VictoriaMetrics/app/vminsert/graphite/parser.go

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2019-05-22 23:16:55 +02:00
package graphite
import (
"fmt"
"strings"
"github.com/valyala/fastjson/fastfloat"
)
// Rows contains parsed graphite rows.
type Rows struct {
Rows []Row
tagsPool []Tag
}
// Reset resets rs.
func (rs *Rows) Reset() {
// Reset items, so they can be GC'ed
for i := range rs.Rows {
rs.Rows[i].reset()
}
rs.Rows = rs.Rows[:0]
for i := range rs.tagsPool {
rs.tagsPool[i].reset()
}
rs.tagsPool = rs.tagsPool[:0]
}
// Unmarshal unmarshals grahite plaintext protocol rows from s.
//
// See https://graphite.readthedocs.io/en/latest/feeding-carbon.html#the-plaintext-protocol
//
// s must be unchanged until rs is in use.
func (rs *Rows) Unmarshal(s string) error {
var err error
rs.Rows, rs.tagsPool, err = unmarshalRows(rs.Rows[:0], s, rs.tagsPool[:0])
if err != nil {
return err
}
return err
}
// Row is a single graphite row.
type Row struct {
Metric string
Tags []Tag
Value float64
Timestamp int64
}
func (r *Row) reset() {
r.Metric = ""
r.Tags = nil
r.Value = 0
r.Timestamp = 0
}
func (r *Row) unmarshal(s string, tagsPool []Tag) ([]Tag, error) {
r.reset()
n := strings.IndexByte(s, ' ')
if n < 0 {
return tagsPool, fmt.Errorf("cannot find whitespace between metric and value in %q", s)
}
metricAndTags := s[:n]
tail := s[n+1:]
n = strings.IndexByte(metricAndTags, ';')
if n < 0 {
// No tags
r.Metric = metricAndTags
} else {
// Tags found
r.Metric = metricAndTags[:n]
tagsStart := len(tagsPool)
var err error
tagsPool, err = unmarshalTags(tagsPool, metricAndTags[n+1:])
if err != nil {
return tagsPool, fmt.Errorf("cannot umarshal tags: %s", err)
}
tags := tagsPool[tagsStart:]
r.Tags = tags[:len(tags):len(tags)]
}
n = strings.IndexByte(tail, ' ')
if n < 0 {
// There is no timestamp. Use default timestamp instead.
r.Value = fastfloat.ParseBestEffort(tail)
return tagsPool, nil
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}
r.Value = fastfloat.ParseBestEffort(tail[:n])
r.Timestamp = fastfloat.ParseInt64BestEffort(tail[n+1:])
return tagsPool, nil
}
func unmarshalRows(dst []Row, s string, tagsPool []Tag) ([]Row, []Tag, error) {
for len(s) > 0 {
n := strings.IndexByte(s, '\n')
if n == 0 {
// Skip empty line
s = s[1:]
continue
}
if cap(dst) > len(dst) {
dst = dst[:len(dst)+1]
} else {
dst = append(dst, Row{})
}
r := &dst[len(dst)-1]
if n < 0 {
// The last line.
var err error
tagsPool, err = r.unmarshal(s, tagsPool)
if err != nil {
err = fmt.Errorf("cannot unmarshal Graphite line %q: %s", s, err)
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return dst, tagsPool, err
}
return dst, tagsPool, nil
}
var err error
tagsPool, err = r.unmarshal(s[:n], tagsPool)
if err != nil {
err = fmt.Errorf("cannot unmarshal Graphite line %q: %s", s[:n], err)
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return dst, tagsPool, err
}
s = s[n+1:]
}
return dst, tagsPool, nil
}
func unmarshalTags(dst []Tag, s string) ([]Tag, error) {
for {
if cap(dst) > len(dst) {
dst = dst[:len(dst)+1]
} else {
dst = append(dst, Tag{})
}
tag := &dst[len(dst)-1]
n := strings.IndexByte(s, ';')
if n < 0 {
// The last tag found
if err := tag.unmarshal(s); err != nil {
return dst[:len(dst)-1], err
}
return dst, nil
}
if err := tag.unmarshal(s[:n]); err != nil {
return dst[:len(dst)-1], err
}
s = s[n+1:]
}
}
// Tag is a graphite tag.
type Tag struct {
Key string
Value string
}
func (t *Tag) reset() {
t.Key = ""
t.Value = ""
}
func (t *Tag) unmarshal(s string) error {
t.reset()
n := strings.IndexByte(s, '=')
if n < 0 {
return fmt.Errorf("missing tag value for %q", s)
}
t.Key = s[:n]
if len(t.Key) == 0 {
return fmt.Errorf("tag key cannot be empty for %q", s)
}
t.Value = s[n+1:]
return nil
}