device filtering support

[Xiaofan Chen]

On Mon, Feb 6, 2012 at 9:46 AM, Pete Batard <pete at akeo.ie> wrote:
> OK. I thought I had explained this before:
> - Xiaofan and Travis see the alleged pollution from our current enum process
> unacceptable, even if done once per app (because launching a new app would
> still pollute => eliminated a threaded approach)
> - Their proposed solution to remedy that is to change the general libusbx
> enum process on Windows to _always_ filter, as libusb-win32 and libusbK
> currently do

Please refer to my latest reply to Segher's libusb_init_with_filter()
and libusb_get_device_list_with_filter() proposal which keep the
existing libusb_init and libusb_get_device_list(). Do you think that
is a reasonable compromise which covers both sides?

In that case, a threaded approach is feasible and no need your
proposed separate process.

> - My solution to avoid the above and meet their request of non pollution is
> a cross application process that would do the polluting enum once. Also has
> the advantage of querying the OS and USB common data we need once and could
> handle hotplug, which would probably benefit more than just Windows.

The keyword is "USB common data we need". What we see now is that
in the current implementation  the information queried is too much and in
some cases might not only be "once" and thus the need to be filtered out
if the user perceives this as unacceptable.

-- 
Xiaofan