diff options
Diffstat (limited to 'gems/gitlab-utils/lib/gitlab/utils/strong_memoize.rb')
| -rw-r--r-- | gems/gitlab-utils/lib/gitlab/utils/strong_memoize.rb | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/gems/gitlab-utils/lib/gitlab/utils/strong_memoize.rb b/gems/gitlab-utils/lib/gitlab/utils/strong_memoize.rb new file mode 100644 index 00000000000..2b3841b8f09 --- /dev/null +++ b/gems/gitlab-utils/lib/gitlab/utils/strong_memoize.rb @@ -0,0 +1,147 @@ +# frozen_string_literal: true + +module Gitlab + module Utils + module StrongMemoize + # Instead of writing patterns like this: + # + # def trigger_from_token + # return @trigger if defined?(@trigger) + # + # @trigger = Ci::Trigger.find_by_token(params[:token].to_s) + # end + # + # We could write it like: + # + # include Gitlab::Utils::StrongMemoize + # + # def trigger_from_token + # Ci::Trigger.find_by_token(params[:token].to_s) + # end + # strong_memoize_attr :trigger_from_token + # + # def enabled? + # Feature.enabled?(:some_feature) + # end + # strong_memoize_attr :enabled? + # + def strong_memoize(name) + key = ivar(name) + + if instance_variable_defined?(key) + instance_variable_get(key) + else + instance_variable_set(key, yield) + end + end + + # Works the same way as "strong_memoize" but takes + # a second argument - expire_in. This allows invalidate + # the data after specified number of seconds + def strong_memoize_with_expiration(name, expire_in) + key = ivar(name) + expiration_key = "#{key}_expired_at" + + if instance_variable_defined?(expiration_key) + expire_at = instance_variable_get(expiration_key) + clear_memoization(name) if Time.current > expire_at + end + + if instance_variable_defined?(key) + instance_variable_get(key) + else + value = instance_variable_set(key, yield) + instance_variable_set(expiration_key, Time.current + expire_in) + value + end + end + + def strong_memoize_with(name, *args) + container = strong_memoize(name) { {} } + + if container.key?(args) + container[args] + else + container[args] = yield + end + end + + def strong_memoized?(name) + key = ivar(StrongMemoize.normalize_key(name)) + instance_variable_defined?(key) + end + + def clear_memoization(name) + key = ivar(StrongMemoize.normalize_key(name)) + remove_instance_variable(key) if instance_variable_defined?(key) + end + + module StrongMemoizeClassMethods + def strong_memoize_attr(method_name) + member_name = StrongMemoize.normalize_key(method_name) + + StrongMemoize.send(:do_strong_memoize, self, method_name, member_name) # rubocop:disable GitlabSecurity/PublicSend + end + end + + def self.included(base) + base.singleton_class.prepend(StrongMemoizeClassMethods) + end + + private + + # Convert `"name"`/`:name` into `:@name` + # + # Depending on a type ensure that there's a single memory allocation + def ivar(name) + case name + when Symbol + name.to_s.prepend("@").to_sym + when String + :"@#{name}" + else + raise ArgumentError, "Invalid type of '#{name}'" + end + end + + class << self + def normalize_key(key) + return key unless key.end_with?('!', '?') + + # Replace invalid chars like `!` and `?` with allowed Unicode codeparts. + key.to_s.tr('!?', "\uFF01\uFF1F") + end + + private + + def do_strong_memoize(klass, method_name, member_name) + method = klass.instance_method(method_name) + + unless method.arity == 0 + raise <<~ERROR + Using `strong_memoize_attr` on methods with parameters is not supported. + + Use `strong_memoize_with` instead. + See https://docs.gitlab.com/ee/development/utilities.html#strongmemoize + ERROR + end + + # Methods defined within a class method are already public by default, so we don't need to + # explicitly make them public. + scope = %i[private protected].find do |scope| + klass.send("#{scope}_instance_methods") # rubocop:disable GitlabSecurity/PublicSend + .include? method_name + end + + klass.define_method(method_name) do |&block| + strong_memoize(member_name) do + method.bind_call(self, &block) + end + end + + klass.send(scope, method_name) if scope # rubocop:disable GitlabSecurity/PublicSend + end + end + end + end +end |