ipld-eth-server/vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/context.go

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2018-09-04 16:35:38 +00:00
package tracer
import (
"context"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/internal"
)
type contextKey struct{}
var activeSpanKey = contextKey{}
// ContextWithSpan returns a copy of the given context which includes the span s.
func ContextWithSpan(ctx context.Context, s Span) context.Context {
return context.WithValue(ctx, activeSpanKey, s)
}
// SpanFromContext returns the span contained in the given context. A second return
// value indicates if a span was found in the context. If no span is found, a no-op
// span is returned.
func SpanFromContext(ctx context.Context) (Span, bool) {
if ctx == nil {
return &internal.NoopSpan{}, false
}
v := ctx.Value(activeSpanKey)
if s, ok := v.(ddtrace.Span); ok {
return s, true
}
return &internal.NoopSpan{}, false
}
// StartSpanFromContext returns a new span with the given operation name and options. If a span
// is found in the context, it will be used as the parent of the resulting span. If the ChildOf
// option is passed, the span from context will take precedence over it as the parent span.
func StartSpanFromContext(ctx context.Context, operationName string, opts ...StartSpanOption) (Span, context.Context) {
if s, ok := SpanFromContext(ctx); ok {
opts = append(opts, ChildOf(s.Context()))
}
s := StartSpan(operationName, opts...)
return s, ContextWithSpan(ctx, s)
}