diff options
Diffstat (limited to 'activerecord/lib/active_record/attribute_methods/read.rb')
-rw-r--r-- | activerecord/lib/active_record/attribute_methods/read.rb | 140 |
1 files changed, 68 insertions, 72 deletions
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb index 3c03cce838..20f0936e52 100644 --- a/activerecord/lib/active_record/attribute_methods/read.rb +++ b/activerecord/lib/active_record/attribute_methods/read.rb @@ -1,40 +1,16 @@ +require 'active_support/core_ext/module/method_transplanting' + module ActiveRecord module AttributeMethods module Read - extend ActiveSupport::Concern - - ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date] - - included do - class_attribute :attribute_types_cached_by_default, instance_writer: false - self.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT - end - - module ClassMethods - # +cache_attributes+ allows you to declare which converted attribute - # values should be cached. Usually caching only pays off for attributes - # with expensive conversion methods, like time related columns (e.g. - # +created_at+, +updated_at+). - def cache_attributes(*attribute_names) - cached_attributes.merge attribute_names.map { |attr| attr.to_s } - end - - # Returns the attributes which are cached. By default time related columns - # with datatype <tt>:datetime, :timestamp, :time, :date</tt> are cached. - def cached_attributes - @cached_attributes ||= columns.select { |c| cacheable_column?(c) }.map { |col| col.name }.to_set - end - - # Returns +true+ if the provided attribute is being cached. - def cache_attribute?(attr_name) - cached_attributes.include?(attr_name) - end - - protected - + ReaderMethodCache = Class.new(AttributeMethodCache) { + private # We want to generate the methods via module_eval rather than - # define_method, because define_method is slower on dispatch and - # uses more memory (because it creates a closure). + # define_method, because define_method is slower on dispatch. + # Evaluating many similar methods may use more memory as the instruction + # sequences are duplicated and cached (in MRI). define_method may + # be slower on dispatch, but if you're careful about the closure + # created, then define_method will consume much less memory. # # But sometimes the database might return columns with # characters that are not allowed in normal method names (like @@ -46,61 +22,81 @@ module ActiveRecord # the attribute name. Using a constant means that we do not have # to allocate an object on each call to the attribute method. # Making it frozen means that it doesn't get duped when used to - # key the @attributes_cache in read_attribute. - def define_method_attribute(name) - safe_name = name.unpack('h*').first - generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1 - def __temp__#{safe_name} - read_attribute(AttrNames::ATTR_#{safe_name}) { |n| missing_attribute(n, caller) } - end - alias_method #{name.inspect}, :__temp__#{safe_name} - undef_method :__temp__#{safe_name} - STR + # key the @attributes in read_attribute. + def method_body(method_name, const_name) + <<-EOMETHOD + def #{method_name} + name = ::ActiveRecord::AttributeMethods::AttrNames::ATTR_#{const_name} + _read_attribute(name) { |n| missing_attribute(n, caller) } + end + EOMETHOD end + }.new - private + extend ActiveSupport::Concern - def cacheable_column?(column) - if attribute_types_cached_by_default == ATTRIBUTE_TYPES_CACHED_BY_DEFAULT - ! serialized_attributes.include? column.name - else - attribute_types_cached_by_default.include?(column.type) + module ClassMethods + [:cache_attributes, :cached_attributes, :cache_attribute?].each do |method_name| + define_method method_name do |*| + cached_attributes_deprecation_warning(method_name) + true + end + end + + protected + + def cached_attributes_deprecation_warning(method_name) + ActiveSupport::Deprecation.warn "Calling `#{method_name}` is no longer necessary. All attributes are cached." + end + + if Module.methods_transplantable? + def define_method_attribute(name) + method = ReaderMethodCache[name] + generated_attribute_methods.module_eval { define_method name, method } + end + else + def define_method_attribute(name) + safe_name = name.unpack('h*').first + temp_method = "__temp__#{safe_name}" + + ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name + + generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1 + def #{temp_method} + name = ::ActiveRecord::AttributeMethods::AttrNames::ATTR_#{safe_name} + _read_attribute(name) { |n| missing_attribute(n, caller) } + end + STR + + generated_attribute_methods.module_eval do + alias_method name, temp_method + undef_method temp_method + end end end end + ID = 'id'.freeze + # Returns the value of the attribute identified by <tt>attr_name</tt> after - # it has been typecast (for example, "2004-12-12" in a data column is cast + # it has been typecast (for example, "2004-12-12" in a date column is cast # to a date object, like Date.new(2004, 12, 12)). - def read_attribute(attr_name) - # If it's cached, just return it - # We use #[] first as a perf optimization for non-nil values. See https://gist.github.com/3552829. + def read_attribute(attr_name, &block) name = attr_name.to_s - @attributes_cache[name] || @attributes_cache.fetch(name) { - column = @columns_hash.fetch(name) { - return @attributes.fetch(name) { - if name == 'id' && self.class.primary_key != name - read_attribute(self.class.primary_key) - end - } - } - - value = @attributes.fetch(name) { - return block_given? ? yield(name) : nil - } + name = self.class.primary_key if name == ID + _read_attribute(name, &block) + end - if self.class.cache_attribute?(name) - @attributes_cache[name] = column.type_cast(value) - else - column.type_cast value - end - } + # This method exists to avoid the expensive primary_key check internally, without + # breaking compatibility with the read_attribute API + def _read_attribute(attr_name) # :nodoc: + @attributes.fetch_value(attr_name.to_s) { |n| yield n if block_given? } end private def attribute(attribute_name) - read_attribute(attribute_name) + _read_attribute(attribute_name) end end end |