1 files changed, 74 insertions, 0 deletions
diff --git a/app/models/concerns/cacheable_attributes.rb b/app/models/concerns/cacheable_attributes.rb
new file mode 100644
index 00000000000..d58d7165969
--- /dev/null
+++ b/app/models/concerns/cacheable_attributes.rb
@@ -0,0 +1,74 @@
+module CacheableAttributes
+  extend ActiveSupport::Concern
+
+  included do
+    after_commit { self.class.expire }
+  end
+
+  class_methods do
+    def cache_key
+      "#{name}:#{Gitlab::VERSION}:#{Gitlab.migrations_hash}:#{Rails.version}".freeze
+    end
+
+    # Can be overriden
+    def current_without_cache
+      last
+    end
+
+    # Can be overriden
+    def defaults
+      {}
+    end
+
+    def build_from_defaults(attributes = {})
+      new(defaults.merge(attributes))
+    end
+
+    def cached
+      if RequestStore.active?
+        RequestStore[:"#{name}_cached_attributes"] ||= retrieve_from_cache
+      else
+        retrieve_from_cache
+      end
+    end
+
+    def retrieve_from_cache
+      record = Rails.cache.read(cache_key)
+      ensure_cache_setup if record.present?
+
+      record
+    end
+
+    def current
+      cached_record = cached
+      return cached_record if cached_record.present?
+
+      current_without_cache.tap { |current_record| current_record&.cache! }
+    rescue => e
+      if Rails.env.production?
+        Rails.logger.warn("Cached record for #{name} couldn't be loaded, falling back to uncached record: #{e}")
+      else
+        raise e
+      end
+      # Fall back to an uncached value if there are any problems (e.g. Redis down)
+      current_without_cache
+    end
+
+    def expire
+      Rails.cache.delete(cache_key)
+    rescue
+      # Gracefully handle when Redis is not available. For example,
+      # omnibus may fail here during gitlab:assets:compile.
+    end
+
+    def ensure_cache_setup
+      # This is a workaround for a Rails bug that causes attribute methods not
+      # to be loaded when read from cache: https://github.com/rails/rails/issues/27348
+      define_attribute_methods
+    end
+  end
+
+  def cache!
+    Rails.cache.write(self.class.cache_key, self)
+  end
+end