Re: [boost] [afio] Formal review of Boost.AFIO

Subject: Re: [boost] [afio] Formal review of Boost.AFIO
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2015-08-23 21:13:40

On 24 Aug 2015 at 0:46, Klaim - Joël Lamotte wrote:

> Small side question:
> some time last year there was a discussion about filesystem/directory
> watcher libraries,
> with mention about one that would be part (or an example implementation) of
> boost AFIO.
> Looking at github, the branches that seem to be related (dir_monitor) are
> "staled".

Paul was working on that back in 2013/2014. It's his branch.

> Am I correct that the directory monitoring "feature" is not part of this
> library review (I can't find it in the documentation)?

Correct. He never finished it. It's surprisingly hard to do correctly 
- most implementations out there are broken in subtle ways (mainly in 
handling change in large directories without racing on the delta 
calculation, and doing that with a good complexity and without using 
tons of RAM).

I have some watch side code here for forthcoming async byte range 
locking, but it is not well tested, plus it only monitors single file 
entries (i.e. the lock file). I don't expect to finish that code 
until late 2016.

In the meantime, simply poll async_enumerate(). It's a very fast call 
with good race guarantees on Windows at least, and I took care to 
make sure the afio::directory_entry structure is as tightly packed as 
possible.

Niall

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