micro/tracer/trace.go

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// Package trace provides an interface for distributed tracing
package tracer
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import (
"context"
"time"
"github.com/unistack-org/micro/v3/metadata"
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)
var (
DefaultTracer Tracer = newTracer()
)
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// Tracer is an interface for distributed tracing
type Tracer interface {
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// Start a trace
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Start(ctx context.Context, name string) (context.Context, *Span)
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// Finish the trace
Finish(*Span) error
// Read the traces
Read(...ReadOption) ([]*Span, error)
}
// SpanType describe the nature of the trace span
type SpanType int
const (
// SpanTypeRequestInbound is a span created when serving a request
SpanTypeRequestInbound SpanType = iota
// SpanTypeRequestOutbound is a span created when making a service call
SpanTypeRequestOutbound
)
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// Span is used to record an entry
type Span struct {
// Id of the trace
Trace string
// name of the span
Name string
// id of the span
Id string
// parent span id
Parent string
// Start time
Started time.Time
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// Duration in nano seconds
Duration time.Duration
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// associated data
Metadata map[string]string
// Type
Type SpanType
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}
const (
traceIDKey = "Micro-Trace-Id"
spanIDKey = "Micro-Span-Id"
)
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// FromContext returns a span from context
func FromContext(ctx context.Context) (traceID string, parentSpanID string, isFound bool) {
traceID, traceOk := metadata.Get(ctx, traceIDKey)
microID, microOk := metadata.Get(ctx, "Micro-Id")
if !traceOk && !microOk {
isFound = false
return
}
if !traceOk {
traceID = microID
}
parentSpanID, ok := metadata.Get(ctx, spanIDKey)
return traceID, parentSpanID, ok
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}
// ToContext saves the trace and span ids in the context
func ToContext(ctx context.Context, traceID, parentSpanID string) context.Context {
return metadata.MergeContext(ctx, map[string]string{
traceIDKey: traceID,
spanIDKey: parentSpanID,
}, true)
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}