mirror of
https://github.com/golang/go
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b378960d5b
This allows us to hide the implementation details of how tags are stored on a context from the normal interface, to allow us to explore more efficient mechanisms. The current storage is not intended as the most efficient choice, this cl is about isolating the API so we can experiment with benchmarks in the future. Change-Id: Ib101416bccd8ecdee269cee636b1564d51e1da8a Reviewed-on: https://go-review.googlesource.com/c/tools/+/222854 Run-TryBot: Ian Cottrell <iancottrell@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>
90 lines
2.0 KiB
Go
90 lines
2.0 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package export
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import (
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"context"
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"fmt"
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"time"
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"golang.org/x/tools/internal/telemetry/event"
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)
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type SpanContext struct {
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TraceID TraceID
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SpanID SpanID
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}
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type Span struct {
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Name string
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ID SpanContext
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ParentID SpanID
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Start time.Time
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Finish time.Time
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Tags event.TagSet
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Events []event.Event
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}
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type contextKeyType int
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const (
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spanContextKey = contextKeyType(iota)
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)
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func GetSpan(ctx context.Context) *Span {
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v := ctx.Value(spanContextKey)
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if v == nil {
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return nil
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}
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return v.(*Span)
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}
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// ContextSpan is an exporter that maintains hierarchical span structure in the
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// context.
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// It creates new spans on EventStartSpan, adds events to the current span on
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// EventLog or EventTag, and closes the span on EventEndSpan.
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// The span structure can then be used by other exporters.
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func ContextSpan(ctx context.Context, ev event.Event) (context.Context, event.Event) {
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switch {
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case ev.IsLog(), ev.IsLabel():
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if span := GetSpan(ctx); span != nil {
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span.Events = append(span.Events, ev)
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}
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case ev.IsStartSpan():
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span := &Span{
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Name: ev.Message,
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Start: ev.At,
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Tags: ev.Tags,
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}
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if parent := GetSpan(ctx); parent != nil {
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span.ID.TraceID = parent.ID.TraceID
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span.ParentID = parent.ID.SpanID
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} else {
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span.ID.TraceID = newTraceID()
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}
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span.ID.SpanID = newSpanID()
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ctx = context.WithValue(ctx, spanContextKey, span)
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case ev.IsEndSpan():
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if span := GetSpan(ctx); span != nil {
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span.Finish = ev.At
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}
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case ev.IsDetach():
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return context.WithValue(ctx, spanContextKey, nil), ev
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}
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return ctx, ev
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}
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func (s *SpanContext) Format(f fmt.State, r rune) {
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fmt.Fprintf(f, "%v:%v", s.TraceID, s.SpanID)
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}
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func (s *Span) Format(f fmt.State, r rune) {
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fmt.Fprintf(f, "%v %v", s.Name, s.ID)
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if s.ParentID.IsValid() {
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fmt.Fprintf(f, "[%v]", s.ParentID)
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}
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fmt.Fprintf(f, " %v->%v", s.Start, s.Finish)
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}
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