gotosocial/vendor/github.com/godbus/dbus/v5/variant_lexer.go
Daniele Sluijters acc333c40b
[feature] Inherit resource limits from cgroups ()
When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.
2023-01-17 20:59:04 +00:00

284 lines
4.7 KiB
Go

package dbus
import (
"fmt"
"strings"
"unicode"
"unicode/utf8"
)
// Heavily inspired by the lexer from text/template.
type varToken struct {
typ varTokenType
val string
}
type varTokenType byte
const (
tokEOF varTokenType = iota
tokError
tokNumber
tokString
tokBool
tokArrayStart
tokArrayEnd
tokDictStart
tokDictEnd
tokVariantStart
tokVariantEnd
tokComma
tokColon
tokType
tokByteString
)
type varLexer struct {
input string
start int
pos int
width int
tokens []varToken
}
type lexState func(*varLexer) lexState
func varLex(s string) []varToken {
l := &varLexer{input: s}
l.run()
return l.tokens
}
func (l *varLexer) accept(valid string) bool {
if strings.ContainsRune(valid, l.next()) {
return true
}
l.backup()
return false
}
func (l *varLexer) backup() {
l.pos -= l.width
}
func (l *varLexer) emit(t varTokenType) {
l.tokens = append(l.tokens, varToken{t, l.input[l.start:l.pos]})
l.start = l.pos
}
func (l *varLexer) errorf(format string, v ...interface{}) lexState {
l.tokens = append(l.tokens, varToken{
tokError,
fmt.Sprintf(format, v...),
})
return nil
}
func (l *varLexer) ignore() {
l.start = l.pos
}
func (l *varLexer) next() rune {
var r rune
if l.pos >= len(l.input) {
l.width = 0
return -1
}
r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
l.pos += l.width
return r
}
func (l *varLexer) run() {
for state := varLexNormal; state != nil; {
state = state(l)
}
}
func (l *varLexer) peek() rune {
r := l.next()
l.backup()
return r
}
func varLexNormal(l *varLexer) lexState {
for {
r := l.next()
switch {
case r == -1:
l.emit(tokEOF)
return nil
case r == '[':
l.emit(tokArrayStart)
case r == ']':
l.emit(tokArrayEnd)
case r == '{':
l.emit(tokDictStart)
case r == '}':
l.emit(tokDictEnd)
case r == '<':
l.emit(tokVariantStart)
case r == '>':
l.emit(tokVariantEnd)
case r == ':':
l.emit(tokColon)
case r == ',':
l.emit(tokComma)
case r == '\'' || r == '"':
l.backup()
return varLexString
case r == '@':
l.backup()
return varLexType
case unicode.IsSpace(r):
l.ignore()
case unicode.IsNumber(r) || r == '+' || r == '-':
l.backup()
return varLexNumber
case r == 'b':
pos := l.start
if n := l.peek(); n == '"' || n == '\'' {
return varLexByteString
}
// not a byte string; try to parse it as a type or bool below
l.pos = pos + 1
l.width = 1
fallthrough
default:
// either a bool or a type. Try bools first.
l.backup()
if l.pos+4 <= len(l.input) {
if l.input[l.pos:l.pos+4] == "true" {
l.pos += 4
l.emit(tokBool)
continue
}
}
if l.pos+5 <= len(l.input) {
if l.input[l.pos:l.pos+5] == "false" {
l.pos += 5
l.emit(tokBool)
continue
}
}
// must be a type.
return varLexType
}
}
}
var varTypeMap = map[string]string{
"boolean": "b",
"byte": "y",
"int16": "n",
"uint16": "q",
"int32": "i",
"uint32": "u",
"int64": "x",
"uint64": "t",
"double": "f",
"string": "s",
"objectpath": "o",
"signature": "g",
}
func varLexByteString(l *varLexer) lexState {
q := l.next()
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != -1 {
break
}
fallthrough
case -1:
return l.errorf("unterminated bytestring")
case q:
break Loop
}
}
l.emit(tokByteString)
return varLexNormal
}
func varLexNumber(l *varLexer) lexState {
l.accept("+-")
digits := "0123456789"
if l.accept("0") {
if l.accept("x") {
digits = "0123456789abcdefABCDEF"
} else {
digits = "01234567"
}
}
for strings.ContainsRune(digits, l.next()) {
}
l.backup()
if l.accept(".") {
for strings.ContainsRune(digits, l.next()) {
}
l.backup()
}
if l.accept("eE") {
l.accept("+-")
for strings.ContainsRune("0123456789", l.next()) {
}
l.backup()
}
if r := l.peek(); unicode.IsLetter(r) {
l.next()
return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
}
l.emit(tokNumber)
return varLexNormal
}
func varLexString(l *varLexer) lexState {
q := l.next()
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != -1 {
break
}
fallthrough
case -1:
return l.errorf("unterminated string")
case q:
break Loop
}
}
l.emit(tokString)
return varLexNormal
}
func varLexType(l *varLexer) lexState {
at := l.accept("@")
for {
r := l.next()
if r == -1 {
break
}
if unicode.IsSpace(r) {
l.backup()
break
}
}
if at {
if _, err := ParseSignature(l.input[l.start+1 : l.pos]); err != nil {
return l.errorf("%s", err)
}
} else {
if _, ok := varTypeMap[l.input[l.start:l.pos]]; ok {
l.emit(tokType)
return varLexNormal
}
return l.errorf("unrecognized type %q", l.input[l.start:l.pos])
}
l.emit(tokType)
return varLexNormal
}