| 1 | // Copyright 2022 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 | // Package bug provides utilities for reporting internal bugs, and being |
| 6 | // notified when they occur. |
| 7 | // |
| 8 | // Philosophically, because gopls runs as a sidecar process that the user does |
| 9 | // not directly control, sometimes it keeps going on broken invariants rather |
| 10 | // than panicking. In those cases, bug reports provide a mechanism to alert |
| 11 | // developers and capture relevant metadata. |
| 12 | package bug |
| 13 | |
| 14 | import ( |
| 15 | "fmt" |
| 16 | "runtime" |
| 17 | "runtime/debug" |
| 18 | "sort" |
| 19 | "sync" |
| 20 | ) |
| 21 | |
| 22 | // PanicOnBugs controls whether to panic when bugs are reported. |
| 23 | // |
| 24 | // It may be set to true during testing. |
| 25 | var PanicOnBugs = false |
| 26 | |
| 27 | var ( |
| 28 | mu sync.Mutex |
| 29 | exemplars map[string]Bug |
| 30 | waiters []chan<- Bug |
| 31 | ) |
| 32 | |
| 33 | // A Bug represents an unexpected event or broken invariant. They are used for |
| 34 | // capturing metadata that helps us understand the event. |
| 35 | type Bug struct { |
| 36 | File string // file containing the call to bug.Report |
| 37 | Line int // line containing the call to bug.Report |
| 38 | Description string // description of the bug |
| 39 | Data Data // additional metadata |
| 40 | Key string // key identifying the bug (file:line if available) |
| 41 | Stack string // call stack |
| 42 | } |
| 43 | |
| 44 | // Data is additional metadata to record for a bug. |
| 45 | type Data map[string]interface{} |
| 46 | |
| 47 | // Reportf reports a formatted bug message. |
| 48 | func Reportf(format string, args ...interface{}) { |
| 49 | Report(fmt.Sprintf(format, args...), nil) |
| 50 | } |
| 51 | |
| 52 | // Errorf calls fmt.Errorf for the given arguments, and reports the resulting |
| 53 | // error message as a bug. |
| 54 | func Errorf(format string, args ...interface{}) error { |
| 55 | err := fmt.Errorf(format, args...) |
| 56 | Report(err.Error(), nil) |
| 57 | return err |
| 58 | } |
| 59 | |
| 60 | // Report records a new bug encountered on the server. |
| 61 | // It uses reflection to report the position of the immediate caller. |
| 62 | func Report(description string, data Data) { |
| 63 | _, file, line, ok := runtime.Caller(1) |
| 64 | |
| 65 | key := "<missing callsite>" |
| 66 | if ok { |
| 67 | key = fmt.Sprintf("%s:%d", file, line) |
| 68 | } |
| 69 | |
| 70 | if PanicOnBugs { |
| 71 | panic(fmt.Sprintf("%s: %s", key, description)) |
| 72 | } |
| 73 | |
| 74 | bug := Bug{ |
| 75 | File: file, |
| 76 | Line: line, |
| 77 | Description: description, |
| 78 | Data: data, |
| 79 | Key: key, |
| 80 | Stack: string(debug.Stack()), |
| 81 | } |
| 82 | |
| 83 | mu.Lock() |
| 84 | defer mu.Unlock() |
| 85 | |
| 86 | if exemplars == nil { |
| 87 | exemplars = make(map[string]Bug) |
| 88 | } |
| 89 | |
| 90 | if _, ok := exemplars[key]; !ok { |
| 91 | exemplars[key] = bug // capture one exemplar per key |
| 92 | } |
| 93 | |
| 94 | for _, waiter := range waiters { |
| 95 | waiter <- bug |
| 96 | } |
| 97 | waiters = nil |
| 98 | } |
| 99 | |
| 100 | // Notify returns a channel that will be sent the next bug to occur on the |
| 101 | // server. This channel only ever receives one bug. |
| 102 | func Notify() <-chan Bug { |
| 103 | mu.Lock() |
| 104 | defer mu.Unlock() |
| 105 | |
| 106 | ch := make(chan Bug, 1) // 1-buffered so that bug reporting is non-blocking |
| 107 | waiters = append(waiters, ch) |
| 108 | return ch |
| 109 | } |
| 110 | |
| 111 | // List returns a slice of bug exemplars -- the first bugs to occur at each |
| 112 | // callsite. |
| 113 | func List() []Bug { |
| 114 | mu.Lock() |
| 115 | defer mu.Unlock() |
| 116 | |
| 117 | var bugs []Bug |
| 118 | |
| 119 | for _, bug := range exemplars { |
| 120 | bugs = append(bugs, bug) |
| 121 | } |
| 122 | |
| 123 | sort.Slice(bugs, func(i, j int) bool { |
| 124 | return bugs[i].Key < bugs[j].Key |
| 125 | }) |
| 126 | |
| 127 | return bugs |
| 128 | } |
| 129 |
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