Watcher prototype » History » Revision 10
Revision 9 (Greg Burri, 08/04/2009 10:24 AM) → Revision 10/17 (Greg Burri, 08/07/2009 10:49 AM)
h1. Watcher prototype
The cache file structure store all the hashes of the shared files. If a file is added or removed from a shared directory (or a subfolder) it should be added or removed from the cache.
As far as I know there is no way to watch changes recursively of a folder tree with Qt. The Qt class _QFileSystemWatcher_ cannot watch recursively.
The only way to synchronize is to periodically scan all the shared data and compare to the cached one. It can be a bit CPU consumer so it should be done with a low priority thread and maybe with a pause between each file hashing.
h2. Native solution
A better solution would be to use native platform API.
h3. Linux : inotify
On Linux it exists a function called "inotify":http://linux.die.net/man/7/inotify
* The big issue is that inotify doesn't support the recursive watch of a directory.
* There is a limitation of the number of watcher, see @/proc/sys/fs/inotify/max_user_watches@, for example : 8192 under Debian.
h3. Windows : FindFirstChangeNotification
On Windows a directory and its subtree can be watched, see : http://msdn.microsoft.com/en-us/library/aa365261%28VS.85%29.aspx
There is a simple function called _ReadDirectoryChangesW_ : http://msdn.microsoft.com/en-us/library/aa365465%28VS.85%29.aspx