Finish "email address visibility" feature

[timabbott]

I'm opening this issue to track the follow-up work related to our email address visibility feature (#2369) once #10850 merges. There are a few critical items:

• Some end-to-end testing
• Make sure we send gravatars even if client_gravatar is set, with this setting.
• Ensure that the mobile apps won't completely break when you toggle this setting. One valid approach would be to send a "restart server" event (and/or delete all active event queues for the realm), and then confirm that the mobile app's caching of users is properly reset with that code path (it should be).
• Figure out a way to avoid doing a linear number of queries for the do_set_realm_property code for switching an organization; the existing code will likely timeout and thus fail to finish the transition for a large enough realm. The critical bit here is refactoring the changes to do a bulk save. We roughly want this:

if name == "email_address_visibility":                                              
    user_profiles_to_save = []                                                      
    for user_profile in UserProfile.objects.filter(realm=realm, is_bot=False):      
        # Save the old email address as a temporary value on the UserProfile object.
        user_profile.old_email = user_profile.email                                 
        user_profile.email = get_display_email_address(user_profile, realm)         
        user_profiles_to_save.append(user_profile)                                  
                                                                                    
    # We do a bulk database update and then flush the realm's                       
    # caches to avoid doing database queries linear in the number                   
    # of users.                                                                     
    UserProfile.objects.bulk_update(user_profiles_to_save)                          
    # The update_fields value here is a bit of a hack.                              
    flush_realm(instance=realm, update_fields=['string_id'])                        
                                                                                    
    for user_profile in user_profiles_to_save:                                      
        # TODO: Design a bulk event for this or force-reload all                    
        # clients, since this is linear work for our Tornado                        
        # infrastructure.                                                           
        if user_profile.email != user_profile.old_email:                            
            send_user_email_update_event(user_profile)                              

but Django doesn't actually have a .objects.bulk_update feature. One reasonable solution would be to move the code we currently have to a different queue processor (e.g. the deferred_work one), where timeouts aren't as much of a problem.

[zulipbot]

Hello @zulip/server-settings members, this issue was labeled with the "area: settings (admin/org)" label, so you may want to check it out!

[varkor]

Is this issue complete? There seem to be options for setting organisation email visibility now.

[timabbott]

Yes, closing as all of these have been resolved.