statsd_exporter/mapper.go

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// Copyright (c) 2013, Prometheus Team
// All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"io/ioutil"
"regexp"
"strings"
)
var (
identifierRE = `[a-zA-Z_][a-zA-Z0-9_]+`
metricLineRE = regexp.MustCompile(`^(\*\.|` + identifierRE + `\.)+(\*|` + identifierRE + `)$`)
labelLineRE = regexp.MustCompile(`^(` + identifierRE + `)\s*=\s*"(.*)"$`)
)
type metricMapping struct {
regex *regexp.Regexp
labels map[string]string
}
type metricMapper struct {
mappings []metricMapping
}
type configLoadStates int
const (
SEARCHING configLoadStates = iota
METRIC_DEFINITION
)
func (l *metricMapper) initFromString(fileContents string) error {
lines := strings.Split(fileContents, "\n")
state := SEARCHING
mapping := metricMapping{labels: map[string]string{}}
for i, line := range lines {
line := strings.TrimSpace(line)
switch state {
case SEARCHING:
if line == "" {
continue
}
if !metricLineRE.MatchString(line) {
return fmt.Errorf("Line %d: expected metric match line, got: %s", i, line)
}
metricRe := strings.Replace(line, ".", "\\.", -1)
metricRe = strings.Replace(metricRe, "*", "([^.]+)", -1)
mapping.regex = regexp.MustCompile("^" + metricRe + "$")
state = METRIC_DEFINITION
case METRIC_DEFINITION:
if line == "" {
if len(mapping.labels) == 0 {
return fmt.Errorf("Line %d: metric mapping didn't set any labels", i)
}
if _, ok := mapping.labels["name"]; !ok {
return fmt.Errorf("Line %d: metric mapping didn't set a metric name", i)
}
l.mappings = append(l.mappings, mapping)
state = SEARCHING
mapping = metricMapping{labels: map[string]string{}}
continue
}
matches := labelLineRE.FindStringSubmatch(line)
if len(matches) != 3 {
return fmt.Errorf("Line %d: expected label mapping line, got: %s", i, line)
}
mapping.labels[matches[1]] = matches[2]
default:
panic("illegal state")
}
}
return nil
}
func (l *metricMapper) initFromFile(fileName string) error {
mappingStr, err := ioutil.ReadFile(fileName)
if err != nil {
return err
}
return l.initFromString(string(mappingStr))
}
func (l *metricMapper) getMapping(statsdMetric string) (labels map[string]string, present bool) {
for _, mapping := range l.mappings {
matches := mapping.regex.FindStringSubmatchIndex(statsdMetric)
if len(matches) == 0 {
continue
}
labels := map[string]string{}
for label, valueExpr := range mapping.labels {
value := mapping.regex.ExpandString([]byte{}, valueExpr, statsdMetric, matches)
labels[label] = string(value)
}
return labels, true
}
return nil, false
}