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go/internal/event/export/trace.go
Ian Cottrell a82abb5396 internal/event: extract keys to their own package
Now key types can be implemented outside the package that holds labels or events, they should be.
This prevents the large list of types from poluting the public interface of the core packages.

Change-Id: I927f31cb5e4e1d0c29619681015962f890623e5c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/229240
Run-TryBot: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
2020-04-23 18:13:43 +00:00

118 lines
2.6 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"
"sync"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/event/core"
"golang.org/x/tools/internal/event/keys"
"golang.org/x/tools/internal/event/label"
)
type SpanContext struct {
TraceID TraceID
SpanID SpanID
}
type Span struct {
Name string
ID SpanContext
ParentID SpanID
mu sync.Mutex
start core.Event
finish core.Event
events []core.Event
}
type contextKeyType int
const (
spanContextKey = contextKeyType(iota)
labelContextKey
)
func GetSpan(ctx context.Context) *Span {
v := ctx.Value(spanContextKey)
if v == nil {
return nil
}
return v.(*Span)
}
// Spans creates an exporter that maintains hierarchical span structure in the
// context.
// It creates new spans on start events, adds events to the current span on
// log or label, and closes the span on end events.
// The span structure can then be used by other exporters.
func Spans(output event.Exporter) event.Exporter {
return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
switch {
case ev.IsLog(), ev.IsLabel():
if span := GetSpan(ctx); span != nil {
span.mu.Lock()
span.events = append(span.events, ev)
span.mu.Unlock()
}
case ev.IsStartSpan():
span := &Span{
Name: keys.Name.Get(lm),
start: ev,
}
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.mu.Lock()
span.finish = ev
span.mu.Unlock()
}
case ev.IsDetach():
ctx = context.WithValue(ctx, spanContextKey, nil)
}
return output(ctx, ev, lm)
}
}
func (s *SpanContext) Format(f fmt.State, r rune) {
fmt.Fprintf(f, "%v:%v", s.TraceID, s.SpanID)
}
func (s *Span) Start() core.Event {
// start never changes after construction, so we dont need to hold the mutex
return s.start
}
func (s *Span) Finish() core.Event {
s.mu.Lock()
defer s.mu.Unlock()
return s.finish
}
func (s *Span) Events() []core.Event {
s.mu.Lock()
defer s.mu.Unlock()
return s.events
}
func (s *Span) Format(f fmt.State, r rune) {
s.mu.Lock()
defer s.mu.Unlock()
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)
}