moraine.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.aggregation;

import java.util.Arrays;

import rice.Continuation;
import rice.environment.Environment;
import rice.environment.logging.Logger;
import rice.p2p.commonapi.Id;
import rice.p2p.commonapi.NodeHandle;
import rice.p2p.glacier.VersioningPast;
import rice.p2p.past.Past;
import rice.p2p.past.PastContent;
import rice.p2p.past.PastContentHandle;
import rice.p2p.past.gc.GCPast;
import rice.p2p.past.rawserialization.PastContentDeserializer;
import rice.p2p.past.rawserialization.PastContentHandleDeserializer;

/**
 * This Past takes 2 pasts, an old Past and a new Past. It treats the old Past
 * as a backing store for the new Past. Pretty much it's only going to work with
 * glacier, and maybe aggregation A Moraine is the hill of rubble (aggregate as
 * it were) left behind at the edges of a glacier or at the end of a retreating
 * glacier
 *
 * @version $Id: pretty.settings 2305 2005-03-11 20:22:33Z jeffh $
 * @author jstewart
 */
public class Moraine implements GCPast, VersioningPast {
  /**
   * DESCRIBE THE FIELD
   */
  protected GCPast newPast;
  /**
   * DESCRIBE THE FIELD
   */
  protected GCPast oldPast;
  // convenience variables to prevent casting everywhere
  // identical to the above vars, just different types
  /**
   * DESCRIBE THE FIELD
   */
  protected VersioningPast vNewPast;
  /**
   * DESCRIBE THE FIELD
   */
  protected VersioningPast vOldPast;

  /**
   * DESCRIBE THE FIELD
   */
  protected Logger logger;

  /**
   * Constructor for Moraine.
   *
   * @param newPast DESCRIBE THE PARAMETER
   * @param oldPast DESCRIBE THE PARAMETER
   */
  public Moraine(GCPast newPast, GCPast oldPast) {
    this.newPast = newPast;
    this.oldPast = oldPast;
    this.vNewPast = (VersioningPast) newPast;
    this.vOldPast = (VersioningPast) oldPast;
    this.logger = newPast.getEnvironment().getLogManager().getLogger(Moraine.class, newPast.getInstance());
  }

  /**
   * Gets the LocalNodeHandle attribute of the Moraine object
   *
   * @return The LocalNodeHandle value
   */
  public NodeHandle getLocalNodeHandle() {
    return newPast.getLocalNodeHandle();
  }

  /**
   * Gets the ReplicationFactor attribute of the Moraine object
   *
   * @return The ReplicationFactor value
   */
  public int getReplicationFactor() {
    return newPast.getReplicationFactor();
  }

  /**
   * Gets the Environment attribute of the Moraine object
   *
   * @return The Environment value
   */
  public Environment getEnvironment() {
    return newPast.getEnvironment();
  }

  /**
   * Gets the Instance attribute of the Moraine object
   *
   * @return The Instance value
   */
  public String getInstance() {
    return newPast.getInstance();
  }

  /**
   * Sets the ContentDeserializer attribute of the Moraine object
   *
   * @param deserializer The new ContentDeserializer value
   */
  public void setContentDeserializer(PastContentDeserializer deserializer) {
    newPast.setContentDeserializer(deserializer);
    oldPast.setContentDeserializer(deserializer);
    // XXX maybe force this on the members and just throw an UnsupportedOperationException
  }

  /**
   * Sets the ContentHandleDeserializer attribute of the Moraine object
   *
   * @param deserializer The new ContentHandleDeserializer value
   */
  public void setContentHandleDeserializer(
                                           PastContentHandleDeserializer deserializer) {
    newPast.setContentHandleDeserializer(deserializer);
    oldPast.setContentHandleDeserializer(deserializer);
    // XXX maybe force this on the members and just throw an UnsupportedOperationException
  }

  // --------------------------------------------------------------------------------
  // Past methods

  /**
   * DESCRIBE THE METHOD
   *
   * @param obj DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void insert(PastContent obj, Continuation command) {
    newPast.insert(obj, command);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param id DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void lookup(Id id, Continuation command) {
    // assume caching
    lookup(id, true, command);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param id DESCRIBE THE PARAMETER
   * @param cache DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void lookup(final Id id, final boolean cache, final Continuation command) {
    newPast.lookup(id, cache,
      new Continuation() {
        public void receiveResult(Object result) {
          if (result == null) {
            oldPast.lookup(id, cache,
              new Continuation() {
                public void receiveResult(Object result) {
                  // XXX store the result in newPast
                  command.receiveResult(result);
                }

                public void receiveException(Exception result) {
                  command.receiveException(result);
                }
              });
          } else {
            command.receiveResult(result);
          }
        }

        public void receiveException(Exception result) {
          // XXX do we try the other Past?
          command.receiveException(result);
        }
      });
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param id DESCRIBE THE PARAMETER
   * @param max DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void lookupHandles(final Id id, final int max, final Continuation command) {
    newPast.lookupHandles(id, max,
      new Continuation() {
        public void receiveResult(Object result) {
          Object[] results = (Object[]) result;
          if (results.length == 1 && results[0] == null) {
            oldPast.lookupHandles(id, max, command);
          } else {
            command.receiveResult(result);
          }
        }

        public void receiveException(Exception result) {
          if (logger.level <= Logger.WARNING) {
            logger.logException("in Moraine.lookupHandles, newPast threw up: ", result);
          }
          oldPast.lookupHandles(id, max, command);
        }
      });
  }

  // this is unsupported by Glacier and Aggregation anyway
  /**
   * DESCRIBE THE METHOD
   *
   * @param id DESCRIBE THE PARAMETER
   * @param handle DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void lookupHandle(Id id, NodeHandle handle, Continuation command) {
    command.receiveException(new UnsupportedOperationException("LookupHandle() is not supported on Moraine"));
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param handle DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void fetch(final PastContentHandle handle, final Continuation command) {
    newPast.fetch(handle,
      new Continuation() {
        public void receiveResult(Object result) {
          if (result == null) {
            // XXX store the result of the fetch in the newPast
            oldPast.fetch(handle, command);
          } else {
            command.receiveResult(result);
          }
        }

        public void receiveException(Exception result) {
          // XXX do we try the other Past?
          command.receiveException(result);
        }
      });
  }

  // --------------------------------------------------------------------------------
  // GCPast methods

  /**
   * DESCRIBE THE METHOD
   *
   * @param obj DESCRIBE THE PARAMETER
   * @param expiration DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void insert(PastContent obj, long expiration, Continuation command) {
    newPast.insert(obj, expiration, command);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param ids DESCRIBE THE PARAMETER
   * @param expirations DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void refresh(final Id[] ids, final long[] expirations, final Continuation command) {
    oldPast.refresh(ids, expirations,
      new Continuation() {
        public void receiveResult(Object result) {
          newPast.refresh(ids, expirations, command);
        }

        public void receiveException(Exception result) {
          if (logger.level <= Logger.WARNING) {
            logger.logException("in Moraine.refresh, oldPast threw up: ", result);
          }
          receiveResult(null);
        }
      });
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param ids DESCRIBE THE PARAMETER
   * @param expiration DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void refresh(Id[] ids, long expiration, Continuation command) {
    long[] expirations = new long[ids.length];
    Arrays.fill(expirations, expiration);
    refresh(ids, expirations, command);
  }

  // --------------------------------------------------------------------------------
  // VersioningPast methods

  /**
   * DESCRIBE THE METHOD
   *
   * @param id DESCRIBE THE PARAMETER
   * @param version DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void lookup(final Id id, final long version, final Continuation command) {
    vNewPast.lookup(id, version,
      new Continuation() {
        public void receiveResult(Object result) {
          if (result == null) {
            vOldPast.lookup(id, version,
              new Continuation() {
                public void receiveResult(Object result) {
                  // XXX store the result in newPast
                  command.receiveResult(result);
                }

                public void receiveException(Exception result) {
                  command.receiveException(result);
                }
              });
          } else {
            command.receiveResult(result);
          }
        }

        public void receiveException(Exception result) {
          // XXX do we try the other Past?
          command.receiveException(result);
        }
      });
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param id DESCRIBE THE PARAMETER
   * @param version DESCRIBE THE PARAMETER
   * @param num DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void lookupHandles(final Id id, final long version, final int num, final Continuation command) {
    vNewPast.lookupHandles(id, version, num,
      new Continuation() {
        public void receiveResult(Object result) {
          Object[] results = (Object[]) result;
          if (results.length == 1 && results[0] == null) {
            vOldPast.lookupHandles(id, version, num, command);
          } else {
            command.receiveResult(result);
          }
        }

        public void receiveException(Exception result) {
          if (logger.level <= Logger.WARNING) {
            logger.logException("in Moraine.lookupHandles, newPast threw up: ", result);
          }
          vOldPast.lookupHandles(id, version, num, command);
        }
      });
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param ids DESCRIBE THE PARAMETER
   * @param versions DESCRIBE THE PARAMETER
   * @param expirations DESCRIBE THE PARAMETER
   * @param command DESCRIBE THE PARAMETER
   */
  public void refresh(final Id[] ids, final long[] versions, final long[] expirations, final Continuation command) {
    vOldPast.refresh(ids, versions, expirations,
      new Continuation() {
        public void receiveResult(Object result) {
          vNewPast.refresh(ids, versions, expirations, command);
        }

        public void receiveException(Exception result) {
          if (logger.level <= Logger.WARNING) {
            logger.logException("in Moraine.refresh, oldPast threw up: ", result);
          }
          receiveResult(null);
        }
      });
  }

}