Method findHistogramSpans

src/core/TsdbQuery.java:926–963

Finds all the HistogramSpans that match this query. This is what actually scans the HBase table and loads the data into HistogramSpans. @return A map from HBase row key to the HistogramSpan for that row key. Since a HistogramSpan actually contains multiple HBase rows

()

   * @throws IllegalArgumentException if bad data was retreived from HBase.
   */
  private Deferred<SortedMap<byte[], HistogramSpan>> findHistogramSpans() throws HBaseException {
    final short metric_width = tsdb.metrics.width();
    final TreeMap<byte[], HistogramSpan> histSpans = new TreeMap<byte[], HistogramSpan>(new SpanCmp(metric_width));
    
    // Copy only the filters that should trigger a tag resolution. If this list
    // is empty due to literals or a wildcard star, then we'll save a TON of
    // UID lookups
    final List<TagVFilter> scanner_filters;
    if (filters != null) {
      scanner_filters = new ArrayList<TagVFilter>(filters.size());
      for (final TagVFilter filter : filters) {
        if (filter.postScan()) {
          scanner_filters.add(filter);
        }
      }
    } else {
      scanner_filters = null;
    }

    scan_start_time = System.nanoTime();
    final List<Scanner> scanners;
    if (Const.SALT_WIDTH() > 0) {
      scanners = new ArrayList<Scanner>(Const.SALT_BUCKETS());
      for (int i = 0; i < Const.SALT_BUCKETS(); i++) {
        scanners.add(getScanner(i));
      }
      scan_start_time = DateTime.nanoTime();
      return new SaltScanner(tsdb, metric, scanners, null, scanner_filters, 
          delete, rollup_query, query_stats, query_index, histSpans, 
          max_bytes, max_data_points).scanHistogram();
    } else {
      scanners = Lists.newArrayList(getScanner());
      scan_start_time = DateTime.nanoTime();
      return new SaltScanner(tsdb, metric, scanners, null, scanner_filters, 
          delete, rollup_query, query_stats, query_index, histSpans, 
          max_bytes, max_data_points).scanHistogram();
    }
  }
  
  private Deferred<SortedMap<byte[], HistogramSpan>> findHistogramSpansWithMultiGetter() throws HBaseException {
    final short metric_width = tsdb.metrics.width();