This function sends D-Bus messages directly (in huntAndEmit), so it
should only be called from the QDBusConnectionManager thread. Somehow, I
missed this in the Qt 5.6 refactoring of QtDBus.
Being called in the wrong thread means that there's a visible behavior
change compared to Qt 5.5: if the user code sent a method call or method
return/error and then emitted a signal, we'd have two threads racing to
send the D-Bus messages. This was observed in Telepathy-Qt code: certain
signals arrived before a method return, even though they were clearly
emitted by a queued QMetaObject::invokeMethod.
In addition to that, we have has an internal problem (though not
observed): the libdbus-1 timer and socket callbacks would be called in
the wrong thread and we no longer have protection against that.
Unit testing not possible since this is a race condition.
Change-Id: I9e96ecd4f6aa4ff0ae08fffd1471d002142613d6
Reviewed-by: Gustavo Pichorim Boiko <gustavo.boiko@canonical.com>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
ebf0b12108