Revert "Key the attributes hash with symbols"

This reverts commit 86c3dfbd47cb96af02daaa655963292b1a1b110e.

Conflicts:
	activerecord/lib/active_record/attribute_methods/read.rb

Reason: whilst this increased performance, it also presents a DoS risk
via memory exhaustion if users were allowing user input to dictate the
arguments of read/write_attribute. I will investigate alternative ways
to cut down on string allocations here.

3 files changed, 8 insertions, 12 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/read.rb b/activerecord/lib/active_record/attribute_methods/read.rb
index 6213b5dcd5..a26c5e0f5b 100644
--- a/activerecord/lib/active_record/attribute_methods/read.rb
+++ b/activerecord/lib/active_record/attribute_methods/read.rb
@@ -46,7 +46,7 @@ module ActiveRecord
         def define_method_attribute(attr_name)
           generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1
             def __temp__
-              read_attribute(:'#{attr_name}') { |n| missing_attribute(n, caller) }
+              read_attribute('#{attr_name}') { |n| missing_attribute(n, caller) }
             end
             alias_method '#{attr_name}', :__temp__
             undef_method :__temp__
@@ -70,17 +70,13 @@ module ActiveRecord
       # it has been typecast (for example, "2004-12-12" in a data column is cast
       # to a date object, like Date.new(2004, 12, 12)).
       def read_attribute(attr_name)
-        return unless attr_name
-        name_sym = attr_name.to_sym
-
         # If it's cached, just return it
         # We use #[] first as a perf optimization for non-nil values. See https://gist.github.com/3552829.
-        @attributes_cache[name_sym] || @attributes_cache.fetch(name_sym) {
-          name = attr_name.to_s
-
+        name = attr_name.to_s
+        @attributes_cache[name] || @attributes_cache.fetch(name) {
           column = @columns_hash.fetch(name) {
             return @attributes.fetch(name) {
-              if name_sym == :id && self.class.primary_key != name
+              if name == 'id' && self.class.primary_key != name
                 read_attribute(self.class.primary_key)
               end
             }
@@ -91,7 +87,7 @@ module ActiveRecord
           }
 
           if self.class.cache_attribute?(name)
-            @attributes_cache[name_sym] = column.type_cast(value)
+            @attributes_cache[name] = column.type_cast(value)
           else
             column.type_cast value
           end
diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
index b9a69cdb0a..f36a5806a9 100644
--- a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -50,7 +50,7 @@ module ActiveRecord
                 if (rounded_value != rounded_time) || (!rounded_value && original_time)
                   write_attribute("#{attr_name}", original_time)
                   #{attr_name}_will_change!
-                  @attributes_cache[:"#{attr_name}"] = zoned_time
+                  @attributes_cache["#{attr_name}"] = zoned_time
                 end
               end
             EOV
diff --git a/activerecord/lib/active_record/attribute_methods/write.rb b/activerecord/lib/active_record/attribute_methods/write.rb
index 6eb9e25fd9..fa9097db1f 100644
--- a/activerecord/lib/active_record/attribute_methods/write.rb
+++ b/activerecord/lib/active_record/attribute_methods/write.rb
@@ -26,13 +26,13 @@ module ActiveRecord
       def write_attribute(attr_name, value)
         attr_name = attr_name.to_s
         attr_name = self.class.primary_key if attr_name == 'id' && self.class.primary_key
-        @attributes_cache.delete(attr_name.to_sym)
+        @attributes_cache.delete(attr_name)
         column = column_for_attribute(attr_name)
 
         # If we're dealing with a binary column, write the data to the cache
         # so we don't attempt to typecast multiple times.
         if column && column.binary?
-          @attributes_cache[attr_name.to_sym] = value
+          @attributes_cache[attr_name] = value
         end
 
         if column || @attributes.has_key?(attr_name)