@Test
public void calculatesAStdDevOfZeroForASingletonSnapshot() throws Exception {
final Snapshot singleItemSnapshot =
new WeightedSnapshot(WeightedArray(new long[] {1}, new double[] {1.0}));
assertThat(singleItemSnapshot.getStdDev()).isZero();
}
@Test
public void calculatesAStdDevOfZeroForAnEmptySnapshot() throws Exception {
final Snapshot emptySnapshot =
new WeightedSnapshot(WeightedArray(new long[] {}, new double[] {}));
assertThat(emptySnapshot.getStdDev()).isZero();
}
private void collectTimerReports(
List<DBObject> docs, SortedMap<String, Timer> timers, Date timestamp) {
if (timers.isEmpty()) return;
for (Map.Entry<String, Timer> entry : timers.entrySet()) {
final BasicDBObject report = getBasicDBObject(timestamp, entry.getKey(), "timer");
final Timer v = entry.getValue();
final Snapshot s = v.getSnapshot();
// meter part
report.put("count", v.getCount());
report.put("rate-unit", getRateUnit());
report.put("1-minute-rate", convertRate(v.getOneMinuteRate()));
report.put("5-minute-rate", convertRate(v.getFiveMinuteRate()));
report.put("15-minute-rate", convertRate(v.getFifteenMinuteRate()));
report.put("mean-rate", convertRate(v.getMeanRate()));
// histogram part
report.put("duration-unit", getDurationUnit());
report.put("75-percentile", convertDuration(s.get75thPercentile()));
report.put("95-percentile", convertDuration(s.get95thPercentile()));
report.put("98-percentile", convertDuration(s.get98thPercentile()));
report.put("99-percentile", convertDuration(s.get99thPercentile()));
report.put("999-percentile", convertDuration(s.get999thPercentile()));
report.put("max", convertDuration(s.getMax()));
report.put("min", convertDuration(s.getMin()));
report.put("mean", convertDuration(s.getMean()));
report.put("median", convertDuration(s.getMedian()));
report.put("stddev", convertDuration(s.getStdDev()));
docs.add(report);
}
}
private void collectHistogramReports(
List<DBObject> docs, SortedMap<String, Histogram> histograms, Date timestamp) {
if (histograms.isEmpty()) return;
for (Map.Entry<String, Histogram> entry : histograms.entrySet()) {
final BasicDBObject report = getBasicDBObject(timestamp, entry.getKey(), "histogram");
final Histogram histogram = entry.getValue();
final Snapshot s = histogram.getSnapshot();
report.put("count", s.size());
report.put("75th_percentile", s.get75thPercentile());
report.put("95th_percentile", s.get95thPercentile());
report.put("98th_percentile", s.get98thPercentile());
report.put("99th_percentile", s.get99thPercentile());
report.put("999th_percentile", s.get999thPercentile());
report.put("max", s.getMax());
report.put("min", s.getMin());
report.put("mean", s.getMean());
report.put("median", s.getMedian());
report.put("std_dev", s.getStdDev());
docs.add(report);
}
}
@Test
public void calculatesTheStdDev() throws Exception {
assertThat(snapshot.getStdDev()).isEqualTo(1.2688, offset(0.0001));
}