Class Downsampler

src/core/Downsampler.java:28–515

Iterator that downsamples data points using an Aggregator.

 * Iterator that downsamples data points using an {@link Aggregator}.
 */
public class Downsampler implements SeekableView, DataPoint {
  
  /** Matches the weekly downsampler as it requires special handling. */
  protected final static int WEEK_UNIT = DateTime.unitsToCalendarType("w");
  protected final static int DAY_UNIT = DateTime.unitsToCalendarType("d");
  protected final static int WEEK_LENGTH = 7;
  
  /** The downsampling specification when provided */
  protected final DownsamplingSpecification specification;
  
  /** The start timestamp of the actual query for use with "all" */
  protected final long query_start;
  
  /** The end timestamp of the actual query for use with "all" */
  protected final long query_end;
  
  /** The data source */
  protected final SeekableView source;
  
  /** Iterator to iterate the values of the current interval. */
  protected final ValuesInInterval values_in_interval;
  
  /** Last normalized timestamp */ 
  protected long timestamp;
  
  /** Last value as a double */
  protected double value;
  
  /** An optional rollup query. */
  protected RollupQuery rollup_query;
  
  /** Whether or not to merge all DPs in the source into one vaalue */
  protected final boolean run_all;
  
  /** The interval to use with a calendar */
  protected final int interval;
  
  /** The unit to use with a calendar as a Calendar integer */
  protected final int unit;
  
  /**
   * Ctor.
   * @param source The iterator to access the underlying data.
   * @param interval_ms The interval in milli seconds wanted between each data
   * point.
   * @param downsampler The downsampling function to use.
   * @deprecated as of 2.3
   */
  Downsampler(final SeekableView source,
              final long interval_ms,
              final Aggregator downsampler) {
    this.source = source;
    if (downsampler == Aggregators.NONE) {
      throw new IllegalArgumentException("cannot use the NONE "
          + "aggregator for downsampling");
    }
    specification = new DownsamplingSpecification(interval_ms, downsampler, 
        DownsamplingSpecification.DEFAULT_FILL_POLICY);