ERP5Type: Patch AccessControl.owner.Owned.getWrappedOwner .

This method is called on every __getattr__ (guarded_getattr, actually) of
every restricted python scripts. Which means each "." in the code triggers:
- traversal to relevant acl_user folder
- a user lookup
just to get the same value throughout the execution of a script (as its
owner does not change during execution).
Also, in practice we have extremely few possible owners: very few users are
allowed to edit code in an ERP5 instance, and if such instance is managed
using the upgrader alarms, they will even further reduce this owner set to
System Processes only.
On a real-world web page rendering, this reduces the total number of
traversal calls from 1500 to 1100, getting rid of the two hottest spots:
/acl_users and /$site_id/acl_users .

product/ERP5Type/ZopePatch.py

@@ -21,6 +21,7 @@
 ##############################################################################
 
 # Load all monkey patches
+from Products.ERP5Type.patches import AccessControl_patch
 from Products.ERP5Type.patches import Restricted
 from Products.ERP5Type.patches import m2crypto
 from Products.ERP5Type.patches import ObjectManager

product/ERP5Type/patches/AccessControl_patch.py

+##############################################################################
+#
+# Copyright (c) 2002 Zope Foundation and Contributors.
+# Copyright (c) 2018 Nexedi SARL and Contributors. All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+from __future__ import absolute_import
+import AccessControl.owner
+from AccessControl import SpecialUsers as SU
+from Products.ERP5Type.TransactionalVariable import getTransactionalVariable
+
+# Patch description:
+# Original method is called very often: multiple times per restricted python
+# script/expression: once per __getattr__ (restricted getattr, actually) call.
+# Each call pulls self's owner information, traverses to relevant user database
+# and then use it to retrieve user object. These last two operations are
+# expensive, and should produce the same result within a given transaction.
+# So cache the first result for each owner tuple in a transactional cache.
+UnownableOwner = AccessControl.owner.UnownableOwner
+def getWrappedOwner(self):
+    """Get the owner, modestly wrapped in the user folder.
+    o If the object is not owned, return None.
+    o If the owner's user database doesn't exist, return Nobody.
+    o If the owner ID does not exist in the user database, return Nobody.
+    """
+    owner = self.getOwnerTuple()
+    if owner is None or owner is UnownableOwner:
+        return None
+    udb_path, oid = owner
+    cache_key = ('getWrappedOwner', ) + (
+        (tuple(udb_path), oid)
+        if isinstance(udb_path, list) else
+        owner
+    )
+    try:
+        return getTransactionalVariable()[cache_key]
+    except KeyError:
+        pass
+    root = self.getPhysicalRoot()
+    udb = root.unrestrictedTraverse(udb_path, None)
+    if udb is None:
+        result = SU.nobody
+    else:
+        user = udb.getUserById(oid, None)
+        if user is None:
+            result = SU.nobody
+        else:
+            result = user.__of__(udb)
+    getTransactionalVariable()[cache_key] = result
+    return result
+
+AccessControl.owner.Owned.getWrappedOwner = getWrappedOwner