using KDBusConnectionPool in libraries

[Aaron J. Seigo]

Hi..

I ran into an interesting situation the other day with libkactivities: it uses 
KDBusConnectionPool to create connections in a thread-safe manner. 
KDBusConnectionPool creates a connection in whatever thread it happens to be 
executed from. In libkactivities this creates a problem as a singleton that is 
internal to the library uses KDBusConnectionPool .. so whatever thread it 
happens to be called from first: that’s the thread it gets its QDBusConnection 
object put into.

Of course, if that thread has no event loop and/or exits, then things stop 
working as expected. In the case of libkactivities, things just stop working, 
period.

Either a better solution needs to be found for KDBusConnectionPool or a 
warning should be placed prominently in the apidox about this “gotcha” and 
perhaps it should be completely avoided in other frameworks where it is 
impossible to know the threading model of the application that will be using 
it. Or, I suppose, we could invent a policy that applications should do all 
dbus related activities in a specific thread .. though that can be difficult to 
know as dbus calls are often hidden within libraries.

.. or, does anyone have a pointer to what exactly in QDBusConnection is not 
thread safe?

-- 
Aaron J. Seigo