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go/internal/telemetry/export/trace.go
Ian Cottrell d780ff7bdd internal/telemetry: unify the event handling to an event package
This is now the only package that is exposed to normal use, and should
be the only thing to appear in libraries.

Change-Id: I90ee47c6519f30db16ff5d5d2910be86e91e5df2
Reviewed-on: https://go-review.googlesource.com/c/tools/+/222557
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
2020-03-12 03:58:56 +00:00

90 lines
2.0 KiB
Go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package export
import (
"context"
"fmt"
"time"
"golang.org/x/tools/internal/telemetry/event"
)
type SpanContext struct {
TraceID TraceID
SpanID SpanID
}
type Span struct {
Name string
ID SpanContext
ParentID SpanID
Start time.Time
Finish time.Time
Tags event.TagList
Events []event.Event
}
type contextKeyType int
const (
spanContextKey = contextKeyType(iota)
)
func GetSpan(ctx context.Context) *Span {
v := ctx.Value(spanContextKey)
if v == nil {
return nil
}
return v.(*Span)
}
// ContextSpan is an exporter that maintains hierarchical span structure in the
// context.
// It creates new spans on EventStartSpan, adds events to the current span on
// EventLog or EventTag, and closes the span on EventEndSpan.
// The span structure can then be used by other exporters.
func ContextSpan(ctx context.Context, ev event.Event) context.Context {
switch {
case ev.IsLog(), ev.IsTag():
if span := GetSpan(ctx); span != nil {
span.Events = append(span.Events, ev)
}
case ev.IsStartSpan():
span := &Span{
Name: ev.Message,
Start: ev.At,
Tags: ev.Tags,
}
if parent := GetSpan(ctx); parent != nil {
span.ID.TraceID = parent.ID.TraceID
span.ParentID = parent.ID.SpanID
} else {
span.ID.TraceID = newTraceID()
}
span.ID.SpanID = newSpanID()
ctx = context.WithValue(ctx, spanContextKey, span)
case ev.IsEndSpan():
if span := GetSpan(ctx); span != nil {
span.Finish = ev.At
}
case ev.IsDetach():
return context.WithValue(ctx, spanContextKey, nil)
}
return ctx
}
func (s *SpanContext) Format(f fmt.State, r rune) {
fmt.Fprintf(f, "%v:%v", s.TraceID, s.SpanID)
}
func (s *Span) Format(f fmt.State, r rune) {
fmt.Fprintf(f, "%v %v", s.Name, s.ID)
if s.ParentID.IsValid() {
fmt.Fprintf(f, "[%v]", s.ParentID)
}
fmt.Fprintf(f, " %v->%v", s.Start, s.Finish)
}