if less, 0 if equal, and 1 if greater
   *
   * @param other The object ot compare to
   * @return the comparison
   */
  public int compareTo(Object other) {
    GCPastMetadata metadata = (GCPastMetadata) other;

    if (metadata.expiration > expiration) {
      return -1;
    } else if (metadata.expiration < expiration) {
      return 1;
    } else {
      return 0;
    }
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public String toString() {
    return "GCPMetadata " + expiration;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param ois DESCRIBE THE PARAMETER
   * @exception IOException DESCRIBE THE EXCEPTION
   * @exception ClassNotFoundException DESCRIBE THE EXCEPTION
   */
  private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
    ois.defaultReadObject();

    if (expiration == 1096560000000L) {
      expiration = GCPastImpl.DEFAULT_EXPIRATION;
    }
  }
}