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