Пример #1
0
  /**
   * Determines whether to remove, forward or to do nothing with the value that is associated with
   * the given valueId.
   */
  private Operation getOperation(Contact node, Contact existing, KUID valueId) {
    // To avoid redundant STORE forward, a node only transfers a value
    // if it is the closest to the key or if its ID is closer than any
    // other ID (except the new closest one of course)
    // TODO: maybe relax this a little bit: what if we're not the closest
    // and the closest is stale?

    int k = KademliaSettings.REPLICATION_PARAMETER.getValue();
    RouteTable routeTable = context.getRouteTable();
    List<Contact> nodes =
        org.limewire.collection.CollectionUtils.toList(
            routeTable.select(valueId, k, SelectMode.ALL));
    Contact closest = nodes.get(0);
    Contact furthest = nodes.get(nodes.size() - 1);

    if (LOG.isDebugEnabled()) {
      LOG.debug(
          MessageFormat.format(
              "node: {0}, existing: {1}, close nodes: {2}", node, existing, nodes));
    }

    //        StringBuilder sb = new StringBuilder();
    //        sb.append("ME: "+context.getLocalNode()+"\n");
    //        sb.append("Them: "+node).append("\n");
    //        sb.append("RT nearest: " + closest).append("\n");
    //        sb.append("RT furthest: " + furthest).append("\n");
    //        sb.append(CollectionUtils.toString(nodes)).append("\n");

    // We store forward if:
    // #1 We're the nearest Node of the k-closest Nodes to
    //    the given valueId
    //
    // #2 We're the second nearest of the k-closest Nodes to
    //    the given valueId AND the other Node is the nearest.
    //    In other words it changed its instance ID 'cause it
    //    was offline for a short period of time or whatsoever.
    //    (see also pre-condition(s) from where we're calling
    //    this method)
    //
    // The first condition applies if the Node is new
    // and we're the closest Node. The second condition
    // applies if the Node has changed it's instanceId.
    // That means we're the second closest and since
    // the other Node has changed its instanceId we must
    // re-send the values
    if (context.isLocalNode(closest)
        || (node.equals(closest) && nodes.size() > 1 && context.isLocalNode(nodes.get(1)))) {

      KUID nodeId = node.getNodeID();
      KUID furthestId = furthest.getNodeID();

      // #3 The other Node must be equal to the furthest Node
      //    or better
      if (nodeId.equals(furthestId) || nodeId.isNearerTo(valueId, furthestId)) {

        //                sb.append("CONDITION B (FORWARD)").append("\n");
        //                sb.append("Local (from): " + context.getLocalNode()).append("\n");
        //                sb.append("Remote (to): " + node).append("\n");
        //                sb.append(CollectionUtils.toString(nodes)).append("\n");
        //                System.out.println(sb.toString());

        if (LOG.isTraceEnabled()) {
          LOG.trace(
              "Node " + node + " is now close enough to a value and we are responsible for xfer");
        }

        return Operation.FORWARD;
      }

      // We remove a value if:
      // #1 The value is stored at k Nodes
      //    (i.e. the total number of Nodes in the DHT
      //     is equal or greater than k. If the DHT has
      //     less than k Nodes then there's no reason to
      //     remove a value)
      //
      // #2 This Node is the furthest of the k-closest Nodes
      //
      // #3 The new Node isn't in our RouteTable yet. That means
      //    adding it will push this Node out of the club of the
      //    k-closest Nodes and makes it the (k+1)-closest Node.
      //
      // #4 The new Node is nearer to the given valueId then
      //    the furthest away Node (we).
    } else if (nodes.size() >= k
        && context.isLocalNode(furthest)
        && (existing == null || existing.isDead())) {

      KUID nodeId = node.getNodeID();
      KUID furthestId = furthest.getNodeID();

      if (nodeId.isNearerTo(valueId, furthestId)) {
        //                sb.append("CONDITION C").append("\n");
        //                sb.append("ME:").append(context.getLocalNode()).append("\n");
        //                sb.append("VALUE:").append(valueId).append("\n");
        //                sb.append("NODE:").append(node).append("\n");
        //                sb.append(CollectionUtils.toString(nodes)).append("\n");
        //                System.out.println(sb.toString());

        return Operation.DELETE;
      }
    }

    return Operation.NOTHING;
  }
Пример #2
0
  /**
   * Adds the given <code>Contact</code> or updates it if it's already in our <code>RouteTable
   * </code>
   */
  private synchronized void addLiveContactInfo(Contact node, DHTMessage message) {

    RouteTable routeTable = context.getRouteTable();

    // If the Node is going to shutdown then don't bother
    // further than this.
    if (node.isShutdown()) {
      if (LOG.isInfoEnabled()) {
        LOG.info(node + " is going to shut down");
      }

      synchronized (routeTable) {
        // Make sure there's an existing Contact in the RouteTable.
        // Otherwise don't bother!
        Contact existing = routeTable.get(node.getNodeID());
        if (node.equals(existing)) {

          // Update the new Contact in the RouteTable and
          // mark it as shutdown
          // mark the existing contact as shutdown if its alive or
          // it will not be removed.
          if (existing.isAlive()) existing.shutdown(true);
          routeTable.add(node);
          node.shutdown(true);
        }
      }
      return;
    }

    // Ignore firewalled Nodes
    if (node.isFirewalled()) {
      if (LOG.isInfoEnabled()) {
        LOG.info(node + " is firewalled");
      }
      return;
    }

    if (ContactUtils.isPrivateAddress(node)) {
      if (LOG.isInfoEnabled()) {
        LOG.info(node + " has a private address");
      }
      return;
    }

    KUID nodeId = node.getNodeID();
    if (context.isLocalNodeID(nodeId)) {

      // This is expected if there's a Node ID collision
      assert (message instanceof PingResponse)
          : "Expected a PingResponse but got a "
              + message.getClass()
              + " from "
              + message.getContact();

      if (LOG.isInfoEnabled()) {
        LOG.info("Looks like our NodeID collides with " + node);
      }

      return;
    }

    if (StoreSettings.STORE_FORWARD_ENABLED.getValue()) {
      // Only do store forward if it is a new node in our routing table
      // (we are (re)connecting to the network) or a node that is reconnecting
      Contact existing = routeTable.get(nodeId);

      if (existing == null
          || existing.isDead()
          || existing.getInstanceID() != node.getInstanceID()) {

        // Store forward only if we're bootstrapped
        if (context.isBootstrapped()) {
          int k = KademliaSettings.REPLICATION_PARAMETER.getValue();
          // we select the 2*k closest nodes in order to also check those values
          // where the local node is part of the k closest to the value but not part
          // of the k closest to the new joining node.
          Collection<Contact> nodes = routeTable.select(nodeId, 2 * k, SelectMode.ALL);

          // Are we one of the K nearest Nodes to the contact?
          if (containsNodeID(nodes, context.getLocalNodeID())) {
            if (LOG.isTraceEnabled()) {
              LOG.trace(
                  "Node "
                      + node
                      + " is new or has changed his instanceID, will check for store forward!");
            }

            forwardOrRemoveValues(node, existing, message);
          }
        }
      }
    }

    // Add the Node to our RouteTable or if it's
    // already there update its timeStamp and whatsoever
    routeTable.add(node);
  }