Tag all transaction metrics with an "action" tag

Without this it's impossible to find out what methods/views/queries are
executed by a certain controller or Sidekiq worker. While this will
increase the total number of series it should stay within reasonable
limits due to the amount of "actions" being small enough.

3 files changed, 18 insertions, 12 deletions

diff --git a/lib/gitlab/metrics/rack_middleware.rb b/lib/gitlab/metrics/rack_middleware.rb
index e7a2f26d48b..6f179789d3e 100644
--- a/lib/gitlab/metrics/rack_middleware.rb
+++ b/lib/gitlab/metrics/rack_middleware.rb
@@ -39,10 +39,8 @@ module Gitlab
       end
 
       def tag_controller(trans, env)
-        controller = env[CONTROLLER_KEY]
-        label      = "#{controller.class.name}##{controller.action_name}"
-
-        trans.add_tag(:action, label)
+        controller   = env[CONTROLLER_KEY]
+        trans.action = "#{controller.class.name}##{controller.action_name}"
       end
     end
   end
diff --git a/lib/gitlab/metrics/sidekiq_middleware.rb b/lib/gitlab/metrics/sidekiq_middleware.rb
index ad441decfa2..fd98aa3412e 100644
--- a/lib/gitlab/metrics/sidekiq_middleware.rb
+++ b/lib/gitlab/metrics/sidekiq_middleware.rb
@@ -5,19 +5,14 @@ module Gitlab
     # This middleware is intended to be used as a server-side middleware.
     class SidekiqMiddleware
       def call(worker, message, queue)
-        trans = Transaction.new
+        trans = Transaction.new("#{worker.class.name}#perform")
 
         begin
           trans.run { yield }
         ensure
-          tag_worker(trans, worker)
           trans.finish
         end
       end
-
-      def tag_worker(trans, worker)
-        trans.add_tag(:action, "#{worker.class.name}#perform")
-      end
     end
   end
 end
diff --git a/lib/gitlab/metrics/transaction.rb b/lib/gitlab/metrics/transaction.rb
index 73131cc6ef2..86606b1c6d6 100644
--- a/lib/gitlab/metrics/transaction.rb
+++ b/lib/gitlab/metrics/transaction.rb
@@ -6,11 +6,15 @@ module Gitlab
 
       attr_reader :tags, :values
 
+      attr_accessor :action
+
       def self.current
         Thread.current[THREAD_KEY]
       end
 
-      def initialize
+      # action - A String describing the action performed, usually the class
+      #          plus method name.
+      def initialize(action = nil)
         @metrics = []
 
         @started_at  = nil
@@ -18,6 +22,7 @@ module Gitlab
 
         @values = Hash.new(0)
         @tags   = {}
+        @action = action
       end
 
       def duration
@@ -70,7 +75,15 @@ module Gitlab
       end
 
       def submit
-        Metrics.submit_metrics(@metrics.map(&:to_hash))
+        metrics = @metrics.map do |metric|
+          hash = metric.to_hash
+
+          hash[:tags][:action] ||= @action if @action
+
+          hash
+        end
+
+        Metrics.submit_metrics(metrics)
       end
 
       def sidekiq?