move metrics for ActiveRecord, RailsCache and queue duration to instance variables

lib/gitlab/metrics/subscribers/active_record.rb

@@ -5,18 +5,9 @@ module Gitlab
       class ActiveRecord < ActiveSupport::Subscriber
         attach_to :active_record
 
-        def self.metric_sql_duration_seconds
-          @metric_sql_duration_seconds ||= Gitlab::Metrics.histogram(
-            :gitlab_sql_duration_seconds,
-            'SQL time',
-            Transaction::BASE_LABELS,
-            [0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.500, 2.0, 10.0]
-          )
-        end
-
         def sql(event)
           return unless current_transaction
-          self.class.metric_sql_duration_seconds.observe(current_transaction.labels, event.duration / 1000.0)
+          metric_sql_duration_seconds.observe(current_transaction.labels, event.duration / 1000.0)
 
           current_transaction.increment(:sql_duration, event.duration, false)
           current_transaction.increment(:sql_count, 1, false)
@@ -27,6 +18,15 @@ module Gitlab
         def current_transaction
           Transaction.current
         end
+
+        def metric_sql_duration_seconds
+          @metric_sql_duration_seconds ||= Gitlab::Metrics.histogram(
+            :gitlab_sql_duration_seconds,
+            'SQL time',
+            Transaction::BASE_LABELS,
+            [0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.500, 2.0, 10.0]
+          )
+        end
       end
     end
   end

lib/gitlab/metrics/subscribers/rails_cache.rb

@@ -6,23 +6,6 @@ module Gitlab
       class RailsCache < ActiveSupport::Subscriber
         attach_to :active_support
 
-        def self.metric_cache_operation_duration_seconds
-          @metric_cache_operation_duration_seconds ||= Gitlab::Metrics.histogram(
-            :gitlab_cache_operation_duration_seconds,
-            'Cache access time',
-            Transaction::BASE_LABELS.merge({ action: nil }),
-            [0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.500, 2.0, 10.0]
-          )
-        end
-
-        def self.metric_cache_misses_total
-          @metric_cache_misses_total ||= Gitlab::Metrics.counter(
-            :gitlab_cache_misses_total,
-            'Cache read miss',
-            Transaction::BASE_LABELS
-          )
-        end
-
         def cache_read(event)
           observe(:read, event.duration)
 
@@ -32,7 +15,7 @@ module Gitlab
           if event.payload[:hit]
             current_transaction.increment(:cache_read_hit_count, 1, false)
           else
-            self.class.metric_cache_misses_total.increment(current_transaction.labels)
+            self.metric_cache_misses_total.increment(current_transaction.labels)
             current_transaction.increment(:cache_read_miss_count, 1, false)
           end
         end
@@ -58,14 +41,14 @@ module Gitlab
         def cache_generate(event)
           return unless current_transaction
 
-          self.class.metric_cache_misses_total.increment(current_transaction.labels)
+          self.metric_cache_misses_total.increment(current_transaction.labels)
           current_transaction.increment(:cache_read_miss_count, 1)
         end
 
         def observe(key, duration)
           return unless current_transaction
 
-          self.class.metric_cache_operation_duration_seconds.observe(current_transaction.labels.merge({ operation: key }), duration / 1000.0)
+          self.metric_cache_operation_duration_seconds.observe(current_transaction.labels.merge({ operation: key }), duration / 1000.0)
           current_transaction.increment(:cache_duration, duration, false)
           current_transaction.increment(:cache_count, 1, false)
           current_transaction.increment("cache_#{key}_duration".to_sym, duration, false)
@@ -77,6 +60,23 @@ module Gitlab
         def current_transaction
           Transaction.current
         end
+
+        def metric_cache_operation_duration_seconds
+          @metric_cache_operation_duration_seconds ||= Gitlab::Metrics.histogram(
+            :gitlab_cache_operation_duration_seconds,
+            'Cache access time',
+            Transaction::BASE_LABELS.merge({ action: nil }),
+            [0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.500, 2.0, 10.0]
+          )
+        end
+
+        def metric_cache_misses_total
+          @metric_cache_misses_total ||= Gitlab::Metrics.counter(
+            :gitlab_cache_misses_total,
+            'Cache read miss',
+            Transaction::BASE_LABELS
+          )
+        end
       end
     end
   end

lib/gitlab/middleware/rails_queue_duration.rb

@@ -5,13 +5,6 @@
 module Gitlab
   module Middleware
     class RailsQueueDuration
-      def self.metric_rails_queue_duration_seconds
-        @metric_rails_queue_duration_seconds ||= Gitlab::Metrics.histogram(
-          :gitlab_rails_queue_duration_seconds,
-          Gitlab::Metrics::Transaction::BASE_LABELS
-        )
-      end
-
       def initialize(app)
         @app = app
       end
@@ -23,11 +16,20 @@ module Gitlab
           # Time in milliseconds since gitlab-workhorse started the request
           duration = Time.now.to_f * 1_000 - proxy_start.to_f / 1_000_000
           trans.set(:rails_queue_duration, duration)
-          self.class.metric_rails_queue_duration_seconds.observe(trans.labels, duration / 1_000)
+          metric_rails_queue_duration_seconds.observe(trans.labels, duration / 1_000)
         end
 
         @app.call(env)
       end
+
+      private
+
+      def metric_rails_queue_duration_seconds
+        @metric_rails_queue_duration_seconds ||= Gitlab::Metrics.histogram(
+          :gitlab_rails_queue_duration_seconds,
+          Gitlab::Metrics::Transaction::BASE_LABELS
+        )
+      end
     end
   end
 end