Merge pull request #2137 from DataDog/compute-top-level

Compute top-level span in tracer

Author: marcotc

lib/datadog/tracing/metadata/ext.rb

@@ -22,6 +22,9 @@ module Ext
 
         TAG_KIND = 'span.kind'
 
+        # Set this tag to `1.0` if the span is a Service Entry span.
+        TAG_TOP_LEVEL = '_dd.top_level'
+
         # Defines constants for trace analytics
         # @public_api
         module Analytics

lib/datadog/tracing/span.rb

@@ -110,6 +110,9 @@ def initialize(
         @duration = duration
 
         @service_entry = service_entry
+
+        # Mark with the service entry span metric, if applicable
+        set_metric(Metadata::Ext::TAG_TOP_LEVEL, 1.0) if service_entry
       end
 
       # Return whether the duration is started or not

spec/datadog/tracing/span_spec.rb

@@ -51,6 +51,32 @@
         end
       end
     end
+
+    context 'service_entry' do
+      context 'with nil' do
+        let(:span_options) { { service_entry: nil } }
+
+        it 'does not tag as top-level' do
+          expect(span).to_not have_metadata('_dd.top_level')
+        end
+      end
+
+      context 'with false' do
+        let(:span_options) { { service_entry: false } }
+
+        it 'does not tag as top-level' do
+          expect(span).to_not have_metadata('_dd.top_level')
+        end
+      end
+
+      context 'with true' do
+        let(:span_options) { { service_entry: true } }
+
+        it 'tags as top-level' do
+          expect(span).to have_metadata('_dd.top_level' => 1.0)
+        end
+      end
+    end
   end
 
   context 'ids' do