EVFILT_VNODE doesn't scale to large directory trees?
bonomi at mail.r-bonomi.com
Mon Oct 25 04:48:41 UTC 2010
> From owner-freebsd-questions at freebsd.org Sun Oct 24 22:17:42 2010
> Date: Sun, 24 Oct 2010 18:05:34 -0700
> From: Kenton Varda <temporal at gmail.com>
> To: freebsd-questions at freebsd.org
> Subject: EVFILT_VNODE doesn't scale to large directory trees?
> Hi all,
> I am trying to write some code which monitors a possibly-large directory
> tree for changes. Specifically, it's a build system, and I want it to
> automatically start rebuilding whenever I modify a source file.
> So far the approach I've taken is to use EVFILT_VNODE to watch every file
> and directory in the tree. This seems to work OK so far, but it worries me
> that I have to open() every single file. When I ran the same code on
> Darwin, it promptly hit the open file descriptor limit, and I'm worried that
> FreeBSD will do the same on larger code trees.
> Is there any better way to accomplish this? Hate to say it, but Linux's
> inotify() seems more scalable here. From what I can tell from the docs, it
> doesn't require opening the watched files and it will even watch all files
> in a directory with one call.
You're re-inventing the wheel.
1) Set up a 'makefile' for the entire tree.
2) set up a daemon task that
a) cd's to the root direcory of the build tree,
b) executes a loop, consisting of
1) the 'make all' command,
2) a reasonably short 'sleep'
If 'efficiency' is a concern, then establish a procedure for checking-out/
checking-in files from the repository. When a file is checked in, check
for (a) it being a new file, *OR* (b) having changes from the prior version.
If either condition is true, fire off 'make' to do the necessary re-build.
NOTE: 'cvs' has the above feature as a built-in option. simply specify
'make' as a program to be run when you do a 'cvs commit' to store changes
back into the repository.
Did I say soemthing about re-inventing the wheel?? <grin>
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