Method handleLastDataPointQuery

src/tsd/QueryRpc.java:346–511

Processes a last data point query @param tsdb The TSDB to which we belong @param query The HTTP query to parse/respond

(final TSDB tsdb, final HttpQuery query)

   * @param query The HTTP query to parse/respond
   */
  private void handleLastDataPointQuery(final TSDB tsdb, final HttpQuery query) {
    
    final LastPointQuery data_query;
    if (query.method() == HttpMethod.POST) {
      switch (query.apiVersion()) {
      case 0:
      case 1:
        data_query = query.serializer().parseLastPointQueryV1();
        break;
      default: 
        throw new BadRequestException(HttpResponseStatus.NOT_IMPLEMENTED, 
            "Requested API version not implemented", "Version " + 
            query.apiVersion() + " is not implemented");
      }
    } else {
      data_query = this.parseLastPointQuery(tsdb, query);
    }
    
    if (data_query.sub_queries == null || data_query.sub_queries.isEmpty()) {
      throw new BadRequestException(HttpResponseStatus.BAD_REQUEST, 
          "Missing sub queries");
    }
    
    // a list of deferreds to wait on
    final ArrayList<Deferred<Object>> calls = new ArrayList<Deferred<Object>>();
    // final results for serialization
    final List<IncomingDataPoint> results = new ArrayList<IncomingDataPoint>();
    
    /**
     * Used to catch exceptions 
     */
    final class ErrBack implements Callback<Object, Exception> {
      public Object call(final Exception e) throws Exception {
        Throwable ex = e;
        while (ex.getClass().equals(DeferredGroupException.class)) {
          if (ex.getCause() == null) {
            LOG.warn("Unable to get to the root cause of the DGE");
            break;
          }
          ex = ex.getCause();
        }
        if (ex instanceof RuntimeException) {
          throw new BadRequestException(ex);
        } else {
          throw e;
        }
      }
      @Override
      public String toString() {
        return "Error back";
      }
    }
    
    final class FetchCB implements Callback<Deferred<Object>, ArrayList<IncomingDataPoint>> {
      @Override
      public Deferred<Object> call(final ArrayList<IncomingDataPoint> dps) throws Exception {
        synchronized(results) {
          for (final IncomingDataPoint dp : dps) {