1 files changed, 42 insertions, 17 deletions
diff --git a/lib/gitlab/metrics/sli.rb b/lib/gitlab/metrics/sli.rb
index de73db0755d..fcd893b675f 100644
--- a/lib/gitlab/metrics/sli.rb
+++ b/lib/gitlab/metrics/sli.rb
@@ -2,12 +2,10 @@
 
 module Gitlab
   module Metrics
-    class Sli
-      SliNotInitializedError = Class.new(StandardError)
-
+    module Sli
       COUNTER_PREFIX = 'gitlab_sli'
 
-      class << self
+      module ClassMethods
         INITIALIZATION_MUTEX = Mutex.new
 
         def [](name)
@@ -16,6 +14,8 @@ module Gitlab
 
         def initialize_sli(name, possible_label_combinations)
           INITIALIZATION_MUTEX.synchronize do
+            next known_slis[name] if initialized?(name)
+
             sli = new(name)
             sli.initialize_counters(possible_label_combinations)
             known_slis[name] = sli
@@ -33,6 +33,10 @@ module Gitlab
         end
       end
 
+      def self.included(mod)
+        mod.extend(ClassMethods)
+      end
+
       attr_reader :name
 
       def initialize(name)
@@ -41,16 +45,17 @@ module Gitlab
       end
 
       def initialize_counters(possible_label_combinations)
-        @initialized_with_combinations = possible_label_combinations.any?
+        # This module is effectively an abstract class
+        @initialized_with_combinations = possible_label_combinations.any? # rubocop:disable Gitlab/ModuleWithInstanceVariables
         possible_label_combinations.each do |label_combination|
           total_counter.get(label_combination)
-          success_counter.get(label_combination)
+          numerator_counter.get(label_combination)
         end
       end
 
-      def increment(labels:, success:)
+      def increment(labels:, increment_numerator:)
         total_counter.increment(labels)
-        success_counter.increment(labels) if success
+        numerator_counter.increment(labels) if increment_numerator
       end
 
       def initialized?
@@ -60,23 +65,43 @@ module Gitlab
       private
 
       def total_counter
-        prometheus.counter(total_counter_name.to_sym, "Total number of measurements for #{name}")
+        prometheus.counter(counter_name('total'), "Total number of measurements for #{name}")
       end
 
-      def success_counter
-        prometheus.counter(success_counter_name.to_sym, "Number of successful measurements for #{name}")
+      def counter_name(suffix)
+        :"#{COUNTER_PREFIX}:#{name}_#{self.class.name.demodulize.underscore}:#{suffix}"
       end
 
-      def total_counter_name
-        "#{COUNTER_PREFIX}:#{name}:total"
+      def prometheus
+        Gitlab::Metrics
       end
 
-      def success_counter_name
-        "#{COUNTER_PREFIX}:#{name}:success_total"
+      class Apdex
+        include Sli
+
+        def increment(labels:, success:)
+          super(labels: labels, increment_numerator: success)
+        end
+
+        private
+
+        def numerator_counter
+          prometheus.counter(counter_name('success_total'), "Number of successful measurements for #{name}")
+        end
       end
 
-      def prometheus
-        Gitlab::Metrics
+      class ErrorRate
+        include Sli
+
+        def increment(labels:, error:)
+          super(labels: labels, increment_numerator: error)
+        end
+
+        private
+
+        def numerator_counter
+          prometheus.counter(counter_name('error_total'), "Number of error measurements for #{name}")
+        end
       end
     end
   end