| 1 | // Copyright 2020 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 stack |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "fmt" |
| 10 | "io" |
| 11 | "runtime" |
| 12 | "sort" |
| 13 | ) |
| 14 | |
| 15 | // Capture get the current stack traces from the runtime. |
| 16 | func Capture() Dump { |
| 17 | buf := make([]byte, 2<<20) |
| 18 | buf = buf[:runtime.Stack(buf, true)] |
| 19 | scanner := NewScanner(bytes.NewReader(buf)) |
| 20 | dump, _ := Parse(scanner) |
| 21 | return dump |
| 22 | } |
| 23 | |
| 24 | // Summarize a dump for easier consumption. |
| 25 | // This collates goroutines with equivalent stacks. |
| 26 | func Summarize(dump Dump) Summary { |
| 27 | s := Summary{ |
| 28 | Total: len(dump), |
| 29 | } |
| 30 | for _, gr := range dump { |
| 31 | s.addGoroutine(gr) |
| 32 | } |
| 33 | return s |
| 34 | } |
| 35 | |
| 36 | // Process and input stream to an output stream, summarizing any stacks that |
| 37 | // are detected in place. |
| 38 | func Process(out io.Writer, in io.Reader) error { |
| 39 | scanner := NewScanner(in) |
| 40 | for { |
| 41 | dump, err := Parse(scanner) |
| 42 | summary := Summarize(dump) |
| 43 | switch { |
| 44 | case len(dump) > 0: |
| 45 | fmt.Fprintf(out, "%+v\n\n", summary) |
| 46 | case err != nil: |
| 47 | return err |
| 48 | case scanner.Done(): |
| 49 | return scanner.Err() |
| 50 | default: |
| 51 | // must have been a line that is not part of a dump |
| 52 | fmt.Fprintln(out, scanner.Next()) |
| 53 | } |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | // Diff calculates the delta between two dumps. |
| 58 | func Diff(before, after Dump) Delta { |
| 59 | result := Delta{} |
| 60 | processed := make(map[int]bool) |
| 61 | for _, gr := range before { |
| 62 | processed[gr.ID] = false |
| 63 | } |
| 64 | for _, gr := range after { |
| 65 | if _, found := processed[gr.ID]; found { |
| 66 | result.Shared = append(result.Shared, gr) |
| 67 | } else { |
| 68 | result.After = append(result.After, gr) |
| 69 | } |
| 70 | processed[gr.ID] = true |
| 71 | } |
| 72 | for _, gr := range before { |
| 73 | if done := processed[gr.ID]; !done { |
| 74 | result.Before = append(result.Before, gr) |
| 75 | } |
| 76 | } |
| 77 | return result |
| 78 | } |
| 79 | |
| 80 | // TODO: do we want to allow contraction of stacks before comparison? |
| 81 | func (s *Summary) addGoroutine(gr Goroutine) { |
| 82 | index := sort.Search(len(s.Calls), func(i int) bool { |
| 83 | return !s.Calls[i].Stack.less(gr.Stack) |
| 84 | }) |
| 85 | if index >= len(s.Calls) || !s.Calls[index].Stack.equal(gr.Stack) { |
| 86 | // insert new stack, first increase the length |
| 87 | s.Calls = append(s.Calls, Call{}) |
| 88 | // move the top part upward to make space |
| 89 | copy(s.Calls[index+1:], s.Calls[index:]) |
| 90 | // insert the new call |
| 91 | s.Calls[index] = Call{ |
| 92 | Stack: gr.Stack, |
| 93 | } |
| 94 | } |
| 95 | // merge the goroutine into the matched call |
| 96 | s.Calls[index].merge(gr) |
| 97 | } |
| 98 | |
| 99 | // TODO: do we want other grouping strategies? |
| 100 | func (c *Call) merge(gr Goroutine) { |
| 101 | for i := range c.Groups { |
| 102 | canditate := &c.Groups[i] |
| 103 | if canditate.State == gr.State { |
| 104 | canditate.Goroutines = append(canditate.Goroutines, gr) |
| 105 | return |
| 106 | } |
| 107 | } |
| 108 | c.Groups = append(c.Groups, Group{ |
| 109 | State: gr.State, |
| 110 | Goroutines: []Goroutine{gr}, |
| 111 | }) |
| 112 | } |
| 113 |
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