public static void percentiles()

in spectator-api/src/main/java/com/netflix/spectator/api/histogram/PercentileBuckets.java [181:228]

44 lines of code
9 McCabe index (conditional complexity)


  public static void percentiles(double[] counts, double[] pcts, double[] results) {
    Preconditions.checkArg(counts.length == BUCKET_VALUES.length,
        "counts is not the same size as buckets array");
    Preconditions.checkArg(pcts.length > 0, "pct array cannot be empty");
    Preconditions.checkArg(pcts.length == results.length,
        "pcts is not the same size as results array");

    int lastNonZeroIdx = 0;
    double total = 0.0;
    for (int i = 0; i < counts.length; ++i) {
      double c = counts[i];
      if (c > 0.0 && Double.isFinite(c)) {
        total += c;
        lastNonZeroIdx = i;
      }
    }

    int pctIdx = 0;

    double prev = 0.0;
    double prevP = 0.0;
    long prevB = 0;
    for (int i = 0; i <= lastNonZeroIdx; ++i) {
      double next = prev + counts[i];
      double nextP = 100.0 * next / total;
      long nextB = BUCKET_VALUES[i];
      while (pctIdx < pcts.length && nextP >= pcts[pctIdx]) {
        double f = (pcts[pctIdx] - prevP) / (nextP - prevP);
        if (Double.isNaN(f))
          results[pctIdx] = 0.0;
        else
          results[pctIdx] = f * (nextB - prevB) + prevB;
        ++pctIdx;
      }
      if (pctIdx >= pcts.length) break;
      prev = next;
      prevP = nextP;
      prevB = nextB;
    }

    double nextP = 100.0;
    long nextB = BUCKET_VALUES[lastNonZeroIdx];
    while (pctIdx < pcts.length) {
      double f = (pcts[pctIdx] - prevP) / (nextP - prevP);
      results[pctIdx] = f * (nextB - prevB) + prevB;
      ++pctIdx;
    }
  }