コード例 #1
0
  private DataNodeIdentifier pickReplacement(
      SegmentGroup affectedGroup, DataNodeIdentifier oldNode) {
    DataNodeIdentifier replacementNode = null;
    List<DataNodeStatusPair> removedPairs = new ArrayList<DataNodeStatusPair>();

    while (replacementNode == null) {
      DataNodeStatusPair next = datanodeStatuses.poll();
      removedPairs.add(next);
      DataNodeIdentifier nextId = next.getIdentifier();
      if (!nextId.equals(oldNode) && !affectedGroup.isMember(nextId)) {
        replacementNode = nextId;
      }
    }

    for (DataNodeStatusPair each : removedPairs) {
      datanodeStatuses.add(each);
    }

    return replacementNode;
  }
コード例 #2
0
  @Override
  public void action() {
    /* what do we do? this is what we do...

        while not balanced:
            pick a segment group of the to put the new node in / remove the old node from
            run the reconfigureSegmentGroup() function

        when all reconfiguration is done:
            if (oldNodeIsUp):
                coordinator.attachDatanode(affectedNode)
            else
                coordinator.detachDatanode(affectedNode)

            signal that all reconfiguration is done (set the result and let the handler terminate)
    */

    if (affectedNodeIsUp) {
      server.attachDataNode(affectedNode);
    }

    while (coordinator.startReconfiguration()) {
      // spin!!!
    }

    if (!affectedNodeIsUp) {
      List<SegmentGroup> affectedGroups = volumeTable.getAllSegmentGroupsContaining(affectedNode);

      for (SegmentGroup eachGroup : affectedGroups) {
        DataNodeIdentifier replacementNode = pickReplacement(eachGroup, affectedNode);
        updateStatus(affectedNode, replacementNode);
        reconfigureSegmentGroup(eachGroup, affectedNode, replacementNode, false);
      }
    }

    if (affectedNodeIsUp) {
      System.out.println("Attached the node to the coordinator.");
      coordinator.attachDataNode(affectedNode);
    } else {
      coordinator.detachDataNode(affectedNode);
    }

    /*
        "while not balanced"
        balanced means that all nodes have close to the same number of segment groups assigned
        1. determine appropriate average load range (+- k segments)...
            this could be something like [0.95 * average - 1, 1.05 * average + 1] (the +/- 1 is for
            extremely low-load clusters, where not everything might have an assignment; like when you first
            turn on the cluster)
        2. if any nodes are below the range, assign them to a segment group
           else if any nodes are above the range, remove them from a group
           rinse-and-repeat until the cluster is balanced appropriately
    */

    float numberOfSegmentGroupsAssigned = 0.0f;
    int numberOfNodes = datanodes.size();
    for (DataNodeStatusPair eachPair : datanodeStatuses) {
      DataNodeStatus status = eachPair.getStatus();
      numberOfSegmentGroupsAssigned += status.getSegmentsStored();
    }

    int segmentsPerSegmentGroup = coordinator.getSegmentsPerSegmentGroup();
    float expectedLoad = numberOfSegmentGroupsAssigned / numberOfNodes;
    float lowerBound = (0.99f * expectedLoad) - segmentsPerSegmentGroup;
    float upperBound = (1.01f * expectedLoad) + segmentsPerSegmentGroup;

    System.out.println("lower: " + lowerBound);
    System.out.println("upper: " + upperBound);

    boolean balanced = false;

    while (!balanced) {
      for (DataNodeStatusPair eachPair : datanodeStatuses) {
        DataNodeStatus status = eachPair.getStatus();
        if (status.getSegmentsStored() < lowerBound) {
          DataNodeIdentifier replacementNode = eachPair.getIdentifier();
          DataNodeIdentifier oldNode = pickHeaviestLoad(replacementNode);
          SegmentGroup affectedGroup = volumeTable.getAllSegmentGroupsContaining(oldNode).get(0);
          updateStatus(oldNode, replacementNode);
          // TODO FIXME make this asynchronous so writes can occur concurrently
          System.out.println("Replacing " + oldNode + " with " + replacementNode);
          reconfigureSegmentGroup(affectedGroup, oldNode, replacementNode, true);
          break;
        } else if (status.getSegmentsStored() > upperBound) {
          DataNodeIdentifier oldNode = eachPair.getIdentifier();
          SegmentGroup affectedGroup = volumeTable.getAllSegmentGroupsContaining(oldNode).get(0);
          DataNodeIdentifier replacementNode = pickReplacement(affectedGroup, oldNode);
          updateStatus(oldNode, replacementNode);
          // TODO FIXME make this asynchronous so writes can occur concurrently
          System.out.println("Replacing " + oldNode + " with " + replacementNode);
          reconfigureSegmentGroup(affectedGroup, oldNode, replacementNode, true);
          break;
        } else {
          balanced = true;
        }
      }
    }

    coordinator.finishReconfiguration();

    requestResult = new ReconfigurationRequestResult(requestId, true, true);
    coordinator.setRequestResult(requestId, (RequestResult) requestResult);
  }
コード例 #3
0
  protected void reconfigureSegmentGroup(
      SegmentGroup affectedGroup,
      DataNodeIdentifier oldNode,
      DataNodeIdentifier replacementNode,
      boolean oldNodeIsUp) {
    System.out.println("Reconfiguring");
    /* what do we do? this is what we do...
        note: we do NOT worry about the status of the node here; we assume that is set by the coordinator

        for each segment in the segment group:
            if (oldNodeIsUp):
                send an unset-segment request
            perform a read on the segment group
            send a write request to the new node

        swap the new node into the segment group
    */

    int volumeId = affectedGroup.getVolumeId();
    long startingOffset = affectedGroup.getStartingBlock();
    long stoppingOffset = affectedGroup.getStoppingBlock();

    if (oldNodeIsUp) {
      List<DataNodeIdentifier> targets = new ArrayList<DataNodeIdentifier>();
      targets.add(oldNode);
      int unsetId =
          coordinator
              .getServer()
              .issueUnsetSegmentRequest(targets, volumeId, startingOffset, stoppingOffset);

      boolean waiting = true;

      while (waiting) {
        List<UnsetSegmentRequestResult> results =
            coordinator.getServer().getUnsetSegmentRequestResults(unsetId);
        if (results.get(0).wasSuccessful()) {
          waiting = false;
        }
      }
    }

    List<DataNodeIdentifier> replacementMembers =
        new ArrayList<DataNodeIdentifier>(affectedGroup.getMembers());
    int oldNodeIndex = replacementMembers.indexOf(oldNode);
    replacementMembers.set(oldNodeIndex, replacementNode);
    SegmentGroup replacementGroup =
        new SegmentGroup(replacementMembers, volumeId, startingOffset, stoppingOffset);

    for (long offset = startingOffset; offset <= stoppingOffset; ++offset)
    // TODO FIXME eventual improvement: make this whole loop asynchronous
    // that is, issue each read request, then as the results come in, issue the write requests
    {
      int readId = coordinator.read(volumeId, logicalOffset);
      while (!coordinator.requestFinished(readId)) {
        // spin!!!
      }

      ReadRequestResult readResult = coordinator.readResult(readId);
      byte[] block = readResult.getBlock();

      int writeId = coordinator.writeWithTarget(replacementGroup, volumeId, offset, block);
      while (!coordinator.requestFinished(writeId)) {
        // spin!!!
      }

      // TODO FIXME check for success of the read (above) and the write (here)
    }

    affectedGroup.replace(oldNode, replacementNode);
  }