From 05ba58c595e74655b8332f66c984b6852091bfbc Mon Sep 17 00:00:00 2001
From: Daniel Schierbeck <daniel@dasch.io>
Date: Wed, 19 Aug 2020 11:02:22 +0200
Subject: [PATCH 1/2] Add a single top level span for Racecar consumers

Right now, Racecar consumer processes use one of two top level span
names based on the mode of operation: `racecar.message` or
`racecar.batch`. Because of this, the Datadog interface cannot show
single message consumers and batch consumers in the same list.

This change subscribes to the `main_loop` event which wraps both of
these more specific events. The new span is called `racecar.consume`
since that is the logical operation.
---
 lib/ddtrace/contrib/racecar/events.rb         |  2 ++
 lib/ddtrace/contrib/racecar/events/consume.rb | 27 +++++++++++++++++++
 lib/ddtrace/contrib/racecar/ext.rb            |  1 +
 3 files changed, 30 insertions(+)
 create mode 100644 lib/ddtrace/contrib/racecar/events/consume.rb

diff --git a/lib/ddtrace/contrib/racecar/events.rb b/lib/ddtrace/contrib/racecar/events.rb
index f9abc604d3..a0a18e4255 100644
--- a/lib/ddtrace/contrib/racecar/events.rb
+++ b/lib/ddtrace/contrib/racecar/events.rb
@@ -1,5 +1,6 @@
 require 'ddtrace/contrib/racecar/events/batch'
 require 'ddtrace/contrib/racecar/events/message'
+require 'ddtrace/contrib/racecar/events/consume'
 
 module Datadog
   module Contrib
@@ -7,6 +8,7 @@ module Racecar
       # Defines collection of instrumented Racecar events
       module Events
         ALL = [
+          Events::Consume,
           Events::Batch,
           Events::Message
         ].freeze
diff --git a/lib/ddtrace/contrib/racecar/events/consume.rb b/lib/ddtrace/contrib/racecar/events/consume.rb
new file mode 100644
index 0000000000..b488ca3eb2
--- /dev/null
+++ b/lib/ddtrace/contrib/racecar/events/consume.rb
@@ -0,0 +1,27 @@
+require 'ddtrace/contrib/racecar/ext'
+require 'ddtrace/contrib/racecar/event'
+
+module Datadog
+  module Contrib
+    module Racecar
+      module Events
+        # Defines instrumentation for main_loop.racecar event
+        module Consume
+          include Racecar::Event
+
+          EVENT_NAME = 'main_loop.racecar'.freeze
+
+          module_function
+
+          def event_name
+            self::EVENT_NAME
+          end
+
+          def span_name
+            Ext::SPAN_CONSUME
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/ddtrace/contrib/racecar/ext.rb b/lib/ddtrace/contrib/racecar/ext.rb
index 81f2a3a36b..44d6f6f451 100644
--- a/lib/ddtrace/contrib/racecar/ext.rb
+++ b/lib/ddtrace/contrib/racecar/ext.rb
@@ -10,6 +10,7 @@ module Ext
         ENV_ANALYTICS_SAMPLE_RATE = 'DD_TRACE_RACECAR_ANALYTICS_SAMPLE_RATE'.freeze
         ENV_ANALYTICS_SAMPLE_RATE_OLD = 'DD_RACECAR_ANALYTICS_SAMPLE_RATE'.freeze
         SERVICE_NAME = 'racecar'.freeze
+        SPAN_CONSUME = 'racecar.consume'.freeze
         SPAN_BATCH = 'racecar.batch'.freeze
         SPAN_MESSAGE = 'racecar.message'.freeze
         TAG_CONSUMER = 'kafka.consumer'.freeze

From 3b16692c66340dc39b4199363413c88f9cb4b9c8 Mon Sep 17 00:00:00 2001
From: Daniel Schierbeck <daniel@dasch.io>
Date: Fri, 21 Aug 2020 10:02:25 +0200
Subject: [PATCH 2/2] Add a spec

---
 spec/ddtrace/contrib/racecar/patcher_spec.rb | 58 ++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/spec/ddtrace/contrib/racecar/patcher_spec.rb b/spec/ddtrace/contrib/racecar/patcher_spec.rb
index e59e54503b..5890c0a609 100644
--- a/spec/ddtrace/contrib/racecar/patcher_spec.rb
+++ b/spec/ddtrace/contrib/racecar/patcher_spec.rb
@@ -21,6 +21,64 @@
     Datadog.registry[:racecar].reset_configuration!
   end
 
+  describe 'for both single and batch message processing' do
+    let(:consumer) { 'DummyConsumer' }
+    let(:payload) { { consumer_class: consumer } }
+
+    let(:span) do
+      spans.select { |s| s.name == Datadog::Contrib::Racecar::Ext::SPAN_CONSUME }.first
+    end
+
+    context 'that doesn\'t raise an error' do
+      it 'is expected to send a span' do
+        ActiveSupport::Notifications.instrument('main_loop.racecar', payload)
+
+        span.tap do |span|
+          expect(span).to_not be nil
+          expect(span.service).to eq('racecar')
+          expect(span.name).to eq('racecar.consume')
+          expect(span.resource).to eq(consumer)
+          expect(span.get_tag('kafka.consumer')).to eq(consumer)
+          expect(span).to_not have_error
+        end
+      end
+    end
+
+    context 'that raises an error' do
+      let(:error_class) { Class.new(StandardError) }
+
+      it 'is expected to send a span' do
+        # Emulate failure
+        begin
+          ActiveSupport::Notifications.instrument('main_loop.racecar', payload) do
+            raise error_class
+          end
+        rescue error_class
+          nil
+        end
+
+        span.tap do |span|
+          expect(span).to_not be nil
+          expect(span.service).to eq('racecar')
+          expect(span.name).to eq('racecar.consume')
+          expect(span.resource).to eq(consumer)
+          expect(span.get_tag('kafka.consumer')).to eq(consumer)
+          expect(span).to have_error
+        end
+      end
+    end
+
+    it_behaves_like 'analytics for integration' do
+      before { ActiveSupport::Notifications.instrument('main_loop.racecar', payload) }
+      let(:analytics_enabled_var) { Datadog::Contrib::Racecar::Ext::ENV_ANALYTICS_ENABLED }
+      let(:analytics_sample_rate_var) { Datadog::Contrib::Racecar::Ext::ENV_ANALYTICS_SAMPLE_RATE }
+    end
+
+    it_behaves_like 'measured span for integration', true do
+      before { ActiveSupport::Notifications.instrument('main_loop.racecar', payload) }
+    end
+  end
+
   describe 'for single message processing' do
     let(:topic) { 'dd_trace_test_dummy' }
     let(:consumer) { 'DummyConsumer' }