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trace.go
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trace.go
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// 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"
"github.com/anz-bank/sysl/pkg/lspimpl/lspframework/telemetry"
)
type SpanContext struct {
TraceID TraceID
SpanID SpanID
}
type Span struct {
Name string
ID SpanContext
ParentID SpanID
Start time.Time
Finish time.Time
Tags telemetry.TagList
Events []telemetry.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, event telemetry.Event) context.Context {
switch event.Type {
case telemetry.EventLog, telemetry.EventTag:
if span := GetSpan(ctx); span != nil {
span.Events = append(span.Events, event)
}
case telemetry.EventStartSpan:
span := &Span{
Name: event.Message,
Start: event.At,
Tags: event.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 telemetry.EventEndSpan:
if span := GetSpan(ctx); span != nil {
span.Finish = event.At
}
case telemetry.EventDetach:
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)
}