file system change notifications

[Kim Shrier]

On Mar 12, 2015, at 10:24 AM, Jordan Hubbard <jkh at mail.turbofuzz.com> wrote:
> 
> 
>> On Mar 12, 2015, at 6:37 AM, Guy Helmer <guy.helmer at gmail.com> wrote:
>> 
>> How are Darwin (OS X) fsevents implemented? It’s a been a handy interface for some of my work.
> 
> They have their own tap from the kernel and their own daemon (fseventsd) to handle coalescing and a publish/subscribe model that will feed multiple consumers without duplicating or losing events (I haven’t looked deeply into the implementation, but presumably all the cache management is there as well so that memory consumption can be kept manageable.
> 
> Maybe someone should keep a list of “OS X features we would really like in FreeBSD” (add purgeable memory and memory pressure bands to that list while you’re at it) and parcel them out as GSoC projects. :-)
> 
> - Jordan

I was curious if the OS X code, which I believe adds some functionality to VFS along with fseventd for actually handling the notifications, would be a good model for FreeBSD.  I need to study the OS X code some more to make sure I understand it.

Also, to clarify, I am not proposing this as a GSoC project.  I was just referring to a GSoC project that seemed to address this problem.  If I can figure out a good approach for adding this to FreeBSD, I would do it myself.

Kim