Allow benchmarking of ThreadLocalVar

Author: pitr-ch

lib/concurrent/atomic/thread_local_var.rb

@@ -73,18 +73,10 @@ def set(value)
 
   end
 
-  class ThreadLocalVar
+  class AbstractThreadLocalVar
 
     NIL_SENTINEL = Object.new
 
-    if RUBY_PLATFORM == 'java'
-      include ThreadLocalJavaStorage
-    elsif Thread.current.respond_to?(:thread_variable_set)
-      include ThreadLocalNewStorage
-    else
-      include ThreadLocalOldStorage
-    end
-
     def initialize(default = nil)
       @default = default
       allocate_storage
@@ -116,4 +108,14 @@ def value=(value)
 
   end
 
+  class ThreadLocalVar < AbstractThreadLocalVar
+    if RUBY_PLATFORM == 'java'
+      include ThreadLocalJavaStorage
+    elsif Thread.current.respond_to?(:thread_variable_set)
+      include ThreadLocalNewStorage
+    else
+      include ThreadLocalOldStorage
+    end
+  end
+
 end