Race condition while buddy initiation

[alsroot]

The problem is that right after becoming online, buddy (jabber user) is in inconsistent state before all pep ( http://xmpp.org/extensions/xep-0163.html) properties will be published on jabber server.

[alsroot]

Attached patch is a workaround that shows the affected place in sugar shell code.

[sascha_silbe]

We should probably call  SetProperties right after creating the connection in  jarabe.model.neighborhood._Account._prepare_connection(), not in  __connection_ready_cb() after the connection has been established.

Nevertheless Sugar should cope with this race condition on the receiver side. As PEP is used we should get notified of the properties as soon as the sender publishes them ( PropertiesChanged signal,  __buddy_info_updated_cb()).

If I grok the code right, this should be race-free: The signal callbacks get set up in  __get_self_handle_cb(), as part of the callback for the Status call in  __connection_ready_cb(). The  GetProperties call happens in  _update_buddy_activities() and  __get_contact_attributes_cb(), both times only in response to the signals we subscribed to in  __get_self_handle_cb():

•  MembersChanged signal ->  __members_changed_cb() ->  _add_buddy_handles() ->  GetContactAttributes ->  __get_contact_attributes_cb()
•  ActivitiesChanged signal ->  __buddy_activities_changed_cb()
•  ActivityPropertiesChanged signal ->  __activity_properties_changed_cb() ->  _update_activity() ->  GetActivities ->  __got_activities_cb()
•  MembersChanged signal ->  __members_changed_cb() ->  _add_buddy_handles() ->  GetContactAttributes ->  __get_contact_attributes_cb() ->  GetActivities ->  __got_activities_cb()

We should consider the use case of non-Sugar buddies when fixing the receiver side of this bug: When  GetProperties fails, it can be due to this bug ( SetProperties called too late on the sender side) or because the buddy isn't running Sugar. We should be able to distinguish these two cases by examining the  capabilities (see  PEP: Filtered Notifications). In the non-Sugar case we should show the buddy right away. For Sugar buddies we might want to wait for the  PropertiesChanged signal, potentially forever.