{"topic":{"id":15591,"title":"兴趣笔记","slug":"topic","categoryId":11,"createdAt":"2026-06-08 17:09:23.107979","bumpedAt":"2026-08-08T15:58:14.589Z","views":1055,"postsCount":30,"highestPostNumber":30,"likeCount":8,"closed":false,"pinned":false,"excerpt":"我觉得有意思的学习内容以前我一直认为自己对知识的渴望是纯粹的，认知、建模是我所有的意义。应试的学习让我感到不屑，却又因这份借口而无需过多进行实践现在看来，对学习进步的需求无非来自三种追求：获得知识本身优越感逃避劣等的恐惧也许大部份人都有这些追求，只是不同的人和学习的内容，三种占比不同吧我曾经自以为的纯粹知识渴望，也不过很大程度是对劣等感的逃避，为了没有胆量承认的虚荣然而也许内心并不纯粹，追求俗不可耐，这样的自己才是真实的…","deletedAt":null,"isAnonymous":false,"category":{"id":11,"name":"深入交流","slug":"distilled","color":"c01c28"},"author":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif"},"tags":[]},"posts":[{"id":72255,"postNumber":1,"raw":"我觉得有意思的学习内容 :innocent_cat:\n\n以前我一直认为自己对知识的渴望是纯粹的，认知、建模是我所有的意义。应试的学习让我感到不屑，却又因这份借口而无需过多进行实践\n\n现在看来，对学习进步的需求无非来自三种追求：\n- 获得知识本身\n- 优越感\n- 逃避劣等的恐惧\n\n也许大部份人都有这些追求，只是不同的人和学习的内容，三种占比不同吧\n\n我曾经自以为的纯粹知识渴望，也不过很大程度是对劣等感的逃避，为了没有胆量承认的虚荣\n\n然而也许内心并不纯粹，追求俗不可耐，这样的自己才是真实的，而非想象中某种完美的幻影\n\n无论出发点如何，如果还有兴趣能让我感到幸福，那便足够了吧 :slightly_smiling_face:","cooked":"

我觉得有意思的学习内容 $\":innocent_cat:\"$

以前我一直认为自己对知识的渴望是纯粹的，认知、建模是我所有的意义。应试的学习让我感到不屑，却又因这份借口而无需过多进行实践

现在看来，对学习进步的需求无非来自三种追求：

获得知识本身
优越感
逃避劣等的恐惧

也许大部份人都有这些追求，只是不同的人和学习的内容，三种占比不同吧

我曾经自以为的纯粹知识渴望，也不过很大程度是对劣等感的逃避，为了没有胆量承认的虚荣

然而也许内心并不纯粹，追求俗不可耐，这样的自己才是真实的，而非想象中某种完美的幻影

无论出发点如何，如果还有兴趣能让我感到幸福，那便足够了吧 🙂

\n","createdAt":"2026-06-08 17:09:23.558407","updatedAt":"2026-06-08 18:28:44.591789","replyToPostNumber":null,"replyCount":0,"likeCount":6,"wordCount":258,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"wave_gif","count":1,"users":[{"id":5351,"username":"Xrystal-line","name":"羽流弦ノ迹"}],"hasReacted":false},{"reaction":"👍","count":1,"users":[{"id":7444,"username":"周末","name":"😀"}],"hasReacted":false},{"reaction":"❤️","count":6,"users":[{"id":2902,"username":"1313","name":"ᐕ)ﾉ"},{"id":5351,"username":"Xrystal-line","name":"羽流弦ノ迹"},{"id":5905,"username":"PipaQinse233","name":"PipaQinse233"},{"id":5940,"username":"water","name":null},{"id":7444,"username":"周末","name":"😀"},{"id":8040,"username":"dvm","name":"Dvm"}],"hasReacted":false}],"wiki":false,"version":2,"publicVersion":2,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

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"}},{"id":72256,"postNumber":2,"raw":"# SplitArgs\n\n- 把字符串根据空格/引号分割成多个 token\n- 无引号 token 按照字面字符处理\n- 单引号 token 仅 unescape `''` -> `'`\n- 双引号 token 按照 YAML 双引号字符串 unescape\n\n## FSM\n![splitargs|690x343](/uploads/image/f6/e6/f6e6497bfa2b37038c5169dcf08b41904db763a3e02e8eda6c133b5bdd1f03da.avif)\n\n## Go 实现\n这样用闭包按照我的理解应该不会有性能问题？可惜因为需要 unescape 无法做到 zero-allocation\n```go\nconst (\n\tsplitArgsLookForToken int = iota\n\tsplitArgsInToken\n\tsplitArgsInSingleQuotes\n\tsplitArgsInDoubleQuotes\n\tsplitArgsSingleQuoteEscape\n\tsplitArgsDoubleQuoteEscape\n\tsplitArgsEndSuccess\n\tsplitArgsEndFail\n)\n\nfunc SplitArgs(s string) (result []string, err error) {\n\tvar sb strings.Builder\n\tvar current rune\n\tvar currentSize int\n\tvar errMsg string\n\tpeeked := false\n\teoi := false\n\tidx := 0\n\n\tstate := splitArgsLookForToken\n\n\tpeek := func() {\n\t\tif peeked {\n\t\t\treturn\n\t\t}\n\t\tpeeked = true\n\t\tif idx >= len(s) {\n\t\t\teoi = true\n\t\t} else {\n\t\t\tcurrent, currentSize = utf8.DecodeRuneInString(s[idx:])\n\t\t}\n\t}\n\n\tpeekHex := func(size int) error {\n\t\tif idx+size > len(s) {\n\t\t\treturn errors.New(\"early EOI at index \" + strconv.Itoa(idx))\n\t\t}\n\n\t\tr := rune(0)\n\n\t\tfor i := range size {\n\t\t\tc := s[idx+i]\n\t\t\tvar v rune\n\t\t\tswitch {\n\t\t\tcase c >= '0' && c <= '9':\n\t\t\t\tv = rune(c - '0')\n\t\t\tcase c >= 'a' && c <= 'f':\n\t\t\t\tv = rune(c - 'a' + 10)\n\t\t\tcase c >= 'A' && c <= 'F':\n\t\t\t\tv = rune(c - 'A' + 10)\n\t\t\tdefault:\n\t\t\t\treturn errors.New(\"bad hex digit at index \" + strconv.Itoa(idx+i))\n\t\t\t}\n\t\t\tr = (r << 4) | v\n\t\t}\n\n\t\tcurrent = r\n\t\tcurrentSize = size\n\t\treturn nil\n\t}\n\n\t// Must only be called after calling peek()\n\tpop := func() {\n\t\tidx += currentSize\n\t\tpeeked = false\n\t}\n\n\tbegin := func() {\n\t\tsb.Reset()\n\t}\n\n\tend := func() {\n\t\tresult = append(result, sb.String())\n\t}\n\n\t// Must only be called after calling peek() and before calling pop()\n\twrite := func() {\n\t\tsb.WriteRune(current)\n\t}\n\n\tfor {\n\t\tswitch state {\n\t\tcase splitArgsEndFail:\n\t\t\terr = errors.New(\"SplitArgs: \" + errMsg)\n\t\t\tfallthrough\n\t\tcase splitArgsEndSuccess:\n\t\t\treturn\n\t\tcase splitArgsLookForToken:\n\t\t\tpeek()\n\t\t\tif eoi {\n\t\t\t\tstate = splitArgsEndSuccess\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\\t', '\\n', '\\v', '\\f', '\\r', ' ':\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\tcase '\\'':\n\t\t\t\tpop()\n\t\t\t\tbegin()\n\t\t\t\tstate = splitArgsInSingleQuotes\n\t\t\t\tcontinue\n\t\t\tcase '\"':\n\t\t\t\tpop()\n\t\t\t\tbegin()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\tbegin()\n\t\t\t\tstate = splitArgsInToken\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsInToken:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\tend()\n\t\t\t\tstate = splitArgsEndSuccess\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\\t', '\\n', '\\v', '\\f', '\\r', ' ':\n\t\t\t\tpop()\n\t\t\t\tend()\n\t\t\t\tstate = splitArgsLookForToken\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsInSingleQuotes:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\terrMsg = \"early EOI at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\\'':\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsSingleQuoteEscape\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsInDoubleQuotes:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\terrMsg = \"early EOI at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\"':\n\t\t\t\tend()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsLookForToken\n\t\t\t\tcontinue\n\t\t\tcase '\\\\':\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsDoubleQuoteEscape\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsSingleQuoteEscape:\n\t\t\tpeek()\n\n\t\t\tif !eoi && current == '\\'' {\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInSingleQuotes\n\t\t\t\tcontinue\n\t\t\t} else {\n\t\t\t\tend()\n\t\t\t\tstate = splitArgsLookForToken\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsDoubleQuoteEscape:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\terrMsg = \"early EOI at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\"', '\\\\', '/', ' ', '\\x09':\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tcase '0', 'a', 'b', 't', 'n', 'v', 'f', 'r', 'e', 'N', '_', 'L', 'P':\n\t\t\t\tswitch current {\n\t\t\t\tcase '0':\n\t\t\t\t\tcurrent = '\\x00'\n\t\t\t\tcase 'a':\n\t\t\t\t\tcurrent = '\\a'\n\t\t\t\tcase 'b':\n\t\t\t\t\tcurrent = '\\b'\n\t\t\t\tcase 't':\n\t\t\t\t\tcurrent = '\\t'\n\t\t\t\tcase 'n':\n\t\t\t\t\tcurrent = '\\n'\n\t\t\t\tcase 'v':\n\t\t\t\t\tcurrent = '\\v'\n\t\t\t\tcase 'f':\n\t\t\t\t\tcurrent = '\\f'\n\t\t\t\tcase 'r':\n\t\t\t\t\tcurrent = '\\r'\n\t\t\t\tcase 'e':\n\t\t\t\t\tcurrent = '\\x1b'\n\t\t\t\tcase 'N':\n\t\t\t\t\tcurrent = '\\x85'\n\t\t\t\tcase '_':\n\t\t\t\t\tcurrent = '\\xa0'\n\t\t\t\tcase 'L':\n\t\t\t\t\tcurrent = '\\u2028'\n\t\t\t\tcase 'P':\n\t\t\t\t\tcurrent = '\\u2029'\n\t\t\t\t}\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tcase 'x', 'u', 'U':\n\t\t\t\tvar size int\n\t\t\t\tswitch current {\n\t\t\t\tcase 'x':\n\t\t\t\t\tsize = 2\n\t\t\t\tcase 'u':\n\t\t\t\t\tsize = 4\n\t\t\t\tcase 'U':\n\t\t\t\t\tsize = 8\n\t\t\t\t}\n\t\t\t\tpop()\n\t\t\t\tif err := peekHex(size); err != nil {\n\t\t\t\t\terrMsg = err.Error()\n\t\t\t\t\tstate = splitArgsEndFail\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\terrMsg = \"bad escape sequence at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tdefault:\n\t\t\terrMsg = \"internal error\"\n\t\t\tstate = splitArgsEndFail\n\t\t\tcontinue\n\t\t}\n\t}\n}\n```\n\n感觉接口设计有点问题，似乎应该把 unescape 和 split 分开？ :thinking:\n\n~~才发现状态名写错了应该是 unescape~~\n\n## 方法论\n写这种复杂状态机之前，先用表格大致设计出状态和迁移会顺利很多\n\n![image|689x102](/uploads/image/b7/bf/b7bf0d630673b0678a464cd8242817b9b0e621d99b90f638a80f47f624c496fc.avif)\n\n\n我第一次写 IP Prefix trie 的时候完全梦到哪写到哪，哪里有问题就多加一个分支，最后变得非常莫名其妙 :grinning_face_with_sweat:","cooked":"

SplitArgs

把字符串根据空格/引号分割成多个 token
无引号 token 按照字面字符处理
单引号 token 仅 unescape '' -> '
双引号 token 按照 YAML 双引号字符串 unescape

FSM

$\"splitargs|690x343\"$

Go 实现

这样用闭包按照我的理解应该不会有性能问题？可惜因为需要 unescape 无法做到 zero-allocation

const (\n\tsplitArgsLookForToken int = iota\n\tsplitArgsInToken\n\tsplitArgsInSingleQuotes\n\tsplitArgsInDoubleQuotes\n\tsplitArgsSingleQuoteEscape\n\tsplitArgsDoubleQuoteEscape\n\tsplitArgsEndSuccess\n\tsplitArgsEndFail\n)\n\nfunc SplitArgs(s string) (result []string, err error) {\n\tvar sb strings.Builder\n\tvar current rune\n\tvar currentSize int\n\tvar errMsg string\n\tpeeked := false\n\teoi := false\n\tidx := 0\n\n\tstate := splitArgsLookForToken\n\n\tpeek := func() {\n\t\tif peeked {\n\t\t\treturn\n\t\t}\n\t\tpeeked = true\n\t\tif idx >= len(s) {\n\t\t\teoi = true\n\t\t} else {\n\t\t\tcurrent, currentSize = utf8.DecodeRuneInString(s[idx:])\n\t\t}\n\t}\n\n\tpeekHex := func(size int) error {\n\t\tif idx+size > len(s) {\n\t\t\treturn errors.New(\"early EOI at index \" + strconv.Itoa(idx))\n\t\t}\n\n\t\tr := rune(0)\n\n\t\tfor i := range size {\n\t\t\tc := s[idx+i]\n\t\t\tvar v rune\n\t\t\tswitch {\n\t\t\tcase c >= '0' && c <= '9':\n\t\t\t\tv = rune(c - '0')\n\t\t\tcase c >= 'a' && c <= 'f':\n\t\t\t\tv = rune(c - 'a' + 10)\n\t\t\tcase c >= 'A' && c <= 'F':\n\t\t\t\tv = rune(c - 'A' + 10)\n\t\t\tdefault:\n\t\t\t\treturn errors.New(\"bad hex digit at index \" + strconv.Itoa(idx+i))\n\t\t\t}\n\t\t\tr = (r << 4) | v\n\t\t}\n\n\t\tcurrent = r\n\t\tcurrentSize = size\n\t\treturn nil\n\t}\n\n\t// Must only be called after calling peek()\n\tpop := func() {\n\t\tidx += currentSize\n\t\tpeeked = false\n\t}\n\n\tbegin := func() {\n\t\tsb.Reset()\n\t}\n\n\tend := func() {\n\t\tresult = append(result, sb.String())\n\t}\n\n\t// Must only be called after calling peek() and before calling pop()\n\twrite := func() {\n\t\tsb.WriteRune(current)\n\t}\n\n\tfor {\n\t\tswitch state {\n\t\tcase splitArgsEndFail:\n\t\t\terr = errors.New(\"SplitArgs: \" + errMsg)\n\t\t\tfallthrough\n\t\tcase splitArgsEndSuccess:\n\t\t\treturn\n\t\tcase splitArgsLookForToken:\n\t\t\tpeek()\n\t\t\tif eoi {\n\t\t\t\tstate = splitArgsEndSuccess\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\\t', '\\n', '\\v', '\\f', '\\r', ' ':\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\tcase '\\'':\n\t\t\t\tpop()\n\t\t\t\tbegin()\n\t\t\t\tstate = splitArgsInSingleQuotes\n\t\t\t\tcontinue\n\t\t\tcase '\"':\n\t\t\t\tpop()\n\t\t\t\tbegin()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\tbegin()\n\t\t\t\tstate = splitArgsInToken\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsInToken:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\tend()\n\t\t\t\tstate = splitArgsEndSuccess\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\\t', '\\n', '\\v', '\\f', '\\r', ' ':\n\t\t\t\tpop()\n\t\t\t\tend()\n\t\t\t\tstate = splitArgsLookForToken\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsInSingleQuotes:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\terrMsg = \"early EOI at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\\'':\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsSingleQuoteEscape\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsInDoubleQuotes:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\terrMsg = \"early EOI at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\"':\n\t\t\t\tend()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsLookForToken\n\t\t\t\tcontinue\n\t\t\tcase '\\\\':\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsDoubleQuoteEscape\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsSingleQuoteEscape:\n\t\t\tpeek()\n\n\t\t\tif !eoi && current == '\\'' {\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInSingleQuotes\n\t\t\t\tcontinue\n\t\t\t} else {\n\t\t\t\tend()\n\t\t\t\tstate = splitArgsLookForToken\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase splitArgsDoubleQuoteEscape:\n\t\t\tpeek()\n\n\t\t\tif eoi {\n\t\t\t\terrMsg = \"early EOI at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch current {\n\t\t\tcase '\"', '\\\\', '/', ' ', '\\x09':\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tcase '0', 'a', 'b', 't', 'n', 'v', 'f', 'r', 'e', 'N', '_', 'L', 'P':\n\t\t\t\tswitch current {\n\t\t\t\tcase '0':\n\t\t\t\t\tcurrent = '\\x00'\n\t\t\t\tcase 'a':\n\t\t\t\t\tcurrent = '\\a'\n\t\t\t\tcase 'b':\n\t\t\t\t\tcurrent = '\\b'\n\t\t\t\tcase 't':\n\t\t\t\t\tcurrent = '\\t'\n\t\t\t\tcase 'n':\n\t\t\t\t\tcurrent = '\\n'\n\t\t\t\tcase 'v':\n\t\t\t\t\tcurrent = '\\v'\n\t\t\t\tcase 'f':\n\t\t\t\t\tcurrent = '\\f'\n\t\t\t\tcase 'r':\n\t\t\t\t\tcurrent = '\\r'\n\t\t\t\tcase 'e':\n\t\t\t\t\tcurrent = '\\x1b'\n\t\t\t\tcase 'N':\n\t\t\t\t\tcurrent = '\\x85'\n\t\t\t\tcase '_':\n\t\t\t\t\tcurrent = '\\xa0'\n\t\t\t\tcase 'L':\n\t\t\t\t\tcurrent = '\\u2028'\n\t\t\t\tcase 'P':\n\t\t\t\t\tcurrent = '\\u2029'\n\t\t\t\t}\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tcase 'x', 'u', 'U':\n\t\t\t\tvar size int\n\t\t\t\tswitch current {\n\t\t\t\tcase 'x':\n\t\t\t\t\tsize = 2\n\t\t\t\tcase 'u':\n\t\t\t\t\tsize = 4\n\t\t\t\tcase 'U':\n\t\t\t\t\tsize = 8\n\t\t\t\t}\n\t\t\t\tpop()\n\t\t\t\tif err := peekHex(size); err != nil {\n\t\t\t\t\terrMsg = err.Error()\n\t\t\t\t\tstate = splitArgsEndFail\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\n\t\t\t\twrite()\n\t\t\t\tpop()\n\t\t\t\tstate = splitArgsInDoubleQuotes\n\t\t\t\tcontinue\n\t\t\tdefault:\n\t\t\t\terrMsg = \"bad escape sequence at index \" + strconv.Itoa(idx)\n\t\t\t\tstate = splitArgsEndFail\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tdefault:\n\t\t\terrMsg = \"internal error\"\n\t\t\tstate = splitArgsEndFail\n\t\t\tcontinue\n\t\t}\n\t}\n}\n

感觉接口设计有点问题，似乎应该把 unescape 和 split 分开？ 🤔

~~才发现状态名写错了应该是 unescape~~

方法论

写这种复杂状态机之前，先用表格大致设计出状态和迁移会顺利很多

$\"image|689x102\"$

我第一次写 IP Prefix trie 的时候完全梦到哪写到哪，哪里有问题就多加一个分支，最后变得非常莫名其妙 😅

\n","createdAt":"2026-06-08 17:22:36.155132","updatedAt":"2026-06-08 17:38:58.16724","replyToPostNumber":null,"replyCount":0,"likeCount":3,"wordCount":854,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"❤️","count":3,"users":[{"id":2902,"username":"1313","name":"ᐕ)ﾉ"},{"id":5940,"username":"water","name":null},{"id":8040,"username":"dvm","name":"Dvm"}],"hasReacted":false}],"wiki":false,"version":3,"publicVersion":3,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

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"}},{"id":72272,"postNumber":3,"raw":"每过一两个月就觉得以前写的东西依托构使，恨不得狠狠 refactor 但是又没精力有没有懂的","cooked":"

每过一两个月就觉得以前写的东西依托构使，恨不得狠狠 refactor 但是又没精力有没有懂的

\n","createdAt":"2026-06-09 08:15:44.247144","updatedAt":"2026-06-09 08:15:44.247144","replyToPostNumber":null,"replyCount":0,"likeCount":1,"wordCount":37,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"plus1","count":1,"users":[{"id":2902,"username":"1313","name":"ᐕ)ﾉ"}],"hasReacted":false},{"reaction":"❤️","count":1,"users":[{"id":2902,"username":"1313","name":"ᐕ)ﾉ"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

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"}},{"id":72412,"postNumber":4,"raw":"# Ring Buffer Read/Write\n---\n行为：\n- 写入/读取异步安全\n- 读取时，如果有效数据不足，仅读取有效数据并报错\n- 写入时，如果有效空间不足，仅写入有效空间并报错\n- 保留 1 字节区分完全空/完全满\n\n### 结构体\n```go\ntype Ring struct {\n\tbuffer []byte\n\n\twp atomic.Int64 // write pointer\n\t_ [64 - 24 - 8]byte\n\n\trp atomic.Int64 // read pointer\n\t_ [64 - 8]byte\n}\n```\n\n### 读取\n```go\nfunc (ring *Ring) Read(p []byte) (n int, err error) {\n\twp := int(ring.wp.Load()) // Might be stale but it's ok\n\trp := int(ring.rp.Load())\n\n\tdefer func() {\n\t\tring.rp.Store(int64(rp))\n\t}()\n\n\t// data size\n\tn = wp - rp\n\tif n < 0 {\n\t\tn += len(ring.buffer)\n\t}\n\n\tif n < len(p) {\n\t\terr = io.EOF // B, D\n\t} else {\n\t\tn = len(p) // A, C\n\t}\n\n\tif rem := n - copy(p[:n], ring.buffer[rp:]); rem > 0 {\n\t\tcopy(p[n-rem:], ring.buffer[:rem]) // C, D\n\t\trp = rem\n\t} else {\n\t\trp += n // A, B\n\t}\n\n\treturn\n}\n```\n状态变量：\n- EOF: `len(p)` 大于有效数据\n- Wrap: 读取跨越切片结尾\n\n| | Not EOF | EOF |\n| :---: | :---: | :---: |\n| **Not Wrap** | A |B |\n| **Wrap** | C|D |\n\n#### A\n```plaintext\n0 1 2 3 4 5 6 7\nx x o o #[x x]x\n ^ ^\n wp rp\n\nRead(p), len(p): 2\n\nn = 2 - 5 + 8 = 5 > 2: n = 2\nrem = 2 - copy(p[:2], buf[5:]) = 0\nrp += 2 = 7\n```\n\n#### B\n```plaintext\n0 1 2 3 4 5 6 7\no #[x x x]o o o\n ^ ^\n rp wp\n\nRead(p), len(p): 4\n\nn = 5 - 2 = 3 < 4: EOF\nrem = 3 - copy(p[:3], buf[2:]) = 0\nrp += 3 = 5\n```\n\n#### C\n```plaintext\n0 1 2 3 4 5 6 7\nx]x o o #[x x x\n ^ ^\n wp rp\n\nRead(p), len(p): 4\n\nn = 2 - 5 + 8 = 5 > 4: n = 4\nrem = 4 - copy(p[:4], buf[5:]) = 1\ncopy(p[4-1:], buf[:1])\nrp = 1\n```\n\n#### D\n```plaintext\n0 1 2 3 4 5 6 7\nx]x o o #[x x x\n ^ ^\n wp rp\n\nRead(p), len(p): 6\n\nn = 2 - 5 + 8 = 5 < 6: EOF\nrem = 5 - copy(p[:5], buf[5:]) = 2\ncopy(p[5-2:], buf[:2])\nrp = 2\n```\n\n### 写入\n```go\nfunc (ring *Ring) Write(p []byte) (n int, err error) {\n\trp := int(ring.rp.Load()) // Might be stale but it's ok\n\twp := int(ring.wp.Load())\n\n\tdefer func() {\n\t\tring.wp.Store(int64(wp))\n\t}()\n\n\t// free space\n\tn = rp - wp - 1\n\tif n < 0 {\n\t\tn += len(ring.buffer)\n\t}\n\n\tif n < len(p) {\n\t\terr = ErrBufferFull // B, D\n\t} else {\n\t\tn = len(p) // A, C\n\t}\n\n\tif rem := n - copy(ring.buffer[wp:], p[:n]); rem > 0 {\n\t\tcopy(ring.buffer[:rem], p[n-rem:]) // C, D\n\t\twp = rem\n\t} else {\n\t\twp += n // A, B\n\t}\n\n\treturn\n}\n```\n状态变量：\n- Full: `len(p)` 大于有效空间\n- Wrap: 写入跨越切片结尾\n\n| | Not Full | Full |\n| :---: | :---: | :---: |\n| **Not Wrap** | A |B |\n| **Wrap** | C|D |\n\n#### A\n```plaintext\n0 1 2 3 4 5 6 7\nx x[o o]# x x x\n ^ ^\n wp rp\n\nWrite(p), len(p): 2\n\nn = 5 - 2 - 1 = 2 >= 2: n = 2\nrem = 2 - copy(buf[2:], p[:2]) = 0\nwp += 2 = 4\n```\n\n#### B\n```plaintext\n0 1 2 3 4 5 6 7\nx x[o o]# x x x\n ^ ^\n wp rp\n\nWrite(p), len(p): 4\n\nn = 5 - 2 - 1 = 2 < 4: Full\nrem = 2 - copy(buf[2:], p[:2]) = 0\nwp += 2 = 4\n```\n\n#### C\n```plaintext\n0 1 2 3 4 5 6 7\no #[x x x]o o o\n ^ ^\n rp wp\n\nWrite(p), len(p): 4\n\nn = 2 - 5 - 1 + 8 = 4 >= 4: n = 4\nrem = 4 - copy(p[:4], buf[5:]) = 1\ncopy(buf[:1], p[4-1:])\nwp = 1\n```\n\n#### D\n```plaintext\n0 1 2 3 4 5 6 7\no #[x x x]o o o\n ^ ^\n rp wp\n\nWrite(p), len(p): 6\n\nn = 2 - 5 - 1 + 8 = 4 < 6: Full\nrem = 4 - copy(p[:4], buf[5:]) = 1\ncopy(buf[:1], p[4-1:])\nwp = 1\n```","cooked":"

Ring Buffer Read/Write

行为：

写入/读取异步安全
读取时，如果有效数据不足，仅读取有效数据并报错
写入时，如果有效空间不足，仅写入有效空间并报错
保留 1 字节区分完全空/完全满

结构体

type Ring struct {\n\tbuffer []byte\n\n\twp atomic.Int64 // write pointer\n\t_  [64 - 24 - 8]byte\n\n\trp atomic.Int64 // read pointer\n\t_  [64 - 8]byte\n}\n

读取

func (ring *Ring) Read(p []byte) (n int, err error) {\n\twp := int(ring.wp.Load()) // Might be stale but it's ok\n\trp := int(ring.rp.Load())\n\n\tdefer func() {\n\t\tring.rp.Store(int64(rp))\n\t}()\n\n\t// data size\n\tn = wp - rp\n\tif n < 0 {\n\t\tn += len(ring.buffer)\n\t}\n\n\tif n < len(p) {\n\t\terr = io.EOF // B, D\n\t} else {\n\t\tn = len(p) // A, C\n\t}\n\n\tif rem := n - copy(p[:n], ring.buffer[rp:]); rem > 0 {\n\t\tcopy(p[n-rem:], ring.buffer[:rem]) // C, D\n\t\trp = rem\n\t} else {\n\t\trp += n // A, B\n\t}\n\n\treturn\n}\n

状态变量：

EOF: len(p) 大于有效数据
Wrap: 读取跨越切片结尾

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n

	Not EOF	EOF
Not Wrap	A	B
Wrap	C	D

A

0 1 2 3 4 5 6 7\nx x o o #[x x]x\n    ^     ^\n    wp    rp\n\nRead(p), len(p): 2\n\nn = 2 - 5 + 8 = 5 > 2: n = 2\nrem = 2 - copy(p[:2], buf[5:]) = 0\nrp += 2 = 7\n

B

0 1 2 3 4 5 6 7\no #[x x x]o o o\n    ^     ^\n    rp    wp\n\nRead(p), len(p): 4\n\nn = 5 - 2 = 3 < 4: EOF\nrem = 3 - copy(p[:3], buf[2:]) = 0\nrp += 3 = 5\n

C

0 1 2 3 4 5 6 7\nx]x o o #[x x x\n    ^     ^\n    wp    rp\n\nRead(p), len(p): 4\n\nn = 2 - 5 + 8 = 5 > 4: n = 4\nrem = 4 - copy(p[:4], buf[5:]) = 1\ncopy(p[4-1:], buf[:1])\nrp = 1\n

D

0 1 2 3 4 5 6 7\nx]x o o #[x x x\n    ^     ^\n    wp    rp\n\nRead(p), len(p): 6\n\nn = 2 - 5 + 8 = 5 < 6: EOF\nrem = 5 - copy(p[:5], buf[5:]) = 2\ncopy(p[5-2:], buf[:2])\nrp = 2\n

写入

func (ring *Ring) Write(p []byte) (n int, err error) {\n\trp := int(ring.rp.Load()) // Might be stale but it's ok\n\twp := int(ring.wp.Load())\n\n\tdefer func() {\n\t\tring.wp.Store(int64(wp))\n\t}()\n\n\t// free space\n\tn = rp - wp - 1\n\tif n < 0 {\n\t\tn += len(ring.buffer)\n\t}\n\n\tif n < len(p) {\n\t\terr = ErrBufferFull // B, D\n\t} else {\n\t\tn = len(p) // A, C\n\t}\n\n\tif rem := n - copy(ring.buffer[wp:], p[:n]); rem > 0 {\n\t\tcopy(ring.buffer[:rem], p[n-rem:]) // C, D\n\t\twp = rem\n\t} else {\n\t\twp += n // A, B\n\t}\n\n\treturn\n}\n

状态变量：

Full: len(p) 大于有效空间
Wrap: 写入跨越切片结尾

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n

	Not Full	Full
Not Wrap	A	B
Wrap	C	D

A

0 1 2 3 4 5 6 7\nx x[o o]# x x x\n    ^     ^\n    wp    rp\n\nWrite(p), len(p): 2\n\nn = 5 - 2 - 1 = 2 >= 2: n = 2\nrem = 2 - copy(buf[2:], p[:2]) = 0\nwp += 2 = 4\n

B

0 1 2 3 4 5 6 7\nx x[o o]# x x x\n    ^     ^\n    wp    rp\n\nWrite(p), len(p): 4\n\nn = 5 - 2 - 1 = 2 < 4: Full\nrem = 2 - copy(buf[2:], p[:2]) = 0\nwp += 2 = 4\n

C

0 1 2 3 4 5 6 7\no #[x x x]o o o\n    ^     ^\n    rp    wp\n\nWrite(p), len(p): 4\n\nn = 2 - 5 - 1 + 8 = 4 >= 4: n = 4\nrem = 4 - copy(p[:4], buf[5:]) = 1\ncopy(buf[:1], p[4-1:])\nwp = 1\n

D

0 1 2 3 4 5 6 7\no #[x x x]o o o\n    ^     ^\n    rp    wp\n\nWrite(p), len(p): 6\n\nn = 2 - 5 - 1 + 8 = 4 < 6: Full\nrem = 4 - copy(p[:4], buf[5:]) = 1\ncopy(buf[:1], p[4-1:])\nwp = 1\n

\n","createdAt":"2026-06-23 15:12:39.082249","updatedAt":"2026-06-23 15:12:39.082249","replyToPostNumber":null,"replyCount":0,"likeCount":0,"wordCount":830,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72423,"postNumber":5,"raw":"# ID Counter\n---\n```go\ntype IDCounter interface {\n\tGetID() uint64\n}\n```\n\n行为：\n- 异步安全\n- 有限时间内 ID 唯一\n\n---\n#### SimpleIDCounter\n```go\ntype SimpleIDCounter struct{ atomic.Uint64 }\n\nfunc (c *SimpleIDCounter) GetID() uint64 {\n\treturn c.Add(1)\n}\n```\n\n异步安全，`uint64` 可生成 `1 << 64` 个唯一 ID，高并发下由于锁竞争延迟线性提高\n\n---\n#### RandomShardedIDCounter\n```go\ntype shard struct {\n\tvalue atomic.Uint64\n\t_ [64 - 8]byte\n}\n\ntype RandomShardedIDCounter struct {\n\tshards []shard\n\tmask int\n\tshifts int\n}\n\nfunc NewRandomShardedIDCounter(n int) *RandomShardedIDCounter {\n\tif n <= 0 {\n\t\tn = 1\n\t}\n\n\tnumShards := 1\n\tshifts := 1\n\n\tfor numShards < n {\n\t\tnumShards <<= 1\n\t\tshifts++\n\t}\n\n\treturn &RandomShardedIDCounter{\n\t\tshards: make([]shard, numShards),\n\t\tmask: numShards - 1,\n\t\tshifts: shifts,\n\t}\n}\n\nfunc (c *RandomShardedIDCounter) GetID() uint64 {\n\tidx := rand.Int() & c.mask\n\n\tval := c.shards[idx].value.Add(1)\n\n\treturn (val << uint64(c.shifts)) | uint64(idx)\n}\n```\n异步安全，用 `shardIdx` 作为 ID 低位，每个 shard 可连续生成 `1 << (64 - bitWidth(shardIdx))` 个唯一 ID\n\n用随机 `shardIdx` 均分请求到各 shard 缓解锁竞争\n\n这里 `rand` 是 `math/rand/v2`，因为 `v1` 的全局函数是同步的\n\n---\n#### 跑分\n\n![benchplot|690x431](/uploads/image/64/8c/648c302645bf89e9a77cebd687243850dfba46220af229175ee1e3acf682f8dd.avif)\n\nSharded `2 <= GOMAXPROCS <= 4` 突然很慢是怎么回事有没有懂的？ :melt:\n`pprof` 我还不太能用明白","cooked":"

ID Counter

type IDCounter interface {\n\tGetID() uint64\n}\n

行为：

异步安全
有限时间内 ID 唯一

SimpleIDCounter

type SimpleIDCounter struct{ atomic.Uint64 }\n\nfunc (c *SimpleIDCounter) GetID() uint64 {\n\treturn c.Add(1)\n}\n

异步安全，uint64 可生成 1 << 64 个唯一 ID，高并发下由于锁竞争延迟线性提高

RandomShardedIDCounter

type shard struct {\n\tvalue atomic.Uint64\n\t_     [64 - 8]byte\n}\n\ntype RandomShardedIDCounter struct {\n\tshards []shard\n\tmask   int\n\tshifts int\n}\n\nfunc NewRandomShardedIDCounter(n int) *RandomShardedIDCounter {\n\tif n <= 0 {\n\t\tn = 1\n\t}\n\n\tnumShards := 1\n\tshifts := 1\n\n\tfor numShards < n {\n\t\tnumShards <<= 1\n\t\tshifts++\n\t}\n\n\treturn &RandomShardedIDCounter{\n\t\tshards: make([]shard, numShards),\n\t\tmask:   numShards - 1,\n\t\tshifts: shifts,\n\t}\n}\n\nfunc (c *RandomShardedIDCounter) GetID() uint64 {\n\tidx := rand.Int() & c.mask\n\n\tval := c.shards[idx].value.Add(1)\n\n\treturn (val << uint64(c.shifts)) | uint64(idx)\n}\n

异步安全，用 shardIdx 作为 ID 低位，每个 shard 可连续生成 1 << (64 - bitWidth(shardIdx)) 个唯一 ID

用随机 shardIdx 均分请求到各 shard 缓解锁竞争

这里 rand 是 math/rand/v2，因为 v1 的全局函数是同步的

跑分

$\"benchplot|690x431\"$

Sharded 2 <= GOMAXPROCS <= 4 突然很慢是怎么回事有没有懂的？ 🫠
\npprof 我还不太能用明白

\n","createdAt":"2026-06-26 14:14:51.103626","updatedAt":"2026-06-26 14:20:48.753541","replyToPostNumber":null,"replyCount":1,"likeCount":0,"wordCount":269,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":2,"publicVersion":2,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72424,"postNumber":6,"raw":"```plaintext\n Total: 2.23s 2.33s (flat, cum) 98.73%\n 60 . . \t\tmask: numShards - 1, \n 61 . . \t\tshifts: shifts, \n 62 . . \t} \n 63 . . } \n 64 . . \n 65 10ms 10ms func (c *RandomShardedIDCounter) GetID() uint64 { \n 66 60ms 160ms \tidx := rand.Int() & c.mask \n 67 . . \n 68 60ms 60ms \tval := c.shards[idx].value.Add(1) \n 69 . . \n 70 2.10s 2.10s \treturn (val << uint64(c.shifts)) | uint64(idx) \n 71 . . } \n```\n何意味","cooked":"

  Total:       2.23s      2.33s (flat, cum) 98.73%\n     60            .          .           \t\tmask:   numShards - 1, \n     61            .          .           \t\tshifts: shifts, \n     62            .          .           \t} \n     63            .          .           } \n     64            .          .            \n     65         10ms       10ms           func (c *RandomShardedIDCounter) GetID() uint64 { \n     66         60ms      160ms           \tidx := rand.Int() & c.mask \n     67            .          .            \n     68         60ms       60ms           \tval := c.shards[idx].value.Add(1) \n     69            .          .            \n     70        2.10s      2.10s           \treturn (val << uint64(c.shifts)) | uint64(idx) \n     71            .          .           } \n

何意味

\n","createdAt":"2026-06-26 14:29:49.219966","updatedAt":"2026-06-26 14:29:49.219966","replyToPostNumber":5,"replyCount":0,"likeCount":0,"wordCount":76,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72562,"postNumber":7,"raw":"

\r\n签名的 Anon 酱老是被 GC 掉，在这里放一个也许就不会了吧\r\n\r\nBtw 上传 webp 似乎有问题，转换后的 avif 图片无法正确显示","cooked":"

\n签名的 Anon 酱老是被 GC 掉，在这里放一个也许就不会了吧\n

Btw 上传 webp 似乎有问题，转换后的 avif 图片无法正确显示

\n","createdAt":"2026-07-13T15:33:17.724Z","updatedAt":"2026-07-13T15:37:39.259Z","replyToPostNumber":null,"replyCount":1,"likeCount":0,"wordCount":51,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"cat_rabbit","count":1,"users":[{"id":30,"username":"一只玉米人","name":"玉米🌽"}],"hasReacted":false},{"reaction":"❤️","count":1,"users":[{"id":30,"username":"一只玉米人","name":"玉米🌽"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72563,"postNumber":8,"raw":"我这边可以正常显示 :heart_eyes:","cooked":"

我这边可以正常显示 😍

\n","createdAt":"2026-07-13T15:56:17.079Z","updatedAt":"2026-07-13T15:56:17.079Z","replyToPostNumber":7,"replyCount":1,"likeCount":0,"wordCount":10,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"plus1","count":1,"users":[{"id":4668,"username":"IO","name":null}],"hasReacted":false},{"reaction":"wave_gif","count":1,"users":[{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":30,"username":"一只玉米人","name":"玉米🌽","avatarUrl":"/uploads/blob/14/96/14961aeaa46ccbb75a61eec0c27b26e74fb5d1c00ccdcbbe898ca9ea37087dd6.svg","admin":false,"moderator":true,"signatureRaw":"*年月擦身过，暂且问，会更好吗？*","signatureCooked":"

年月擦身过，暂且问，会更好吗？

\n"}},{"id":72564,"postNumber":9,"raw":"# Log file change watcher\r\n## 接口\r\n```go\r\ntype Change uint8\r\n\r\nconst (\r\n\tChangeCreated Change = iota\r\n\tChangeDeleted\r\n\tChangeMoved\r\n\tChangeModified\r\n\tChangeTruncated\r\n)\r\n\r\ntype Watcher interface {\r\n\tBlockUntilChange(ctx context.Context) (Change, error)\r\n}\r\n```\r\n\r\n## Polling 实现\r\n```go\r\npackage tail\r\n\r\nimport (\r\n\t\"context\"\r\n\t\"os\"\r\n\t\"time\"\r\n)\r\n\r\nvar _ Watcher = (*PollWatcher)(nil)\r\n\r\ntype PollWatcher struct {\r\n\tinterval time.Duration\r\n\tfilepath string\r\n\tfi os.FileInfo\r\n\tsize int64\r\n\tmodified time.Time\r\n}\r\n\r\nfunc NewPollWatcher(path string, interval time.Duration) (*PollWatcher, error) {\r\n\tfi, err := os.Stat(path)\r\n\tif err != nil {\r\n\t\tif os.IsNotExist(err) {\r\n\t\t\tfi = nil\r\n\t\t} else {\r\n\t\t\treturn nil, err\r\n\t\t}\r\n\t}\r\n\r\n\tpw := &PollWatcher{\r\n\t\tfilepath: path,\r\n\t\tinterval: interval,\r\n\t\tfi: fi,\r\n\t}\r\n\r\n\tif fi != nil {\r\n\t\tpw.size = fi.Size()\r\n\t\tpw.modified = fi.ModTime()\r\n\t}\r\n\r\n\treturn pw, nil\r\n}\r\n\r\nfunc (pw *PollWatcher) BlockUntilChange(ctx context.Context) (Change, error) {\r\n\tticker := time.NewTicker(pw.interval)\r\n\tdefer ticker.Stop()\r\n\r\n\tfor {\r\n\t\tselect {\r\n\t\tcase <-ctx.Done():\r\n\t\t\treturn 0, ctx.Err()\r\n\t\tcase <-ticker.C:\r\n\t\t\tfi, err := os.Stat(pw.filepath)\r\n\t\t\tif err != nil {\r\n\t\t\t\tif os.IsNotExist(err) {\r\n\t\t\t\t\tif pw.fi != nil {\r\n\t\t\t\t\t\tpw.fi = nil\r\n\t\t\t\t\t\treturn ChangeDeleted, nil\r\n\t\t\t\t\t}\r\n\t\t\t\t\tcontinue\r\n\t\t\t\t}\r\n\t\t\t\treturn 0, err\r\n\t\t\t}\r\n\r\n\t\t\tlastSize := pw.size\r\n\t\t\tlastModified := pw.modified\r\n\t\t\tlastFi := pw.fi\r\n\t\t\tpw.size = fi.Size()\r\n\t\t\tpw.modified = fi.ModTime()\r\n\t\t\tpw.fi = fi\r\n\r\n\t\t\tif lastFi == nil {\r\n\t\t\t\treturn ChangeCreated, nil\r\n\t\t\t}\r\n\r\n\t\t\tif !os.SameFile(lastFi, fi) {\r\n\t\t\t\treturn ChangeMoved, nil\r\n\t\t\t}\r\n\r\n\t\t\tif pw.size < lastSize {\r\n\t\t\t\treturn ChangeTruncated, nil\r\n\t\t\t}\r\n\r\n\t\t\tif pw.size > lastSize || !pw.modified.Equal(lastModified) {\r\n\t\t\t\treturn ChangeModified, nil\r\n\t\t\t}\r\n\t\t}\r\n\t}\r\n}\r\n```\r\n| 情况 | 判定 |\r\n|----------|-----------|\r\n| **正常 append** | `pw.size > lastSize` -> `ChangeModified` |\r\n| **Log rotate (重命名 + 新建)** | `!os.SameFile(lastFi, fi)` -> `ChangeMoved` |\r\n| **Log rotate (复制 + 截短)** | `pw.size < lastSize` -> `ChangeTruncated` |\r\n| **新建** | `lastFi == nil` -> `ChangeCreated` |\r\n| **删除** | `pw.fi != nil` + `os.IsNotExist` -> `ChangeDeleted` |","cooked":"

Log file change watcher

接口

type Change uint8\n\nconst (\n\tChangeCreated Change = iota\n\tChangeDeleted\n\tChangeMoved\n\tChangeModified\n\tChangeTruncated\n)\n\ntype Watcher interface {\n\tBlockUntilChange(ctx context.Context) (Change, error)\n}\n

Polling 实现

package tail\n\nimport (\n\t\"context\"\n\t\"os\"\n\t\"time\"\n)\n\nvar _ Watcher = (*PollWatcher)(nil)\n\ntype PollWatcher struct {\n\tinterval time.Duration\n\tfilepath string\n\tfi       os.FileInfo\n\tsize     int64\n\tmodified time.Time\n}\n\nfunc NewPollWatcher(path string, interval time.Duration) (*PollWatcher, error) {\n\tfi, err := os.Stat(path)\n\tif err != nil {\n\t\tif os.IsNotExist(err) {\n\t\t\tfi = nil\n\t\t} else {\n\t\t\treturn nil, err\n\t\t}\n\t}\n\n\tpw := &PollWatcher{\n\t\tfilepath: path,\n\t\tinterval: interval,\n\t\tfi:       fi,\n\t}\n\n\tif fi != nil {\n\t\tpw.size = fi.Size()\n\t\tpw.modified = fi.ModTime()\n\t}\n\n\treturn pw, nil\n}\n\nfunc (pw *PollWatcher) BlockUntilChange(ctx context.Context) (Change, error) {\n\tticker := time.NewTicker(pw.interval)\n\tdefer ticker.Stop()\n\n\tfor {\n\t\tselect {\n\t\tcase <-ctx.Done():\n\t\t\treturn 0, ctx.Err()\n\t\tcase <-ticker.C:\n\t\t\tfi, err := os.Stat(pw.filepath)\n\t\t\tif err != nil {\n\t\t\t\tif os.IsNotExist(err) {\n\t\t\t\t\tif pw.fi != nil {\n\t\t\t\t\t\tpw.fi = nil\n\t\t\t\t\t\treturn ChangeDeleted, nil\n\t\t\t\t\t}\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\t\t\t\treturn 0, err\n\t\t\t}\n\n\t\t\tlastSize := pw.size\n\t\t\tlastModified := pw.modified\n\t\t\tlastFi := pw.fi\n\t\t\tpw.size = fi.Size()\n\t\t\tpw.modified = fi.ModTime()\n\t\t\tpw.fi = fi\n\n\t\t\tif lastFi == nil {\n\t\t\t\treturn ChangeCreated, nil\n\t\t\t}\n\n\t\t\tif !os.SameFile(lastFi, fi) {\n\t\t\t\treturn ChangeMoved, nil\n\t\t\t}\n\n\t\t\tif pw.size < lastSize {\n\t\t\t\treturn ChangeTruncated, nil\n\t\t\t}\n\n\t\t\tif pw.size > lastSize || !pw.modified.Equal(lastModified) {\n\t\t\t\treturn ChangeModified, nil\n\t\t\t}\n\t\t}\n\t}\n}\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n

情况	判定
正常 append	`pw.size > lastSize` -> `ChangeModified`
Log rotate (重命名 + 新建)	`!os.SameFile(lastFi, fi)` -> `ChangeMoved`
Log rotate (复制 + 截短)	`pw.size < lastSize` -> `ChangeTruncated`
新建	`lastFi == nil` -> `ChangeCreated`
删除	`pw.fi != nil` + `os.IsNotExist` -> `ChangeDeleted`

\n","createdAt":"2026-07-13T16:02:14.770Z","updatedAt":"2026-07-13T17:52:06.722Z","replyToPostNumber":null,"replyCount":2,"likeCount":0,"wordCount":316,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":3,"publicVersion":3,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72565,"postNumber":10,"raw":"![anon.webp|375x500](/uploads/image/ad/c8/adc89f2248f451f288966812fb69ec6cffcaa801066524f9d129da91a0e613f2.avif)\r\n刚才那是 png，这个能显示吗？","cooked":"

$\"anon.webp|375x500\"$
\n刚才那是 png，这个能显示吗？

\n","createdAt":"2026-07-13T16:03:03.857Z","updatedAt":"2026-07-13T16:03:03.857Z","replyToPostNumber":8,"replyCount":1,"likeCount":0,"wordCount":13,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72566,"postNumber":11,"raw":"[quote=\"stateless_trash_can, post:9, topic:15591\"]\r\n**Log rotate (复制 + 截短)**\r\n`pw.size < lastSize` -> `ChangeTruncated`\r\n[/quote]\r\n\r\n这里如果在一次迭代期间，截短并写入超过原来文件大小的内容，会误判为 `ChangeModified`，暂时想不到怎么办 :melt: （不过这种情况对于日志来说不太可能？）\r\n\r\n后果是丢失一部分行","cooked":"

\n\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\tstateless_trash_can:\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t

\n
Log rotate (复制 + 截短)
\npw.size < lastSize -> ChangeTruncated
\n

\n\t\t\t\t\t\t

这里如果在一次迭代期间，截短并写入超过原来文件大小的内容，会误判为 ChangeModified，暂时想不到怎么办 🫠 （不过这种情况对于日志来说不太可能？）

后果是丢失一部分行

\n","createdAt":"2026-07-13T16:16:20.934Z","updatedAt":"2026-07-13T17:44:51.943Z","replyToPostNumber":9,"replyCount":0,"likeCount":0,"wordCount":88,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":2,"publicVersion":2,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72568,"postNumber":12,"raw":"## FSNotify 实现\r\n```go\r\npackage tail\r\n\r\nimport (\r\n\t\"context\"\r\n\t\"errors\"\r\n\t\"fmt\"\r\n\t\"os\"\r\n\t\"path/filepath\"\r\n\r\n\t\"github.com/fsnotify/fsnotify\"\r\n)\r\n\r\nvar _ Watcher = (*FSNotifyWatcher)(nil)\r\n\r\ntype FSNotifyWatcher struct {\r\n\twatcher *fsnotify.Watcher\r\n\tfilepath string\r\n\tsize int64\r\n\twasPresent bool\r\n}\r\n\r\nfunc NewFSNotifyWatcher(path string) (*FSNotifyWatcher, error) {\r\n\twatcher, err := fsnotify.NewWatcher()\r\n\tif err != nil {\r\n\t\treturn nil, err\r\n\t}\r\n\r\n\tcleanPath := filepath.Clean(path)\r\n\tparentDir := filepath.Dir(cleanPath)\r\n\r\n\t// Watch parent and filter by Event.Name\r\n\terr = watcher.Add(parentDir)\r\n\tif err != nil {\r\n\t\twatcher.Close()\r\n\t\treturn nil, err\r\n\t}\r\n\r\n\t// Get initial size and presence\r\n\tvar size int64\r\n\twasPresent := false\r\n\tfi, err := os.Stat(path)\r\n\tif err == nil {\r\n\t\tsize = fi.Size()\r\n\t\twasPresent = true\r\n\t}\r\n\r\n\treturn &FSNotifyWatcher{\r\n\t\twatcher: watcher,\r\n\t\tfilepath: cleanPath,\r\n\t\tsize: size,\r\n\t\twasPresent: wasPresent,\r\n\t}, nil\r\n}\r\n\r\nfunc (fw *FSNotifyWatcher) Close() error {\r\n\treturn fw.watcher.Close()\r\n}\r\n\r\nfunc (fw *FSNotifyWatcher) BlockUntilChange(ctx context.Context) (Change, error) {\r\n\tfor {\r\n\t\tselect {\r\n\t\tcase <-ctx.Done():\r\n\t\t\treturn 0, ctx.Err()\r\n\r\n\t\tcase err, ok := <-fw.watcher.Errors:\r\n\t\t\tif !ok {\r\n\t\t\t\treturn 0, errors.New(\"watcher channel closed\")\r\n\t\t\t}\r\n\t\t\treturn 0, err\r\n\r\n\t\tcase event, ok := <-fw.watcher.Events:\r\n\t\t\tif !ok {\r\n\t\t\t\treturn 0, errors.New(\"watcher channel closed\")\r\n\t\t\t}\r\n\r\n\t\t\tif filepath.Clean(event.Name) != fw.filepath {\r\n\t\t\t\tcontinue\r\n\t\t\t}\r\n\r\n\t\t\tswitch {\r\n\t\t\tcase event.Has(fsnotify.Create):\r\n\t\t\t\tif fw.wasPresent {\r\n\t\t\t\t\tif fi, err := os.Stat(fw.filepath); err == nil {\r\n\t\t\t\t\t\tfw.size = fi.Size()\r\n\t\t\t\t\t}\r\n\t\t\t\t\tcontinue\r\n\t\t\t\t}\r\n\t\t\t\tfw.wasPresent = true\r\n\t\t\t\treturn ChangeCreated, nil\r\n\r\n\t\t\tcase event.Has(fsnotify.Write):\r\n\t\t\t\tif fi, err := os.Stat(fw.filepath); err == nil {\r\n\t\t\t\t\tlastSize := fw.size\r\n\t\t\t\t\tfw.size = fi.Size()\r\n\r\n\t\t\t\t\tif fw.size < lastSize {\r\n\t\t\t\t\t\treturn ChangeTruncated, nil\r\n\t\t\t\t\t} else {\r\n\t\t\t\t\t\treturn ChangeModified, nil\r\n\t\t\t\t\t}\r\n\t\t\t\t} else {\r\n\t\t\t\t\treturn 0, fmt.Errorf(\"os.Stat failed: %w\", err)\r\n\t\t\t\t}\r\n\r\n\t\t\tcase event.Has(fsnotify.Remove):\r\n\t\t\t\tfw.wasPresent = false\r\n\t\t\t\treturn ChangeDeleted, nil\r\n\r\n\t\t\tcase event.Has(fsnotify.Rename):\r\n\t\t\t\treturn ChangeMoved, nil\r\n\t\t\t}\r\n\t\t}\r\n\t}\r\n}\r\n```","cooked":"

FSNotify 实现

package tail\n\nimport (\n\t\"context\"\n\t\"errors\"\n\t\"fmt\"\n\t\"os\"\n\t\"path/filepath\"\n\n\t\"github.com/fsnotify/fsnotify\"\n)\n\nvar _ Watcher = (*FSNotifyWatcher)(nil)\n\ntype FSNotifyWatcher struct {\n\twatcher    *fsnotify.Watcher\n\tfilepath   string\n\tsize       int64\n\twasPresent bool\n}\n\nfunc NewFSNotifyWatcher(path string) (*FSNotifyWatcher, error) {\n\twatcher, err := fsnotify.NewWatcher()\n\tif err != nil {\n\t\treturn nil, err\n\t}\n\n\tcleanPath := filepath.Clean(path)\n\tparentDir := filepath.Dir(cleanPath)\n\n\t// Watch parent and filter by Event.Name\n\terr = watcher.Add(parentDir)\n\tif err != nil {\n\t\twatcher.Close()\n\t\treturn nil, err\n\t}\n\n\t// Get initial size and presence\n\tvar size int64\n\twasPresent := false\n\tfi, err := os.Stat(path)\n\tif err == nil {\n\t\tsize = fi.Size()\n\t\twasPresent = true\n\t}\n\n\treturn &FSNotifyWatcher{\n\t\twatcher:    watcher,\n\t\tfilepath:   cleanPath,\n\t\tsize:       size,\n\t\twasPresent: wasPresent,\n\t}, nil\n}\n\nfunc (fw *FSNotifyWatcher) Close() error {\n\treturn fw.watcher.Close()\n}\n\nfunc (fw *FSNotifyWatcher) BlockUntilChange(ctx context.Context) (Change, error) {\n\tfor {\n\t\tselect {\n\t\tcase <-ctx.Done():\n\t\t\treturn 0, ctx.Err()\n\n\t\tcase err, ok := <-fw.watcher.Errors:\n\t\t\tif !ok {\n\t\t\t\treturn 0, errors.New(\"watcher channel closed\")\n\t\t\t}\n\t\t\treturn 0, err\n\n\t\tcase event, ok := <-fw.watcher.Events:\n\t\t\tif !ok {\n\t\t\t\treturn 0, errors.New(\"watcher channel closed\")\n\t\t\t}\n\n\t\t\tif filepath.Clean(event.Name) != fw.filepath {\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\tswitch {\n\t\t\tcase event.Has(fsnotify.Create):\n\t\t\t\tif fw.wasPresent {\n\t\t\t\t\tif fi, err := os.Stat(fw.filepath); err == nil {\n\t\t\t\t\t\tfw.size = fi.Size()\n\t\t\t\t\t}\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\t\t\t\tfw.wasPresent = true\n\t\t\t\treturn ChangeCreated, nil\n\n\t\t\tcase event.Has(fsnotify.Write):\n\t\t\t\tif fi, err := os.Stat(fw.filepath); err == nil {\n\t\t\t\t\tlastSize := fw.size\n\t\t\t\t\tfw.size = fi.Size()\n\n\t\t\t\t\tif fw.size < lastSize {\n\t\t\t\t\t\treturn ChangeTruncated, nil\n\t\t\t\t\t} else {\n\t\t\t\t\t\treturn ChangeModified, nil\n\t\t\t\t\t}\n\t\t\t\t} else {\n\t\t\t\t\treturn 0, fmt.Errorf(\"os.Stat failed: %w\", err)\n\t\t\t\t}\n\n\t\t\tcase event.Has(fsnotify.Remove):\n\t\t\t\tfw.wasPresent = false\n\t\t\t\treturn ChangeDeleted, nil\n\n\t\t\tcase event.Has(fsnotify.Rename):\n\t\t\t\treturn ChangeMoved, nil\n\t\t\t}\n\t\t}\n\t}\n}\n

\n","createdAt":"2026-07-13T17:51:29.141Z","updatedAt":"2026-07-13T18:56:07.677Z","replyToPostNumber":9,"replyCount":0,"likeCount":0,"wordCount":272,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":2,"publicVersion":2,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72569,"postNumber":13,"raw":"能正常显示。所有的图片除了svg之外，不管是什么格式，都会被[ImageMagick](https://imagemagick.org/)转换为AVIF格式。如果没法正常显示，可能是浏览器不支持： https://caniuse.com/avif\r\n\r\n其实普遍的做法是根据不同的浏览器UserAgent，服务器发送支持的格式。\r\n\r\n另外AVIF虽然压缩率比较高，浏览器广泛支持，但也存在一些问题：\r\n* 压缩/转码成avif较慢。\r\n* 不支持progrssive decoding，导致没法在网络较慢时像jpg一样一行一行地加载，只能全部下载后才能加载。\r\n\r\n比较理想的是jpeg-xl，支持progressive decoding, encoding较快。\r\n但是目前仅支持最新版Chrome/Firefox并需要启用experimental setting：\r\n* Chrome： \r\n访问 chrome://flags/\r\nenable-jxl-image-format \r\n* Firefox： \r\n访问 about:config\r\nimage.jxl.enabled","cooked":"

能正常显示。所有的图片除了svg之外，不管是什么格式，都会被ImageMagick转换为AVIF格式。如果没法正常显示，可能是浏览器不支持： https://caniuse.com/avif

其实普遍的做法是根据不同的浏览器UserAgent，服务器发送支持的格式。

另外AVIF虽然压缩率比较高，浏览器广泛支持，但也存在一些问题：

压缩/转码成avif较慢。
不支持progrssive decoding，导致没法在网络较慢时像jpg一样一行一行地加载，只能全部下载后才能加载。

比较理想的是jpeg-xl，支持progressive decoding, encoding较快。
\n但是目前仅支持最新版Chrome/Firefox并需要启用experimental setting：

Chrome：
\n访问 chrome://flags/
\nenable-jxl-image-format
Firefox：
\n访问 about:config
\nimage.jxl.enabled

\n","createdAt":"2026-07-14T01:19:10.979Z","updatedAt":"2026-07-14T01:19:49.516Z","replyToPostNumber":10,"replyCount":2,"likeCount":0,"wordCount":209,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"👍","count":1,"users":[{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":4668,"username":"IO","name":null,"avatarUrl":"/uploads/image/86/f2/86f267c0aaa73835a999b7cc3a7e7a701605574eda9a2c2a56f5ddbbba64d1a9.avif","admin":true,"moderator":false,"signatureRaw":"","signatureCooked":null}},{"id":72570,"postNumber":14,"raw":"现在可以了，之前疑似没加载出来\r\n\r\n不过之前确实上传 webp 无法立即显示，但是 png 可以\r\n\r\n现在无法复现了\r\n\r\nEdit: 编辑器内上传图片无法立即加载，手动在新标签页访问图片路径后就可以在编辑器内显示了，不知道是不是网络问题","cooked":"

现在可以了，之前疑似没加载出来

不过之前确实上传 webp 无法立即显示，但是 png 可以

现在无法复现了

Edit: 编辑器内上传图片无法立即加载，手动在新标签页访问图片路径后就可以在编辑器内显示了，不知道是不是网络问题

\n","createdAt":"2026-07-14T04:16:00.504Z","updatedAt":"2026-07-14T04:31:33.691Z","replyToPostNumber":13,"replyCount":0,"likeCount":0,"wordCount":95,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":2,"publicVersion":2,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72571,"postNumber":15,"raw":"## Tail\r\n```go\r\npackage tail\r\n\r\nimport (\r\n\t\"bufio\"\r\n\t\"bytes\"\r\n\t\"context\"\r\n\t\"errors\"\r\n\t\"fmt\"\r\n\t\"io\"\r\n\t\"os\"\r\n\t\"sync\"\r\n\t\"time\"\r\n)\r\n\r\nconst (\r\n\tpollInterval = 250 * time.Millisecond\r\n)\r\n\r\ntype fakeReader struct{}\r\n\r\nfunc (*fakeReader) Read(p []byte) (n int, err error) {\r\n\treturn 0, nil\r\n}\r\n\r\ntype Config struct {\r\n\t// Seek to before tailing.\r\n\tSeek SeekInfo\r\n\r\n\t// Provide appended data as the file grows.\r\n\tFollow bool\r\n\r\n\t// Keep trying to open a file if it is inaccessible.\r\n\t// Ignored when Follow is false.\r\n\tRetry bool\r\n\r\n\t// Use PollWatcher for file changes.\r\n\t// FSNotifyWatcher is used if false.\r\n\tPoll bool\r\n\r\n\t// Disable seeking.\r\n\t// Enable this for named pipes (mkfifo).\r\n\tNoSeek bool\r\n\r\n\t// Line delimiter.\r\n\tDelimiter byte\r\n}\r\n\r\nfunc DefaultConfig() Config {\r\n\treturn Config{\r\n\t\tDelimiter: '\\n',\r\n\t}\r\n}\r\n\r\n// SeekInfo\r\ntype SeekInfo struct {\r\n\tOffset int64\r\n\tWhence int\r\n}\r\n\r\ntype Tail struct {\r\n\tcfg Config\r\n\tfilename string\r\n\tfile *os.File\r\n\twatcher Watcher\r\n\r\n\treader *bufio.Reader\r\n\r\n\tfirstOpen bool\r\n\r\n\tmu sync.Mutex\r\n\tctx context.Context\r\n\tcancel context.CancelFunc\r\n}\r\n\r\nfunc New(ctx context.Context, filename string, cfg Config) (*Tail, error) {\r\n\r\n\tvar watcher Watcher\r\n\tvar err error\r\n\tif cfg.Poll {\r\n\t\twatcher, err = NewPollWatcher(filename, pollInterval)\r\n\t\tif err != nil {\r\n\t\t\treturn nil, fmt.Errorf(\"failed to create PollWatcher: %w\", err)\r\n\t\t}\r\n\t} else {\r\n\t\twatcher, err = NewFSNotifyWatcher(filename)\r\n\t\tif err != nil {\r\n\t\t\treturn nil, fmt.Errorf(\"failed to create FSNotifyWatcher: %w\", err)\r\n\t\t}\r\n\t}\r\n\r\n\treturn newTailWithWatcher(ctx, filename, cfg, watcher), nil\r\n}\r\n\r\nfunc newTailWithWatcher(ctx context.Context, filename string, cfg Config, watcher Watcher) *Tail {\r\n\tctx, cancel := context.WithCancel(ctx)\r\n\r\n\treturn &Tail{\r\n\t\tcfg: cfg,\r\n\t\tfilename: filename,\r\n\t\twatcher: watcher,\r\n\t\treader: bufio.NewReader(&fakeReader{}),\r\n\t\tfirstOpen: true,\r\n\t\tctx: ctx,\r\n\t\tcancel: cancel,\r\n\t}\r\n}\r\n\r\nvar (\r\n\tErrBufferTooShort = errors.New(\"buffer is too short to read complete line\")\r\n)\r\n\r\nfunc (t *Tail) ReadLine(b []byte) (n int, err error) {\r\n\tt.mu.Lock()\r\n\tdefer t.mu.Unlock()\r\n\r\n\tfor {\r\n\t\t// Try to read a complete line already in the buffer\r\n\t\tif t.file != nil {\r\n\t\t\tn, found, err := t.tryReadLine(b)\r\n\t\t\tif found || err != nil {\r\n\t\t\t\treturn n, err\r\n\t\t\t}\r\n\t\t\t// No complete line in buffer\r\n\t\t\tif !t.cfg.Follow {\r\n\t\t\t\treturn 0, io.EOF\r\n\t\t\t}\r\n\t\t}\r\n\r\n\t\t// Eagerly open file\r\n\t\tif t.file == nil && !t.cfg.Follow {\r\n\t\t\tif err := t.openFile(); err == nil {\r\n\t\t\t\tcontinue\r\n\t\t\t}\r\n\t\t}\r\n\r\n\t\t// Wait for next file change\r\n\t\tch, bErr := t.watcher.BlockUntilChange(t.ctx)\r\n\t\tif bErr != nil {\r\n\t\t\treturn 0, bErr\r\n\t\t}\r\n\r\n\t\tfileWasOpen := t.file != nil\r\n\r\n\t\tif t.file == nil {\r\n\t\t\tif ch != ChangeDeleted {\r\n\t\t\t\terr = t.openFile()\r\n\t\t\t\tif err != nil {\r\n\t\t\t\t\tif t.cfg.Retry && t.cfg.Follow {\r\n\t\t\t\t\t\tcontinue\r\n\t\t\t\t\t}\r\n\t\t\t\t\treturn\r\n\t\t\t\t}\r\n\t\t\t} else {\r\n\t\t\t\tcontinue\r\n\t\t\t}\r\n\t\t}\r\n\r\n\t\tswitch ch {\r\n\t\tcase ChangeCreated:\r\n\t\t\tif fileWasOpen {\r\n\t\t\t\terr = t.reopenFile()\r\n\t\t\t\tif err != nil {\r\n\t\t\t\t\treturn\r\n\t\t\t\t}\r\n\t\t\t}\r\n\t\tcase ChangeDeleted:\r\n\t\t\terr = t.closeFile()\r\n\t\t\tif err != nil {\r\n\t\t\t\treturn\r\n\t\t\t}\r\n\t\tcase ChangeModified:\r\n\t\t\tt.reader.Reset(t.file)\r\n\t\tcase ChangeTruncated:\r\n\t\t\tif !t.cfg.NoSeek {\r\n\t\t\t\t_, err = t.file.Seek(0, io.SeekStart)\r\n\t\t\t\tif err != nil {\r\n\t\t\t\t\treturn\r\n\t\t\t\t}\r\n\t\t\t}\r\n\t\t}\r\n\t}\r\n}\r\n\r\nfunc (t *Tail) tryReadLine(b []byte) (n int, found bool, err error) {\r\n\tnBuf := t.reader.Buffered()\r\n\tif nBuf == 0 {\r\n\t\tif _, err := t.reader.Peek(1); err != nil {\r\n\t\t\tif errors.Is(err, io.EOF) {\r\n\t\t\t\treturn 0, false, nil\r\n\t\t\t}\r\n\t\t\treturn 0, false, err\r\n\t\t}\r\n\t\tnBuf = t.reader.Buffered()\r\n\t}\r\n\r\n\tpeeked, err := t.reader.Peek(nBuf)\r\n\tif err != nil && !errors.Is(err, io.EOF) {\r\n\t\treturn 0, false, err\r\n\t}\r\n\r\n\tidx := bytes.IndexByte(peeked, t.cfg.Delimiter)\r\n\tif idx < 0 {\r\n\t\treturn 0, false, nil\r\n\t}\r\n\r\n\tif len(b) < idx {\r\n\t\treturn 0, false, ErrBufferTooShort\r\n\t}\r\n\r\n\tcopied := copy(b, peeked[:idx])\r\n\tt.reader.Discard(idx + 1)\r\n\treturn copied, true, nil\r\n}\r\n\r\nfunc (t *Tail) Close() error {\r\n\tt.cancel()\r\n\treturn t.closeFile()\r\n}\r\n\r\nfunc (t *Tail) closeFile() (err error) {\r\n\tif t.file != nil {\r\n\t\terr = t.file.Close()\r\n\t\tt.file = nil\r\n\t}\r\n\treturn\r\n}\r\n\r\nfunc (t *Tail) openFile() error {\r\n\tfile, err := os.Open(t.filename)\r\n\tif err != nil {\r\n\t\treturn err\r\n\t}\r\n\r\n\tif !t.cfg.NoSeek && t.firstOpen {\r\n\t\tif _, err := file.Seek(t.cfg.Seek.Offset, t.cfg.Seek.Whence); err != nil {\r\n\t\t\tfile.Close()\r\n\t\t\treturn err\r\n\t\t}\r\n\t}\r\n\tt.firstOpen = false\r\n\r\n\tt.file = file\r\n\tt.reader.Reset(t.file)\r\n\treturn nil\r\n}\r\n\r\nfunc (t *Tail) reopenFile() (err error) {\r\n\terr = t.closeFile()\r\n\tif err != nil {\r\n\t\treturn\r\n\t}\r\n\terr = t.openFile()\r\n\treturn\r\n}\r\n```\r\n\r\n合并了 `ChangeMoved` 和 `ChangeDeleted`（全部当作 `ChangeDeleted`）\r\n\r\n#### FSM\r\n![tail.svg|690x496](/uploads/image/20/4f/204f18deb48bc0b1155a91674881dc586e2e2b91deecf707e7909bafebc2291b.svg)\r\n\r\n> ref: https://github.com/nxadm/tail\r\n\r\n好复杂，能 syslog over UDP 就别搞这种（","cooked":"

Tail

package tail\n\nimport (\n\t\"bufio\"\n\t\"bytes\"\n\t\"context\"\n\t\"errors\"\n\t\"fmt\"\n\t\"io\"\n\t\"os\"\n\t\"sync\"\n\t\"time\"\n)\n\nconst (\n\tpollInterval = 250 * time.Millisecond\n)\n\ntype fakeReader struct{}\n\nfunc (*fakeReader) Read(p []byte) (n int, err error) {\n\treturn 0, nil\n}\n\ntype Config struct {\n\t// Seek to before tailing.\n\tSeek SeekInfo\n\n\t// Provide appended data as the file grows.\n\tFollow bool\n\n\t// Keep trying to open a file if it is inaccessible.\n\t// Ignored when Follow is false.\n\tRetry bool\n\n\t// Use PollWatcher for file changes.\n\t// FSNotifyWatcher is used if false.\n\tPoll bool\n\n\t// Disable seeking.\n\t// Enable this for named pipes (mkfifo).\n\tNoSeek bool\n\n\t// Line delimiter.\n\tDelimiter byte\n}\n\nfunc DefaultConfig() Config {\n\treturn Config{\n\t\tDelimiter: '\\n',\n\t}\n}\n\n// SeekInfo\ntype SeekInfo struct {\n\tOffset int64\n\tWhence int\n}\n\ntype Tail struct {\n\tcfg      Config\n\tfilename string\n\tfile     *os.File\n\twatcher  Watcher\n\n\treader *bufio.Reader\n\n\tfirstOpen bool\n\n\tmu     sync.Mutex\n\tctx    context.Context\n\tcancel context.CancelFunc\n}\n\nfunc New(ctx context.Context, filename string, cfg Config) (*Tail, error) {\n\n\tvar watcher Watcher\n\tvar err error\n\tif cfg.Poll {\n\t\twatcher, err = NewPollWatcher(filename, pollInterval)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"failed to create PollWatcher: %w\", err)\n\t\t}\n\t} else {\n\t\twatcher, err = NewFSNotifyWatcher(filename)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"failed to create FSNotifyWatcher: %w\", err)\n\t\t}\n\t}\n\n\treturn newTailWithWatcher(ctx, filename, cfg, watcher), nil\n}\n\nfunc newTailWithWatcher(ctx context.Context, filename string, cfg Config, watcher Watcher) *Tail {\n\tctx, cancel := context.WithCancel(ctx)\n\n\treturn &Tail{\n\t\tcfg:       cfg,\n\t\tfilename:  filename,\n\t\twatcher:   watcher,\n\t\treader:    bufio.NewReader(&fakeReader{}),\n\t\tfirstOpen: true,\n\t\tctx:       ctx,\n\t\tcancel:    cancel,\n\t}\n}\n\nvar (\n\tErrBufferTooShort = errors.New(\"buffer is too short to read complete line\")\n)\n\nfunc (t *Tail) ReadLine(b []byte) (n int, err error) {\n\tt.mu.Lock()\n\tdefer t.mu.Unlock()\n\n\tfor {\n\t\t// Try to read a complete line already in the buffer\n\t\tif t.file != nil {\n\t\t\tn, found, err := t.tryReadLine(b)\n\t\t\tif found || err != nil {\n\t\t\t\treturn n, err\n\t\t\t}\n\t\t\t// No complete line in buffer\n\t\t\tif !t.cfg.Follow {\n\t\t\t\treturn 0, io.EOF\n\t\t\t}\n\t\t}\n\n\t\t// Eagerly open file\n\t\tif t.file == nil && !t.cfg.Follow {\n\t\t\tif err := t.openFile(); err == nil {\n\t\t\t\tcontinue\n\t\t\t}\n\t\t}\n\n\t\t// Wait for next file change\n\t\tch, bErr := t.watcher.BlockUntilChange(t.ctx)\n\t\tif bErr != nil {\n\t\t\treturn 0, bErr\n\t\t}\n\n\t\tfileWasOpen := t.file != nil\n\n\t\tif t.file == nil {\n\t\t\tif ch != ChangeDeleted {\n\t\t\t\terr = t.openFile()\n\t\t\t\tif err != nil {\n\t\t\t\t\tif t.cfg.Retry && t.cfg.Follow {\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t} else {\n\t\t\t\tcontinue\n\t\t\t}\n\t\t}\n\n\t\tswitch ch {\n\t\tcase ChangeCreated:\n\t\t\tif fileWasOpen {\n\t\t\t\terr = t.reopenFile()\n\t\t\t\tif err != nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t}\n\t\tcase ChangeDeleted:\n\t\t\terr = t.closeFile()\n\t\t\tif err != nil {\n\t\t\t\treturn\n\t\t\t}\n\t\tcase ChangeModified:\n\t\t\tt.reader.Reset(t.file)\n\t\tcase ChangeTruncated:\n\t\t\tif !t.cfg.NoSeek {\n\t\t\t\t_, err = t.file.Seek(0, io.SeekStart)\n\t\t\t\tif err != nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n}\n\nfunc (t *Tail) tryReadLine(b []byte) (n int, found bool, err error) {\n\tnBuf := t.reader.Buffered()\n\tif nBuf == 0 {\n\t\tif _, err := t.reader.Peek(1); err != nil {\n\t\t\tif errors.Is(err, io.EOF) {\n\t\t\t\treturn 0, false, nil\n\t\t\t}\n\t\t\treturn 0, false, err\n\t\t}\n\t\tnBuf = t.reader.Buffered()\n\t}\n\n\tpeeked, err := t.reader.Peek(nBuf)\n\tif err != nil && !errors.Is(err, io.EOF) {\n\t\treturn 0, false, err\n\t}\n\n\tidx := bytes.IndexByte(peeked, t.cfg.Delimiter)\n\tif idx < 0 {\n\t\treturn 0, false, nil\n\t}\n\n\tif len(b) < idx {\n\t\treturn 0, false, ErrBufferTooShort\n\t}\n\n\tcopied := copy(b, peeked[:idx])\n\tt.reader.Discard(idx + 1)\n\treturn copied, true, nil\n}\n\nfunc (t *Tail) Close() error {\n\tt.cancel()\n\treturn t.closeFile()\n}\n\nfunc (t *Tail) closeFile() (err error) {\n\tif t.file != nil {\n\t\terr = t.file.Close()\n\t\tt.file = nil\n\t}\n\treturn\n}\n\nfunc (t *Tail) openFile() error {\n\tfile, err := os.Open(t.filename)\n\tif err != nil {\n\t\treturn err\n\t}\n\n\tif !t.cfg.NoSeek && t.firstOpen {\n\t\tif _, err := file.Seek(t.cfg.Seek.Offset, t.cfg.Seek.Whence); err != nil {\n\t\t\tfile.Close()\n\t\t\treturn err\n\t\t}\n\t}\n\tt.firstOpen = false\n\n\tt.file = file\n\tt.reader.Reset(t.file)\n\treturn nil\n}\n\nfunc (t *Tail) reopenFile() (err error) {\n\terr = t.closeFile()\n\tif err != nil {\n\t\treturn\n\t}\n\terr = t.openFile()\n\treturn\n}\n

合并了 ChangeMoved 和 ChangeDeleted（全部当作 ChangeDeleted）

FSM

$\"tail.svg|690x496\"$

\n
ref: https://github.com/nxadm/tail
\n

好复杂，能 syslog over UDP 就别搞这种（

\n","createdAt":"2026-07-14T04:27:02.289Z","updatedAt":"2026-07-14T11:44:54.348Z","replyToPostNumber":null,"replyCount":2,"likeCount":0,"wordCount":698,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":3,"publicVersion":3,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72572,"postNumber":16,"raw":"Minor issue\r\n![Screenshot From 2026-07-14 12-24-23.png|690x77](/uploads/image/95/69/9569895e53cd1911a317db9e05b271c7b88dd4772dd1f31d679569eb5eb7821f.avif)","cooked":"

Minor issue
\n $\"Screenshot$

\n","createdAt":"2026-07-14T04:28:04.311Z","updatedAt":"2026-07-14T04:28:04.311Z","replyToPostNumber":13,"replyCount":1,"likeCount":0,"wordCount":6,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72573,"postNumber":17,"raw":"![github.svg|16x16](/uploads/image/33/56/33565671098c29c555f8e34d4932ff907f8aeafea1d3436d8b60a2e75d423319.svg)\r\n已配置，刷新一下","cooked":"

$\"github.svg|16x16\"$
\n已配置，刷新一下

\n","createdAt":"2026-07-14T06:40:02.210Z","updatedAt":"2026-07-14T06:40:02.210Z","replyToPostNumber":16,"replyCount":0,"likeCount":0,"wordCount":9,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"👍","count":1,"users":[{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":4668,"username":"IO","name":null,"avatarUrl":"/uploads/image/86/f2/86f267c0aaa73835a999b7cc3a7e7a701605574eda9a2c2a56f5ddbbba64d1a9.avif","admin":true,"moderator":false,"signatureRaw":"","signatureCooked":null}},{"id":72578,"postNumber":18,"raw":"[quote=\"stateless_trash_can, post:15, topic:15591\"]\r\nTail\r\n[/quote]\r\n\r\n我是垃圾桶，这写的就是垃圾","cooked":"

\n\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\tstateless_trash_can:\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t

\n\t\t\t\t\t\t\t

\n
Tail
\n

\n\t\t\t\t\t\t

我是垃圾桶，这写的就是垃圾

\n","createdAt":"2026-07-15T09:52:57.562Z","updatedAt":"2026-07-15T09:53:20.231Z","replyToPostNumber":15,"replyCount":1,"likeCount":1,"wordCount":18,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"❤️","count":1,"users":[{"id":2902,"username":"1313","name":"ᐕ)ﾉ"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶","avatarUrl":"/uploads/image/f4/69/f469375c27cd72c6970425e94b999be00fed8fe6234b977b14f5bdb65da24b4e.avif","admin":false,"moderator":false,"signatureRaw":"

","signatureCooked":"

"}},{"id":72581,"postNumber":19,"raw":"![image.png|447x447](/uploads/image/9f/9b/9f9b1af823bdcdba1af14a3e7d75a24d355c30632d66386cdbd4231649985fc9.avif)\r\n\r\nhttps://www.rockstargames.com/newswire/article/25kkao323155a8/presenting-junk-energy-skydives","cooked":"

$\"image.png|447x447\"$

https://www.rockstargames.com/newswire/article/25kkao323155a8/presenting-junk-energy-skydives

\n","createdAt":"2026-07-15T12:13:25.368Z","updatedAt":"2026-07-15T12:13:25.368Z","replyToPostNumber":18,"replyCount":0,"likeCount":0,"wordCount":2,"liked":false,"bookmarked":false,"polls":[],"reactions":[{"reaction":"❤️","count":1,"users":[{"id":2902,"username":"1313","name":"ᐕ)ﾉ"}],"hasReacted":false},{"reaction":"🤣️","count":1,"users":[{"id":7830,"username":"stateless_trash_can","name":"无状态垃圾桶"}],"hasReacted":false}],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":4668,"username":"IO","name":null,"avatarUrl":"/uploads/image/86/f2/86f267c0aaa73835a999b7cc3a7e7a701605574eda9a2c2a56f5ddbbba64d1a9.avif","admin":true,"moderator":false,"signatureRaw":"","signatureCooked":null}},{"id":72585,"postNumber":20,"raw":"[quote=\"stateless_trash_can, post:15, topic:15591\"]\r\nTail\r\n[/quote]\r\n\r\n重构\r\n\r\n```go\r\npackage tail\r\n\r\nimport (\r\n\t\"bufio\"\r\n\t\"bytes\"\r\n\t\"context\"\r\n\t\"errors\"\r\n\t\"fmt\"\r\n\t\"io\"\r\n\t\"os\"\r\n\t\"sync\"\r\n\t\"time\"\r\n)\r\n\r\nconst (\r\n\tpollInterval = 250 * time.Millisecond\r\n)\r\n\r\ntype fakeReader struct{}\r\n\r\nfunc (*fakeReader) Read(p []byte) (n int, err error) {\r\n\treturn 0, nil\r\n}\r\n\r\ntype Config struct {\r\n\t// Seek to before tailing.\r\n\tSeek SeekInfo\r\n\r\n\t// Provide appended data as the file grows.\r\n\tFollow bool\r\n\r\n\t// Keep trying to open a file if it is inaccessible.\r\n\t// Requires Follow to be set.\r\n\tRetry bool\r\n\r\n\t// Use PollWatcher for file changes.\r\n\t// FSNotifyWatcher is used if false.\r\n\tPoll bool\r\n\r\n\t// Disable seeking.\r\n\t// Enable this for named pipes (mkfifo).\r\n\tNoSeek bool\r\n\r\n\t// MaxLineSize sets the maximum line length in bytes.\r\n\t// Lines exceeding this are returned in chunks of MaxLineSize with error ErrMaxLineSizeExceeded.\r\n\t// Defaults to 4096 when <= 0.\r\n\tMaxLineSize int\r\n\r\n\t// Line delimiter.\r\n\tDelimiter byte\r\n}\r\n\r\nfunc DefaultConfig() Config {\r\n\treturn Config{\r\n\t\tDelimiter: '\\n',\r\n\t\tMaxLineSize: 4096,\r\n\t}\r\n}\r\n\r\n// SeekInfo\r\ntype SeekInfo struct {\r\n\tOffset int64\r\n\tWhence int\r\n}\r\n\r\ntype tailState int8\r\n\r\nconst (\r\n\tstateInit tailState = iota\r\n\tstateReady\r\n\tstateEOF\r\n\tstateNotOpen\r\n\tstateFailed\r\n)\r\n\r\ntype Tail struct {\r\n\tcfg Config\r\n\tfilename string\r\n\r\n\tfile *os.File\r\n\twatcher Watcher\r\n\treader *bufio.Reader\r\n\r\n\tstate tailState\r\n\tfailErr error\r\n\r\n\tmu sync.Mutex\r\n\tctx context.Context\r\n\tcancel context.CancelFunc\r\n}\r\n\r\nfunc New(ctx context.Context, filename string, cfg Config) (*Tail, error) {\r\n\tif !cfg.Follow && cfg.Retry {\r\n\t\treturn nil, errors.New(\"Retry set without Follow\")\r\n\t}\r\n\r\n\tvar watcher Watcher\r\n\tvar err error\r\n\tif cfg.Poll {\r\n\t\twatcher, err = NewPollWatcher(filename, pollInterval)\r\n\t\tif err != nil {\r\n\t\t\treturn nil, fmt.Errorf(\"failed to create PollWatcher: %w\", err)\r\n\t\t}\r\n\t} else {\r\n\t\twatcher, err = NewFSNotifyWatcher(filename)\r\n\t\tif err != nil {\r\n\t\t\treturn nil, fmt.Errorf(\"failed to create FSNotifyWatcher: %w\", err)\r\n\t\t}\r\n\t}\r\n\r\n\treturn newTailWithWatcher(ctx, filename, cfg, watcher), nil\r\n}\r\n\r\nfunc newTailWithWatcher(ctx context.Context, filename string, cfg Config, watcher Watcher) *Tail {\r\n\tctx, cancel := context.WithCancel(ctx)\r\n\r\n\tif cfg.MaxLineSize <= 0 {\r\n\t\tcfg.MaxLineSize = 4096\r\n\t}\r\n\r\n\treturn &Tail{\r\n\t\tcfg: cfg,\r\n\t\tfilename: filename,\r\n\t\twatcher: watcher,\r\n\t\treader: bufio.NewReaderSize(&fakeReader{}, cfg.MaxLineSize),\r\n\t\tstate: stateInit,\r\n\t\tctx: ctx,\r\n\t\tcancel: cancel,\r\n\t}\r\n}\r\n\r\nvar (\r\n\tErrMaxLineSizeExceeded = errors.New(\"line exceeds MaxLineSize\")\r\n\tErrShortBuffer = io.ErrShortBuffer\r\n\tErrClosed = errors.New(\"closed\")\r\n)\r\n\r\nfunc (t *Tail) ReadLine(b []byte) (int, error) {\r\n\tt.mu.Lock()\r\n\tdefer t.mu.Unlock()\r\n\r\n\tfor {\r\n\t\tswitch t.state {\r\n\t\tcase stateInit:\r\n\t\t\t// Try to open file\r\n\t\t\tfile, err := os.Open(t.filename)\r\n\t\t\tif err != nil {\r\n\t\t\t\tt.failErr = err\r\n\t\t\t\tt.state = stateNotOpen\r\n\t\t\t\tcontinue\r\n\t\t\t} else {\r\n\t\t\t\tif !t.cfg.NoSeek {\r\n\t\t\t\t\t_, err = file.Seek(t.cfg.Seek.Offset, t.cfg.Seek.Whence)\r\n\t\t\t\t\tif err != nil {\r\n\t\t\t\t\t\tt.failErr = err\r\n\t\t\t\t\t\tt.state = stateFailed\r\n\t\t\t\t\t\treturn 0, err\r\n\t\t\t\t\t}\r\n\t\t\t\t}\r\n\t\t\t\tt.file = file\r\n\t\t\t\tt.reader.Reset(file)\r\n\t\t\t\tt.state = stateReady\r\n\t\t\t\tcontinue\r\n\t\t\t}\r\n\r\n\t\tcase stateReady:\r\n\t\t\t// Try to read line\r\n\t\t\tn := t.reader.Buffered()\r\n\t\t\tif n == 0 {\r\n\t\t\t\tif _, err := t.reader.Peek(1); err != nil {\r\n\t\t\t\t\tif errors.Is(err, io.EOF) {\r\n\t\t\t\t\t\tt.state = stateEOF\r\n\t\t\t\t\t\tcontinue\r\n\t\t\t\t\t} else {\r\n\t\t\t\t\t\tt.failErr = err\r\n\t\t\t\t\t\tt.state = stateFailed\r\n\t\t\t\t\t\treturn 0, err\r\n\t\t\t\t\t}\r\n\t\t\t\t}\r\n\t\t\t\tn = t.reader.Buffered()\r\n\t\t\t}\r\n\r\n\t\t\tpeeked, err := t.reader.Peek(n)\r\n\t\t\tif err != nil && !errors.Is(err, io.EOF) {\r\n\t\t\t\tt.failErr = err\r\n\t\t\t\tt.state = stateFailed\r\n\t\t\t\treturn 0, err\r\n\t\t\t}\r\n\r\n\t\t\tidx := bytes.IndexByte(peeked, t.cfg.Delimiter)\r\n\t\t\tif idx < 0 {\r\n\t\t\t\t// No delimiter found\r\n\t\t\t\tif n >= t.cfg.MaxLineSize {\r\n\t\t\t\t\t// Line exceeds MaxLineSize\r\n\t\t\t\t\t// Return chunk\r\n\t\t\t\t\tn = t.cfg.MaxLineSize\r\n\t\t\t\t\tif len(b) < n {\r\n\t\t\t\t\t\treturn 0, ErrShortBuffer\r\n\t\t\t\t\t}\r\n\t\t\t\t\tpeeked, _ = t.reader.Peek(n)\r\n\t\t\t\t\tcopied := copy(b, peeked[:n])\r\n\t\t\t\t\tt.reader.Discard(n)\r\n\t\t\t\t\treturn copied, ErrMaxLineSizeExceeded\r\n\t\t\t\t}\r\n\t\t\t\tt.state = stateEOF\r\n\t\t\t\tcontinue\r\n\t\t\t}\r\n\r\n\t\t\t// Delimiter found\r\n\t\t\t// Chunk if line exceeds MaxLineSize\r\n\t\t\tif idx >= t.cfg.MaxLineSize {\r\n\t\t\t\tn = t.cfg.MaxLineSize\r\n\t\t\t\tif len(b) < n {\r\n\t\t\t\t\treturn 0, ErrShortBuffer\r\n\t\t\t\t}\r\n\t\t\t\tpeeked, _ = t.reader.Peek(n)\r\n\t\t\t\tcopied := copy(b, peeked[:n])\r\n\t\t\t\tt.reader.Discard(n)\r\n\t\t\t\treturn copied, ErrMaxLineSizeExceeded\r\n\t\t\t}\r\n\r\n\t\t\tif len(b) < idx {\r\n\t\t\t\treturn 0, ErrShortBuffer\r\n\t\t\t}\r\n\r\n\t\t\tcopied := copy(b, peeked[:idx])\r\n\t\t\tt.reader.Discard(idx + 1)\r\n\t\t\treturn copied, nil\r\n\r\n\t\tcase stateEOF:\r\n\t\t\tif !t.cfg.Follow {\r\n\t\t\t\tn := t.reader.Buffered()\r\n\t\t\t\tif n > 0 {\r\n\t\t\t\t\t// Probe for more data\r\n\t\t\t\t\t_, peekErr := t.reader.Peek(n + 1)\r\n\t\t\t\t\tif errors.Is(peekErr, io.EOF) {\r\n\t\t\t\t\t\t// True EOF\r\n\t\t\t\t\t\t// Return as final line\r\n\t\t\t\t\t\tpeeked, _ := t.reader.Peek(n)\r\n\t\t\t\t\t\tcopied := copy(b, peeked[:n])\r\n\t\t\t\t\t\tt.reader.Discard(n)\r\n\t\t\t\t\t\treturn copied, nil\r\n\t\t\t\t\t}\r\n\t\t\t\t\tif peekErr != nil {\r\n\t\t\t\t\t\tt.failErr = peekErr\r\n\t\t\t\t\t\tt.state = stateFailed\r\n\t\t\t\t\t\treturn 0, peekErr\r\n\t\t\t\t\t}\r\n\t\t\t\t\t// Has more\r\n\t\t\t\t\tt.state = stateReady\r\n\t\t\t\t\tcontinue\r\n\t\t\t\t}\r\n\t\t\t\tt.failErr = io.EOF\r\n\t\t\t\tt.state = stateFailed\r\n\t\t\t\treturn 0, io.EOF\r\n\t\t\t}\r\n\r\n\t\t\tch, err := t.watcher.BlockUntilChange(t.ctx)\r\n\t\t\tif err != nil {\r\n\t\t\t\tt.failErr = err\r\n\t\t\t\tt.state = stateFailed\r\n\t\t\t\treturn 0, err\r\n\t\t\t}\r\n\r\n\t\t\tswitch ch {\r\n\t\t\tcase ChangeModified, ChangeCreated:\r\n\t\t\t\t// Drain EOF error in bufio.Reader\r\n\t\t\t\tif n := t.reader.Buffered(); n > 0 && n < t.cfg.MaxLineSize {\r\n\t\t\t\t\tt.reader.Peek(n + 1) // trigger file read\r\n\t\t\t\t}\r\n\t\t\t\tt.state = stateReady\r\n\t\t\t\tcontinue\r\n\t\t\tcase ChangeDeleted:\r\n\t\t\t\t// Drain buffer from old file\r\n\t\t\t\tif n := t.reader.Buffered(); n > 0 {\r\n\t\t\t\t\tif len(b) < n {\r\n\t\t\t\t\t\treturn 0, ErrShortBuffer\r\n\t\t\t\t\t}\r\n\t\t\t\t\tpeeked, _ := t.reader.Peek(n)\r\n\t\t\t\t\tcopied := copy(b, peeked[:n])\r\n\t\t\t\t\tt.reader.Discard(n)\r\n\t\t\t\t\tt.file.Close()\r\n\t\t\t\t\tt.file = nil\r\n\t\t\t\t\tt.state = stateNotOpen\r\n\t\t\t\t\treturn copied, nil\r\n\t\t\t\t}\r\n\t\t\t\terr = t.file.Close()\r\n\t\t\t\tif err != nil {\r\n\t\t\t\t\tt.failErr = err\r\n\t\t\t\t\tt.state = stateFailed\r\n\t\t\t\t\treturn 0, err\r\n\t\t\t\t}\r\n\t\t\t\tt.file = nil\r\n\t\t\t\tt.state = stateNotOpen\r\n\t\t\t\tcontinue\r\n\r\n\t\t\tcase ChangeTruncated:\r\n\t\t\t\tif !t.cfg.NoSeek {\r\n\t\t\t\t\t_, err := t.file.Seek(0, io.SeekStart)\r\n\t\t\t\t\tif err != nil {\r\n\t\t\t\t\t\tt.failErr = err\r\n\t\t\t\t\t\tt.state = stateFailed\r\n\t\t\t\t\t\treturn 0, err\r\n\t\t\t\t\t}\r\n\t\t\t\t}\r\n\t\t\t\tt.reader.Reset(t.file)\r\n\t\t\t\tt.state = stateReady\r\n\t\t\t\tcontinue\r\n\t\t\t}\r\n\r\n\t\tcase stateNotOpen:\r\n\t\t\tif !t.cfg.Retry {\r\n\t\t\t\tt.state = stateFailed\r\n\t\t\t\treturn 0, errors.New(\"cannot open file\")\r\n\t\t\t}\r\n\r\n\t\t\tch, err := t.watcher.BlockUntilChange(t.ctx)\r\n\t\t\tif err != nil {\r\n\t\t\t\tt.failErr = err\r\n\t\t\t\tt.state = stateFailed\r\n\t\t\t\treturn 0, err\r\n\t\t\t}\r\n\r\n\t\t\tswitch ch {\r\n\t\t\tcase ChangeCreated, ChangeModified, ChangeTruncated:\r\n\t\t\t\t// Try to open file\r\n\t\t\t\tfile, err := os.Open(t.filename)\r\n\t\t\t\tif err != nil {\r\n\t\t\t\t\tcontinue\r\n\t\t\t\t} else {\r\n\t\t\t\t\tt.file = file\r\n\t\t\t\t\tt.reader.Reset(file)\r\n\t\t\t\t\tt.state = stateReady\r\n\t\t\t\t\tcontinue\r\n\t\t\t\t}\r\n\r\n\t\t\tcase ChangeDeleted:\r\n\t\t\t\tt.failErr = errors.New(\"got ChangeDeleted in stateNotOpen\")\r\n\t\t\t\tt.state = stateFailed\r\n\t\t\t\treturn 0, t.failErr\r\n\r\n\t\t\t}\r\n\r\n\t\tcase stateFailed:\r\n\t\t\treturn 0, t.failErr\r\n\t\t}\r\n\t}\r\n}\r\n\r\nfunc (t *Tail) Close() error {\r\n\tt.cancel()\r\n\tt.mu.Lock()\r\n\tdefer t.mu.Unlock()\r\n\r\n\tt.failErr = ErrClosed\r\n\tt.state = stateFailed\r\n\tif t.file != nil {\r\n\t\tif err := t.file.Close(); err != nil {\r\n\t\t\treturn err\r\n\t\t}\r\n\t}\r\n\treturn nil\r\n}\r\n```","cooked":"

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Tail
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重构

package tail\n\nimport (\n\t\"bufio\"\n\t\"bytes\"\n\t\"context\"\n\t\"errors\"\n\t\"fmt\"\n\t\"io\"\n\t\"os\"\n\t\"sync\"\n\t\"time\"\n)\n\nconst (\n\tpollInterval = 250 * time.Millisecond\n)\n\ntype fakeReader struct{}\n\nfunc (*fakeReader) Read(p []byte) (n int, err error) {\n\treturn 0, nil\n}\n\ntype Config struct {\n\t// Seek to before tailing.\n\tSeek SeekInfo\n\n\t// Provide appended data as the file grows.\n\tFollow bool\n\n\t// Keep trying to open a file if it is inaccessible.\n\t// Requires Follow to be set.\n\tRetry bool\n\n\t// Use PollWatcher for file changes.\n\t// FSNotifyWatcher is used if false.\n\tPoll bool\n\n\t// Disable seeking.\n\t// Enable this for named pipes (mkfifo).\n\tNoSeek bool\n\n\t// MaxLineSize sets the maximum line length in bytes.\n\t// Lines exceeding this are returned in chunks of MaxLineSize with error ErrMaxLineSizeExceeded.\n\t// Defaults to 4096 when <= 0.\n\tMaxLineSize int\n\n\t// Line delimiter.\n\tDelimiter byte\n}\n\nfunc DefaultConfig() Config {\n\treturn Config{\n\t\tDelimiter:   '\\n',\n\t\tMaxLineSize: 4096,\n\t}\n}\n\n// SeekInfo\ntype SeekInfo struct {\n\tOffset int64\n\tWhence int\n}\n\ntype tailState int8\n\nconst (\n\tstateInit tailState = iota\n\tstateReady\n\tstateEOF\n\tstateNotOpen\n\tstateFailed\n)\n\ntype Tail struct {\n\tcfg      Config\n\tfilename string\n\n\tfile    *os.File\n\twatcher Watcher\n\treader  *bufio.Reader\n\n\tstate   tailState\n\tfailErr error\n\n\tmu     sync.Mutex\n\tctx    context.Context\n\tcancel context.CancelFunc\n}\n\nfunc New(ctx context.Context, filename string, cfg Config) (*Tail, error) {\n\tif !cfg.Follow && cfg.Retry {\n\t\treturn nil, errors.New(\"Retry set without Follow\")\n\t}\n\n\tvar watcher Watcher\n\tvar err error\n\tif cfg.Poll {\n\t\twatcher, err = NewPollWatcher(filename, pollInterval)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"failed to create PollWatcher: %w\", err)\n\t\t}\n\t} else {\n\t\twatcher, err = NewFSNotifyWatcher(filename)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"failed to create FSNotifyWatcher: %w\", err)\n\t\t}\n\t}\n\n\treturn newTailWithWatcher(ctx, filename, cfg, watcher), nil\n}\n\nfunc newTailWithWatcher(ctx context.Context, filename string, cfg Config, watcher Watcher) *Tail {\n\tctx, cancel := context.WithCancel(ctx)\n\n\tif cfg.MaxLineSize <= 0 {\n\t\tcfg.MaxLineSize = 4096\n\t}\n\n\treturn &Tail{\n\t\tcfg:      cfg,\n\t\tfilename: filename,\n\t\twatcher:  watcher,\n\t\treader:   bufio.NewReaderSize(&fakeReader{}, cfg.MaxLineSize),\n\t\tstate:    stateInit,\n\t\tctx:      ctx,\n\t\tcancel:   cancel,\n\t}\n}\n\nvar (\n\tErrMaxLineSizeExceeded = errors.New(\"line exceeds MaxLineSize\")\n\tErrShortBuffer         = io.ErrShortBuffer\n\tErrClosed              = errors.New(\"closed\")\n)\n\nfunc (t *Tail) ReadLine(b []byte) (int, error) {\n\tt.mu.Lock()\n\tdefer t.mu.Unlock()\n\n\tfor {\n\t\tswitch t.state {\n\t\tcase stateInit:\n\t\t\t// Try to open file\n\t\t\tfile, err := os.Open(t.filename)\n\t\t\tif err != nil {\n\t\t\t\tt.failErr = err\n\t\t\t\tt.state = stateNotOpen\n\t\t\t\tcontinue\n\t\t\t} else {\n\t\t\t\tif !t.cfg.NoSeek {\n\t\t\t\t\t_, err = file.Seek(t.cfg.Seek.Offset, t.cfg.Seek.Whence)\n\t\t\t\t\tif err != nil {\n\t\t\t\t\t\tt.failErr = err\n\t\t\t\t\t\tt.state = stateFailed\n\t\t\t\t\t\treturn 0, err\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tt.file = file\n\t\t\t\tt.reader.Reset(file)\n\t\t\t\tt.state = stateReady\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase stateReady:\n\t\t\t// Try to read line\n\t\t\tn := t.reader.Buffered()\n\t\t\tif n == 0 {\n\t\t\t\tif _, err := t.reader.Peek(1); err != nil {\n\t\t\t\t\tif errors.Is(err, io.EOF) {\n\t\t\t\t\t\tt.state = stateEOF\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t} else {\n\t\t\t\t\t\tt.failErr = err\n\t\t\t\t\t\tt.state = stateFailed\n\t\t\t\t\t\treturn 0, err\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tn = t.reader.Buffered()\n\t\t\t}\n\n\t\t\tpeeked, err := t.reader.Peek(n)\n\t\t\tif err != nil && !errors.Is(err, io.EOF) {\n\t\t\t\tt.failErr = err\n\t\t\t\tt.state = stateFailed\n\t\t\t\treturn 0, err\n\t\t\t}\n\n\t\t\tidx := bytes.IndexByte(peeked, t.cfg.Delimiter)\n\t\t\tif idx < 0 {\n\t\t\t\t// No delimiter found\n\t\t\t\tif n >= t.cfg.MaxLineSize {\n\t\t\t\t\t// Line exceeds MaxLineSize\n\t\t\t\t\t// Return chunk\n\t\t\t\t\tn = t.cfg.MaxLineSize\n\t\t\t\t\tif len(b) < n {\n\t\t\t\t\t\treturn 0, ErrShortBuffer\n\t\t\t\t\t}\n\t\t\t\t\tpeeked, _ = t.reader.Peek(n)\n\t\t\t\t\tcopied := copy(b, peeked[:n])\n\t\t\t\t\tt.reader.Discard(n)\n\t\t\t\t\treturn copied, ErrMaxLineSizeExceeded\n\t\t\t\t}\n\t\t\t\tt.state = stateEOF\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\t\t// Delimiter found\n\t\t\t// Chunk if line exceeds MaxLineSize\n\t\t\tif idx >= t.cfg.MaxLineSize {\n\t\t\t\tn = t.cfg.MaxLineSize\n\t\t\t\tif len(b) < n {\n\t\t\t\t\treturn 0, ErrShortBuffer\n\t\t\t\t}\n\t\t\t\tpeeked, _ = t.reader.Peek(n)\n\t\t\t\tcopied := copy(b, peeked[:n])\n\t\t\t\tt.reader.Discard(n)\n\t\t\t\treturn copied, ErrMaxLineSizeExceeded\n\t\t\t}\n\n\t\t\tif len(b) < idx {\n\t\t\t\treturn 0, ErrShortBuffer\n\t\t\t}\n\n\t\t\tcopied := copy(b, peeked[:idx])\n\t\t\tt.reader.Discard(idx + 1)\n\t\t\treturn copied, nil\n\n\t\tcase stateEOF:\n\t\t\tif !t.cfg.Follow {\n\t\t\t\tn := t.reader.Buffered()\n\t\t\t\tif n > 0 {\n\t\t\t\t\t// Probe for more data\n\t\t\t\t\t_, peekErr := t.reader.Peek(n + 1)\n\t\t\t\t\tif errors.Is(peekErr, io.EOF) {\n\t\t\t\t\t\t// True EOF\n\t\t\t\t\t\t// Return as final line\n\t\t\t\t\t\tpeeked, _ := t.reader.Peek(n)\n\t\t\t\t\t\tcopied := copy(b, peeked[:n])\n\t\t\t\t\t\tt.reader.Discard(n)\n\t\t\t\t\t\treturn copied, nil\n\t\t\t\t\t}\n\t\t\t\t\tif peekErr != nil {\n\t\t\t\t\t\tt.failErr = peekErr\n\t\t\t\t\t\tt.state = stateFailed\n\t\t\t\t\t\treturn 0, peekErr\n\t\t\t\t\t}\n\t\t\t\t\t// Has more\n\t\t\t\t\tt.state = stateReady\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\t\t\t\tt.failErr = io.EOF\n\t\t\t\tt.state = stateFailed\n\t\t\t\treturn 0, io.EOF\n\t\t\t}\n\n\t\t\tch, err := t.watcher.BlockUntilChange(t.ctx)\n\t\t\tif err != nil {\n\t\t\t\tt.failErr = err\n\t\t\t\tt.state = stateFailed\n\t\t\t\treturn 0, err\n\t\t\t}\n\n\t\t\tswitch ch {\n\t\t\tcase ChangeModified, ChangeCreated:\n\t\t\t\t// Drain EOF error in bufio.Reader\n\t\t\t\tif n := t.reader.Buffered(); n > 0 && n < t.cfg.MaxLineSize {\n\t\t\t\t\tt.reader.Peek(n + 1) // trigger file read\n\t\t\t\t}\n\t\t\t\tt.state = stateReady\n\t\t\t\tcontinue\n\t\t\tcase ChangeDeleted:\n\t\t\t\t// Drain buffer from old file\n\t\t\t\tif n := t.reader.Buffered(); n > 0 {\n\t\t\t\t\tif len(b) < n {\n\t\t\t\t\t\treturn 0, ErrShortBuffer\n\t\t\t\t\t}\n\t\t\t\t\tpeeked, _ := t.reader.Peek(n)\n\t\t\t\t\tcopied := copy(b, peeked[:n])\n\t\t\t\t\tt.reader.Discard(n)\n\t\t\t\t\tt.file.Close()\n\t\t\t\t\tt.file = nil\n\t\t\t\t\tt.state = stateNotOpen\n\t\t\t\t\treturn copied, nil\n\t\t\t\t}\n\t\t\t\terr = t.file.Close()\n\t\t\t\tif err != nil {\n\t\t\t\t\tt.failErr = err\n\t\t\t\t\tt.state = stateFailed\n\t\t\t\t\treturn 0, err\n\t\t\t\t}\n\t\t\t\tt.file = nil\n\t\t\t\tt.state = stateNotOpen\n\t\t\t\tcontinue\n\n\t\t\tcase ChangeTruncated:\n\t\t\t\tif !t.cfg.NoSeek {\n\t\t\t\t\t_, err := t.file.Seek(0, io.SeekStart)\n\t\t\t\t\tif err != nil {\n\t\t\t\t\t\tt.failErr = err\n\t\t\t\t\t\tt.state = stateFailed\n\t\t\t\t\t\treturn 0, err\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tt.reader.Reset(t.file)\n\t\t\t\tt.state = stateReady\n\t\t\t\tcontinue\n\t\t\t}\n\n\t\tcase stateNotOpen:\n\t\t\tif !t.cfg.Retry {\n\t\t\t\tt.state = stateFailed\n\t\t\t\treturn 0, errors.New(\"cannot open file\")\n\t\t\t}\n\n\t\t\tch, err := t.watcher.BlockUntilChange(t.ctx)\n\t\t\tif err != nil {\n\t\t\t\tt.failErr = err\n\t\t\t\tt.state = stateFailed\n\t\t\t\treturn 0, err\n\t\t\t}\n\n\t\t\tswitch ch {\n\t\t\tcase ChangeCreated, ChangeModified, ChangeTruncated:\n\t\t\t\t// Try to open file\n\t\t\t\tfile, err := os.Open(t.filename)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcontinue\n\t\t\t\t} else {\n\t\t\t\t\tt.file = file\n\t\t\t\t\tt.reader.Reset(file)\n\t\t\t\t\tt.state = stateReady\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\n\t\t\tcase ChangeDeleted:\n\t\t\t\tt.failErr = errors.New(\"got ChangeDeleted in stateNotOpen\")\n\t\t\t\tt.state = stateFailed\n\t\t\t\treturn 0, t.failErr\n\n\t\t\t}\n\n\t\tcase stateFailed:\n\t\t\treturn 0, t.failErr\n\t\t}\n\t}\n}\n\nfunc (t *Tail) Close() error {\n\tt.cancel()\n\tt.mu.Lock()\n\tdefer t.mu.Unlock()\n\n\tt.failErr = ErrClosed\n\tt.state = stateFailed\n\tif t.file != nil {\n\t\tif err := t.file.Close(); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil\n}\n

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