Exemplar: move to metricdata.

metric/metricdata/exemplar.go

@@ -15,7 +15,6 @@
 package metricdata
 
 import (
-	"context"
 	"time"
 )
 
@@ -38,40 +37,4 @@ type Exemplar struct {
 }
 
 // Attachments is a map of extra values associated with a recorded data point.
-// The map should only be mutated from AttachmentExtractor functions.
 type Attachments map[string]string
-
-// AttachmentExtractor is a function capable of extracting exemplar attachments
-// from the context used to record measurements.
-// The map passed to the function should be mutated and returned. It will
-// initially be nil: the first AttachmentExtractor that would like to add keys to the
-// map is responsible for initializing it.
-type AttachmentExtractor func(ctx context.Context, a Attachments) Attachments
-
-var extractors []AttachmentExtractor
-
-// RegisterAttachmentExtractor registers the given extractor associated with the exemplar
-// type name.
-//
-// Extractors will be used to attempt to extract exemplars from the context
-// associated with each recorded measurement.
-//
-// Packages that support exemplars should register their extractor functions on
-// initialization.
-//
-// RegisterAttachmentExtractor should not be called after any measurements have
-// been recorded.
-func RegisterAttachmentExtractor(e AttachmentExtractor) {
-	extractors = append(extractors, e)
-}
-
-// AttachmentsFromContext extracts exemplars from the given context.
-// Each registered AttachmentExtractor (see RegisterAttachmentExtractor) is called in an
-// unspecified order to add attachments to the exemplar.
-func AttachmentsFromContext(ctx context.Context) Attachments {
-	var a Attachments
-	for _, extractor := range extractors {
-		a = extractor(ctx, a)
-	}
-	return a
-}

stats/record.go

@@ -18,7 +18,6 @@ package stats
 import (
 	"context"
 
-	"go.opencensus.io/metric/metricdata"
 	"go.opencensus.io/stats/internal"
 	"go.opencensus.io/tag"
 )
@@ -51,7 +50,8 @@ func Record(ctx context.Context, ms ...Measurement) {
 	if !record {
 		return
 	}
-	recorder(tag.FromContext(ctx), ms, metricdata.AttachmentsFromContext(ctx))
+	// TODO(songy23): fix attachments.
+	recorder(tag.FromContext(ctx), ms, map[string]string{})
 }
 
 // RecordWithTags records one or multiple measurements at once.

stats/view/view_test.go

@@ -179,7 +179,7 @@ func Test_View_MeasureFloat64_AggregationDistribution(t *testing.T) {
 			}
 			e := &metricdata.Exemplar{
 				Value:       r.f,
-				Attachments: metricdata.AttachmentsFromContext(ctx),
+				Attachments: map[string]string{},
 			}
 			view.addSample(tag.FromContext(ctx), e)
 		}

tag/context.go

@@ -17,8 +17,6 @@ package tag
 
 import (
 	"context"
-
-	"go.opencensus.io/metric/metricdata"
 )
 
 // FromContext returns the tag map stored in the context.
@@ -43,25 +41,3 @@ func NewContext(ctx context.Context, m *Map) context.Context {
 type ctxKey struct{}
 
 var mapCtxKey = ctxKey{}
-
-func init() {
-	metricdata.RegisterAttachmentExtractor(extractTagsAttachments)
-}
-
-func extractTagsAttachments(ctx context.Context, a metricdata.Attachments) metricdata.Attachments {
-	m := FromContext(ctx)
-	if m == nil {
-		return a
-	}
-	if len(m.m) == 0 {
-		return a
-	}
-	if a == nil {
-		a = make(map[string]string)
-	}
-
-	for k, v := range m.m {
-		a[metricdata.KeyPrefixTag+k.Name()] = v
-	}
-	return a
-}