Re: [libvirt] mingw: test-poll pipe part fails

On Tue, Jul 19, 2011 at 09:31:59AM -0600, Eric Blake wrote: > On 07/19/2011 09:30 AM, Daniel P. Berrange wrote: > >>I'm wondering if the problem here is that libvirt is trying to use the > >>pipe-to-self mechanism as a fundamental event loop idiom.  That is, the > >>reason libvirt is calling poll is in order to minimize CPU until > >>something interesting happens, where interesting includes needing to > >>wake up a helper thread to do an action inside locks in response to the > >>receipt of a signal. > >> > >>Maybe you are on to something, and replacing all uses of pipe() with > >>virPipeToSelf() (which uses pipe() for efficiency on Linux, but > >>socketpair() on mingw), would allow libvirt to continue to use the > >>pipe-to-self idiom while also using fds that can actually be poll'd on > >>mingw. > > > >IIRC, we never resolved this for the last release. I think we should > >do as you suggest and just use socketpair() on Win32. Given the way > >in which libvirt uses these capabilities, I don't think the overheads > >of socketpair() vs pipe() are so onerous that we need worry about an > >even more fancy Win32 impl or eventfd for linux. Of course if someone > >wants todo a full job for gnulib meawhile, we won't complain... > > Well, right now, we don't even have socketpair() for Win32.  We'd > have to wire up some other native APIs for this to work. Oh I read your mail above as indicating we did have socketpair() on Mingw32. A quick look through google, suggests most people go down the route of creating a TCP socket bound to localhost for this purpose. Daniel -- |: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org              -o-             http://virt-manager.org :| |: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|