Disable clearCache, while memcached server does not support isolation of databases

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@29063 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/CachePlugins/DistributedRamCache.py

@@ -175,9 +175,12 @@ class DistributedRamCache(BaseCache):
     return []
 
   def clearCache(self):
+    """This method is disabled because it clear unique storage shared by other
+    client.
+    Use expiration time instead.
+    """
     BaseCache.clearCache(self)
-    cache_storage = self.getCacheStorage()
-    cache_storage.flush_all()
+    LOG('DistributedRamCache', WARNING, 'not allowed to clear memcache storage')
 
   def clearCacheForScope(self, scope):
     ## memcached doesn't support namespaces (cache scopes) neither getting cached key list.