Automatically prefix transaction series names

This ensures Rails and Sidekiq transactions are split into the series
"rails_transactions" and "sidekiq_transactions" respectively.

lib/gitlab/metrics/rack_middleware.rb

@@ -4,8 +4,6 @@ module Gitlab
     class RackMiddleware
       CONTROLLER_KEY = 'action_controller.instance'
-      SERIES = 'rails_transactions'
-
       def initialize(app)
         @app = app
       end
@@ -32,7 +30,7 @@ module Gitlab
       end
       def transaction_from_env(env)
-        trans = Transaction.new(SERIES)
+        trans = Transaction.new
         trans.add_tag(:request_method, env['REQUEST_METHOD'])
         trans.add_tag(:request_uri, env['REQUEST_URI'])

lib/gitlab/metrics/sidekiq_middleware.rb

@@ -4,10 +4,8 @@ module Gitlab
     #
     # This middleware is intended to be used as a server-side middleware.
     class SidekiqMiddleware
-      SERIES = 'sidekiq_transactions'
-
       def call(worker, message, queue)
-        trans = Transaction.new(SERIES)
+        trans = Transaction.new
         begin
           trans.run { yield }

lib/gitlab/metrics/transaction.rb

@@ -10,9 +10,7 @@ module Gitlab
         Thread.current[THREAD_KEY]
       end
-      # name - The name of this transaction as a String.
-      def initialize(series)
-        @series  = series
+      def initialize
         @metrics = []
         @uuid    = SecureRandom.uuid
@@ -40,9 +38,10 @@ module Gitlab
       end
       def add_metric(series, values, tags = {})
-        tags = tags.merge(transaction_id: @uuid)
-        @metrics << Metric.new(series, values, tags)
+        tags   = tags.merge(transaction_id: @uuid)
+        prefix = sidekiq? ? 'sidekiq_' : 'rails_'
+        @metrics << Metric.new("#{prefix}#{series}", values, tags)
       end
       def increment(name, value)
@@ -65,12 +64,16 @@ module Gitlab
           values[name] = value
         end
-        add_metric(@series, values, @tags)
+        add_metric('transactions', values, @tags)
       end
       def submit
         Metrics.submit_metrics(@metrics.map(&:to_hash))
       end
+
+      def sidekiq?
+        Sidekiq.server?
+      end
     end
   end
 end

spec/lib/gitlab/metrics/instrumentation_spec.rb

 require 'spec_helper'
 describe Gitlab::Metrics::Instrumentation do
-  let(:transaction) { Gitlab::Metrics::Transaction.new('rspec') }
+  let(:transaction) { Gitlab::Metrics::Transaction.new }
   before do
     @dummy = Class.new do

spec/lib/gitlab/metrics/sidekiq_middleware_spec.rb

@@ -15,7 +15,7 @@ describe Gitlab::Metrics::SidekiqMiddleware do
   describe '#tag_worker' do
     it 'adds the worker class and action to the transaction' do
-      trans  = Gitlab::Metrics::Transaction.new('rspec')
+      trans  = Gitlab::Metrics::Transaction.new
       worker = double(:worker, class: double(:class, name: 'TestWorker'))
       expect(trans).to receive(:add_tag).with(:action, 'TestWorker#perform')

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

 require 'spec_helper'
 describe Gitlab::Metrics::Subscribers::ActionView do
-  let(:transaction) { Gitlab::Metrics::Transaction.new('rspec') }
+  let(:transaction) { Gitlab::Metrics::Transaction.new }
   let(:subscriber) { described_class.new }

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

 require 'spec_helper'
 describe Gitlab::Metrics::Subscribers::ActiveRecord do
-  let(:transaction) { Gitlab::Metrics::Transaction.new('rspec') }
+  let(:transaction) { Gitlab::Metrics::Transaction.new }
   let(:subscriber)  { described_class.new }
   let(:event) do

spec/lib/gitlab/metrics/transaction_spec.rb

 require 'spec_helper'
 describe Gitlab::Metrics::Transaction do
-  let(:transaction) { described_class.new('rspec') }
+  let(:transaction) { described_class.new }
   describe '#duration' do
     it 'returns the duration of a transaction in seconds' do
@@ -32,7 +32,7 @@ describe Gitlab::Metrics::Transaction do
   describe '#add_metric' do
     it 'adds a metric tagged with the transaction UUID' do
       expect(Gitlab::Metrics::Metric).to receive(:new).
-        with('foo', { number: 10 }, { transaction_id: transaction.uuid })
+        with('rails_foo', { number: 10 }, { transaction_id: transaction.uuid })
       transaction.add_metric('foo', number: 10)
     end
@@ -44,7 +44,7 @@ describe Gitlab::Metrics::Transaction do
       transaction.increment(:time, 2)
       expect(transaction).to receive(:add_metric).
-        with('rspec', { duration: 0.0, time: 3 }, {})
+        with('transactions', { duration: 0.0, time: 3 }, {})
       transaction.track_self
     end
@@ -70,7 +70,7 @@ describe Gitlab::Metrics::Transaction do
   describe '#track_self' do
     it 'adds a metric for the transaction itself' do
       expect(transaction).to receive(:add_metric).
-        with('rspec', { duration: transaction.duration }, {})
+        with('transactions', { duration: transaction.duration }, {})
       transaction.track_self
     end