micro/debug/trace/trace.go

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// Package trace provides an interface for distributed tracing
package trace
import (
"context"
"time"
)
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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)
}
// 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 spanKey struct{}
// FromContext returns a span from context
func FromContext(ctx context.Context) (*Span, bool) {
s, ok := ctx.Value(spanKey{}).(*Span)
return s, ok
}
// NewContext creates a new context with the span
func NewContext(ctx context.Context, s *Span) context.Context {
return context.WithValue(ctx, spanKey{}, s)
}
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var (
DefaultTracer Tracer = new(noop)
)
type noop struct{}
func (n *noop) Init(...Option) error {
return nil
}
func (n *noop) Start(ctx context.Context, name string) (context.Context, *Span) {
return nil, nil
}
func (n *noop) Finish(*Span) error {
return nil
}
func (n *noop) Read(...ReadOption) ([]*Span, error) {
return nil, nil
}