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app/vmselect/promql: add lifetime(q[d]) function, which returns the lifetime of q over d in seconds.

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This function is useful for determining time series lifetime.
`d` must exceed the expected lifetime of the time series, otherwise
the function would return values close to `d`.
This commit is contained in:
Aliaksandr Valialkin 2019-08-16 11:57:56 +03:00
parent d6b5ed6d39
commit 1c108fc494
2 changed files with 44 additions and 0 deletions
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16
app/vmselect/promql/rollup.go
View file

@ -45,6 +45,7 @@ var rollupFuncs = map[string]newRollupFunc{
"distinct_over_time": newRollupFuncOneArg(rollupDistinct),
"integrate": newRollupFuncOneArg(rollupIntegrate),
"ideriv": newRollupFuncOneArg(rollupIderiv),
"lifetime": newRollupFuncOneArg(rollupLifetime),
"rollup": newRollupFuncOneArg(rollupFake),
"rollup_rate": newRollupFuncOneArg(rollupFake), // + rollupFuncsRemoveCounterResets
"rollup_deriv": newRollupFuncOneArg(rollupFake),
@ -725,6 +726,21 @@ func rollupIderiv(rfa *rollupFuncArg) float64 {
return dv / (float64(dt) * 1e-3)
}
func rollupLifetime(rfa *rollupFuncArg) float64 {
// Calculate the duration between the first and the last data points.
timestamps := rfa.timestamps
if math.IsNaN(rfa.prevValue) {
if len(timestamps) < 2 {
return nan
}
return float64(timestamps[len(timestamps)-1]-timestamps[0]) * 1e-3
}
if len(timestamps) == 0 {
return nan
}
return float64(timestamps[len(timestamps)-1]-rfa.prevTimestamp) * 1e-3
}
func rollupChanges(rfa *rollupFuncArg) float64 {
// There is no need in handling NaNs here, since they must be cleaned up
// before calling rollup funcs.

28
app/vmselect/promql/rollup_test.go
View file

@ -584,6 +584,34 @@ func TestRollupFuncsNoWindow(t *testing.T) {
timestampsExpected := []int64{10, 50, 90, 130}
testRowsEqual(t, values, rc.Timestamps, valuesExpected, timestampsExpected)
})
t.Run("lifetime", func(t *testing.T) {
rc := rollupConfig{
Func: rollupLifetime,
Start: 0,
End: 160,
Step: 40,
Window: 0,
}
rc.Timestamps = getTimestamps(rc.Start, rc.End, rc.Step)
values := rc.Do(nil, testValues, testTimestamps)
valuesExpected := []float64{nan, 0.031, 0.044, 0.04, 0.01}
timestampsExpected := []int64{0, 40, 80, 120, 160}
testRowsEqual(t, values, rc.Timestamps, valuesExpected, timestampsExpected)
})
t.Run("lifetime", func(t *testing.T) {
rc := rollupConfig{
Func: rollupLifetime,
Start: 0,
End: 160,
Step: 40,
Window: 200,
}
rc.Timestamps = getTimestamps(rc.Start, rc.End, rc.Step)
values := rc.Do(nil, testValues, testTimestamps)
valuesExpected := []float64{nan, 0.031, 0.075, 0.115, 0.125}
timestampsExpected := []int64{0, 40, 80, 120, 160}
testRowsEqual(t, values, rc.Timestamps, valuesExpected, timestampsExpected)
})
t.Run("changes", func(t *testing.T) {
rc := rollupConfig{
Func: rollupChanges,