Stop tracking call stacks for instrumented views

Where a vew is called from doesn't matter as much. We already know what
action they belong to and this is more than enough information. By
removing the file/line number from the list of tags we should also be
able to reduce the number of series stored in InfluxDB.

Author: Yorick Peterse

lib/gitlab/metrics.rb

@@ -36,20 +36,6 @@ def self.pool
       @pool
     end
 
-    # Returns a relative path and line number based on the last application call
-    # frame.
-    def self.last_relative_application_frame
-      frame = caller_locations.find do |l|
-        l.path.start_with?(RAILS_ROOT) && !l.path.start_with?(METRICS_ROOT)
-      end
-
-      if frame
-        return frame.path.sub(PATH_REGEX, ''), frame.lineno
-      else
-        return nil, nil
-      end
-    end
-
     def self.submit_metrics(metrics)
       prepared = prepare_metrics(metrics)
 

lib/gitlab/metrics/subscribers/action_view.rb

@@ -33,16 +33,8 @@ def values_for(event)
 
         def tags_for(event)
           path = relative_path(event.payload[:identifier])
-          tags = { view: path }
 
-          file, line = Metrics.last_relative_application_frame
-
-          if file and line
-            tags[:file] = file
-            tags[:line] = line
-          end
-
-          tags
+          { view: path }
         end
 
         def current_transaction

spec/lib/gitlab/metrics/subscribers/action_view_spec.rb

@@ -14,19 +14,12 @@
 
   before do
     allow(subscriber).to receive(:current_transaction).and_return(transaction)
-
-    allow(Gitlab::Metrics).to receive(:last_relative_application_frame).
-      and_return(['app/views/x.html.haml', 4])
   end
 
   describe '#render_template' do
     it 'tracks rendering of a template' do
       values = { duration: 2.1 }
-      tags   = {
-        view: 'app/views/x.html.haml',
-        file: 'app/views/x.html.haml',
-        line: 4
-      }
+      tags   = { view: 'app/views/x.html.haml' }
 
       expect(transaction).to receive(:increment).
         with(:view_duration, 2.1)

spec/lib/gitlab/metrics_spec.rb

@@ -13,15 +13,6 @@
     end
   end
 
-  describe '.last_relative_application_frame' do
-    it 'returns an Array containing a file path and line number' do
-      file, line = described_class.last_relative_application_frame
-
-      expect(line).to eq(__LINE__ - 2)
-      expect(file).to eq('spec/lib/gitlab/metrics_spec.rb')
-    end
-  end
-
   describe '#submit_metrics' do
     it 'prepares and writes the metrics to InfluxDB' do
       connection = double(:connection)