scribeimpl.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.scribe;

import java.io.IOException;
import java.util.*;
import java.util.prefs.*;

import rice.*;
import rice.environment.Environment;
import rice.environment.logging.Logger;
import rice.environment.params.Parameters;
import rice.p2p.commonapi.*;
import rice.p2p.commonapi.rawserialization.*;
import rice.p2p.scribe.messaging.*;
import rice.p2p.scribe.rawserialization.*;

/**
 * @(#) ScribeImpl.java Thie provided implementation of Scribe.
 *
 * @version $Id: ScribeImpl.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 */
public class ScribeImpl implements Scribe, Application {

  /**
   * The interval with which to perform maintenance
   */
  public final int MAINTENANCE_INTERVAL;

  /**
   * the timeout for a subscribe message
   */
  public final int MESSAGE_TIMEOUT;

  /**
   * the hashtable of topic -> TopicManager
   */
  public Hashtable topics;

  /**
   * this scribe's policy
   */
  protected ScribePolicy policy;

  /**
   * this application's endpoint
   */
  protected Endpoint endpoint;

  /**
   * the local node handle
   */
  protected NodeHandle handle;

  /**
   * the hashtable of outstanding messages
   */
  private Hashtable outstanding;

  /**
   * The hashtable of outstanding lost messags
   */
  private Hashtable lost;

  /**
   * the next unique id
   */
  private int id;

  Environment environment;

  Logger logger;

  private String instance;

  ScribeContentDeserializer contentDeserializer;

  /**
   * Constructor for Scribe, using the default policy.
   *
   * @param node The node below this Scribe implementation
   * @param instance The unique instance name of this Scribe
   */
  public ScribeImpl(Node node, String instance) {
    this(node, new ScribePolicy.DefaultScribePolicy(node.getEnvironment()), instance);
  }

  /**
   * Constructor for Scribe
   *
   * @param node The node below this Scribe implementation
   * @param policy The policy for this Scribe
   * @param instance The unique instance name of this Scribe
   */
  public ScribeImpl(Node node, ScribePolicy policy, String instance) {
    this.environment = node.getEnvironment();
    logger = environment.getLogManager().getLogger(ScribeImpl.class, instance);

    Parameters p = environment.getParameters();
    MAINTENANCE_INTERVAL = p.getInt("p2p_scribe_maintenance_interval");
    MESSAGE_TIMEOUT = p.getInt("p2p_scribe_message_timeout");
    this.instance = instance;
    this.endpoint = node.buildEndpoint(this, instance);
    this.contentDeserializer = new JavaScribeContentDeserializer();
    this.endpoint.setDeserializer(
      new MessageDeserializer() {

        public Message deserialize(InputBuffer buf, short type, byte priority,
                                   NodeHandle sender) throws IOException {
          try {
            switch (type) {
              case AnycastMessage.TYPE:
                return AnycastMessage.build(buf, endpoint, contentDeserializer);
              case SubscribeMessage.TYPE:
                return SubscribeMessage.buildSM(buf, endpoint, contentDeserializer);
              case SubscribeAckMessage.TYPE:
                return SubscribeAckMessage.build(buf, endpoint);
              case SubscribeFailedMessage.TYPE:
                return SubscribeFailedMessage.build(buf, endpoint);
              case DropMessage.TYPE:
                return DropMessage.build(buf, endpoint);
              case PublishMessage.TYPE:
                return PublishMessage.build(buf, endpoint, contentDeserializer);
              case PublishRequestMessage.TYPE:
                return PublishRequestMessage.build(buf, endpoint, contentDeserializer);
              case UnsubscribeMessage.TYPE:
                return UnsubscribeMessage.build(buf, endpoint);
            }
          } catch (IOException e) {
            if (logger.level <= Logger.SEVERE) {
              logger.log("Exception in deserializer in " + ScribeImpl.this.endpoint.toString() + ":" + ScribeImpl.this.instance + " " + contentDeserializer + " " + e);
            }
            throw e;
          }
          throw new IllegalArgumentException("Unknown type:" + type);
        }

      });
    this.topics = new Hashtable();
    this.outstanding = new Hashtable();
    this.lost = new Hashtable();
    this.policy = policy;
    this.handle = endpoint.getLocalNodeHandle();
    this.id = Integer.MIN_VALUE;

    endpoint.register();

    // schedule the period liveness checks of the parent
    endpoint.scheduleMessage(new MaintenanceMessage(), environment.getRandomSource().nextInt(MAINTENANCE_INTERVAL), MAINTENANCE_INTERVAL);

    if (logger.level <= Logger.FINER) {
      logger.log(endpoint.getId() + ": Starting up Scribe");
    }
  }

  /**
   * Gets the Environment attribute of the ScribeImpl object
   *
   * @return The Environment value
   */
  public Environment getEnvironment() {
    return environment;
  }

  /**
   * Returns the current policy for this scribe object
   *
   * @return The current policy for this scribe
   */
  public ScribePolicy getPolicy() {
    return policy;
  }

  /**
   * Returns the Id of the local node
   *
   * @return The Id of the local node
   */
  public Id getId() {
    return endpoint.getId();
  }

  /**
   * Returns the list of clients for a given topic
   *
   * @param topic The topic to return the clients of
   * @return The clients of the topic
   */
  public ScribeClient[] getClients(Topic topic) {
    if (topics.get(topic) != null) {
      return ((TopicManager) topics.get(topic)).getClients();
    }

    return new ScribeClient[0];
  }

  /**
   * Returns the list of children for a given topic
   *
   * @param topic The topic to return the children of
   * @return The children of the topic
   */
  public NodeHandle[] getChildren(Topic topic) {
    if (topics.get(topic) != null) {
      return ((TopicManager) topics.get(topic)).getChildren();
    }

    return new NodeHandle[0];
  }

  /**
   * Returns the parent for a given topic
   *
   * @param topic The topic to return the parent of
   * @return The parent of the topic
   */
  public NodeHandle getParent(Topic topic) {
    if (topics.get(topic) != null) {
      return ((TopicManager) topics.get(topic)).getParent();
    }

    return null;
  }

  /**
   * Returns whether or not this Scribe is the root for the given topic
   *
   * @param topic The topic in question
   * @return Whether or not we are currently the root
   */
  public boolean isRoot(Topic topic) {
    NodeHandleSet set = endpoint.replicaSet(topic.getId(), 1);

    if (set.size() == 0) {
      return false;
    } else {
      return set.getHandle(0).getId().equals(endpoint.getId());
    }
  }

  /**
   * Returns the list of topics the given client is subscribed to.
   *
   * @param client The client in question
   * @return The list of topics
   */
  public Topic[] getTopics(ScribeClient client) {
    Vector result = new Vector();

    Enumeration e = topics.keys();

    while (e.hasMoreElements()) {
      Topic topic = (Topic) e.nextElement();
      if (((TopicManager) topics.get(topic)).containsClient(client)) {
        result.add(topic);
      }
    }

    return (Topic[]) result.toArray(new Topic[0]);
  }

  /**
   * Sets the current policy for this scribe object
   *
   * @param policy The current policy for this scribe
   */
  public void setPolicy(ScribePolicy policy) {
    this.policy = policy;
  }

  /**
   * Sets the ContentDeserializer attribute of the ScribeImpl object
   *
   * @param deserializer The new ContentDeserializer value
   */
  public void setContentDeserializer(ScribeContentDeserializer deserializer) {
    contentDeserializer = deserializer;
  }

  /**
   * Internal method for sending a subscribe message
   *
   * @param topic DESCRIBE THE PARAMETER
   * @param client DESCRIBE THE PARAMETER
   * @param content DESCRIBE THE PARAMETER
   */
  private void sendSubscribe(Topic topic, ScribeClient client, RawScribeContent content) {
    sendSubscribe(topic, client, content, null);
  }

  /**
   * Internal method for sending a subscribe message
   *
   * @param topic DESCRIBE THE PARAMETER
   * @param client DESCRIBE THE PARAMETER
   * @param content DESCRIBE THE PARAMETER
   * @param previousParent DESCRIBE THE PARAMETER
   */
  private void sendSubscribe(Topic topic, ScribeClient client, RawScribeContent content, Id previousParent) {
    id++;

    if (logger.level <= Logger.FINEST) {
      logger.log(endpoint.getId() + ": Sending subscribe message for topic " + topic + " client:" + client);
    }
    //logException(Logger.FINEST,"Stack Trace",new Exception("StackTrace"));

    // TODO: This should go to the ScribeImpl
    if (client == null) {
      ScribeClient[] clients = getClients(topic);
      if (clients.length > 0) {
        client = clients[0];
      }
    }

    if (client != null) {
      outstanding.put(new Integer(id), client);
    }

    endpoint.route(topic.getId(), new SubscribeMessage(handle, topic, previousParent, id, content), null);