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|
package context
import (
"bytes"
"errors"
"fmt"
"runtime"
"strconv"
"sync"
)
// Sourced https://github.com/bradfitz/http2/blob/dc0c5c000ec33e263612939744d51a3b68b9cece/gotrack.go
var goroutineSpace = []byte("goroutine ")
var littleBuf = sync.Pool{
New: func() interface{} {
buf := make([]byte, 64)
return &buf
},
}
func curGoroutineID() uint64 {
bp := littleBuf.Get().(*[]byte)
defer littleBuf.Put(bp)
b := *bp
b = b[:runtime.Stack(b, false)]
// Parse the 4707 out of "goroutine 4707 ["
b = bytes.TrimPrefix(b, goroutineSpace)
i := bytes.IndexByte(b, ' ')
if i < 0 {
panic(fmt.Sprintf("No space found in %q", b))
}
b = b[:i]
n, err := parseUintBytes(b, 10, 64)
if err != nil {
panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err))
}
return n
}
// parseUintBytes is like strconv.ParseUint, but using a []byte.
func parseUintBytes(s []byte, base int, bitSize int) (n uint64, err error) {
var cutoff, maxVal uint64
if bitSize == 0 {
bitSize = int(strconv.IntSize)
}
s0 := s
switch {
case len(s) < 1:
err = strconv.ErrSyntax
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
case 2 <= base && base <= 36:
// valid base; nothing to do
case base == 0:
// Look for octal, hex prefix.
switch {
case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
base = 16
s = s[2:]
if len(s) < 1 {
err = strconv.ErrSyntax
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
}
case s[0] == '0':
base = 8
default:
base = 10
}
default:
err = errors.New("invalid base " + strconv.Itoa(base))
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
}
n = 0
cutoff = cutoff64(base)
maxVal = 1<<uint(bitSize) - 1
for i := 0; i < len(s); i++ {
var v byte
d := s[i]
switch {
case '0' <= d && d <= '9':
v = d - '0'
case 'a' <= d && d <= 'z':
v = d - 'a' + 10
case 'A' <= d && d <= 'Z':
v = d - 'A' + 10
default:
n = 0
err = strconv.ErrSyntax
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
}
if int(v) >= base {
n = 0
err = strconv.ErrSyntax
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
}
if n >= cutoff {
// n*base overflows
n = 1<<64 - 1
err = strconv.ErrRange
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
}
n *= uint64(base)
n1 := n + uint64(v)
if n1 < n || n1 > maxVal {
// n+v overflows
n = 1<<64 - 1
err = strconv.ErrRange
return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
}
n = n1
}
return n, nil
}
// Return the first number n such that n*base >= 1<<64.
func cutoff64(base int) uint64 {
if base < 2 {
return 0
}
return (1<<64-1)/uint64(base) + 1
}
|
