345 lines
11 KiB
Ruby
345 lines
11 KiB
Ruby
# frozen_string_literal: true
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require 'flipper/adapters/active_record'
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require 'flipper/adapters/active_support_cache_store'
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class Feature
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# Classes to override flipper table names
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class FlipperFeature < Flipper::Adapters::ActiveRecord::Feature
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include DatabaseReflection
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# Using `self.table_name` won't work. ActiveRecord bug?
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superclass.table_name = 'features'
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def self.feature_names
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pluck(:key)
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end
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end
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class FlipperGate < Flipper::Adapters::ActiveRecord::Gate
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superclass.table_name = 'feature_gates'
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end
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# To enable EE overrides
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class ActiveSupportCacheStoreAdapter < Flipper::Adapters::ActiveSupportCacheStore
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end
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InvalidFeatureFlagError = Class.new(Exception) # rubocop:disable Lint/InheritException
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class << self
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delegate :group, to: :flipper
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def feature_flags_available?
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# When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
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active_db_connection = ActiveRecord::Base.connection.active? rescue false # rubocop:disable Database/MultipleDatabases
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active_db_connection && Feature::FlipperFeature.table_exists?
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rescue ActiveRecord::NoDatabaseError
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false
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end
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def all
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flipper.features.to_a
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end
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RecursionError = Class.new(RuntimeError)
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def get(key)
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with_feature(key, &:itself)
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end
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def persisted_names
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return [] unless ApplicationRecord.database.exists?
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# This loads names of all stored feature flags
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# and returns a stable Set in the following order:
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# - Memoized: using Gitlab::SafeRequestStore or @flipper
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# - L1: using Process cache
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# - L2: using Redis cache
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# - DB: using a single SQL query
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flipper.adapter.features
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end
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def persisted_name?(feature_name)
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# Flipper creates on-memory features when asked for a not-yet-created one.
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# If we want to check if a feature has been actually set, we look for it
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# on the persisted features list.
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persisted_names.include?(feature_name.to_s)
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end
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# The default state of feature flag is read from `YAML`:
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# 1. If feature flag does not have YAML it will fallback to `default_enabled: false`
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# in production environment, but raise exception in development or tests.
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# 2. The `default_enabled_if_undefined:` is tech debt related to Gitaly flags
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# and should not be used outside of Gitaly's `lib/feature/gitaly.rb`
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def enabled?(key, thing = nil, type: :development, default_enabled_if_undefined: nil)
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if check_feature_flags_definition?
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if thing && !thing.respond_to?(:flipper_id)
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raise InvalidFeatureFlagError,
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"The thing '#{thing.class.name}' for feature flag '#{key}' needs to include `FeatureGate` or implement `flipper_id`"
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end
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Feature::Definition.valid_usage!(key, type: type)
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end
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default_enabled = Feature::Definition.default_enabled?(key, default_enabled_if_undefined: default_enabled_if_undefined)
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feature_value = with_feature(key) do |feature|
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feature_value = current_feature_value(feature, thing, default_enabled: default_enabled)
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end
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# If not yielded, then either recursion is happening, or the database does not exist yet, so use default_enabled.
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feature_value = default_enabled if feature_value.nil?
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# If we don't filter out this flag here we will enter an infinite loop
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log_feature_flag_state(key, feature_value) if log_feature_flag_states?(key)
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feature_value
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end
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def disabled?(key, thing = nil, type: :development, default_enabled_if_undefined: nil)
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# we need to make different method calls to make it easy to mock / define expectations in test mode
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thing.nil? ? !enabled?(key, type: type, default_enabled_if_undefined: default_enabled_if_undefined) : !enabled?(key, thing, type: type, default_enabled_if_undefined: default_enabled_if_undefined)
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end
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def enable(key, thing = true)
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log(key: key, action: __method__, thing: thing)
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with_feature(key) { _1.enable(thing) }
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end
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def disable(key, thing = false)
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log(key: key, action: __method__, thing: thing)
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with_feature(key) { _1.disable(thing) }
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end
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def enable_percentage_of_time(key, percentage)
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log(key: key, action: __method__, percentage: percentage)
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with_feature(key) { _1.enable_percentage_of_time(percentage) }
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end
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def disable_percentage_of_time(key)
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log(key: key, action: __method__)
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with_feature(key, &:disable_percentage_of_time)
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end
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def enable_percentage_of_actors(key, percentage)
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log(key: key, action: __method__, percentage: percentage)
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with_feature(key) { _1.enable_percentage_of_actors(percentage) }
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end
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def disable_percentage_of_actors(key)
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log(key: key, action: __method__)
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with_feature(key, &:disable_percentage_of_actors)
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end
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def remove(key)
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return unless persisted_name?(key)
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log(key: key, action: __method__)
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with_feature(key, &:remove)
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end
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def reset
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Gitlab::SafeRequestStore.delete(:flipper) if Gitlab::SafeRequestStore.active?
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@flipper = nil
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end
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# This method is called from config/initializers/flipper.rb and can be used
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# to register Flipper groups.
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# See https://docs.gitlab.com/ee/development/feature_flags/index.html
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def register_feature_groups
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end
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def register_definitions
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Feature::Definition.reload!
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end
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def register_hot_reloader
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return unless check_feature_flags_definition?
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Feature::Definition.register_hot_reloader!
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end
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def logger
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@logger ||= Feature::Logger.build
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end
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def log_feature_flag_states?(key)
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Feature::Definition.log_states?(key)
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end
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def log_feature_flag_state(key, feature_value)
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logged_states[key] ||= feature_value
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end
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def logged_states
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RequestStore.fetch(:feature_flag_events) { {} }
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end
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private
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# Evaluate if `default enabled: false` or the feature has been persisted.
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# `persisted_name?` can potentially generate DB queries and also checks for inclusion
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# in an array of feature names (177 at last count), possibly reducing performance by half.
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# So we only perform the `persisted` check if `default_enabled: true`
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def current_feature_value(feature, thing, default_enabled:)
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return true if default_enabled && !Feature.persisted_name?(feature.name)
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feature.enabled?(thing)
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end
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# NOTE: it is not safe to call `Flipper::Feature#enabled?` outside the block
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def with_feature(key)
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feature = unsafe_get(key)
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yield feature if feature.present?
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ensure
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pop_recursion_stack
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end
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def unsafe_get(key)
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# During setup the database does not exist yet. So we haven't stored a value
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# for the feature yet and return the default.
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return unless ApplicationRecord.database.exists?
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flag_stack = ::Thread.current[:feature_flag_recursion_check] || []
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Thread.current[:feature_flag_recursion_check] = flag_stack
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# Prevent more than 10 levels of recursion. This limit was chosen as a fairly
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# low limit while allowing some nesting of flag evaluation. We have not seen
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# this limit hit in production.
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if flag_stack.size > 10
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Gitlab::ErrorTracking.track_exception(RecursionError.new('deep recursion'), stack: flag_stack)
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return
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elsif flag_stack.include?(key)
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Gitlab::ErrorTracking.track_exception(RecursionError.new('self recursion'), stack: flag_stack)
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return
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end
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flag_stack.push(key)
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flipper.feature(key)
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end
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def pop_recursion_stack
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flag_stack = Thread.current[:feature_flag_recursion_check]
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flag_stack.pop if flag_stack
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end
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def flipper
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if Gitlab::SafeRequestStore.active?
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Gitlab::SafeRequestStore[:flipper] ||= build_flipper_instance(memoize: true)
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else
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@flipper ||= build_flipper_instance
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end
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end
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def build_flipper_instance(memoize: false)
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active_record_adapter = Flipper::Adapters::ActiveRecord.new(
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feature_class: FlipperFeature,
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gate_class: FlipperGate)
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# Redis L2 cache
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redis_cache_adapter =
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ActiveSupportCacheStoreAdapter.new(
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active_record_adapter,
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l2_cache_backend,
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expires_in: 1.hour,
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write_through: true)
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# Thread-local L1 cache: use a short timeout since we don't have a
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# way to expire this cache all at once
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flipper_adapter = Flipper::Adapters::ActiveSupportCacheStore.new(
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redis_cache_adapter,
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l1_cache_backend,
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expires_in: 1.minute)
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Flipper.new(flipper_adapter).tap do |flip|
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flip.memoize = memoize
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end
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end
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def check_feature_flags_definition?
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# We want to check feature flags usage only when
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# running in development or test environment
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Gitlab.dev_or_test_env?
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end
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def l1_cache_backend
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Gitlab::ProcessMemoryCache.cache_backend
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end
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def l2_cache_backend
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Rails.cache
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end
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def log(key:, action:, **extra)
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extra ||= {}
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extra = extra.transform_keys { |k| "extra.#{k}" }
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extra = extra.transform_values { |v| v.respond_to?(:flipper_id) ? v.flipper_id : v }
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extra = extra.transform_values(&:to_s)
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logger.info(key: key, action: action, **extra)
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end
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end
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class Target
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UnknowTargetError = Class.new(StandardError)
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attr_reader :params
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def initialize(params)
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@params = params
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end
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def gate_specified?
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%i(user project group feature_group namespace).any? { |key| params.key?(key) }
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end
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def targets
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[feature_group, users, projects, groups, namespaces].flatten.compact
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end
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private
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# rubocop: disable CodeReuse/ActiveRecord
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def feature_group
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return unless params.key?(:feature_group)
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Feature.group(params[:feature_group])
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end
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# rubocop: enable CodeReuse/ActiveRecord
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def users
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return unless params.key?(:user)
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params[:user].split(',').map do |arg|
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UserFinder.new(arg).find_by_username || (raise UnknowTargetError, "#{arg} is not found!")
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end
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end
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def projects
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return unless params.key?(:project)
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params[:project].split(',').map do |arg|
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Project.find_by_full_path(arg) || (raise UnknowTargetError, "#{arg} is not found!")
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end
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end
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def groups
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return unless params.key?(:group)
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params[:group].split(',').map do |arg|
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Group.find_by_full_path(arg) || (raise UnknowTargetError, "#{arg} is not found!")
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end
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end
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def namespaces
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return unless params.key?(:namespace)
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params[:namespace].split(',').map do |arg|
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# We are interested in Group or UserNamespace
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Namespace.without_project_namespaces.find_by_full_path(arg) || (raise UnknowTargetError, "#{arg} is not found!")
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end
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end
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end
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end
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Feature::ActiveSupportCacheStoreAdapter.prepend_mod_with('Feature::ActiveSupportCacheStoreAdapter')
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