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

Merge pull request #11295 from dimitarvdimitrov/dimitar/simplify-evalTimestamp 

Simplify rule group's EvalTimestamp formula
This commit is contained in:
Julien Pivotto 2023-07-18 13:21:20 +02:00 committed by GitHub
parent b7028c1722 03ab8dcca0
commit 782e6f64fb
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 17 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
rules/manager.go
View File

@ -560,11 +560,26 @@ func (g *Group) setLastEvalTimestamp(ts time.Time) {
func (g *Group) EvalTimestamp(startTime int64) time.Time { func (g *Group) EvalTimestamp(startTime int64) time.Time {
var ( var (
offset = int64(g.hash() % uint64(g.interval)) offset = int64(g.hash() % uint64(g.interval))
// This group's evaluation times differ from the perfect time intervals by `offset` nanoseconds.
// But we can only use `% interval` to align with the interval. And `% interval` will always
// align with the perfect time intervals, instead of this group's. Because of this we add
// `offset` _after_ aligning with the perfect time interval.
//
// There can be cases where adding `offset` to the perfect evaluation time can yield a
// timestamp in the future, which is not what EvalTimestamp should do.
// So we subtract one `offset` to make sure that `now - (now % interval) + offset` gives an
// evaluation time in the past.
adjNow = startTime - offset adjNow = startTime - offset
base = adjNow - (adjNow % int64(g.interval))
// Adjust to perfect evaluation intervals.
base = adjNow - (adjNow % int64(g.interval))
// Add one offset to randomize the evaluation times of this group.
next = base + offset
) )
return time.Unix(0, base+offset).UTC() return time.Unix(0, next).UTC()
} }
func nameAndLabels(rule Rule) string { func nameAndLabels(rule Rule) string {