Re: [Libevent-users] WaitForMultipleObjects backend?

[Patrick Pelletier <ppelletier@xxxxxxxxxx>]

On 03/13/2013 08:18 PM, Nick Mathewson wrote:

> Oh, this is going to be a *fun* one!

Yeah, I was afraid of that.

> Here's a brain-dump.  I'm not an expert on Windows APIs, so there may
> be errors or omissions.

Thanks for the brain dump!  I'm afraid I'm in the same boat; I'm a Linux 
programmer who dabbles in Windows when necessary.

> Another thing you could look at for starters is the branch that Chris
> Davis tried to write to handle this code.  I don't think it wound up
> working completely, but it had some good ideas.  I have it archived in
> branch "hybrid-loop2" in my personal repository at
> https://github.com/nmathewson/libevent/tree/hybrid-loop2
>
> It probably has some good ideas!

Thanks!  I've rebased it (which required some massaging and a bit of 
guessing) onto the current libevent master branch, and I've fixed it up 
to the point where it compiles on Windows.  That's all can say, though; 
I've done zero testing (other than a quick run of "regress.exe").  But 
in case this is useful in any way, it's available as my 
"hybrid-loop2-updated" branch in my github repo.

I'll probably use this as a starting point for porting my event-based 
Windows code, and then see what breaks.

> Integration with IOCP could be a clever thing here. IOCP->Event and
> Event->IOCP signals seem to go pretty fast on windows, whereas mucking
> around with stuff like evutil_socketpair() is less so.

I'm afraid I know nothing about IOCP.  I'll have to read up on that.

> You're going to run into the 64-event (or is it 63?) limitation of
> WaitForMultipleEvents.

Yeah, my existing (non-libevent-based) Windows code presumably has this 
limitation, too.  We just haven't run into it yet, but I'm sure a 
customer will find a way to run into it when we least expect it.

Thanks again for the brain dump, and I'll keep you updated if I make any 
further progress!

--Patrick

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