So, I need to monitor a fairly large nested directory tree for changes on Linux. It seems like there are a few different watcher modules that I could use -- fsnotify and notify being the main ones, both of which use the inotify interface and attempt to set watches on each individual subdirectory and maintain all their watchers as things change. I have way too many directories for that to be a workable approach. It looks like the underlying issue is just that this is a difficult problem on Linux; both inotify and fanotify have some issues which make them difficult for library authors to use to present a clean and useful API.
Long story short - I coded up an fanotify-based solution which seems like a good start of what I need, and I'm planning on sharing it back in the hopes that it's useful. I guess my question is, did I miss something? Is there already an easy and straightforward way to monitor a big directory for changes?
Just chiming in to say I was unaware of how limiting inotify is because of the relatively trivial cases in which I’ve used it. I’d be interested to see the alternative you’ve come up with!
Yeah. I think it's moderately likely that I'll try to produce a little command-line tool that can do it effectively for deeply nested directories, with some attempt at making it cross platform. To me it's kind of weird that there's no stock solution existing to this problem. I get that it's actually a deceptively difficult problem to solve for a couple of different reasons, but that's no reason to pass the difficulty on to the programmer instead of just presenting a clean and nice interface.
Update: I looked around for something already-existing, and found watchman and fswatch... IDK, maybe I'll try to talk one of them into letting me write an fanotify backend for those tools instead. It seems like it's purely just a Linux issue, and everything is simple on BSD/Mac/Windows, so maybe I'm just lucky.