Exemplo n.º 1
0
  private void checkLeadership(List<String> children) throws Exception {
    final String localOurPath = ourPath.get();
    List<String> sortedChildren = LockInternals.getSortedChildren(LOCK_NAME, sorter, children);
    int ourIndex =
        (localOurPath != null) ? sortedChildren.indexOf(ZKPaths.getNodeFromPath(localOurPath)) : -1;
    if (ourIndex < 0) {
      log.error("Can't find our node. Resetting. Index: " + ourIndex);
      reset();
    } else if (ourIndex == 0) {
      setLeadership(true);
    } else {
      String watchPath = sortedChildren.get(ourIndex - 1);
      Watcher watcher =
          new Watcher() {
            @Override
            public void process(WatchedEvent event) {
              if ((state.get() == State.STARTED)
                  && (event.getType() == Event.EventType.NodeDeleted)
                  && (localOurPath != null)) {
                try {
                  getChildren();
                } catch (Exception ex) {
                  log.error("An error occurred checking the leadership.", ex);
                }
              }
            }
          };

      BackgroundCallback callback =
          new BackgroundCallback() {
            @Override
            public void processResult(CuratorFramework client, CuratorEvent event)
                throws Exception {
              if (event.getResultCode() == KeeperException.Code.NONODE.intValue()) {
                // previous node is gone - reset
                reset();
              }
            }
          };
      client
          .checkExists()
          .usingWatcher(watcher)
          .inBackground(callback)
          .forPath(ZKPaths.makePath(latchPath, watchPath));
    }
  }
Exemplo n.º 2
0
  private void checkForLeadership() throws Exception {
    List<String> sortedChildren =
        LockInternals.getSortedChildren(client, latchPath, LOCK_NAME, sorter);
    if (sortedChildren.size() == 0) {
      throw new Exception("no children - unexpected state");
    }

    int ourIndex = sortedChildren.indexOf(ZKPaths.getNodeFromPath(ourPath));
    if (ourIndex == 0) {
      setLeadership(true);
    } else {
      final String ourPathWhenWatched =
          ourPath; // protected against a lost/suspended connection and an old watcher - I'm not
                   // sure if this is possible but it can't hurt
      String watchPath = sortedChildren.get(ourIndex - 1);
      Watcher watcher =
          new Watcher() {
            @Override
            public void process(WatchedEvent event) {
              if ((event.getType() == Event.EventType.NodeDeleted)
                  && (ourPath != null)
                  && ourPath.equals(ourPathWhenWatched)) {
                try {
                  checkForLeadership();
                } catch (Exception ex) {
                  log.error("An error ocurred checking the leadership.", ex);
                }
              }
            }
          };
      if (client.checkExists().usingWatcher(watcher).forPath(ZKPaths.makePath(latchPath, watchPath))
          == null) {
        // the previous Participant may be down, so we need to reevaluate the list
        // to get the actual previous Participant or get the leadership
        checkForLeadership();
      }
    }
  }
Exemplo n.º 3
0
 /**
  * Return the id for the current leader. If for some reason there is no current leader, a dummy
  * participant is returned.
  *
  * <p><B>NOTE</B> - this method polls the ZK server. Therefore it can possibly return a value that
  * does not match {@link #hasLeadership()} as hasLeadership uses a local field of the class.
  *
  * @return leader
  * @throws Exception ZK errors, interruptions, etc.
  */
 public Participant getLeader() throws Exception {
   Collection<String> participantNodes =
       LockInternals.getParticipantNodes(client, latchPath, LOCK_NAME, sorter);
   return LeaderSelector.getLeader(client, participantNodes);
 }