Re: GCancellable hints

[Benjamin Otte <otte gnome org>]

Richard Hughes <hughsient <at> gmail.com> writes:

> The only functionality that ZifCancellable adds is two methods:
> 
> void zif_cancellable_set_hint (GCancellable *cancellable, gboolean can_cancel)
> gboolean zif_cancellable_get_hint (GCancellable *cancellable);
> 
> And added the "hint-changed" signal
> 
I'm not Alex, who has final say on API issues, but I don't think this API 
should be part of GCancellable.  And that's because I think you're treating 
GCancellable wrong.

GCancellable's only purpose is as a token that ensures function calls can be 
cancelled over thread or operating system boundaries. In an async program, the 
same cancellable is often used for multiple calls at the same time. Operation 
is one-way: The caller cancels the function call.

What you want is a way to describe a transaction, where the caller and the 
function call interact in two directions and one of the interactions is 
cancellation while another interaction is telling the caller that cancellation 
is currently disabled. Other transaction information you probably have in 
PackageKit is progress information. From my POV this is quite a different 
thing conceptually than what GCancellable does.
I should also note that GIO functions put transaction information into 
separate parameters passed to the function call - g_file_copy() for example 
has the progress_callback parameters. They do not attach this information to 
the cancellable.

Benjamin