Decrease string allocations in apply_inflections

In `apply_inflections` a string is down cased and some whitespace stripped in the front (which allocate strings). This would normally be fine, however `uncountables` is a fairly small array (10 elements out of the box) and this method gets called a TON. Instead we can keep an array of valid regexes for each uncountable so we don't have to allocate new strings.

This change buys us 325,106 bytes of memory and 3,251 fewer objects per request.

2 files changed, 36 insertions, 5 deletions

diff --git a/activesupport/lib/active_support/inflector/inflections.rb b/activesupport/lib/active_support/inflector/inflections.rb
index 486838bd15..8ac1820776 100644
--- a/activesupport/lib/active_support/inflector/inflections.rb
+++ b/activesupport/lib/active_support/inflector/inflections.rb
@@ -27,6 +27,37 @@ module ActiveSupport
     class Inflections
       @__instance__ = ThreadSafe::Cache.new
 
+      class Uncountables < Array
+        def initialize
+          @regex_array = []
+          super
+        end
+
+        def delete(entry)
+          super entry
+          @regex_array.delete(to_regex(entry))
+        end
+
+        def <<(*word)
+          add(word)
+        end
+
+        def add(words)
+          self.concat(words.flatten.map(&:downcase))
+          @regex_array += self.map {|word|  to_regex(word) }
+          self
+        end
+
+        def uncountable?(str)
+          @regex_array.detect {|regex| regex.match(str) }
+        end
+
+        private
+          def to_regex(string)
+            /\b#{::Regexp.escape(string)}\Z/i
+          end
+      end
+
       def self.instance(locale = :en)
         @__instance__[locale] ||= new
       end
@@ -34,7 +65,7 @@ module ActiveSupport
       attr_reader :plurals, :singulars, :uncountables, :humans, :acronyms, :acronym_regex
 
       def initialize
-        @plurals, @singulars, @uncountables, @humans, @acronyms, @acronym_regex = [], [], [], [], {}, /(?=a)b/
+        @plurals, @singulars, @uncountables, @humans, @acronyms, @acronym_regex = [], [], Uncountables.new, [], {}, /(?=a)b/
       end
 
       # Private, for the test suite.
@@ -160,7 +191,7 @@ module ActiveSupport
       #   uncountable 'money', 'information'
       #   uncountable %w( money information rice )
       def uncountable(*words)
-        @uncountables += words.flatten.map(&:downcase)
+        @uncountables.add(words)
       end
 
       # Specifies a humanized form of a string by a regular expression rule or
@@ -185,7 +216,7 @@ module ActiveSupport
       def clear(scope = :all)
         case scope
           when :all
-            @plurals, @singulars, @uncountables, @humans = [], [], [], []
+            @plurals, @singulars, @uncountables, @humans = [], [], Uncountables.new, []
           else
             instance_variable_set "@#{scope}", []
         end
diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index 60ef249e37..899ba70af6 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -354,7 +354,7 @@ module ActiveSupport
     #   const_regexp("Foo::Bar::Baz") # => "Foo(::Bar(::Baz)?)?"
     #   const_regexp("::")            # => "::"
     def const_regexp(camel_cased_word) #:nodoc:
-      parts = camel_cased_word.split("::")
+      parts = camel_cased_word.split("::".freeze)
 
       return Regexp.escape(camel_cased_word) if parts.blank?
 
@@ -372,7 +372,7 @@ module ActiveSupport
     def apply_inflections(word, rules)
       result = word.to_s.dup
 
-      if word.empty? || inflections.uncountables.include?(result.downcase[/\b\w+\Z/])
+      if word.empty? || inflections.uncountables.uncountable?(result)
         result
       else
         rules.each { |(rule, replacement)| break if result.sub!(rule, replacement) }