Infer destination service resource adapt public api

gocontext.go

@@ -90,6 +90,17 @@ func StartSpan(ctx context.Context, name, spanType string) (*Span, context.Conte
 	return StartSpanOptions(ctx, name, spanType, SpanOptions{})
 }
 
+// StartExitSpan starts an exit span. If the provided context already contains
+// an exit span, this function returns a dropped span.
+func StartExitSpan(ctx context.Context, name, spanType string) (*Span, context.Context) {
+	span, ctx := StartSpanOptions(ctx, name, spanType, SpanOptions{})
+	if span.Dropped() {
+		return span, ctx
+	}
+	span.setExitSpan(name, spanType)
+	return span, ctx
+}
+
 // StartSpanOptions starts and returns a new Span within the sampled transaction
 // and parent span in the context, if any. If the span isn't dropped, it will be
 // stored in the resulting context.

model/model.go

@@ -371,10 +371,10 @@ type DestinationSpanContext struct {
 // DestinationServiceSpanContext holds contextual information about a
 // destination service.
 type DestinationServiceSpanContext struct {
-	// Type holds the destination service type.
+	// Type holds the destination service type. Deprecated.
 	Type string `json:"type,omitempty"`
 
-	// Name holds the destination service name.
+	// Name holds the destination service name. Deprecated.
 	Name string `json:"name,omitempty"`
 
 	// Resource identifies the destination service

module/apmawssdkgo/session.go

@@ -173,7 +173,6 @@ func send(req *request.Request) {
 	span.Action = req.Operation.Name
 
 	span.Context.SetDestinationService(apm.DestinationServiceSpanContext{
-		Name:     spanSubtype,
 		Resource: svc.resource(),
 	})
 

span.go

@@ -24,6 +24,7 @@ import (
 	"sync"
 	"time"
 
+	"go.elastic.co/apm/model"
 	"go.elastic.co/apm/stacktrace"
 )
 
@@ -54,6 +55,17 @@ func (tx *Transaction) StartSpan(name, spanType string, parent *Span) *Span {
 	})
 }
 
+// StartExitSpan starts an exit span. If the provided parent is already an exit
+// span, this function returns a dropped span.
+func (tx *Transaction) StartExitSpan(name, spanType string, parent *Span) *Span {
+	span := tx.StartSpan(name, spanType, parent)
+	if span.Dropped() {
+		return span
+	}
+	span.setExitSpan(name, spanType)
+	return span
+}
+
 // StartSpanOptions starts and returns a new Span within the transaction,
 // with the specified name, type, and options.
 //
@@ -64,7 +76,8 @@ func (tx *Transaction) StartSpan(name, spanType string, parent *Span) *Span {
 // span type, subtype, and action; a single dot separates span type and
 // subtype, and the action will not be set.
 func (tx *Transaction) StartSpanOptions(name, spanType string, opts SpanOptions) *Span {
-	if tx == nil {
+	if tx == nil || opts.parent.IsExitSpan() {
+		// TODO: Is this the equivalent of a noop span?
 		return newDroppedSpan()
 	}
 
@@ -143,7 +156,10 @@ func (tx *Transaction) StartSpanOptions(name, spanType string, opts SpanOptions)
 // way will not have the "max spans" configuration applied, nor will they be
 // considered in any transaction's span count.
 func (t *Tracer) StartSpan(name, spanType string, transactionID SpanID, opts SpanOptions) *Span {
-	if opts.Parent.Trace.Validate() != nil || opts.Parent.Span.Validate() != nil || transactionID.Validate() != nil {
+	if opts.Parent.Trace.Validate() != nil ||
+		opts.Parent.Span.Validate() != nil ||
+		transactionID.Validate() != nil ||
+		opts.parent.IsExitSpan() {
 		return newDroppedSpan()
 	}
 	if !opts.Parent.Options.Recorded() {
@@ -384,6 +400,30 @@ func (s *Span) ended() bool {
 	return s.SpanData == nil
 }
 
+func (s *Span) setExitSpan(name, spanType string) {
+	resource := spanType
+	if resource == "" {
+		resource = name
+	}
+	s.exit = true
+	s.Context.SetDestinationService(DestinationServiceSpanContext{
+		Resource: resource,
+	})
+}
+
+// IsExitSpan returns true if the span is an exit span.
+func (s *Span) IsExitSpan() bool {
+	if s == nil || s.SpanData == nil {
+		return false
+	}
+	ctx := s.Context
+	return s.exit ||
+		ctx.destination != model.DestinationSpanContext{} ||
+		ctx.database != model.DatabaseSpanContext{} ||
+		ctx.message != model.MessageSpanContext{} ||
+		ctx.http != model.HTTPSpanContext{}
+}
+
 // SpanData holds the details for a span, and is embedded inside Span.
 // When a span is ended or discarded, its SpanData field will be set
 // to nil.
@@ -392,6 +432,7 @@ type SpanData struct {
 	stackTraceLimit        int
 	timestamp              time.Time
 	childrenTimer          childrenTimer
+	exit                   bool
 
 	// Name holds the span name, initialized with the value passed to StartSpan.
 	Name string

span_test.go

@@ -163,6 +163,72 @@ func TestSpanType(t *testing.T) {
 	check(spans[3], "type", "subtype", "action.figure")
 }
 
+func TestStartExitSpan(t *testing.T) {
+	_, spans, _ := apmtest.WithTransaction(func(ctx context.Context) {
+		span, _ := apm.StartExitSpan(ctx, "name", "type")
+		assert.True(t, span.IsExitSpan())
+		span.End()
+	})
+	require.Len(t, spans, 1)
+	assert.Equal(t, spans[0].Context.Destination.Service.Resource, "type")
+
+	tracer := apmtest.NewRecordingTracer()
+	defer tracer.Close()
+
+	tx := tracer.StartTransaction("name", "type")
+	span := tx.StartExitSpan("name", "type", nil)
+	assert.True(t, span.IsExitSpan())
+	// when the parent span is an exit span, any children should be noops.
+	span2 := tx.StartSpan("name", "type", span)
+	assert.True(t, span2.Dropped())
+	span.End()
+	span2.End()
+
+	// when a span has the correct fields set to qualify as an exit span,
+	// it should be considered as such.
+	span = tx.StartSpan("name", "type", nil)
+	assert.False(t, span.IsExitSpan())
+	span.Context.SetDestinationService(apm.DestinationServiceSpanContext{
+		Resource: "my-resource",
+	})
+	assert.True(t, span.IsExitSpan())
+	span2 = tx.StartSpan("name", "type", span)
+	assert.True(t, span2.Dropped())
+	span.End()
+	span2.End()
+
+	span = tx.StartSpan("name", "type", nil)
+	assert.False(t, span.IsExitSpan())
+	span.Context.SetMessage(apm.MessageSpanContext{
+		QueueName: "my-queue",
+	})
+	assert.True(t, span.IsExitSpan())
+	span2 = tx.StartSpan("name", "type", span)
+	assert.True(t, span2.Dropped())
+	span.End()
+	span2.End()
+
+	span = tx.StartSpan("name", "type", nil)
+	assert.False(t, span.IsExitSpan())
+	span.Context.SetDatabase(apm.DatabaseSpanContext{
+		Instance: "my-instance",
+	})
+	assert.True(t, span.IsExitSpan())
+	span2 = tx.StartSpan("name", "type", span)
+	assert.True(t, span2.Dropped())
+	span.End()
+	span2.End()
+
+	span = tx.StartSpan("name", "type", nil)
+	assert.False(t, span.IsExitSpan())
+	span.Context.SetHTTPStatusCode(200)
+	assert.True(t, span.IsExitSpan())
+	span2 = tx.StartSpan("name", "type", span)
+	assert.True(t, span2.Dropped())
+	span.End()
+	span2.End()
+}
+
 func TestTracerStartSpanIDSpecified(t *testing.T) {
 	spanID := apm.SpanID{0, 1, 2, 3, 4, 5, 6, 7}
 	_, spans, _ := apmtest.WithTransaction(func(ctx context.Context) {

spancontext.go

@@ -57,10 +57,6 @@ type DatabaseSpanContext struct {
 
 // DestinationServiceSpanContext holds destination service span span.
 type DestinationServiceSpanContext struct {
-	// Name holds a name for the destination service, which may be used
-	// for grouping and labeling in service maps.
-	Name string
-
 	// Resource holds an identifier for a destination service resource,
 	// such as a message queue.
 	Resource string
@@ -178,7 +174,6 @@ func (c *SpanContext) SetHTTPRequest(req *http.Request) {
 		}
 	}
 	c.SetDestinationService(DestinationServiceSpanContext{
-		Name:     destinationServiceURL.String(),
 		Resource: destinationServiceResource,
 	})
 }
@@ -222,10 +217,9 @@ func (c *SpanContext) SetMessage(message MessageSpanContext) {
 // Both service.Name and service.Resource are required. If either is empty,
 // then SetDestinationService is a no-op.
 func (c *SpanContext) SetDestinationService(service DestinationServiceSpanContext) {
-	if service.Name == "" || service.Resource == "" {
+	if service.Resource == "" {
 		return
 	}
-	c.destinationService.Name = truncateString(service.Name)
 	c.destinationService.Resource = truncateString(service.Resource)
 	c.destination.Service = &c.destinationService
 	c.model.Destination = &c.destination

spancontext_test.go

@@ -65,37 +65,31 @@ func TestSpanContextSetHTTPRequest(t *testing.T) {
 		url:      "http://localhost/foo/bar",
 		addr:     "localhost",
 		port:     80,
-		name:     "http://localhost",
 		resource: "localhost:80",
 	}, {
 		url:      "http://localhost:80/foo/bar",
 		addr:     "localhost",
 		port:     80,
-		name:     "http://localhost",
 		resource: "localhost:80",
 	}, {
 		url:      "https://[::1]/foo/bar",
 		addr:     "::1",
 		port:     443,
-		name:     "https://[::1]",
 		resource: "[::1]:443",
 	}, {
 		url:      "https://[::1]:8443/foo/bar",
 		addr:     "::1",
 		port:     8443,
-		name:     "https://[::1]:8443",
 		resource: "[::1]:8443",
 	}, {
 		url:      "gopher://gopher.invalid:70",
 		addr:     "gopher.invalid",
 		port:     70,
-		name:     "gopher://gopher.invalid:70",
 		resource: "gopher.invalid:70",
 	}, {
 		url:      "gopher://gopher.invalid",
 		addr:     "gopher.invalid",
 		port:     0,
-		name:     "gopher://gopher.invalid",
 		resource: "gopher.invalid",
 	}}
 
@@ -116,7 +110,6 @@ func TestSpanContextSetHTTPRequest(t *testing.T) {
 				Port:    tc.port,
 				Service: &model.DestinationServiceSpanContext{
 					Type:     spans[0].Type,
-					Name:     tc.name,
 					Resource: tc.resource,
 				},
 			}, spans[0].Context.Destination)
@@ -132,29 +125,23 @@ func TestSetDestinationService(t *testing.T) {
 	}
 
 	testcases := []testcase{{
-		name:        "",
 		resource:    "",
 		expectEmpty: true,
 	}, {
-		name:        "",
 		resource:    "nonempty",
-		expectEmpty: true,
+		expectEmpty: false,
 	}, {
-		name:        "nonempty",
 		resource:    "",
 		expectEmpty: true,
 	}, {
-		name:     "nonempty",
 		resource: "nonempty",
 	}}
-
 	for _, tc := range testcases {
 		t.Run(fmt.Sprintf("%s_%s", tc.name, tc.resource), func(t *testing.T) {
 			_, spans, _ := apmtest.WithTransaction(func(ctx context.Context) {
 				span, _ := apm.StartSpan(ctx, "name", "span_type")
 				span.Context.SetDestinationAddress("testing.invalid", 123)
 				span.Context.SetDestinationService(apm.DestinationServiceSpanContext{
-					Name:     tc.name,
 					Resource: tc.resource,
 				})
 				span.End()
@@ -164,7 +151,6 @@ func TestSetDestinationService(t *testing.T) {
 				assert.Nil(t, spans[0].Context.Destination.Service)
 			} else {
 				assert.Equal(t, &model.DestinationServiceSpanContext{
-					Name:     tc.name,
 					Resource: tc.resource,
 					Type:     "span_type",
 				}, spans[0].Context.Destination.Service)

validation_test.go

@@ -119,12 +119,11 @@ func TestValidateDatabaseSpanContext(t *testing.T) {
 
 func TestValidateDestinationSpanContext(t *testing.T) {
 	overlong := strings.Repeat("x", 1025)
-	for _, name := range []string{"", overlong} {
+	for range []string{"", overlong} {
 		for _, resource := range []string{"", overlong} {
 			validateSpan(t, func(s *apm.Span) {
 				s.Context.SetDestinationAddress(overlong, 0)
 				s.Context.SetDestinationService(apm.DestinationServiceSpanContext{
-					Name:     name,
 					Resource: resource,
 				})
 			})