Add latest changes from gitlab-org/gitlab@master

1 files changed, 87 insertions, 0 deletions

diff --git a/lib/gitlab/cache/metrics.rb b/lib/gitlab/cache/metrics.rb
new file mode 100644
index 00000000000..0143052beb1
--- /dev/null
+++ b/lib/gitlab/cache/metrics.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+# Instrumentation for cache efficiency metrics
+module Gitlab
+  module Cache
+    class Metrics
+      DEFAULT_BUCKETS = [0, 1, 5].freeze
+      VALID_BACKING_RESOURCES = [:cpu, :database, :gitaly, :memory, :unknown].freeze
+      DEFAULT_BACKING_RESOURCE = :unknown
+
+      def initialize(
+        caller_id:,
+        cache_identifier:,
+        feature_category: ::Gitlab::FeatureCategories::FEATURE_CATEGORY_DEFAULT,
+        backing_resource: DEFAULT_BACKING_RESOURCE
+      )
+        @caller_id = caller_id
+        @cache_identifier = cache_identifier
+        @feature_category = Gitlab::FeatureCategories.default.get!(feature_category)
+        @backing_resource = fetch_backing_resource!(backing_resource)
+      end
+
+      # Increase cache hit counter
+      #
+      def increment_cache_hit
+        counter.increment(labels.merge(cache_hit: true))
+      end
+
+      # Increase cache miss counter
+      #
+      def increment_cache_miss
+        counter.increment(labels.merge(cache_hit: false))
+      end
+
+      # Measure the duration of cacheable action
+      #
+      # @example
+      #   observe_cache_generation do
+      #     cacheable_action
+      #   end
+      #
+      def observe_cache_generation(&block)
+        real_start = Gitlab::Metrics::System.monotonic_time
+
+        value = yield
+
+        histogram.observe({}, Gitlab::Metrics::System.monotonic_time - real_start)
+
+        value
+      end
+
+      private
+
+      attr_reader :caller_id, :cache_identifier, :feature_category, :backing_resource
+
+      def counter
+        @counter ||= Gitlab::Metrics.counter(:redis_hit_miss_operations_total, "Hit/miss Redis cache counter")
+      end
+
+      def histogram
+        @histogram ||= Gitlab::Metrics.histogram(
+          :redis_cache_generation_duration_seconds,
+          'Duration of Redis cache generation',
+          labels,
+          DEFAULT_BUCKETS
+        )
+      end
+
+      def labels
+        @labels ||= {
+          caller_id: caller_id,
+          cache_identifier: cache_identifier,
+          feature_category: feature_category,
+          backing_resource: backing_resource
+        }
+      end
+
+      def fetch_backing_resource!(resource)
+        return resource if VALID_BACKING_RESOURCES.include?(resource)
+
+        raise "Unknown backing resource: #{resource}" if Gitlab.dev_or_test_env?
+
+        DEFAULT_BACKING_RESOURCE
+      end
+    end
+  end
+end