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chore(promql): improve doc string in promql/durations.go (#16863)

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Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
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George Krajcsovits 2025-07-11 12:07:54 +02:00 committed by GitHub
parent a740285601
commit 4662722a8e
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1 changed files with 12 additions and 2 deletions
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14
promql/durations.go
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@ -21,11 +21,20 @@ import (
"github.com/prometheus/prometheus/promql/parser"
)
// durationVisitor is a visitor that visits a duration expression and calculates the duration.
// durationVisitor is a visitor that calculates the actual value of
// duration expressions in AST nodes. For example the query
// "http_requests_total offset (1h / 2)" is represented in the AST
// as a VectorSelector with OriginalOffset 0 and the duration expression
// in OriginalOffsetExpr representing (1h / 2). This visitor evaluates
// such duration expression, setting OriginalOffset to 30m.
type durationVisitor struct {
step time.Duration
}
// Visit finds any duration expressions in AST Nodes and modifies the Node to
// store the concrete value. Note that parser.Walk does NOT traverse the
// duration expressions such as OriginalOffsetExpr so we make our own recursive
// call on those to evaluate the result.
func (v *durationVisitor) Visit(node parser.Node, _ []parser.Node) (parser.Visitor, error) {
switch n := node.(type) {
case *parser.VectorSelector:
@ -70,7 +79,8 @@ func (v *durationVisitor) Visit(node parser.Node, _ []parser.Node) (parser.Visit
return v, nil
}
// calculateDuration computes the duration from a duration expression.
// calculateDuration returns the float value of a duration expression as
// time.Duration or an error if the duration is invalid.
func (v *durationVisitor) calculateDuration(expr parser.Expr, allowedNegative bool) (time.Duration, error) {
duration, err := v.evaluateDurationExpr(expr)
if err != nil {