Allow replacing trace SDK (#1234)

go.sum

@@ -48,6 +48,8 @@ golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/text v0.3.3 h1:cokOdA+Jmi5PJGXLlLllQSgYigAEfHXJAERHVMaCc2k=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

plugin/ochttp/client.go

@@ -56,10 +56,10 @@ type Transport struct {
 	// name equals the URL Path.
 	FormatSpanName func(*http.Request) string
 
-	// NewClientTrace may be set to a function allowing the current *trace.Span
+	// NewClientTrace may be set to a function allowing the current trace.Span
 	// to be annotated with HTTP request event information emitted by the
 	// httptrace package.
-	NewClientTrace func(*http.Request, *trace.Span) *httptrace.ClientTrace
+	NewClientTrace func(*http.Request, trace.Span) *httptrace.ClientTrace
 
 	// TODO: Implement tag propagation for HTTP.
 }

plugin/ochttp/server.go

@@ -109,7 +109,7 @@ func (h *Handler) startTrace(w http.ResponseWriter, r *http.Request) (*http.Requ
 		startOpts = h.GetStartOptions(r)
 	}
 
-	var span *trace.Span
+	var span trace.Span
 	sc, ok := h.extractSpanContext(r)
 	if ok && !h.IsPublicEndpoint {
 		ctx, span = trace.StartSpanWithRemoteParent(ctx, name, sc,

plugin/ochttp/server_test.go

@@ -584,7 +584,7 @@ func TestIgnoreHealthEndpoints(t *testing.T) {
 			ts := httptest.NewServer(&Handler{
 				Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 					span := trace.FromContext(r.Context())
-					if span != nil {
+					if span.IsRecordingEvents() {
 						spans++
 					}
 					fmt.Fprint(w, "ok")

plugin/ochttp/span_annotating_client_trace.go

@@ -24,21 +24,21 @@ import (
 )
 
 type spanAnnotator struct {
-	sp *trace.Span
+	sp trace.Span
 }
 
 // TODO: Remove NewSpanAnnotator at the next release.
 
 // NewSpanAnnotator returns a httptrace.ClientTrace which annotates
 // all emitted httptrace events on the provided Span.
 // Deprecated: Use NewSpanAnnotatingClientTrace instead
-func NewSpanAnnotator(r *http.Request, s *trace.Span) *httptrace.ClientTrace {
+func NewSpanAnnotator(r *http.Request, s trace.Span) *httptrace.ClientTrace {
 	return NewSpanAnnotatingClientTrace(r, s)
 }
 
 // NewSpanAnnotatingClientTrace returns a httptrace.ClientTrace which annotates
 // all emitted httptrace events on the provided Span.
-func NewSpanAnnotatingClientTrace(_ *http.Request, s *trace.Span) *httptrace.ClientTrace {
+func NewSpanAnnotatingClientTrace(_ *http.Request, s trace.Span) *httptrace.ClientTrace {
 	sa := spanAnnotator{sp: s}
 
 	return &httptrace.ClientTrace{

plugin/ochttp/trace.go

@@ -44,7 +44,7 @@ type traceTransport struct {
 	startOptions   trace.StartOptions
 	format         propagation.HTTPFormat
 	formatSpanName func(*http.Request) string
-	newClientTrace func(*http.Request, *trace.Span) *httptrace.ClientTrace
+	newClientTrace func(*http.Request, trace.Span) *httptrace.ClientTrace
 }
 
 // TODO(jbd): Add message events for request and response size.
@@ -104,7 +104,7 @@ func (t *traceTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 // the body of the original response.
 type bodyTracker struct {
 	rc   io.ReadCloser
-	span *trace.Span
+	span trace.Span
 }
 
 var _ io.ReadCloser = (*bodyTracker)(nil)

plugin/ochttp/trace_test.go

@@ -106,7 +106,7 @@ func TestTransport_RoundTrip(t *testing.T) {
 	_, parent := trace.StartSpan(context.Background(), "parent")
 	tests := []struct {
 		name   string
-		parent *trace.Span
+		parent trace.Span
 	}{
 		{
 			name:   "no parent",

trace/basetypes.go

@@ -49,6 +49,16 @@ type Attribute struct {
 	value interface{}
 }
 
+// Key returns the attribute's key
+func (a *Attribute) Key() string {
+	return a.key
+}
+
+// Value returns the attribute's value
+func (a *Attribute) Value() interface{} {
+	return a.value
+}
+
 // BoolAttribute returns a bool-valued attribute.
 func BoolAttribute(key string, value bool) Attribute {
 	return Attribute{key: key, value: value}

trace/examples_test.go

@@ -21,7 +21,7 @@ import (
 	"go.opencensus.io/trace"
 )
 
-// This example shows how to use StartSpan and (*Span).End to capture
+// This example shows how to use StartSpan and (Span).End to capture
 // a function execution in a Span. It assumes that the function
 // has a context.Context argument.
 func ExampleStartSpan() {

trace/spanstore.go

@@ -48,8 +48,10 @@ func (i internalOnly) ReportActiveSpans(name string) []*SpanData {
 	var out []*SpanData
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	for span := range s.active {
-		out = append(out, span.makeSpanData())
+	for activeSpan := range s.active {
+		if s, ok := activeSpan.(*span); ok {
+			out = append(out, s.makeSpanData())
+		}
 	}
 	return out
 }
@@ -185,7 +187,7 @@ func (i internalOnly) ReportSpansByLatency(name string, minLatency, maxLatency t
 // bucketed by latency.
 type spanStore struct {
 	mu                     sync.Mutex // protects everything below.
-	active                 map[*Span]struct{}
+	active                 map[Span]struct{}
 	errors                 map[int32]*bucket
 	latency                []bucket
 	maxSpansPerErrorBucket int
@@ -194,7 +196,7 @@ type spanStore struct {
 // newSpanStore creates a span store.
 func newSpanStore(name string, latencyBucketSize int, errorBucketSize int) *spanStore {
 	s := &spanStore{
-		active:                 make(map[*Span]struct{}),
+		active:                 make(map[Span]struct{}),
 		latency:                make([]bucket, len(defaultLatencies)+1),
 		maxSpansPerErrorBucket: errorBucketSize,
 	}
@@ -271,15 +273,15 @@ func (s *spanStore) resize(latencyBucketSize int, errorBucketSize int) {
 }
 
 // add adds a span to the active bucket of the spanStore.
-func (s *spanStore) add(span *Span) {
+func (s *spanStore) add(span Span) {
 	s.mu.Lock()
 	s.active[span] = struct{}{}
 	s.mu.Unlock()
 }
 
 // finished removes a span from the active set, and adds a corresponding
 // SpanData to a latency or error bucket.
-func (s *spanStore) finished(span *Span, sd *SpanData) {
+func (s *spanStore) finished(span Span, sd *SpanData) {
 	latency := sd.EndTime.Sub(sd.StartTime)
 	if latency < 0 {
 		latency = 0