Replace MemoryStore mutex with a monitor to avoid issues with nested calls

activesupport/lib/active_support/cache/memory_store.rb

@@ -3,52 +3,64 @@ module ActiveSupport
     class MemoryStore < Store
       def initialize
         @data = {}
-        @mutex = Mutex.new
+        @guard = Monitor.new
       end
 
       def fetch(key, options = {})
-        @mutex.synchronize do
+        @guard.synchronize do
           super
         end
       end
 
       def read(name, options = nil)
+        @guard.synchronize do
           super
           @data[name]
         end
+      end
 
       def write(name, value, options = nil)
+        @guard.synchronize do
           super
           @data[name] = value
         end
+      end
 
       def delete(name, options = nil)
+        @guard.synchronize do
           @data.delete(name)
         end
+      end
 
       def delete_matched(matcher, options = nil)
+        @guard.synchronize do
           @data.delete_if { |k,v| k =~ matcher }
         end
+      end
 
       def exist?(name,options = nil)
+        @guard.synchronize do
           @data.has_key?(name)
         end
+      end
 
       def increment(key, amount = 1)
-        @mutex.synchronize do
+        @guard.synchronize do
           super
         end
       end
 
       def decrement(key, amount = 1)
-        @mutex.synchronize do
+        @guard.synchronize do
           super
         end
       end
 
       def clear
+        @guard.synchronize do
           @data.clear
         end
       end
     end
+  end
 end

activesupport/test/caching_test.rb

@@ -97,3 +97,27 @@ class FileStoreTest < Test::Unit::TestCase
     File.delete("foo.cache")
   end
 end
+
+class MemoryStoreTest < Test::Unit::TestCase
+  def setup
+    @cache = ActiveSupport::Cache.lookup_store(:memory_store)
+  end
+
+  def test_should_read_and_write
+    @cache.write('foo', 'bar')
+    assert_equal 'bar', @cache.read('foo')
+  end
+
+  def test_fetch_without_cache_miss
+    @cache.write('foo', 'bar')
+    assert_equal 'bar', @cache.fetch('foo') { 'baz' }
+  end
+
+  def test_fetch_with_cache_miss
+    assert_equal 'baz', @cache.fetch('foo') { 'baz' }
+  end
+
+  def test_fetch_with_forced_cache_miss
+    @cache.fetch('foo', :force => true) { 'bar' }
+  end
+end