Class Scale

src/query/expression/Scale.java:28–110

Multiplies each data point in the series by the given factor. @since 2.3

 * @since 2.3
 */
public class Scale implements Expression {
  
  @Override
  public DataPoints[] evaluate(final TSQuery data_query, 
      final List<DataPoints[]> query_results, final List<String> params) {
    if (data_query == null) {
      throw new IllegalArgumentException("Missing time series query");
    }
    if (query_results == null || query_results.isEmpty()) {
      return new DataPoints[]{};
    }
    if (params == null || params.isEmpty()) {
      throw new IllegalArgumentException("Missing scaling factor");
    }

    double scale_factor = 0; // zero is fine, if useless *shrug*
    final String factor = params.get(0);
    if (factor != null && factor.matches("^[-0-9\\.]+$")) {
      try {
        scale_factor = Double.parseDouble(factor);
      } catch (NumberFormatException nfe) {
        throw new IllegalArgumentException(
            "Invalid parameter, must be an integer or floating point", nfe);
      }
    } else {
      throw new IllegalArgumentException("Unparseable scale factor value: " 
          + scale_factor);
    }
    
    int num_results = 0;
    for (DataPoints[] results: query_results) {
      num_results += results.length;
    }
    
    final DataPoints[] results = new DataPoints[num_results];
    int ix = 0;
    // one or more sub queries (m=...&m=...&m=...)
    for (final DataPoints[] sub_query_result : query_results) {
      // group bys (m=sum:foo{host=*})
      for (final DataPoints dps : sub_query_result) {
        results[ix++] = scale(dps, scale_factor);
      }
    }
    return results;
  }
  
  /**
   * Multiplies each data point in the series by the scale factor, maintaining
   * integers if both the data point and scale are integers.
   * @param points The data points to factor
   * @param scale_factor The factor to multiply by
   * @return The resulting data points
   */
  private DataPoints scale(final DataPoints points, final double scale_factor) {
    // TODO(cl) - Using an array as the size function may not return the exact
    // results and we should figure a way to avoid copying data anyway.
    final List<DataPoint> dps = new ArrayList<DataPoint>();
    final boolean scale_is_int = (scale_factor == Math.floor(scale_factor)) &&