From 9b967776a2cf95d9b0767f3c966bf15f6156b278 Mon Sep 17 00:00:00 2001
From: Ryan Bates <ryan@railscasts.com>
Date: Mon, 11 Aug 2008 08:22:28 -0700
Subject: [PATCH] dup in MemoryStore so future changes don't taint cache

---
 .../lib/active_support/cache/memory_store.rb       |   11 +++++++++--
 activesupport/test/caching_test.rb                 |   17 +++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/activesupport/lib/active_support/cache/memory_store.rb b/activesupport/lib/active_support/cache/memory_store.rb
index a44f877..b2a31af 100644
--- a/activesupport/lib/active_support/cache/memory_store.rb
+++ b/activesupport/lib/active_support/cache/memory_store.rb
@@ -14,12 +14,12 @@ module ActiveSupport
 
       def read(name, options = nil)
         super
-        @data[name]
+        dup_value(@data[name])
       end
 
       def write(name, value, options = nil)
         super
-        @data[name] = value
+        @data[name] = dup_value(value)
       end
 
       def delete(name, options = nil)
@@ -49,6 +49,13 @@ module ActiveSupport
       def clear
         @data.clear
       end
+      
+      protected
+        def dup_value(value)
+          value.dup
+        rescue TypeError
+          value
+        end
     end
   end
 end
diff --git a/activesupport/test/caching_test.rb b/activesupport/test/caching_test.rb
index f3220d2..2b897fc 100644
--- a/activesupport/test/caching_test.rb
+++ b/activesupport/test/caching_test.rb
@@ -70,3 +70,20 @@ uses_mocha 'high-level cache store tests' do
     end
   end
 end
+
+class MemoryStoreTest < Test::Unit::TestCase
+  def setup
+    @cache = ActiveSupport::Cache.lookup_store(:memory_store)
+  end
+  
+  def test_should_not_change_state_after_cache
+    hash = {:a => 1}
+    @cache.write('foo', hash)
+    hash[:a] = 2
+    assert_equal 1, @cache.read('foo')[:a]
+  end
+  
+  def test_should_return_nil_for_non_existing_key
+    assert_equal nil, @cache.read('doesntexist')
+  end
+end
-- 
1.5.6.4