[PATCH] Improve attributes_with_quotes method performance by doing less calls to AR::Base::connection

I'm a bit confused by this patch. For example:

       def attributes_with_quotes(include_primary_key = true, include_readonly_attributes = true)
         quoted = {}
+        connection = self.class.connection
         @attributes.each_pair do |name, value|
           if column = column_for_attribute(name)
-            quoted[name] = quote_value(read_attribute(name), column) unless !include_primary_key && column.primary
+            quoted[name] = connection.quote(read_attribute(name), column) unless !include_primary_key && column.primary
           end
         end

Your changes effectively take out the refactored 'quote_value' and replace it with a call to an instance variable with your connection. Wouldn't it just be wiser to cache the connection in 'quote_value'?

Perhaps something more like:

def quote_value(value, column = nil) #:nodoc:
  @quote_value_connection ||= connection.quote(value,column)
end

Oops! I buggered my suggestion. This instead:

def quote_value(value, column = nil) #:nodoc:
  @quote_value_connection ||= connection
  @quote_value_connection.quote(value,column)
end

connection is already cached in AR::Base no?

Yes, it is cached already in @@active_connections class var. But to get it with AR::Base.class#connection, we need extra 2 method calls (one for #connection itself and another for #active_connections). Method calls are not cheap in Ruby (10000 calls cost ~2.7ms on my machine) and if the AR model has many attributes and Rails app is calling #create or #save in a loop, we get significant slowdown just because of those 2 method calls.

(In [8871]) Avoid repeated calls to Base#connection. Closes #11111 [adymo]