Re: [Boost-users] [ASIO] directory monitor ASIO extension

Subject: Re: [Boost-users] [ASIO] directory monitor ASIO extension
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2014-08-06 12:16:35

On 6 Aug 2014 at 6:58, Brian Wood wrote:

> > * Works reliably on Microsoft Windows (hard), Linux (slightly
> > easier), BSD and OS X (easiest by far of the lot).
> 
> I believe you.  Having considered some of your previous
> comments in a different thread, on kqueue, I ported my
> code generator from Linux to BSD.  I only found relief
> from a problem I was having by doing so.

kqueues are indeed the least worst solution available for watching 
for change of anything, though they do consume fd's rapidly for 
directory watching. I personally wish you could use the fd to 
indicate what you want to watch, and then close the fd after 
registering it with kqueue.

The huge problem with Microsoft's otherwise very good API is it can 
spontaneously throw away data under load, and you can't recover and 
retry. inotify under Linux has the same problem. That means you need 
to checkpoint every success, and roll back to that last success and 
run polling to calculate deltas until you can resync the watched 
state with the ground state.

A real shame in that design :(

Niall

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