William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 1 | // Copyright 2014 The Go Authors. 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 | // Defensive debug-only utility to track that functions run on the |
| 6 | // goroutine that they're supposed to. |
| 7 | |
| 8 | package http2 |
| 9 | |
| 10 | import ( |
| 11 | "bytes" |
| 12 | "errors" |
| 13 | "fmt" |
| 14 | "os" |
| 15 | "runtime" |
| 16 | "strconv" |
| 17 | "sync" |
| 18 | ) |
| 19 | |
| 20 | var DebugGoroutines = os.Getenv("DEBUG_HTTP2_GOROUTINES") == "1" |
| 21 | |
| 22 | type goroutineLock uint64 |
| 23 | |
| 24 | func newGoroutineLock() goroutineLock { |
| 25 | if !DebugGoroutines { |
| 26 | return 0 |
| 27 | } |
| 28 | return goroutineLock(curGoroutineID()) |
| 29 | } |
| 30 | |
| 31 | func (g goroutineLock) check() { |
| 32 | if !DebugGoroutines { |
| 33 | return |
| 34 | } |
| 35 | if curGoroutineID() != uint64(g) { |
| 36 | panic("running on the wrong goroutine") |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | func (g goroutineLock) checkNotOn() { |
| 41 | if !DebugGoroutines { |
| 42 | return |
| 43 | } |
| 44 | if curGoroutineID() == uint64(g) { |
| 45 | panic("running on the wrong goroutine") |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | var goroutineSpace = []byte("goroutine ") |
| 50 | |
| 51 | func curGoroutineID() uint64 { |
| 52 | bp := littleBuf.Get().(*[]byte) |
| 53 | defer littleBuf.Put(bp) |
| 54 | b := *bp |
| 55 | b = b[:runtime.Stack(b, false)] |
| 56 | // Parse the 4707 out of "goroutine 4707 [" |
| 57 | b = bytes.TrimPrefix(b, goroutineSpace) |
| 58 | i := bytes.IndexByte(b, ' ') |
| 59 | if i < 0 { |
| 60 | panic(fmt.Sprintf("No space found in %q", b)) |
| 61 | } |
| 62 | b = b[:i] |
| 63 | n, err := parseUintBytes(b, 10, 64) |
| 64 | if err != nil { |
| 65 | panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err)) |
| 66 | } |
| 67 | return n |
| 68 | } |
| 69 | |
| 70 | var littleBuf = sync.Pool{ |
| 71 | New: func() interface{} { |
| 72 | buf := make([]byte, 64) |
| 73 | return &buf |
| 74 | }, |
| 75 | } |
| 76 | |
| 77 | // parseUintBytes is like strconv.ParseUint, but using a []byte. |
| 78 | func parseUintBytes(s []byte, base int, bitSize int) (n uint64, err error) { |
| 79 | var cutoff, maxVal uint64 |
| 80 | |
| 81 | if bitSize == 0 { |
| 82 | bitSize = int(strconv.IntSize) |
| 83 | } |
| 84 | |
| 85 | s0 := s |
| 86 | switch { |
| 87 | case len(s) < 1: |
| 88 | err = strconv.ErrSyntax |
| 89 | goto Error |
| 90 | |
| 91 | case 2 <= base && base <= 36: |
| 92 | // valid base; nothing to do |
| 93 | |
| 94 | case base == 0: |
| 95 | // Look for octal, hex prefix. |
| 96 | switch { |
| 97 | case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'): |
| 98 | base = 16 |
| 99 | s = s[2:] |
| 100 | if len(s) < 1 { |
| 101 | err = strconv.ErrSyntax |
| 102 | goto Error |
| 103 | } |
| 104 | case s[0] == '0': |
| 105 | base = 8 |
| 106 | default: |
| 107 | base = 10 |
| 108 | } |
| 109 | |
| 110 | default: |
| 111 | err = errors.New("invalid base " + strconv.Itoa(base)) |
| 112 | goto Error |
| 113 | } |
| 114 | |
| 115 | n = 0 |
| 116 | cutoff = cutoff64(base) |
| 117 | maxVal = 1<<uint(bitSize) - 1 |
| 118 | |
| 119 | for i := 0; i < len(s); i++ { |
| 120 | var v byte |
| 121 | d := s[i] |
| 122 | switch { |
| 123 | case '0' <= d && d <= '9': |
| 124 | v = d - '0' |
| 125 | case 'a' <= d && d <= 'z': |
| 126 | v = d - 'a' + 10 |
| 127 | case 'A' <= d && d <= 'Z': |
| 128 | v = d - 'A' + 10 |
| 129 | default: |
| 130 | n = 0 |
| 131 | err = strconv.ErrSyntax |
| 132 | goto Error |
| 133 | } |
| 134 | if int(v) >= base { |
| 135 | n = 0 |
| 136 | err = strconv.ErrSyntax |
| 137 | goto Error |
| 138 | } |
| 139 | |
| 140 | if n >= cutoff { |
| 141 | // n*base overflows |
| 142 | n = 1<<64 - 1 |
| 143 | err = strconv.ErrRange |
| 144 | goto Error |
| 145 | } |
| 146 | n *= uint64(base) |
| 147 | |
| 148 | n1 := n + uint64(v) |
| 149 | if n1 < n || n1 > maxVal { |
| 150 | // n+v overflows |
| 151 | n = 1<<64 - 1 |
| 152 | err = strconv.ErrRange |
| 153 | goto Error |
| 154 | } |
| 155 | n = n1 |
| 156 | } |
| 157 | |
| 158 | return n, nil |
| 159 | |
| 160 | Error: |
| 161 | return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err} |
| 162 | } |
| 163 | |
| 164 | // Return the first number n such that n*base >= 1<<64. |
| 165 | func cutoff64(base int) uint64 { |
| 166 | if base < 2 { |
| 167 | return 0 |
| 168 | } |
| 169 | return (1<<64-1)/uint64(base) + 1 |
| 170 | } |