Girish Kumar | 46d7c3a | 2020-05-18 12:06:33 +0000 | [diff] [blame] | 1 | package opentracing |
| 2 | |
| 3 | import "context" |
| 4 | |
| 5 | type contextKey struct{} |
| 6 | |
| 7 | var activeSpanKey = contextKey{} |
| 8 | |
| 9 | // ContextWithSpan returns a new `context.Context` that holds a reference to |
khenaidoo | 2672188 | 2021-08-11 17:42:52 -0400 | [diff] [blame^] | 10 | // the span. If span is nil, a new context without an active span is returned. |
Girish Kumar | 46d7c3a | 2020-05-18 12:06:33 +0000 | [diff] [blame] | 11 | func ContextWithSpan(ctx context.Context, span Span) context.Context { |
khenaidoo | 2672188 | 2021-08-11 17:42:52 -0400 | [diff] [blame^] | 12 | if span != nil { |
| 13 | if tracerWithHook, ok := span.Tracer().(TracerContextWithSpanExtension); ok { |
| 14 | ctx = tracerWithHook.ContextWithSpanHook(ctx, span) |
| 15 | } |
| 16 | } |
Girish Kumar | 46d7c3a | 2020-05-18 12:06:33 +0000 | [diff] [blame] | 17 | return context.WithValue(ctx, activeSpanKey, span) |
| 18 | } |
| 19 | |
| 20 | // SpanFromContext returns the `Span` previously associated with `ctx`, or |
| 21 | // `nil` if no such `Span` could be found. |
| 22 | // |
| 23 | // NOTE: context.Context != SpanContext: the former is Go's intra-process |
| 24 | // context propagation mechanism, and the latter houses OpenTracing's per-Span |
| 25 | // identity and baggage information. |
| 26 | func SpanFromContext(ctx context.Context) Span { |
| 27 | val := ctx.Value(activeSpanKey) |
| 28 | if sp, ok := val.(Span); ok { |
| 29 | return sp |
| 30 | } |
| 31 | return nil |
| 32 | } |
| 33 | |
| 34 | // StartSpanFromContext starts and returns a Span with `operationName`, using |
| 35 | // any Span found within `ctx` as a ChildOfRef. If no such parent could be |
| 36 | // found, StartSpanFromContext creates a root (parentless) Span. |
| 37 | // |
| 38 | // The second return value is a context.Context object built around the |
| 39 | // returned Span. |
| 40 | // |
| 41 | // Example usage: |
| 42 | // |
| 43 | // SomeFunction(ctx context.Context, ...) { |
| 44 | // sp, ctx := opentracing.StartSpanFromContext(ctx, "SomeFunction") |
| 45 | // defer sp.Finish() |
| 46 | // ... |
| 47 | // } |
| 48 | func StartSpanFromContext(ctx context.Context, operationName string, opts ...StartSpanOption) (Span, context.Context) { |
| 49 | return StartSpanFromContextWithTracer(ctx, GlobalTracer(), operationName, opts...) |
| 50 | } |
| 51 | |
| 52 | // StartSpanFromContextWithTracer starts and returns a span with `operationName` |
| 53 | // using a span found within the context as a ChildOfRef. If that doesn't exist |
| 54 | // it creates a root span. It also returns a context.Context object built |
| 55 | // around the returned span. |
| 56 | // |
| 57 | // It's behavior is identical to StartSpanFromContext except that it takes an explicit |
| 58 | // tracer as opposed to using the global tracer. |
| 59 | func StartSpanFromContextWithTracer(ctx context.Context, tracer Tracer, operationName string, opts ...StartSpanOption) (Span, context.Context) { |
| 60 | if parentSpan := SpanFromContext(ctx); parentSpan != nil { |
| 61 | opts = append(opts, ChildOf(parentSpan.Context())) |
| 62 | } |
| 63 | span := tracer.StartSpan(operationName, opts...) |
| 64 | return span, ContextWithSpan(ctx, span) |
| 65 | } |