github.com/searKing/golang/go@v1.2.117/runtime/goroutine/id.go (about)

     1  // Copyright 2020 The searKing Author. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package goroutine
     6  
     7  import (
     8  	"bytes"
     9  	"errors"
    10  	"fmt"
    11  	"runtime"
    12  	"strconv"
    13  	"sync"
    14  )
    15  
    16  var goroutineSpace = []byte("goroutine ")
    17  
    18  // ID returns goroutine id of the goroutine that calls it.
    19  // It calls runtime.Stack with a large enough buffer to capture the entire trace.
    20  func ID() uint64 {
    21  	bp := littleBuf.Get().(*[]byte)
    22  	defer littleBuf.Put(bp)
    23  	b := *bp
    24  	b = b[:runtime.Stack(b, false)]
    25  	// Parse the 4707 out of "goroutine 4707 ["
    26  	b = bytes.TrimPrefix(b, goroutineSpace)
    27  	i := bytes.IndexByte(b, ' ')
    28  	if i < 0 {
    29  		panic(fmt.Sprintf("No space found in %q", b))
    30  	}
    31  	b = b[:i]
    32  	n, err := parseUintBytes(b, 10, 64)
    33  	if err != nil {
    34  		panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err))
    35  	}
    36  	return n
    37  }
    38  
    39  var littleBuf = sync.Pool{
    40  	New: func() any {
    41  		buf := make([]byte, 64)
    42  		return &buf
    43  	},
    44  }
    45  
    46  // parseUintBytes is like strconv.ParseUint, but using a []byte.
    47  func parseUintBytes(s []byte, base int, bitSize int) (n uint64, err error) {
    48  	var cutoff, maxVal uint64
    49  
    50  	if bitSize == 0 {
    51  		bitSize = int(strconv.IntSize)
    52  	}
    53  
    54  	s0 := s
    55  	switch {
    56  	case len(s) < 1:
    57  		err = strconv.ErrSyntax
    58  		goto Error
    59  
    60  	case 2 <= base && base <= 36:
    61  		// valid base; nothing to do
    62  
    63  	case base == 0:
    64  		// Look for octal, hex prefix.
    65  		switch {
    66  		case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
    67  			base = 16
    68  			s = s[2:]
    69  			if len(s) < 1 {
    70  				err = strconv.ErrSyntax
    71  				goto Error
    72  			}
    73  		case s[0] == '0':
    74  			base = 8
    75  		default:
    76  			base = 10
    77  		}
    78  
    79  	default:
    80  		err = errors.New("invalid base " + strconv.Itoa(base))
    81  		goto Error
    82  	}
    83  
    84  	n = 0
    85  	cutoff = cutoff64(base)
    86  	maxVal = 1<<uint(bitSize) - 1
    87  
    88  	for i := 0; i < len(s); i++ {
    89  		var v byte
    90  		d := s[i]
    91  		switch {
    92  		case '0' <= d && d <= '9':
    93  			v = d - '0'
    94  		case 'a' <= d && d <= 'z':
    95  			v = d - 'a' + 10
    96  		case 'A' <= d && d <= 'Z':
    97  			v = d - 'A' + 10
    98  		default:
    99  			n = 0
   100  			err = strconv.ErrSyntax
   101  			goto Error
   102  		}
   103  		if int(v) >= base {
   104  			n = 0
   105  			err = strconv.ErrSyntax
   106  			goto Error
   107  		}
   108  
   109  		if n >= cutoff {
   110  			// n*base overflows
   111  			n = 1<<64 - 1
   112  			err = strconv.ErrRange
   113  			goto Error
   114  		}
   115  		n *= uint64(base)
   116  
   117  		n1 := n + uint64(v)
   118  		if n1 < n || n1 > maxVal {
   119  			// n+v overflows
   120  			n = 1<<64 - 1
   121  			err = strconv.ErrRange
   122  			goto Error
   123  		}
   124  		n = n1
   125  	}
   126  
   127  	return n, nil
   128  
   129  Error:
   130  	return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
   131  }
   132  
   133  // Return the first number n such that n*base >= 1<<64.
   134  func cutoff64(base int) uint64 {
   135  	if base < 2 {
   136  		return 0
   137  	}
   138  	return (1<<64-1)/uint64(base) + 1
   139  }