On Jan 13, 2005, at 15:40, Wolfgang Keller wrote:
recently I read something about the "kqueue" event notification mechanism built into FreeBSD and that it would allow to receive notification when filesystem contents change. Would this mechanism allow to implement a similar function as database triggers for a filesystem, i.e. write a script that does something with files that are added to, modified in or deleted from a certain directory without having to poll the filesystem all the time? Folder actions allow such things on MacOS X, but Applescript is slow and I would prefer Python anyway. ;-) If so, is there a way to write such scripts in Python using Twisted?
Actually Folder Actions don't allow this. I am relatively certain that they are implemented entirely in Finder. They *might* be hooked into at the CoreServices/Carbon APIs, but DEFINITELY NOT the BSD level APIs (in Mac OS X 10.3 and earlier anyway). The kernel in Mac OS X 10.3.0 supports kqueue, so you can use it for this sort of thing -- but Finder still polls. I do not know what is necessary to integrate this with Twisted, though. There is some support for kqueue in Twisted, but last I remember you need to download and patch some years-old extension and compile it in order to get that to work. Another thing of interest to you might be FAM <http://oss.sgi.com/projects/fam/>. -bob