ddtrace/tracer: remove Span.Tag function (reverts #2523)

ddtrace/mocktracer/mockspan.go

@@ -56,7 +56,7 @@ func (s *Span) Tag(k string) interface{} {
 	}
 	// It's possible that a tag wasn't set through mocktracer.Span.SetTag,
 	// in which case we need to retrieve it from the underlying tracer.Span.
-	v := s.sp.Tag(k)
+	v := s.sp.AsMap()[k]
 	if v != nil {
 		return v
 	}

ddtrace/tracer/span.go

@@ -261,40 +261,6 @@ func (s *Span) AddLink(spanContext *SpanContext, attributes map[string]string) {
 	})
 }
 
-// Tag returns the value for a given tag key.
-// If the key does not exist, Tag returns nil.
-// All values may be of type string, float64, or int32 (only for ext.Error).
-// If the original tag value was not one of these types, Tag will return a string
-// representation of the value.
-// Use ext.Error to check if the span has an error, and ext.ErrorMsg, ext.ErrorType,
-// and ext.ErrorStack to get the error details.
-func (s *Span) Tag(k string) interface{} {
-	if s == nil {
-		return nil
-	}
-	s.RLock()
-	defer s.RUnlock()
-	switch k {
-	case ext.Error:
-		return s.error
-	case ext.SpanName:
-		return s.name
-	case ext.ServiceName:
-		return s.service
-	case ext.ResourceName:
-		return s.resource
-	case ext.SpanType:
-		return s.spanType
-	}
-	if v, ok := s.meta[k]; ok {
-		return v
-	}
-	if v, ok := s.metrics[k]; ok {
-		return v
-	}
-	return nil
-}
-
 // setSamplingPriority locks then span, then updates the sampling priority.
 // It also updates the trace's sampling priority.
 func (s *Span) setSamplingPriority(priority int, sampler samplernames.SamplerName) {

ddtrace/tracer/span_test.go

@@ -95,7 +95,7 @@ func TestNilSpan(t *testing.T) {
 		t.Errorf("expected empty string, got %s", v)
 	}
 	span.SetTag("key", "value")
-	if v := span.Tag("key"); v != nil {
+	if v := span.AsMap()["key"]; v != nil {
 		t.Errorf("expected nil, got %s", v)
 	}
 	span.SetUser("user")
@@ -367,37 +367,27 @@ func TestSpanSetTag(t *testing.T) {
 	assert := assert.New(t)
 	span := newBasicSpan("web.request")
 	assert.Equal("web.request", span.name)
-	assert.Equal("web.request", span.Tag(ext.SpanName))
 
 	span.SetTag("component", "tracer")
 	assert.Equal("tracer", span.meta["component"])
-	assert.Equal("tracer", span.Tag("component"))
 
 	span.SetTag("tagInt", 1234)
 	assert.Equal(float64(1234), span.metrics["tagInt"])
-	assert.Equal(float64(1234), span.Tag("tagInt"))
 
 	span.SetTag("tagStruct", struct{ A, B int }{1, 2})
 	assert.Equal("{1 2}", span.meta["tagStruct"])
-	assert.Equal("{1 2}", span.Tag("tagStruct"))
 
 	span.SetTag(ext.Error, true)
 	assert.Equal(int32(1), span.error)
-	assert.Equal(int32(1), span.Tag(ext.Error))
 
 	span.SetTag(ext.Error, nil)
 	assert.Equal(int32(0), span.error)
-	assert.Equal(int32(0), span.Tag(ext.Error))
 
 	span.SetTag(ext.Error, errors.New("abc"))
 	assert.Equal(int32(1), span.error)
-	assert.Equal(int32(1), span.Tag(ext.Error))
 	assert.Equal("abc", span.meta[ext.ErrorMsg])
-	assert.Equal("abc", span.Tag(ext.ErrorMsg))
 	assert.Equal("*errors.errorString", span.meta[ext.ErrorType])
-	assert.Equal("*errors.errorString", span.Tag(ext.ErrorType))
 	assert.NotEmpty(span.meta[ext.ErrorStack])
-	assert.Equal(span.meta[ext.ErrorStack], span.Tag(ext.ErrorStack))
 
 	span.SetTag(ext.Error, "something else")
 	assert.Equal(int32(1), span.error)
@@ -407,19 +397,15 @@ func TestSpanSetTag(t *testing.T) {
 
 	span.SetTag("some.bool", true)
 	assert.Equal("true", span.meta["some.bool"])
-	assert.Equal("true", span.Tag("some.bool"))
 
 	span.SetTag("some.other.bool", false)
 	assert.Equal("false", span.meta["some.other.bool"])
-	assert.Equal("false", span.Tag("some.other.bool"))
 
 	span.SetTag("time", (*time.Time)(nil))
 	assert.Equal("<nil>", span.meta["time"])
-	assert.Equal("<nil>", span.Tag("time"))
 
 	span.SetTag("nilStringer", (*nilStringer)(nil))
 	assert.Equal("<nil>", span.meta["nilStringer"])
-	assert.Equal("<nil>", span.Tag("nilStringer"))
 
 	span.SetTag("somestrings", []string{"foo", "bar"})
 	assert.Equal("foo", span.meta["somestrings.0"])
@@ -466,9 +452,10 @@ func TestSpanTagsStartSpan(t *testing.T) {
 
 	span := tr.StartSpan("operation-name", ServiceName("service"), Tag("tag", "value"))
 
-	assert.Equal("value", span.Tag("tag"))
-	assert.Equal("service", span.Tag(ext.ServiceName))
-	assert.Equal("operation-name", span.Tag(ext.SpanName))
+	tags := span.AsMap()
+	assert.Equal("value", tags["tag"])
+	assert.Equal("service", tags[ext.ServiceName])
+	assert.Equal("operation-name", tags[ext.SpanName])
 }
 
 type testMsgpStruct struct {