Hey! > > Now I just need to understand why even when I call mm_modem_create_bearer and > immediately cancel the GCancellable, My callback is called with the error > "Operation was cancelled", but the bearer is still created. This is an > unrelated issue, so I can create a new email thread on this question if I > can't figure it out. >
That's easy to explain I think. Internally, all the async operations are implemented using GTasks. When the async operation starts, the GTask is created with the input GCancellable associated, and (by default) that means that if the cancellable is ever cancelled, the GTask is ALWAYS going to return a G_IO_ERROR_CANCELLED, even if the actual async operation may have finished successfully. So it may happen that the internal async method finished with a g_task_return_boolean(TRUE) or similar, but the actual g_task_propagate_boolean() called in the _finish() ends up returning a cancelled error instead of TRUE, because the GCancellable was cancelled meanwhile. See the docs for g_task_set_check_cancellable() which is the method that could be used to disable the default behavior. Now, another thing is the rationale of when this logic should be applied, or if it even makes sense to do that in certain operations like mm_modem_create_bearer(). You could argue that if this method fails with whatever reason, it must mean that the bearer object wasn't created, and I could probably agree with you. There would be two ways to solve this: make sure that internally the async method handles the cancellation gracefully and so we make sure the bearer is destroyed if it was created but the operation was cancelled; or otherwise make the operation not cancellable at all (ignoring the input cancellable). This is some thinking that we should put in all APIs I'm afraid; I'm sure there are some that already can be considered safe, but lots of others that change state or create objects probably aren't. -- Aleksander https://aleksander.es _______________________________________________ ModemManager-devel mailing list ModemManager-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/modemmanager-devel
