This method drops the last reference *it* owns to the GTask, but then
continues to call methods on the GTask. This wasn’t resulting in
failures because a ref in another thread kept the GTask alive, but
that’s quite dodgy.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
GTask used a 10-thread thread pool for g_task_run_in_thread() /
g_task_run_in_thread_sync(), but this ran into problems when task
threads blocked waiting for another g_task_run_in_thread_sync()
operation to complete. Previously there was a workaround for this, by
bumping up the thread limit when that case was detected, but deadlocks
could still happen if there were non-GTask threads involved. (Eg, task
A sends a message to thread X and waits for a response, but thread X
needs to complete task B in a thread before returning the response to
task A.)
So, allow GTask's thread pool to be expanded dynamically, by watching
it from the glib worker thread, and growing it (at an
exponentially-decreasing rate) if too much time passes without any
tasks completing. This should solve the deadlocking problems without
causing sudden breakage in apps that assume they can queue huge
numbers of tasks at once without consequences.
https://bugzilla.gnome.org/show_bug.cgi?id=687223
This can be used to query whether the task has completed, in the sense
that it has had a result set on it, and has already – or will soon –
invoke its callback function.
Notifications for this property are emitted immediately after the task’s
main callback, in the same main context as that callback. This allows
for multiple bits of code to listen for completion of the GTask, which
opens the door for blocking on cancellation of the GTask and improved
handling of ‘pending’ behaviour.
https://bugzilla.gnome.org/show_bug.cgi?id=743636
When running a task in a thread, GTask may still be internally holding
a ref on the task in that thread even after the callback is called in
the original thread (depending on thread scheduling). Fix the test to
handle that by using a weak notify that signals a GCond, and wait for
that GCond from the main thread. (And add a corresponding check to
test_return_on_cancel().)
https://bugzilla.gnome.org/show_bug.cgi?id=705152
If tasks block waiting for other tasks to complete then the system can
end up starved for threads. Avoid this by bumping up max-threads in
that case.
This also reverts 7b1f8c58 and reverts max-threads for GTask's
GThreadPool back to 10.
https://bugzilla.gnome.org/show_bug.cgi?id=687223
Very many testcases, some GLib tools (resource compiler, etc) and
GApplication were calling g_type_init().
Remove those uses, as they are no longer required.
https://bugzilla.gnome.org/show_bug.cgi?id=686161
GTask is a replacement for GSimpleAsyncResult and GIOScheduler, that
also allows for making cancellable wrappers around non-cancellable
functions (as in GThreadedResolver).
https://bugzilla.gnome.org/show_bug.cgi?id=661767
