What does open_file_cache_events do?

[Maxim Dounin]

Hello!

On Wed, May 12, 2010 at 06:57:24AM -0400, Costello wrote:

> I'm looking to document directives that are missing from the Wiki.
> I found loads in the source code, especially thanks to Manlio Perillo.
> 
> I've stumbled upon "open_file_cache_events" declared in ngx_http_core_module.c.
> I investigated what this does, here is what I found:
> - it's a on/off directive
> - it's off by default
> - its main purpose is from 1 file, ngx_open_file_cache.c

[...]

> Now I understand what the open file cache does, but I don't 
> understand what exactly what this directive does.
> When the directive is enabled, does Nginx process some kind of 
> event-based cache invalidation?
> Eg. Nginx would subscribe to events for this file, when the file 
> is deleted, Nginx gets notified with an event, and then updates 
> the cache entry?

Yes, it activates event based watching for file descriptor changes 
instead of periodic checks; available with kqueue event method.

It's intentionally left undocumented.  Don't use it, it's 
unfinished code (there are known race which leads to SIGSEGV).

Maxim Dounin