| 1 | // Copyright 2019 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 export |
| 6 | |
| 7 | import ( |
| 8 | "context" |
| 9 | "fmt" |
| 10 | "sync" |
| 11 | |
| 12 | "golang.org/x/tools/internal/event" |
| 13 | "golang.org/x/tools/internal/event/core" |
| 14 | "golang.org/x/tools/internal/event/keys" |
| 15 | "golang.org/x/tools/internal/event/label" |
| 16 | ) |
| 17 | |
| 18 | type SpanContext struct { |
| 19 | TraceID TraceID |
| 20 | SpanID SpanID |
| 21 | } |
| 22 | |
| 23 | type Span struct { |
| 24 | Name string |
| 25 | ID SpanContext |
| 26 | ParentID SpanID |
| 27 | mu sync.Mutex |
| 28 | start core.Event |
| 29 | finish core.Event |
| 30 | events []core.Event |
| 31 | } |
| 32 | |
| 33 | type contextKeyType int |
| 34 | |
| 35 | const ( |
| 36 | spanContextKey = contextKeyType(iota) |
| 37 | labelContextKey |
| 38 | ) |
| 39 | |
| 40 | func GetSpan(ctx context.Context) *Span { |
| 41 | v := ctx.Value(spanContextKey) |
| 42 | if v == nil { |
| 43 | return nil |
| 44 | } |
| 45 | return v.(*Span) |
| 46 | } |
| 47 | |
| 48 | // Spans creates an exporter that maintains hierarchical span structure in the |
| 49 | // context. |
| 50 | // It creates new spans on start events, adds events to the current span on |
| 51 | // log or label, and closes the span on end events. |
| 52 | // The span structure can then be used by other exporters. |
| 53 | func Spans(output event.Exporter) event.Exporter { |
| 54 | return func(ctx context.Context, ev core.Event, lm label.Map) context.Context { |
| 55 | switch { |
| 56 | case event.IsLog(ev), event.IsLabel(ev): |
| 57 | if span := GetSpan(ctx); span != nil { |
| 58 | span.mu.Lock() |
| 59 | span.events = append(span.events, ev) |
| 60 | span.mu.Unlock() |
| 61 | } |
| 62 | case event.IsStart(ev): |
| 63 | span := &Span{ |
| 64 | Name: keys.Start.Get(lm), |
| 65 | start: ev, |
| 66 | } |
| 67 | if parent := GetSpan(ctx); parent != nil { |
| 68 | span.ID.TraceID = parent.ID.TraceID |
| 69 | span.ParentID = parent.ID.SpanID |
| 70 | } else { |
| 71 | span.ID.TraceID = newTraceID() |
| 72 | } |
| 73 | span.ID.SpanID = newSpanID() |
| 74 | ctx = context.WithValue(ctx, spanContextKey, span) |
| 75 | case event.IsEnd(ev): |
| 76 | if span := GetSpan(ctx); span != nil { |
| 77 | span.mu.Lock() |
| 78 | span.finish = ev |
| 79 | span.mu.Unlock() |
| 80 | } |
| 81 | case event.IsDetach(ev): |
| 82 | ctx = context.WithValue(ctx, spanContextKey, nil) |
| 83 | } |
| 84 | return output(ctx, ev, lm) |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | func (s *SpanContext) Format(f fmt.State, r rune) { |
| 89 | fmt.Fprintf(f, "%v:%v", s.TraceID, s.SpanID) |
| 90 | } |
| 91 | |
| 92 | func (s *Span) Start() core.Event { |
| 93 | // start never changes after construction, so we don't need to hold the mutex |
| 94 | return s.start |
| 95 | } |
| 96 | |
| 97 | func (s *Span) Finish() core.Event { |
| 98 | s.mu.Lock() |
| 99 | defer s.mu.Unlock() |
| 100 | return s.finish |
| 101 | } |
| 102 | |
| 103 | func (s *Span) Events() []core.Event { |
| 104 | s.mu.Lock() |
| 105 | defer s.mu.Unlock() |
| 106 | return s.events |
| 107 | } |
| 108 | |
| 109 | func (s *Span) Format(f fmt.State, r rune) { |
| 110 | s.mu.Lock() |
| 111 | defer s.mu.Unlock() |
| 112 | fmt.Fprintf(f, "%v %v", s.Name, s.ID) |
| 113 | if s.ParentID.IsValid() { |
| 114 | fmt.Fprintf(f, "[%v]", s.ParentID) |
| 115 | } |
| 116 | fmt.Fprintf(f, " %v->%v", s.start, s.finish) |
| 117 | } |
| 118 |
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