private static Map interpolateMissingPeriods()

in ambari-metrics-timelineservice/src/main/java/org/apache/ambari/metrics/core/timeline/aggregators/AggregatorUtils.java [139:219]
64 lines of code
20 McCabe index (conditional complexity)

  private static Map<Long, Double> interpolateMissingPeriods(TreeMap<Long, Double> metricValues,
                                                             List<Long[]> timeSlices,
                                                             Map<Long, Double> timeSliceValueMap, String type) {
    Map<Long, Double> resultClusterMetricMap = new HashMap<>();

    if (StringUtils.isNotEmpty(type) && "COUNTER".equalsIgnoreCase(type)) {
      //For Counter Based metrics, ok to do interpolation and extrapolation

      List<Long> requiredTimestamps = new ArrayList<>();
      for (Long[] timeSlice : timeSlices) {
        if (!timeSliceValueMap.containsKey(timeSlice[1])) {
          requiredTimestamps.add(timeSlice[1]);
        }
      }
      Map<Long, Double> interpolatedValuesMap = PostProcessingUtil.interpolate(metricValues, requiredTimestamps);

      if (interpolatedValuesMap != null) {
        for (Map.Entry<Long, Double> entry : interpolatedValuesMap.entrySet()) {
          Double interpolatedValue = entry.getValue();

          if (interpolatedValue != null) {
            resultClusterMetricMap.put( entry.getKey(), interpolatedValue);
          } else {
            LOG.debug("Cannot compute interpolated value, hence skipping.");
          }
        }
      }
    } else {
      //For other metrics, ok to do only interpolation

      Double defaultNextSeenValue = null;
      if (MapUtils.isEmpty(timeSliceValueMap) && MapUtils.isNotEmpty(metricValues)) {
        //If no value was found within the start_time based slices, but the metric has value in the server_time range,
        // use that.

        Map.Entry<Long,Double> firstEntry  = metricValues.firstEntry();
        defaultNextSeenValue = firstEntry.getValue();
        LOG.debug("Found a data point outside timeslice range: " + new Date(firstEntry.getKey()) + ": " + defaultNextSeenValue);
      }

      for (int sliceNum = 0; sliceNum < timeSlices.size(); sliceNum++) {
        Long[] timeSlice = timeSlices.get(sliceNum);

        if (!timeSliceValueMap.containsKey(timeSlice[1])) {
          LOG.debug("Found an empty slice : " + new Date(timeSlice[0]) + ", " + new Date(timeSlice[1]));

          Double lastSeenValue = null;
          int index = sliceNum - 1;
          Long[] prevTimeSlice = null;
          while (lastSeenValue == null && index >= 0) {
            prevTimeSlice = timeSlices.get(index--);
            lastSeenValue = timeSliceValueMap.get(prevTimeSlice[1]);
          }

          Double nextSeenValue = null;
          index = sliceNum + 1;
          Long[] nextTimeSlice = null;
          while (nextSeenValue == null && index < timeSlices.size()) {
            nextTimeSlice = timeSlices.get(index++);
            nextSeenValue = timeSliceValueMap.get(nextTimeSlice[1]);
          }

          if (nextSeenValue == null) {
            nextSeenValue = defaultNextSeenValue;
          }

          Double interpolatedValue = PostProcessingUtil.interpolate(timeSlice[1],
            (prevTimeSlice != null ? prevTimeSlice[1] : null), lastSeenValue,
            (nextTimeSlice != null ? nextTimeSlice[1] : null), nextSeenValue);

          if (interpolatedValue != null) {
            LOG.debug("Interpolated value : " + interpolatedValue);
            resultClusterMetricMap.put(timeSlice[1], interpolatedValue);
          } else {
            LOG.debug("Cannot compute interpolated value, hence skipping.");
          }
        }
      }
    }
    return resultClusterMetricMap;
  }