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if_expression.go
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if_expression.go
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package promrelabel
import (
"encoding/json"
"fmt"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/regexutil"
"github.com/VictoriaMetrics/metricsql"
)
// IfExpression represents `if` expression at RelabelConfig.
//
// The `if` expression can contain arbitrary PromQL-like label filters such as `metric_name{filters...}`
type IfExpression struct {
s string
lfs []*labelFilter
}
// String returns string representation of ie.
func (ie *IfExpression) String() string {
if ie == nil {
return ""
}
return ie.s
}
// Parse parses `if` expression from s and stores it to ie.
func (ie *IfExpression) Parse(s string) error {
expr, err := metricsql.Parse(s)
if err != nil {
return err
}
me, ok := expr.(*metricsql.MetricExpr)
if !ok {
return fmt.Errorf("expecting series selector; got %q", expr.AppendString(nil))
}
lfs, err := metricExprToLabelFilters(me)
if err != nil {
return fmt.Errorf("cannot parse series selector: %w", err)
}
ie.s = s
ie.lfs = lfs
return nil
}
// UnmarshalJSON unmarshals ie from JSON data.
func (ie *IfExpression) UnmarshalJSON(data []byte) error {
var s string
if err := json.Unmarshal(data, &s); err != nil {
return err
}
return ie.Parse(s)
}
// MarshalJSON marshals ie to JSON.
func (ie *IfExpression) MarshalJSON() ([]byte, error) {
return json.Marshal(ie.s)
}
// UnmarshalYAML unmarshals ie from YAML passed to f.
func (ie *IfExpression) UnmarshalYAML(f func(interface{}) error) error {
var s string
if err := f(&s); err != nil {
return fmt.Errorf("cannot unmarshal `if` option: %w", err)
}
if err := ie.Parse(s); err != nil {
return fmt.Errorf("cannot parse `if` series selector: %w", err)
}
return nil
}
// MarshalYAML marshals ie to YAML.
func (ie *IfExpression) MarshalYAML() (interface{}, error) {
return ie.s, nil
}
// Match returns true if ie matches the given labels.
func (ie *IfExpression) Match(labels []prompbmarshal.Label) bool {
for _, lf := range ie.lfs {
if !lf.match(labels) {
return false
}
}
return true
}
func metricExprToLabelFilters(me *metricsql.MetricExpr) ([]*labelFilter, error) {
lfs := make([]*labelFilter, len(me.LabelFilters))
for i := range me.LabelFilters {
lf, err := newLabelFilter(&me.LabelFilters[i])
if err != nil {
return nil, fmt.Errorf("cannot parse %s: %w", me.AppendString(nil), err)
}
lfs[i] = lf
}
return lfs, nil
}
// labelFilter contains PromQL filter for `{label op "value"}`
type labelFilter struct {
label string
op string
value string
// re contains compiled regexp for `=~` and `!~` op.
re *regexutil.PromRegex
}
func newLabelFilter(mlf *metricsql.LabelFilter) (*labelFilter, error) {
lf := &labelFilter{
label: toCanonicalLabelName(mlf.Label),
op: getFilterOp(mlf),
value: mlf.Value,
}
if lf.op == "=~" || lf.op == "!~" {
re, err := regexutil.NewPromRegex(lf.value)
if err != nil {
return nil, fmt.Errorf("cannot parse regexp for %s: %w", mlf.AppendString(nil), err)
}
lf.re = re
}
return lf, nil
}
func (lf *labelFilter) match(labels []prompbmarshal.Label) bool {
switch lf.op {
case "=":
return lf.equalValue(labels)
case "!=":
return !lf.equalValue(labels)
case "=~":
return lf.matchRegexp(labels)
case "!~":
return !lf.matchRegexp(labels)
default:
logger.Panicf("BUG: unexpected operation for label filter: %s", lf.op)
}
return false
}
func (lf *labelFilter) equalValue(labels []prompbmarshal.Label) bool {
labelNameMatches := 0
for _, label := range labels {
if toCanonicalLabelName(label.Name) != lf.label {
continue
}
labelNameMatches++
if label.Value == lf.value {
return true
}
}
if labelNameMatches == 0 {
// Special case for {non_existing_label=""}, which matches anything except of non-empty non_existing_label
return lf.value == ""
}
return false
}
func (lf *labelFilter) matchRegexp(labels []prompbmarshal.Label) bool {
labelNameMatches := 0
for _, label := range labels {
if toCanonicalLabelName(label.Name) != lf.label {
continue
}
labelNameMatches++
if lf.re.MatchString(label.Value) {
return true
}
}
if labelNameMatches == 0 {
// Special case for {non_existing_label=~"something|"}, which matches empty non_existing_label
return lf.re.MatchString("")
}
return false
}
func toCanonicalLabelName(labelName string) string {
if labelName == "__name__" {
return ""
}
return labelName
}
func getFilterOp(mlf *metricsql.LabelFilter) string {
if mlf.IsNegative {
if mlf.IsRegexp {
return "!~"
}
return "!="
}
if mlf.IsRegexp {
return "=~"
}
return "="
}