On 01/22/10 16:10, Ed Schouten wrote:
* Ivan Voras<[email protected]> wrote:
This is a good and useful addition! I think Windows has implemented a
generalization of this (called "wait objects" or something like that),
which effectively allows a select()- (or in this case kqueue())-like
syscall to wait on both file descriptors and condvars (as well as
probably other MS-style objects). It's useful for multiplexing events
for dissimilar sources.
NtWaitForSingleObject(), NtWaitForMultipleObjects(), etc. :-)
Yes, I was thinking about WaitForMultipleObjects() - I sometimes wished
I had it in FreeBSD :)
I think the hackers@ side of the thread is missing the original link to
the patch file offered for review, so here it is:
http://people.freebsd.org/~rrs/kque_umtx.patch
My kqueue-fu level is too low to be really useful here but from what
I've read it looks like a logical and even reasonably clean way of doing it.
If I read the comment at filt_umtxattach() correctly, in the best case
you would need an extension to the kevent structure to add more fields
like data & udata (for passing values back and forth between userland
and kernel). I agree with this - it would be very convenient for some
future purposes (like file modification notification) if the kernel
filter could both accept and return a struct of data from/to the userland.
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