Replace some global Hash usages with the new thread safe cache.

Summary of the changes:
 * Add thread_safe gem.
 * Use thread safe cache for digestor caching.
 * Replace manual synchronization with ThreadSafe::Cache in Relation::Delegation.
 * Replace @attribute_method_matchers_cache Hash with ThreadSafe::Cache.
 * Use TS::Cache to avoid the synchronisation overhead on listener retrieval.
 * Replace synchronisation with TS::Cache usage.
 * Use a preallocated array for performance/memory reasons.
 * Update the controllers cache to the new AS::Dependencies::ClassCache API.
   The original @controllers cache no longer makes much sense after @tenderlove's
   changes in 7b6bfe84f3 and f345e2380c.
 * Use TS::Cache in the connection pool to avoid locking overhead.
 * Use TS::Cache in ConnectionHandler.

1 files changed, 2 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/dependencies.rb b/activesupport/lib/active_support/dependencies.rb
index efd351d741..fff4c776a9 100644
--- a/activesupport/lib/active_support/dependencies.rb
+++ b/activesupport/lib/active_support/dependencies.rb
@@ -1,5 +1,6 @@
 require 'set'
 require 'thread'
+require 'thread_safe'
 require 'pathname'
 require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/module/attribute_accessors'
@@ -517,7 +518,7 @@ module ActiveSupport #:nodoc:
 
     class ClassCache
       def initialize
-        @store = Hash.new
+        @store = ThreadSafe::Cache.new
       end
 
       def empty?