Example #1
0
    /**
     * Merge all MergeData. All MergeData elements should be disjunct (both views and digests).
     * However, this method is prepared to resolve duplicate entries (for the same member).
     * Resolution strategy for views is to merge only 1 of the duplicate members. Resolution
     * strategy for digests is to take the higher seqnos for duplicate digests.
     *
     * <p>After merging all members into a Membership and subsequent sorting, the first member of
     * the sorted membership will be the new coordinator. This method has a lock on merge_rsps.
     *
     * @param merge_rsps A list of MergeData items. Elements with merge_rejected=true were removed
     *     before. Is guaranteed not to be null and to contain at least 1 member.
     */
    private MergeData consolidateMergeData(List<MergeData> merge_rsps) {
      long logical_time = 0; // for new_vid
      List<View> subgroups =
          new ArrayList<View>(11); // contains a list of Views, each View is a subgroup
      Collection<Collection<Address>> sub_mbrships = new ArrayList<Collection<Address>>();

      for (MergeData tmp_data : merge_rsps) {
        View tmp_view = tmp_data.getView();
        if (tmp_view != null) {
          ViewId tmp_vid = tmp_view.getVid();
          if (tmp_vid != null) {
            // compute the new view id (max of all vids +1)
            logical_time = Math.max(logical_time, tmp_vid.getId());
          }
          // merge all membership lists into one (prevent duplicates)
          sub_mbrships.add(new ArrayList<Address>(tmp_view.getMembers()));
          subgroups.add(tmp_view.copy());
        }
      }

      // determine the new digest
      Digest new_digest = consolidateDigests(merge_rsps, merge_rsps.size());
      if (new_digest == null) return null;

      // remove all members from the new member list that are not in the digest
      Collection<Address> digest_mbrs = new_digest.getMembers();
      for (Collection<Address> coll : sub_mbrships) coll.retainAll(digest_mbrs);

      List<Address> merged_mbrs = gms.computeNewMembership(sub_mbrships);

      // the new coordinator is the first member of the consolidated & sorted membership list
      Address new_coord = merged_mbrs.isEmpty() ? null : merged_mbrs.get(0);
      if (new_coord == null) return null;

      // should be the highest view ID seen up to now plus 1
      ViewId new_vid = new ViewId(new_coord, logical_time + 1);

      // determine the new view
      MergeView new_view = new MergeView(new_vid, merged_mbrs, subgroups);

      if (log.isTraceEnabled())
        log.trace(
            gms.local_addr
                + ": consolidated view="
                + new_view
                + "\nconsolidated digest="
                + new_digest);
      return new MergeData(gms.local_addr, new_view, new_digest);
    }
Example #2
0
  public void handleMembershipChange(Collection<Request> requests) {
    boolean joinAndStateTransferInitiated = false;
    boolean useFlushIfPresent = gms.use_flush_if_present;
    Collection<Address> new_mbrs = new LinkedHashSet<>(requests.size());
    Collection<Address> suspected_mbrs = new LinkedHashSet<>(requests.size());
    Collection<Address> leaving_mbrs = new LinkedHashSet<>(requests.size());

    boolean self_leaving = false; // is the coord leaving

    for (Request req : requests) {
      switch (req.type) {
        case Request.JOIN:
          new_mbrs.add(req.mbr);
          if (req.useFlushIfPresent) useFlushIfPresent = true;
          break;
        case Request.JOIN_WITH_STATE_TRANSFER:
          new_mbrs.add(req.mbr);
          joinAndStateTransferInitiated = true;
          if (req.useFlushIfPresent) useFlushIfPresent = true;
          break;
        case Request.LEAVE:
          if (req.suspected) suspected_mbrs.add(req.mbr);
          else {
            leaving_mbrs.add(req.mbr);
            if (gms.local_addr != null && gms.local_addr.equals(req.mbr)) self_leaving = true;
          }
          break;
        case Request.SUSPECT:
          suspected_mbrs.add(req.mbr);
          break;
      }
    }

    new_mbrs.remove(gms.local_addr); // remove myself - cannot join myself (already joined)

    if (gms.getViewId() == null) {
      // we're probably not the coord anymore (we just left ourselves), let someone else do it
      // (client will retry when it doesn't get a response)
      log.debug(
          "gms.view_id is null, I'm not the coordinator anymore (leaving=%b); "
              + "the new coordinator will handle the leave request",
          self_leaving);
      return;
    }

    List<Address> current_members = gms.members.getMembers();
    leaving_mbrs.retainAll(
        current_members); // remove all elements of leaving_mbrs which are not current members
    if (suspected_mbrs.remove(gms.local_addr))
      log.warn("I am the coord and I'm being suspected -- will probably leave shortly");

    suspected_mbrs.retainAll(
        current_members); // remove all elements of suspected_mbrs which are not current members

    // for the members that have already joined, return the current digest and membership
    for (Iterator<Address> it = new_mbrs.iterator(); it.hasNext(); ) {
      Address mbr = it.next();
      if (gms.members.contains(mbr)) { // already joined: return current digest and membership
        log.trace(
            "%s: %s already present; returning existing view %s", gms.local_addr, mbr, gms.view);
        Tuple<View, Digest> tuple = gms.getViewAndDigest();
        if (tuple != null) gms.sendJoinResponse(new JoinRsp(tuple.getVal1(), tuple.getVal2()), mbr);
        else
          log.warn(
              "%s: did not find a digest matching view %s; dropping JOIN-RSP",
              gms.local_addr, gms.view);
        it
            .remove(); // remove it anyway, even if we didn't find a digest matching the view
                       // (joiner will retry)
      }
    }

    if (new_mbrs.isEmpty() && leaving_mbrs.isEmpty() && suspected_mbrs.isEmpty()) {
      log.trace("%s: found no members to add or remove, will not create new view", gms.local_addr);
      return;
    }

    View new_view = gms.getNextView(new_mbrs, leaving_mbrs, suspected_mbrs);

    if (new_view.size() == 0
        && gms.local_addr != null
        && gms.local_addr.equals(new_view.getCreator())) {
      if (self_leaving) gms.initState(); // in case connect() is called again
      return;
    }

    log.trace(
        "%s: joiners=%s, suspected=%s, leaving=%s, new view: %s",
        gms.local_addr, new_mbrs, suspected_mbrs, leaving_mbrs, new_view);

    JoinRsp join_rsp = null;
    boolean hasJoiningMembers = !new_mbrs.isEmpty();
    try {
      boolean successfulFlush =
          !useFlushIfPresent || !gms.flushProtocolInStack || gms.startFlush(new_view);
      if (!successfulFlush && hasJoiningMembers) {
        // Don't send a join response if the flush fails
        // (http://jira.jboss.org/jira/browse/JGRP-759)
        // The joiner should block until the previous FLUSH completed
        sendLeaveResponses(leaving_mbrs); // we still have to send potential leave responses
        // but let the joining client timeout and send another join request
        return;
      }

      // we cannot garbage collect during joining a new member *if* we're the only member
      // Example: {A}, B joins, after returning JoinRsp to B, A garbage collects messages higher
      // than those
      // in the digest returned to the client, so the client will *not* be able to ask for
      // retransmission
      // of those messages if he misses them
      if (hasJoiningMembers) {
        gms.getDownProtocol().down(new Event(Event.SUSPEND_STABLE, MAX_SUSPEND_TIMEOUT));
        // create a new digest, which contains the new members, minus left members
        MutableDigest join_digest =
            new MutableDigest(new_view.getMembersRaw()).set(gms.getDigest());
        for (Address member : new_mbrs)
          join_digest.set(member, 0, 0); // ... and set the new members. their first seqno will be 1

        // If the digest from NAKACK doesn't include all members of the view, we try once more; if
        // it is still
        // incomplete, we don't send a JoinRsp back to the joiner(s). This shouldn't be a problem as
        // they will retry
        if (join_digest.allSet() || join_digest.set(gms.getDigest()).allSet())
          join_rsp = new JoinRsp(new_view, join_digest);
        else
          log.warn(
              "%s: digest does not match view (missing seqnos for %s); dropping JOIN-RSP",
              gms.local_addr, Arrays.toString(join_digest.getNonSetMembers()));
      }

      sendLeaveResponses(leaving_mbrs); // no-op if no leaving members

      // we don't need to send the digest to existing members:
      // https://issues.jboss.org/browse/JGRP-1317
      gms.castViewChange(new_view, null, new_mbrs);
      gms.sendJoinResponses(join_rsp, new_mbrs);
    } finally {
      if (hasJoiningMembers) gms.getDownProtocol().down(new Event(Event.RESUME_STABLE));
      if (!joinAndStateTransferInitiated && useFlushIfPresent) gms.stopFlush();
      if (self_leaving) gms.initState(); // in case connect() is called again
    }
  }