Add RedisMetric instrumentation class

config/metrics/counts_all/20210216182006_source_code_pushes.yml

@@ -10,6 +10,10 @@ value_type: number
 status: data_available
 time_frame: all
 data_source: redis
+instrumentation_class: RedisMetric
+options:
+  counter_class: SourceCodeCounter
+  event: pushes
 distribution:
 - ce
 - ee

lib/generators/gitlab/usage_metric/usage_metric_generator.rb

@@ -11,7 +11,8 @@ module Gitlab
 
     ALLOWED_SUPERCLASSES = {
       generic: 'Generic',
-      database: 'Database'
+      database: 'Database',
+      redis: 'Redis'
     }.freeze
 
     ALLOWED_OPERATIONS = %w(count distinct_count).freeze

lib/gitlab/usage/metrics/instrumentations/redis_metric.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Usage
+    module Metrics
+      module Instrumentations
+        # Usage example
+        #
+        # In metric YAML definition:
+        #
+        # instrumentation_class: RedisMetric
+        # options:
+        #   event: pushes
+        #   counter_class: SourceCodeCounter
+        #
+        class RedisMetric < BaseMetric
+          include Gitlab::UsageDataCounters::RedisCounter
+
+          def initialize(time_frame:, options: {})
+            super
+
+            raise ArgumentError, "'event' option is required" unless metric_event.present?
+            raise ArgumentError, "'counter class' option is required" unless counter_class.present?
+          end
+
+          def metric_event
+            options[:event]
+          end
+
+          def counter_class_name
+            options[:counter_class]
+          end
+
+          def counter_class
+            "Gitlab::UsageDataCounters::#{counter_class_name}".constantize
+          end
+
+          def value
+            redis_usage_data do
+              counter_class.read(metric_event)
+            end
+          end
+
+          def suggested_name
+            Gitlab::Usage::Metrics::NameSuggestion.for(:redis)
+          end
+        end
+      end
+    end
+  end
+end

rubocop/rubocop-usage-data.yml

@@ -122,3 +122,4 @@ UsageData/InstrumentationSuperclass:
     - :DatabaseMetric
     - :GenericMetric
     - :RedisHLLMetric
+    - :RedisMetric

spec/lib/gitlab/usage/metrics/instrumentations/redis_metric_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Usage::Metrics::Instrumentations::RedisMetric, :clean_gitlab_redis_shared_state do
+  before do
+    4.times do
+      Gitlab::UsageDataCounters::SourceCodeCounter.count(:pushes)
+    end
+  end
+
+  let(:expected_value) { 4 }
+
+  it_behaves_like 'a correct instrumented metric value', { options: { event: 'pushes', counter_class: 'SourceCodeCounter' } }
+
+  it 'raises an exception if event option is not present' do
+    expect { described_class.new(counter_class: 'SourceCodeCounter') }.to raise_error(ArgumentError)
+  end
+
+  it 'raises an exception if counter_class option is not present' do
+    expect { described_class.new(event: 'pushes') }.to raise_error(ArgumentError)
+  end
+end