RepoMirrors
/
prometheus
mirror of https://github.com/prometheus/prometheus
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Handle valid cases of mismatched hints when adding 

Signed-off-by: Trevor Whitney <trevorjwhitney@gmail.com>
This commit is contained in:
Trevor Whitney 2023-03-08 14:58:40 -07:00
parent c3e0a83725
commit b4e324f637
No known key found for this signature in database
GPG Key ID: 78F930867F302694
1 changed files with 33 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
model/histogram/float_histogram.go
View File

@ -192,8 +192,25 @@ func (h *FloatHistogram) Scale(factor float64) *FloatHistogram {
//
// This method returns a pointer to the receiving histogram for convenience.
func (h *FloatHistogram) Add(other *FloatHistogram) *FloatHistogram {
// TODO(trevorwhitney): If other.CounterResetHint != h.CounterResetHint then
// we should return some warning.
if other.CounterResetHint != h.CounterResetHint {
// The outcome of adding an increment to a guage histogram will always be a GaugeType
if other.CounterResetHint == GaugeType && h.CounterResetHint != GaugeType {
h.CounterResetHint = GaugeType
}
// This could be legitime if the caller knows what they are doing, but the resulting hint
// must be UnknownCounterReset.
if other.CounterResetHint == UnknownCounterReset && h.CounterResetHint != GaugeType {
h.CounterResetHint = UnknownCounterReset
}
// TODO(trevorwhitney): this leaves CounterReset and NotCounterReset. If we have mismatch of
// these hints, that cannot be right, and we should raise a warning when possible.
// if other.CounterResetHint == CounterReset && h.CounterResetHint == NotCounterReset ||
// other.CounterResetHint == NotCounterReset && h.CounterResetHint == CounterReset {
// }
}
otherZeroCount := h.reconcileZeroBuckets(other)
h.ZeroCount += otherZeroCount
h.Count += other.Count
@ -416,6 +433,10 @@ func (h *FloatHistogram) Compact(maxEmptyBuckets int) *FloatHistogram {
// of observations, but NOT the sum of observations) is smaller in the receiving
// histogram compared to the previous histogram. Otherwise, it returns false.
//
// This method will shortcut to true if a CounterReset is detected, and shortcut
// to false if NotCounterReset is detected. Otherwise it will do the work to detect
// a reset.
//
// Special behavior in case the Schema or the ZeroThreshold are not the same in
// both histograms:
//
@ -434,11 +455,6 @@ func (h *FloatHistogram) Compact(maxEmptyBuckets int) *FloatHistogram {
// - Upon a decrease of the Schema, the buckets of the previous histogram are
// merged so that they match the new, lower-resolution schema (again without
// mutating the provided previous histogram).
//
// Note that this kind of reset detection is quite expensive. Ideally, resets
// are detected at ingest time and stored in the TSDB, so that the reset
// information can be read directly from there rather than be detected each time
// again.
func (h *FloatHistogram) DetectReset(previous *FloatHistogram) bool {
if h.CounterResetHint == CounterReset {
return true
@ -446,9 +462,16 @@ func (h *FloatHistogram) DetectReset(previous *FloatHistogram) bool {
if h.CounterResetHint == NotCounterReset {
return false
}
// In all other cases of CounterResetHint, we go on as we would otherwise.
// Even in the GaugeHistogram case, we pretend this is a counter histogram
// for consistency.
// In all other cases of CounterResetHint (UnknownCounterReset and GaugeType),
// we go on as we would otherwise, for reasons explained below.
//
// If the CounterResetHint is UnknownCounterReset, we do not know yet if this histogram comes
// with a counter reset. Therefore, we have to do all the detailed work to find out if there
// is a counter reset or not.
// We do the same if the CounterResetHint is GaugeType, which should not happen, but PromQL still
// allows the user to apply functions to gauge histograms that are only meant for counter histograms.
// In this case, we treat the gauge histograms as a counter histograms
// (and we plan to return a warning about it to the user).
if h.Count < previous.Count {
return true
}