Hey Enrico, > > So - i was considering using a GList of my own structs to track down objects > and maintain it when observing state transitions. > Now I was wondering how to manage: > - async operation concurrency: am I guaranteed only a single async operation > runs? Or should I lock somehow the list?
If your program doesn't use multiple explicit threads, i.e. if you just have a main loop in the main thread, you're totally safe and there is absolutely no need to do any sync or locking to access that list. > - software shutdown: > - I will have to unref all my objects somehow > - mainloop exiting should be the last thing I do If you want to provide a "clean program exit", then all your async operations must be finished before you quit the mainloop, otherwise the program would exit with pending async operations (which may be fine anyway). If you have a list of structs and each struct holds object references, what you need to do is cleanup each of the structs (the list items) one by one, unref-ing whatever full references you had stored there, and then free the list itself. > > but I should be sure all async operations are complete when I quit my > program, and I know the answer: GCAncellable. :) :) That is a way to do that, yes. If you want to do a clean exit like you're describing, you could have a "program wide cancellable" that is passed around to all async operations you execute, and once the cancellable is cancelled, the async operations should (if they support it) get cancelled all. But beware, cancelling the cancellabel doesn't necessarily mean that all async operations are cancelled instantly; and the cancellation process itself may need further main loop iterations to complete! > But at the moment it's not clear to me how I might use that to make sure that > when the program quits, all async operations are cancelled, and no other are > pending. My question is, why do you really want to make sure all async operations are finished when the program quits. Do you truly need that? If you do need that, then once the program is told to quit, you should launch the "program cancellation logic" which would cancel the program-wide cancellable, and then wait until all async operations are finished. You may for example keep a counter of the async operations you're running concurrently, and once it reaches 0 (meaning all async operations finished) then you would be able to cleanly stop the mainloop at that point. Don't know, something like that. > I did have a look at mmcli use of GCancellables, but it's not clear to me how > I might use them when I only use, and not implement, async ops, amongst other > things. If the async operation doesn't support GCancellable, you cannot do anything. If the async operation supports GCancellable, it is (usually) guaranteed that the async operation will finish with a G_IO_ERROR_CANCELLED error. But, there is no guarantee that cancelling a cancellable will make the async operation actually get cancelled earlier! Some operations allow that (e.g. a network scan) but some others will just wait for the operation to finish normally but then returning a cancelled error instead of whatever the result of the async operation was. -- Aleksander https://aleksander.es _______________________________________________ ModemManager-devel mailing list ModemManager-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/modemmanager-devel
