On Mon, Nov 13, 2017 at 11:50 PM, Julian Andres Klode <j...@debian.org> wrote:
> (forwarding this to ubuntu-devel-discuss and Zygmunt) > > On Mon, Nov 13, 2017 at 10:33:39PM -0800, Shawn Landden wrote: > > Package: command-not-found > > Severity: wishlist > > > > I re-wrote command-not-found to get rid of the python dependancy, and > > to reduce the database size, as to reduce memory usage. > > > > https://github.com/shawnl/command-not-found > > > > I was preparing to upload it to mentors as command-not-found-ng > > I also rewrote it years ago, but using the same database format, > just in C. It was a lot faster. I don't understand the memory usage > bit - it should not matter how large the database is, it's memory > mapped, and not read into memory, as such memory usage should be > roughly constant. > > Questions/Comments for your approach: > > * Did you test your format on a slow HDD with caches dropped? It > must not be slower than the Python one (that one is way too slow > already) - I did, it seems to be faster (0.4 vs 0.68 seconds) > - I believe the database-based C rewrite was even much faster, > though. > Yes, as the disk IO is all the time, I think its best to keep the file size small. Then it has more chance of staying in memory. > * update-command-not-found should use apt-get indextargets > fixed > * You don't store components, hence you cannot tell people to enable > component. That's a very important use case for Ubuntu, where > not all components are enabled by default, but the database is > shipped in the package. > > You could just append /<component> to each package name I think, > and strip it away when displaying. > fixed > * You should use getopt_long() to parse command-line options, and > support -h, --help :) > fixed > * pts_lbsearch belongs into usr/lib/..., not usr/share/... > the seperate binary is gone > > * You don't implement a closest matches function: > > $ command-not-found thunderbrd > No command 'thunderbrd' found, did you mean: > Command 'thunderbird' from package 'thunderbird' (main) > thunderbrd: command not found > $ ./command-not-found thunderbrd > thunderbrd: command not found > > This one is really important. People do make typos or misremember > command names, so the tool needs to be able to deal with that > > Should be easy to implement though, although you might have to > search multiple times - once for each alternative. All you need is > > def similar_words(word): > """ return a set with spelling1 distance alternative spellings > > based on http://norvig.com/spell-correct.html"""; > alphabet = 'abcdefghijklmnopqrstuvwxyz-_' > s = [(word[:i], word[i:]) for i in range(len(word) + 1)] > deletes = [a + b[1:] for a, b in s if b] > transposes = [a + b[1] + b[0] + b[2:] for a, b in s if > len(b)>1] > replaces = [a + c + b[1:] for a, b in s for c in alphabet if > b] > inserts = [a + c + b for a, b in s for c in alphabet] > return set(deletes + transposes + replaces + inserts) > > And search for what that returns. And you don't need to search for > those > at all if you have a direct match. > > fixed, and I believe bit-for-bit identical > * It needs to be translated - also very important. > I made a pot file and used translations from the python version, but I can't get my app to look for translations (as examined through strace). I read the gettext manual and do not know what I am doing wrong. > > * You need to Conflict with command-not-found and not Break AFAIUI > > fixed > * You should not depend on grep, sed, coreutils, they are Essential. > > fixed, now it uses ruby as my shell was hacky. > * You do have to Depend on apt-file, as that configures apt to download > the Contents files > > fixed > * You should not have identifiers starting with _ in the program, these > are reserved for the C implementation (like _cleanup_free_). > > fixed > Yes, and these are basically the same reasons my C prototype is > not in the archive. Also, I did not put a lot of work into it, as > I was waiting for PackageKit to take that over, but that was not > done yet. > > I think it's a worthwhile approach, and I can see it replacing > command-not-found if those tiny issues have been fixed. Then you > could also avoid the -ng moniker, and just take over the main > package (if Zygmunt does not mind), which also avoids a month > long NEW process :) > > -- > Debian Developer - deb.li/jak | jak-linux.org - free software dev > Ubuntu Core Developer de, en speaker >
