Re: ZEditingContextSessioning failing to init

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    Hi Paul,

Paul Mylchreest wrote :
> Greetings,
>=20
> In the process of starting my zope server, getting this error:
>=20
> ------
> 2006-03-03T10:29:05 ERROR(200) Products.ZEditingContextSessioning The
> session data container's destruction callback already set --
> installation aborted
> ------

The message you get is a security mechanism.

It notifies you that an other Product (or maybe you) already set the dest=
ruction callback of the sessions data container.
The ZECS (ZEditingContextSessionning) decides not to override it when it =
is already set, because if you (or another Product) already rely on it, s=
ome special action needs to be taken (namely: calling the already registe=
red callback before or after ZECS's one).

Frankly, you're the 1st person reporting such a collision; I suspect that=
 the zeo configuration is the reason.

Could you please tell us which callback is registered: in the ZMI, go to =
/temp_folder/session_data and look at the value entered under the field '=
Script to call when objects are deleted' ?  I appreciate your time --hope=
fully we'll quickly find a fix for the problem.

In the meantime, if you want to try the ZECS despite the problem, just ap=
ply the attached patch: the installation won't be stopped because of that=
 situation.  Be aware, however, that the patch shouldn't be installed in =
a production environment if you're using SESSION.defaultEditingContext: i=
f the deletion hook is not properly installed, then a session's EC will n=
ever be garnaged collected when a session expires, causing the memory foo=
tprint to grow, and grow, and grow!

In a test/dev environment this should not be a problem however.

-- S=E9bastien.


> My config is:
> OSX Tiger
> python 2.3.5
> Zope 2.7.6
> Modeling-0.9
> ZModeling-0.9
>=20
> I have a zeoclient(1)/zeoserver setup and I used
> <http://longsleep.org/howto/sharesessionwithzeo> for configuration of
> the session storage. Also getting the same error with previous version.
>=20
> Any ideas?
>=20
> Paul




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Index: __init__.py
===================================================================
--- __init__.py	(revision 986)
+++ __init__.py	(working copy)
@@ -89,10 +89,12 @@
   app=context._ProductContext__app
   
   sessionDataContainer=app.temp_folder.session_data
+  install_delete_hook=1
   if sessionDataContainer.getDelNotificationTarget():
-    zLOG.LOG('Products.ZEditingContextSessioning', zLOG.ERROR,
-             "The session data container's destruction callback already set -- installation aborted")
-    return
+    zLOG.LOG('Products.ZEditingContextSessioning', zLOG.WARNING,
+             "The session data container's destruction callback already set (%s)-- THIS IS A MODIFIED VERSION OF THE PRODUCT, WHICH SHOULD NOT BE PUT IN A PRODUCTION ENVIRONMENT"%repr(sessionDataContainer.getDelNotificationTarget()))
+    install_delete_hook=0
+    ##return
   
   # There is no SessionObject, just Transient Object
   if getattr(TransientObject, 'defaultEditingContext', None):
@@ -106,7 +108,8 @@
   ## Transient Object Container's ZMI will not show a meaningful value for
   ## its field 'Script to call when objects are deleted'
   #sessionDataContainer.setDelNotificationTarget(sessionDeletion_hook)
-  sessionDataContainer.setDelNotificationTarget('/Control_Panel/Products/ZEditingContextSessioning/sessionDeletion_hook')
+  if install_delete_hook:
+    sessionDataContainer.setDelNotificationTarget('/Control_Panel/Products/ZEditingContextSessioning/sessionDeletion_hook')
   
   product=app.Control_Panel.Products.ZEditingContextSessioning
 


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