This appears to fix an intermittent failure seen when sending a D-Bus message with either of a cancellable or a timeout set.
In particular, I can reliably reproduce it with:
meson test gdbus-test-codegen-min-required-2-64 --repeat 10000
It can be caught easily with asan when reproduced. Tracking down the
location of the refcount mismatch was a little tricky, but was
simplified by replacing a load of
g_object_ref (message) calls with
g_dbus_message_copy (message, NULL) to switch
to using copy semantics. This allowed asan to home in on where the
refcount mismatch was happening.
The problem was that
send_message_data_deliver_error() takes ownership
GTask passed to it, but the
send_message_with_reply_timeout_cb() functions which were calling it,
were not passing in a strong reference as they should have.
Another approach to fixing this would have been to change the transfer
semantics of Edit: I found more bugs in this area, so eventually did change the transfer semantics of
send_message_data_deliver_error() so it was
(transfer none) on its
GTask. That would probably have resulted in cleaner
code, but would have been a lot harder to verify/review the fix, and
easier to inadvertently introduce new bugs.
send_message_data_deliver_error(), in commit f01adb3d.
The fact that the bug was only triggered by the cancellation and timeout callbacks explains why it was intermittent: these code paths are typically never hit, but the timeout path may sometimes be hit on a very slow test run.
Signed-off-by: Philip Withnall email@example.com