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keep a cache of the reader methods so we can reuse them

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commit a2b847ae49e6a31bbfac8c9843cd0367b85d88db 1 parent 501b27e
@tenderlove tenderlove authored
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48 activerecord/lib/active_record/attribute_methods.rb
@@ -28,6 +28,54 @@ def self.set_name_cache(name, value)
end
}
+ ReaderMethodCache = Class.new {
+ include Mutex_m
+
+ def initialize
+ super
+ @module = Module.new
+ @method_cache = {}
+ end
+
+ # We want to generate the methods via module_eval rather than
+ # 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
+ # 'my_column(omg)'. So to work around this we first define with
+ # the __temp__ identifier, and then use alias method to rename
+ # it to what we want.
+ #
+ # We are also defining a constant to hold the frozen string of
+ # 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 [](name)
+ synchronize do
+ @method_cache.fetch(name) {
+ safe_name = name.unpack('h*').first
+ temp_method = "__temp__#{safe_name}"
+
+ ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
+
+ @module.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
+
+ @method_cache[name] = @module.instance_method temp_method
+ }
+ end
+ end
+ }.new
+
module ClassMethods
def inherited(child_class) #:nodoc:
child_class.initialize_generated_modules
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36 activerecord/lib/active_record/attribute_methods/read.rb
@@ -32,41 +32,9 @@ def cache_attribute?(attr_name)
protected
- # We want to generate the methods via module_eval rather than
- # 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
- # 'my_column(omg)'. So to work around this we first define with
- # the __temp__ identifier, and then use alias method to rename
- # it to what we want.
- #
- # We are also defining a constant to hold the frozen string of
- # 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
- 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
+ method = ActiveRecord::AttributeMethods::ReaderMethodCache[name]
+ generated_attribute_methods.module_eval { define_method name, method }
end
private
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