gcpastimpl.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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This software is provided by RICE and the contributors on an "as is"
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********************************************************************************/

package rice.p2p.past.gc;

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

import rice.*;
import rice.Continuation.*;
import rice.environment.Environment;
import rice.environment.logging.Logger;
import rice.p2p.commonapi.*;
import rice.p2p.commonapi.rawserialization.*;
import rice.p2p.past.*;
import rice.p2p.past.messaging.*;
import rice.p2p.past.rawserialization.SocketStrategy;
import rice.p2p.past.gc.messaging.*;
import rice.persistence.*;

/**
 * @(#) GCPastImpl.java This class is an implementation of the GCPast interface,
 * which provides Past services with garbage collection.
 *
 * @version $Id: GCPastImpl.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 * @author Andreas Haeberlen
 */
public class GCPastImpl extends PastImpl implements GCPast {

  /**
   * The real factory, which is not wrapped with a GCIdFactory
   */
  protected IdFactory realFactory;

  // internal tracing stats
  /**
   * DESCRIBE THE FIELD
   */
  public int collected = 0;
  /**
   * DESCRIBE THE FIELD
   */
  public int refreshed = 0;

  /**
   * The default expiration, or when objects inserted with no timeout will
   * expire
   */
  public final static long DEFAULT_EXPIRATION = INFINITY_EXPIRATION;


  /**
   * Constructor for GCPast
   *
   * @param node The node below this Past implementation
   * @param manager The storage manager to be used by Past
   * @param replicas The number of object replicas
   * @param instance The unique instance name of this Past
   * @param policy The policy this past instance should use
   * @param collectionInterval The frequency with which GCPast should collection
   *      local expired objects
   */
  public GCPastImpl(Node node, StorageManager manager, int replicas, String instance, PastPolicy policy, long collectionInterval) {
    this(node, manager, null, replicas, instance, policy, collectionInterval, null);
  }


  /**
   * Constructor for GCPast
   *
   * @param node The node below this Past implementation
   * @param manager The storage manager to be used by Past
   * @param backup The cache used for previously-responsible objects (can be
   *      null)
   * @param replicas The number of object replicas
   * @param instance The unique instance name of this Past
   * @param trash The storage manager to place the deleted objects into (if
   *      null, they are removed)
   * @param policy The policy this past instance should use
   * @param collectionInterval The frequency with which GCPast should collection
   *      local expired objects
   */
  public GCPastImpl(Node node, StorageManager manager, Cache backup, int replicas, String instance, PastPolicy policy, long collectionInterval, StorageManager trash) {
    super(new GCNode(node), manager, backup, replicas, instance, policy, trash);
    this.realFactory = node.getIdFactory();

    endpoint.scheduleMessage(new GCCollectMessage(0, getLocalNodeHandle(), node.getId()), collectionInterval, collectionInterval);
    endpoint.setDeserializer(new GCPastDeserializer());
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public String toString() {
    if (endpoint == null) {
      return super.toString();
    }
    return "GCPastImpl[" + endpoint.getInstance() + "]";
  }

  /**
   * Inserts an object with the given ID into this instance of Past.
   * Asynchronously returns a PastException to command, if the operation was
   * unsuccessful. If the operation was successful, a Boolean[] is returned
   * representing the responses from each of the replicas which inserted the
   * object. This method is equivalent to insert(obj, INFINITY_EXPIRATION,
   * command) as it inserts the object with a timeout value of infinity. This is
   * done for simplicity, as well as backwards-compatibility for applications.
   *
   * @param obj the object to be inserted
   * @param command Command to be performed when the result is received
   */
  public void insert(PastContent obj, Continuation command) {
    insert(obj, INFINITY_EXPIRATION, command);
  }

  /**
   * Inserts an object with the given ID into this instance of Past.
   * Asynchronously returns a PastException to command, if the operation was
   * unsuccessful. If the operation was successful, a Boolean[] is returned
   * representing the responses from each of the replicas which inserted the
   * object. The contract for this method is that the provided object will be
   * stored until the provided expiration time. Thus, if the application
   * determines that it is still interested in this object, it must refresh the
   * object via the refresh() method.
   *
   * @param obj the object to be inserted
   * @param expiration the time until which the object must be stored
   * @param command Command to be performed when the result is received
   */
  public void insert(final PastContent obj, final long expiration, Continuation command) {
    if (logger.level <= Logger.FINE) {
      logger.log("Inserting data of class " + obj.getClass().getName() + " under " + obj.getId().toStringFull());
    }

    doInsert(obj.getId(),
      new MessageBuilder() {
        public PastMessage buildMessage() {
          return new GCInsertMessage(getUID(), obj, expiration, getLocalNodeHandle(), obj.getId());
        }
      }, command,
      socketStrategy.sendAlongSocket(SocketStrategy.TYPE_INSERT, obj));
  }

  /**
   * Updates the objects stored under the provided keys id to expire no earlier
   * than the provided expiration time. Asyncroniously returns the result to the
   * caller via the provided continuation. The result of this operation is an
   * Object[], which is the same length as the input array of Ids. Each element
   * in the array is either Boolean(true), representing that the refresh
   * succeeded for the cooresponding Id, or an Exception describing why the
   * refresh failed. Specifically, the possible exceptions which can be returned
   * are: ObjectNotFoundException - if no object was found under the given key
   * RefreshFailedException - if the refresh operation failed for any other
   * reason (the getMessage() will describe the failure)
   *
   * @param expiration The time to extend the lifetime to
   * @param command Command to be performed when the result is received
   * @param array DESCRIBE THE PARAMETER
   */
  public void refresh(Id[] array, long expiration, Continuation command) {
    long[] expirations = new long[array.length];
    Arrays.fill(expirations, expiration);

    refresh(array, expirations, command);
  }

  /**
   * Updates the objects stored under the provided keys id to expire no earlier
   * than the provided expiration time. Asyncroniously returns the result to the
   * caller via the provided continuation. The result of this operation is an
   * Object[], which is the same length as the input array of Ids. Each element
   * in the array is either Boolean(true), representing that the refresh
   * succeeded for the cooresponding Id, or an Exception describing why the
   * refresh failed. Specifically, the possible exceptions which can be returned
   * are: ObjectNotFoundException - if no object was found under the given key
   * RefreshFailedException - if the refresh operation failed for any other
   * reason (the getMessage() will describe the failure)
   *
   * @param command Command to be performed when the result is received
   * @param array DESCRIBE THE PARAMETER
   * @param expirations DESCRIBE THE PARAMETER
   */
  public void refresh(final Id[] array, long[] expirations, Continuation command) {
    if (logger.level <= Logger.FINE) {
      logger.log("Refreshing " + array.length + " data elements");
    }

    GCIdSet set = new GCIdSet(realFactory);
    for (int i = 0; i < array.length; i++) {
      set.addId(new GCId(array[i], expirations[i]));
    }

    refresh(set,
      new StandardContinuation(command) {
        public void receiveResult(Object o) {
          Object[] result = new Object[array.length];
          Arrays.fill(result, Boolean.TRUE);

          parent.receiveResult(result);
        }
      });
  }

  /**
   * Internal method which actually does the refreshing. Should not be called by
   * external applications.
   *
   * @param ids The ids to refresh
   * @param command The command to return the result to
   */
  protected void refresh(final GCIdSet ids, Continuation command) {
    final Logger logger = environment.getLogManager().getLogger(GCPastImpl.class, instance);
    if (logger.level <= Logger.FINE) {
      logger.log("REFRESH: CALLED WITH " + ids.numElements() + " ELEMENTS");
    }

    if (ids.numElements() == 0) {
      command.receiveResult(new Object[0]);
      return;
    }

    final Id[] array = ids.asArray();
    GCId start = (GCId) array[0];
    if (logger.level <= Logger.FINE) {
      logger.log("REFRESH: GETTINGS ALL HANDLES OF " + start);
    }

    sendRequest(start.getId(), new GCLookupHandlesMessage(getUID(), start.getId(), getLocalNodeHandle(), start.getId()),
      new NamedContinuation("GCLookupHandles for " + start.getId(), command) {
        public void receiveResult(Object o) {
          final NodeHandleSet set = (NodeHandleSet) o;
          final ReplicaMap map = new ReplicaMap();

          if (logger.level <= Logger.FINE) {
            logger.log("REFRESH: GOT " + set + " SET OF HANDLES!");
          }

          endpoint.process(
            new Executable() {
              public Object execute() {
                if (logger.level <= Logger.FINE) {