Once cancelled, a GTask's callback should not only be invoked
asynchronously with respect to the creation of the task, but also with
respect to the GCancellable::cancelled handler. This is particularly
relevant in cases where the cancellation happened in the same thread
where the task is running.
Spotted by Dan Winship and Michael Catanzaro.
Closes https://gitlab.gnome.org/GNOME/glib/issues/1608
Since commit 290bb0dd, where various members of GTask were converted to
a bitfield, some of the getters:
• g_task_get_check_cancellable()
• g_task_get_return_on_cancel()
• g_task_get_completed()
have been returning truthy ints (zero or an arbitrary non-zero integer)
as boolean values, rather than the canonical boolean ints of 1 and 0.
This broke the `yield` statement in Vala, whose generated C code
compares `g_task_get_completed (…) != TRUE`. i.e. Whether the
`completed` field has a value not equal to 1.
Fix this by explicitly converting truthy ints to canonical boolean ints
in all getters.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/1636
Similarly to g_source_set_name(), this sets a name on a GTask for
debugging and profiling. Importantly, this name is propagated to the
GSource for idle callbacks for the GTask, ending the glorious reign of
`[gio] complete_in_idle_cb`.
The name can be queried using g_task_get_name(). Locking is avoided by
only allowing the name to be set before the GTask is used from another
thread.
Includes tests.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
There are a lot of gbooleans in the private GTask struct, which seems a
bit wasteful. Use a bitfield to compress the struct a bit.
This reduces the size of the struct from 216 bytes to 168 bytes on my
64-bit machine.
One of the fields needs to remain separate, since it’s used from a
TRACE() macro which calls typeof() on it.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
These functions already check to see if a successful result has already
been returned; expand them to also check to see if an error has been
returned.
We can’t just check GTask.result_set, as that’s actually an indicator
for whether the GTask.result member is filled — when
g_task_propagate_*() is called, it’s cleared again. We need a new state
bit.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/1525
For the purposes of debugging, it is quite useful for every GSource to
have a name set. Ensure that any GSource we construct inside GLib has a
name set. For GSources which are then returned to the caller, this name
can then be overridden with something even more useful by the caller.
Since this data is only used for debugging, avoid doing any allocations
for it; just use static strings.
https://gitlab.gnome.org/GNOME/glib/issues/1175
This will fix a few broken links in the documentation, and shut up a
load of gtk-doc warnings (but certainly not all of them).
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://bugzilla.gnome.org/show_bug.cgi?id=790015
If we have an input parameter (or return value) we need to use (nullable).
However, if it is an (inout) or (out) parameter, (optional) is sufficient.
It looks like (nullable) could be used for everything according to the
Annotation documentation, but (optional) is more specific.
The use of past tense in g_task_had_error makes one assume that it
won't forget about any errors that might have occurred. Except, in
reality, it would.
Let's use a boolean flag to remember the error once it's been
propagated, as opposed to keeping the error around. This ensures that
the g_task_propagate_* methods continue to give invalid results when
called more than once, as mentioned in the documentation.
https://bugzilla.gnome.org/show_bug.cgi?id=764163
The new "slowly add more task threads" code doesn't fully deal with
apps that queue lots and lots of tasks which then block on tasks from
their task threads. Fix this by bringing back the "task is blocking
other task" check and making sure that such tasks get bumped to the
front of the queue.
https://bugzilla.gnome.org/show_bug.cgi?id=687223
When a task is cancelled, we want to move it to the front
of the queue - our sort function does that for us, but there
is no need to resort the entire queue here, we can just
move the one item and be done with it. This uses just-introduced
threadpool api for this purpose.
https://bugzilla.gnome.org/show_bug.cgi?id=751160
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
g_thread_pool_push() only returns an error if it fails to spawn a new
thread. However, it unconditionally adds the task to its worker queue,
so:
• if _any_ threads exist in the pool, the task will eventually be
handled; and
• if _no_ threads exist in the pool, the task will be handled if one
is eventually successfully spawned.
If no more threads are ever spawned, the process probably has bigger
problems than a single GTask which is taking forever to complete.
https://bugzilla.gnome.org/show_bug.cgi?id=736806
Since we are no longer using sgml mode, using /* */ to
escape block comments inside examples does not work anymore.
Switch to using line comments with //
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
