On sön, 2013-04-14 at 23:48 +0200, David Faure wrote: > To implement a maximum size for the trash directory, one needs to check the > size every time a new item is being trashed. With the current spec, the only > solution is to do a recursive traversal, which is pretty expensive. > To make this efficient, we need a cache. > My initial idea of a global "total size" cache doesn't work well with older > implementations which don't update that value, so it gets out of date quickly. > > Instead, Ryan Lortie and I came up with the following idea, which we would > like to standardize into the trash spec: > > For files, we get the file from stat. For dirs, we use a cache: > in every trash directory, a metadata file is created, with one entry per > directory (that was trashed by the user). > That entry contains the total size in bytes of the directory, and the > modification time of the trashinfo file [*]. > > The metadata file uses desktop file syntax, where the key is the directory > name, and the value is a pair: size, and mtime. > > However the desktop file standard restricts the available characters for > keys, > so instead of just writing out the directory name, we write the sha1 of the > directory name (a bit like the thumbnail spec uses sha1s too). > > In summary, it would look like this: > > [Directories] > # One entry per sub-directory of the "files" directory > # key = sha1 of the directory name > # value = size in bytes, timestamp of the trashinfo file, in UTC > cb58e5c11a6802db43fd82ca8d3c7393353c0eab=25383,2009-07-11T20:18:30 > f1d2d2f924e986ac86fdf7b36c94bcdf32beec15=2315,2012-04-12T10:05:20
In general this sounds good to me. I have two minor objections: 1: Using sha1 seems wrong to me. There is no need to get an even distribution of the keys (like for thumbnail subdirectories), and a sha1 is slow to calculate. Also, if you ever look at the file manually its says very little. I would much prefer simple character escape model, say you allow A-Za-z0-9 and everyting else you escape as "-" + the hex digits (like "-2d" for "-"). This is valid desktop file keys, are cheap to calculate and makes most files readable by humans. 2: Don't store the mtime in a format that needs parsing. Time and date parsing is a very complicated area that is easy to get wrong. And the source is always a stat which is in epoch format, why not just save it in the same format to avoid any day/month order issues, timezone weirdnesses or whatnot. _______________________________________________ xdg mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/xdg
