prometheus/pkg/textparse/parse.go

404 lines
9.1 KiB
Go

// Copyright 2017 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:generate go get github.com/cznic/golex
//go:generate golex -o=lex.l.go lex.l
// Package textparse contains an efficient parser for the Prometheus text format.
package textparse
import (
"errors"
"fmt"
"io"
"math"
"sort"
"strconv"
"strings"
"unicode/utf8"
"unsafe"
"github.com/prometheus/prometheus/pkg/value"
"github.com/prometheus/prometheus/pkg/labels"
)
type lexer struct {
b []byte
i int
start int
err error
state int
}
type token int
const (
tInvalid token = -1
tEOF token = 0
tLinebreak token = iota
tWhitespace
tHelp
tType
tText
tComment
tBlank
tMName
tBraceOpen
tBraceClose
tLName
tLValue
tComma
tEqual
tTimestamp
tValue
)
func (t token) String() string {
switch t {
case tInvalid:
return "INVALID"
case tEOF:
return "EOF"
case tLinebreak:
return "LINEBREAK"
case tWhitespace:
return "WHITESPACE"
case tHelp:
return "HELP"
case tType:
return "TYPE"
case tText:
return "TEXT"
case tComment:
return "COMMENT"
case tBlank:
return "BLANK"
case tMName:
return "MNAME"
case tBraceOpen:
return "BOPEN"
case tBraceClose:
return "BCLOSE"
case tLName:
return "LNAME"
case tLValue:
return "LVALUE"
case tEqual:
return "EQUAL"
case tComma:
return "COMMA"
case tTimestamp:
return "TIMESTAMP"
case tValue:
return "VALUE"
}
return fmt.Sprintf("<invalid: %d>", t)
}
// buf returns the buffer of the current token.
func (l *lexer) buf() []byte {
return l.b[l.start:l.i]
}
func (l *lexer) cur() byte {
return l.b[l.i]
}
// next advances the lexer to the next character.
func (l *lexer) next() byte {
l.i++
if l.i >= len(l.b) {
l.err = io.EOF
return byte(tEOF)
}
// Lex struggles with null bytes. If we are in a label value, where
// they are allowed, consume them here immediately.
for l.b[l.i] == 0 && l.state == sLValue {
l.i++
}
return l.b[l.i]
}
func (l *lexer) Error(es string) {
l.err = errors.New(es)
}
// Parser parses samples from a byte slice of samples in the official
// Prometheus text exposition format.
type Parser struct {
l *lexer
series []byte
text []byte
mtype MetricType
val float64
ts int64
hasTS bool
start int
offsets []int
}
// New returns a new parser of the byte slice.
func New(b []byte) *Parser {
return &Parser{l: &lexer{b: append(b, '\n')}}
}
// Series returns the bytes of the series, the timestamp if set, and the value
// of the current sample.
func (p *Parser) Series() ([]byte, *int64, float64) {
if p.hasTS {
return p.series, &p.ts, p.val
}
return p.series, nil, p.val
}
// Help returns the metric name and help text in the current entry.
// Must only be called after Next returned a help entry.
// The returned byte slices become invalid after the next call to Next.
func (p *Parser) Help() ([]byte, []byte) {
return p.l.b[p.offsets[0]:p.offsets[1]], p.text
}
// Type returns the metric name and type in the current entry.
// Must only be called after Next returned a type entry.
// The returned byte slices become invalid after the next call to Next.
func (p *Parser) Type() ([]byte, MetricType) {
return p.l.b[p.offsets[0]:p.offsets[1]], p.mtype
}
// Comment returns the text of the current comment.
// Must only be called after Next returned a comment entry.
// The returned byte slice becomes invalid after the next call to Next.
func (p *Parser) Comment() []byte {
return p.text
}
// Metric writes the labels of the current sample into the passed labels.
// It returns the string from which the metric was parsed.
func (p *Parser) Metric(l *labels.Labels) string {
// Allocate the full immutable string immediately, so we just
// have to create references on it below.
s := string(p.series)
*l = append(*l, labels.Label{
Name: labels.MetricName,
Value: s[:p.offsets[0]-p.start],
})
for i := 1; i < len(p.offsets); i += 4 {
a := p.offsets[i] - p.start
b := p.offsets[i+1] - p.start
c := p.offsets[i+2] - p.start
d := p.offsets[i+3] - p.start
// Replacer causes allocations. Replace only when necessary.
if strings.IndexByte(s[c:d], byte('\\')) >= 0 {
*l = append(*l, labels.Label{Name: s[a:b], Value: replacer.Replace(s[c:d])})
continue
}
*l = append(*l, labels.Label{Name: s[a:b], Value: s[c:d]})
}
// Sort labels. We can skip the first entry since the metric name is
// already at the right place.
sort.Sort((*l)[1:])
return s
}
// nextToken returns the next token from the lexer. It skips over tabs
// and spaces.
func (p *Parser) nextToken() token {
for {
if tok := p.l.Lex(); tok != tWhitespace {
return tok
}
}
}
// Entry represents the type of a parsed entry.
type Entry int
const (
EntryInvalid Entry = -1
EntryType Entry = 0
EntryHelp Entry = 1
EntrySeries Entry = 2
EntryComment Entry = 3
)
// MetricType represents metric type values.
type MetricType string
const (
MetricTypeCounter = "counter"
MetricTypeGauge = "gauge"
MetricTypeHistogram = "histogram"
MetricTypeSummary = "summary"
MetricTypeUntyped = "untyped"
)
func parseError(exp string, got token) error {
return fmt.Errorf("%s, got %q", exp, got)
}
// Next advances the parser to the next sample. It returns false if no
// more samples were read or an error occurred.
func (p *Parser) Next() (Entry, error) {
var err error
p.start = p.l.i
p.offsets = p.offsets[:0]
switch t := p.nextToken(); t {
case tEOF:
return EntryInvalid, io.EOF
case tLinebreak:
// Allow full blank lines.
return p.Next()
case tHelp, tType:
switch t := p.nextToken(); t {
case tMName:
p.offsets = append(p.offsets, p.l.start, p.l.i)
default:
return EntryInvalid, parseError("expected metric name after HELP", t)
}
switch t := p.nextToken(); t {
case tText:
p.text = p.l.buf()[1:]
default:
return EntryInvalid, parseError("expected text in HELP", t)
}
if t == tType {
switch s := yoloString(p.text); s {
case "counter":
p.mtype = MetricTypeCounter
case "gauge":
p.mtype = MetricTypeGauge
case "histogram":
p.mtype = MetricTypeHistogram
case "summary":
p.mtype = MetricTypeSummary
case "untyped":
p.mtype = MetricTypeUntyped
default:
return EntryInvalid, fmt.Errorf("invalid metric type %q", s)
}
}
if t := p.nextToken(); t != tLinebreak {
return EntryInvalid, parseError("linebreak expected after metadata", t)
}
switch t {
case tHelp:
return EntryHelp, nil
case tType:
return EntryType, nil
}
case tComment:
p.text = p.l.buf()
if t := p.nextToken(); t != tLinebreak {
return EntryInvalid, parseError("linebreak expected after comment", t)
}
return EntryComment, nil
case tMName:
p.offsets = append(p.offsets, p.l.i)
p.series = p.l.b[p.start:p.l.i]
t2 := p.nextToken()
if t2 == tBraceOpen {
if err := p.parseLVals(); err != nil {
return EntryInvalid, err
}
p.series = p.l.b[p.start:p.l.i]
t2 = p.nextToken()
}
if t2 != tValue {
return EntryInvalid, parseError("expected value after metric", t)
}
if p.val, err = strconv.ParseFloat(yoloString(p.l.buf()), 64); err != nil {
return EntryInvalid, err
}
// Ensure canonical NaN value.
if math.IsNaN(p.val) {
p.val = math.Float64frombits(value.NormalNaN)
}
p.hasTS = false
switch p.nextToken() {
case tLinebreak:
break
case tTimestamp:
p.hasTS = true
if p.ts, err = strconv.ParseInt(yoloString(p.l.buf()), 10, 64); err != nil {
return EntryInvalid, err
}
if t2 := p.nextToken(); t2 != tLinebreak {
return EntryInvalid, parseError("expected next entry after timestamp", t)
}
default:
return EntryInvalid, parseError("expected timestamp or new record", t)
}
return EntrySeries, nil
default:
err = fmt.Errorf("%q is not a valid start token", t)
}
return EntryInvalid, err
}
func (p *Parser) parseLVals() error {
t := p.nextToken()
for {
switch t {
case tBraceClose:
return nil
case tLName:
default:
return parseError("expected label name", t)
}
p.offsets = append(p.offsets, p.l.start, p.l.i)
if t := p.nextToken(); t != tEqual {
return parseError("expected equal", t)
}
if t := p.nextToken(); t != tLValue {
return parseError("expected label value", t)
}
if !utf8.Valid(p.l.buf()) {
return fmt.Errorf("invalid UTF-8 label value")
}
// The lexer ensures the value string is quoted. Strip first
// and last character.
p.offsets = append(p.offsets, p.l.start+1, p.l.i-1)
// Free trailing commas are allowed.
if t = p.nextToken(); t == tComma {
t = p.nextToken()
}
}
}
var replacer = strings.NewReplacer(
`\"`, `"`,
`\\`, `\`,
`\n`, `
`,
`\t`, ` `,
)
func yoloString(b []byte) string {
return *((*string)(unsafe.Pointer(&b)))
}