Provide a way to update MQ cache without changing entry level.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2491 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/client/mq.py

@@ -341,6 +341,15 @@ class MQ(object):
 
     __delitem__ = invalidate
 
+    def update(self, key, callback):
+        """
+        Update entry without changing its level.
+        """
+        data = self._data[key]
+        if data.level < 0:
+            raise KeyError(key)
+        data.value = callback(data.value)
+
 # Here is a test.
 if __name__ == '__main__':
     import hotshot, hotshot.stats