diff --git a/common/utils/ordered_weakvalue_dict.py b/common/utils/ordered_weakvalue_dict.py
new file mode 100644
index 0000000..0c63f67
--- /dev/null
+++ b/common/utils/ordered_weakvalue_dict.py
@@ -0,0 +1,48 @@
+#
+# Copyright 2016 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from _weakref import ref
+from weakref import KeyedRef
+from collections import OrderedDict
+
+
+class OrderedWeakValueDict(OrderedDict):
+    """
+    Modified OrderedDict to use weak references as values. Entries disappear
+    automatically if the referred value has no more strong reference pointing
+    ot it.
+
+    Warning, this is not a complete implementation, only what is needed for
+    now. See test_ordered_wealvalue_dict.py to see what is tested behavior.
+    """
+    def __init__(self, *args, **kw):
+        def remove(wr, selfref=ref(self)):
+            self = selfref()
+            if self is not None:
+                super(OrderedWeakValueDict, self).__delitem__(wr.key)
+        self._remove = remove
+        super(OrderedWeakValueDict, self).__init__(*args, **kw)
+
+    def __setitem__(self, key, value):
+        super(OrderedWeakValueDict, self).__setitem__(
+            key, KeyedRef(value, self._remove, key))
+
+    def __getitem__(self, key):
+        o = super(OrderedWeakValueDict, self).__getitem__(key)()
+        if o is None:
+            raise KeyError, key
+        else:
+            return o
+