Use separate series for Rails/Sidekiq transactions

This removes the need for tagging all metrics with a "process_type" tag.

lib/gitlab/metrics/metric.rb

@@ -19,8 +19,7 @@ module Gitlab
         {
           series: @series,
           tags:   @tags.merge(
-            hostname:     Metrics.hostname,
-            process_type: Sidekiq.server? ? 'sidekiq' : 'rails'
+            hostname: Metrics.hostname
           ),
           values:    @values,
           timestamp: @created_at.to_i * 1_000_000_000

lib/gitlab/metrics/rack_middleware.rb

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

lib/gitlab/metrics/sidekiq_middleware.rb

@@ -4,8 +4,10 @@ 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
+        trans = Transaction.new(SERIES)
         begin
           trans.run { yield }

lib/gitlab/metrics/transaction.rb

@@ -4,8 +4,6 @@ module Gitlab
     class Transaction
       THREAD_KEY = :_gitlab_metrics_transaction
-      SERIES = 'transactions'
-
       attr_reader :uuid, :tags
       def self.current
@@ -13,7 +11,8 @@ module Gitlab
       end
       # name - The name of this transaction as a String.
-      def initialize
+      def initialize(series)
+        @series  = series
         @metrics = []
         @uuid    = SecureRandom.uuid
@@ -55,7 +54,7 @@ module Gitlab
       end
       def track_self
-        add_metric(SERIES, { duration: duration }, @tags)
+        add_metric(@series, { duration: duration }, @tags)
       end
       def submit

spec/lib/gitlab/metrics/instrumentation_spec.rb

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

spec/lib/gitlab/metrics/metric_spec.rb

@@ -39,7 +39,6 @@ describe Gitlab::Metrics::Metric do
         expect(hash[:tags]).to be_an_instance_of(Hash)
         expect(hash[:tags][:hostname]).to be_an_instance_of(String)
-        expect(hash[:tags][:process_type]).to be_an_instance_of(String)
       end
       it 'includes the values' 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
+      trans  = Gitlab::Metrics::Transaction.new('rspec')
       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 }
+  let(:transaction) { Gitlab::Metrics::Transaction.new('rspec') }
   let(:subscriber) { described_class.new }

spec/lib/gitlab/metrics/transaction_spec.rb

 require 'spec_helper'
 describe Gitlab::Metrics::Transaction do
-  let(:transaction) { described_class.new }
+  let(:transaction) { described_class.new('rspec') }
   describe '#duration' do
     it 'returns the duration of a transaction in seconds' do
@@ -58,7 +58,7 @@ 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(described_class::SERIES, { duration: transaction.duration }, {})
+        with('rspec', { duration: transaction.duration }, {})
       transaction.track_self
     end