mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-27 22:49:40 -08:00
4d9b917d11
* Use request.Context() instead of a global map of contexts. * Add some basic opentracing instrumentation on the query path. * Remove tracehandler endpoint.
58 lines
2 KiB
Go
58 lines
2 KiB
Go
package opentracing
|
|
|
|
import "golang.org/x/net/context"
|
|
|
|
type contextKey struct{}
|
|
|
|
var activeSpanKey = contextKey{}
|
|
|
|
// ContextWithSpan returns a new `context.Context` that holds a reference to
|
|
// `span`'s SpanContext.
|
|
func ContextWithSpan(ctx context.Context, span Span) context.Context {
|
|
return context.WithValue(ctx, activeSpanKey, span)
|
|
}
|
|
|
|
// SpanFromContext returns the `Span` previously associated with `ctx`, or
|
|
// `nil` if no such `Span` could be found.
|
|
//
|
|
// NOTE: context.Context != SpanContext: the former is Go's intra-process
|
|
// context propagation mechanism, and the latter houses OpenTracing's per-Span
|
|
// identity and baggage information.
|
|
func SpanFromContext(ctx context.Context) Span {
|
|
val := ctx.Value(activeSpanKey)
|
|
if sp, ok := val.(Span); ok {
|
|
return sp
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// StartSpanFromContext starts and returns a Span with `operationName`, using
|
|
// any Span found within `ctx` as a ChildOfRef. If no such parent could be
|
|
// found, StartSpanFromContext creates a root (parentless) Span.
|
|
//
|
|
// The second return value is a context.Context object built around the
|
|
// returned Span.
|
|
//
|
|
// Example usage:
|
|
//
|
|
// SomeFunction(ctx context.Context, ...) {
|
|
// sp, ctx := opentracing.StartSpanFromContext(ctx, "SomeFunction")
|
|
// defer sp.Finish()
|
|
// ...
|
|
// }
|
|
func StartSpanFromContext(ctx context.Context, operationName string, opts ...StartSpanOption) (Span, context.Context) {
|
|
return startSpanFromContextWithTracer(ctx, GlobalTracer(), operationName, opts...)
|
|
}
|
|
|
|
// startSpanFromContextWithTracer is factored out for testing purposes.
|
|
func startSpanFromContextWithTracer(ctx context.Context, tracer Tracer, operationName string, opts ...StartSpanOption) (Span, context.Context) {
|
|
var span Span
|
|
if parentSpan := SpanFromContext(ctx); parentSpan != nil {
|
|
opts = append(opts, ChildOf(parentSpan.Context()))
|
|
span = tracer.StartSpan(operationName, opts...)
|
|
} else {
|
|
span = tracer.StartSpan(operationName, opts...)
|
|
}
|
|
return span, ContextWithSpan(ctx, span)
|
|
}
|