Improve model attribute accessor method names for backtraces

Ruby uses the original method name, so will show the __temp__ method
name in the backtrace. However, in the common case the method name
is compatible with the `def` keyword, so we can avoid the __temp__
method name in that case to improve the name shown in backtraces
or TracePoint#method_id.

3 files changed, 21 insertions, 53 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index 221ebea8ea..3c785180e1 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -22,15 +22,6 @@ module ActiveRecord
       delegate :column_for_attribute, to: :class
     end
 
-    AttrNames = Module.new {
-      def self.set_name_cache(name, value)
-        const_name = "ATTR_#{name}"
-        unless const_defined? const_name
-          const_set const_name, -value
-        end
-      end
-    }
-
     RESTRICTED_CLASS_METHODS = %w(private public protected allocate new name parent superclass)
 
     class GeneratedAttributeMethods < Module #:nodoc:
diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
index 903fe86e04..ff0e863529 100644
--- a/activerecord/lib/active_record/attribute_methods/read.rb
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -8,42 +8,19 @@ module ActiveRecord
       module ClassMethods # :nodoc:
         private
 
-          # 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 in read_attribute.
           def define_method_attribute(name)
-            safe_name = name.unpack1("h*")
-            temp_method = "__temp__#{safe_name}"
-
-            ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
             sync_with_transaction_state = "sync_with_transaction_state" if name == primary_key
 
-            generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1
-              def #{temp_method}
-                #{sync_with_transaction_state}
-                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
+            ActiveModel::AttributeMethods::AttrNames.define_attribute_accessor_method(
+              generated_attribute_methods, name
+            ) do |temp_method_name, attr_name_expr|
+              generated_attribute_methods.module_eval <<-RUBY, __FILE__, __LINE__ + 1
+                def #{temp_method_name}
+                  #{sync_with_transaction_state}
+                  name = #{attr_name_expr}
+                  _read_attribute(name) { |n| missing_attribute(n, caller) }
+                end
+              RUBY
             end
           end
       end
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index 62743bc9d8..7f246eed46 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -13,19 +13,19 @@ module ActiveRecord
         private
 
           def define_method_attribute=(name)
-            safe_name = name.unpack1("h*")
-            ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
             sync_with_transaction_state = "sync_with_transaction_state" if name == primary_key
 
-            generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1
-              def __temp__#{safe_name}=(value)
-                name = ::ActiveRecord::AttributeMethods::AttrNames::ATTR_#{safe_name}
-                #{sync_with_transaction_state}
-                _write_attribute(name, value)
-              end
-              alias_method #{(name + '=').inspect}, :__temp__#{safe_name}=
-              undef_method :__temp__#{safe_name}=
-            STR
+            ActiveModel::AttributeMethods::AttrNames.define_attribute_accessor_method(
+              generated_attribute_methods, name, writer: true,
+            ) do |temp_method_name, attr_name_expr|
+              generated_attribute_methods.module_eval <<-RUBY, __FILE__, __LINE__ + 1
+                def #{temp_method_name}(value)
+                  name = #{attr_name_expr}
+                  #{sync_with_transaction_state}
+                  _write_attribute(name, value)
+                end
+              RUBY
+            end
           end
       end