From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gummerer Subject: Re: [PATCH 5.5/22] Add documentation for the index api Date: Thu, 11 Jul 2013 13:30:10 +0200 Message-ID: <87ppupcp19.fsf@gmail.com> References: <1373184720-29767-1-git-send-email-t.gummerer@gmail.com> <1373184720-29767-6-git-send-email-t.gummerer@gmail.com> <87pputqowr.fsf@gmail.com> <871u78rcw0.fsf@gmail.com> <87wqozpk9s.fsf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Git Mailing List , Thomas Rast , Michael Haggerty , Junio C Hamano , Robin Rosenberg To: Duy Nguyen X-From: git-owner@vger.kernel.org Thu Jul 11 13:30:23 2013 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UxF4o-0001xZ-3Q for gcvg-git-2@plane.gmane.org; Thu, 11 Jul 2013 13:30:22 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755593Ab3GKLaQ (ORCPT ); Thu, 11 Jul 2013 07:30:16 -0400 Received: from mail-ee0-f42.google.com ([74.125.83.42]:44360 "EHLO mail-ee0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750904Ab3GKLaP (ORCPT ); Thu, 11 Jul 2013 07:30:15 -0400 Received: by mail-ee0-f42.google.com with SMTP id c4so5472469eek.29 for ; Thu, 11 Jul 2013 04:30:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:in-reply-to:references:user-agent:date :message-id:mime-version:content-type; bh=ARPwsE/JrcZPUCqrsX5xIauTdTB9NKrBlUMGgu9A5qM=; b=ckkOW+eChTAeN+SpPLlONh3f+AJMhXKjfG1zqN3RkHzS3jOYDZulmKZJqa7p4bNzbC i3XpyOgYy9c+MKNqgNG2imGmU/VvAEBQEvLTy5p3Nra7E9Ib9jLPmybyXkTjSlzAH+Ab Q/PK8YOAcbVmWHJiV3RIdR/H6DRSQo+tSKXCFYyubUn9dy+036q14iqj7Nudt2QzELlR XaD3p+TyqS8jLieai/l6XZGG7t9qa6divo+2L4sc1m1wA+yu/dGXZM/v4RERHTkKzfT/ /pPTtVmrK4XoFYhqWZN5xBg9qUdFpx7sg32cQuDRUGwKc3BodueIOl+m8eUMhyjbAB+6 oU3w== X-Received: by 10.14.47.196 with SMTP id t44mr30213918eeb.18.1373542213483; Thu, 11 Jul 2013 04:30:13 -0700 (PDT) Received: from localhost ([2a02:27e8:10:1047:0:dacb:1376:714a]) by mx.google.com with ESMTPSA id e44sm68260476eeh.11.2013.07.11.04.30.11 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 11 Jul 2013 04:30:12 -0700 (PDT) In-Reply-To: User-Agent: Notmuch/0.15.2+119~gf0dfda5 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-unknown-linux-gnu) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Duy Nguyen writes: > On Wed, Jul 10, 2013 at 3:10 AM, Thomas Gummerer wrote: >>> If you happen to know that certain entries match the given pathspec, >>> you could help the caller avoid match_pathspec'ing again by set a bit >>> in ce_flags. >> >> I currently don't know which entries do match the pathspec from just >> reading the index file, additional calls would be needed. I don't think >> that would be worth the overhead. > > Yeah I now see that you select what to load in v5 with the adjusted > pathspec, not the input pathspec. Originally I thought you match the > input pathspec against every file entry in the index :P Your adjusted > pathspec looks like what common_prefix is for. It's cheaper than > creating adjusted_pathspec from match_pathspec and reduces loading in > major cases, where glob is not used. > > Still, creating an adjusted pathspec this way looks iffy. You need to > understand pathspec in order to strip the filename part out to match > the directory match only. An alternative is use > tree_entry_interesting. It goes along well with tree traversal and can > be used to match directories with original pathspec. Once you see it > matches an entry in a directory, you could skip matching the rest of > the files and load the whole directory. read_index_filtered_v5 and > read_entries may need some tweaking though. I'll try it and post a > patch later if I succeed. Hrm, I played around a bit with this idea, but I couldn't figure out how to make it work. For it to work we would still have to load some entries in a directory at least? Or is there a way to match the directories, which I just haven't figured out yet? >>> To know which entry exists in the index and which is >>> new, use another flag. Most reader code won't change if we do it this >>> way, all match_pathspec() remain where they are. >> >> Hrm you mean to know which cache entries are added (or changed) in the >> in-memory index and will have to be written later? I'm not sure I >> understand correctly what you mean here. > > Oh.. The "to know.." sentence was nonsense. We probably don't need to > know. We may track changed entries for partial writing, but let's > leave that out for now. Ok, makes sense. >>>> +`index_change_filter_opts(opts)`:: >>>> + This function again has a slightly different functionality for >>>> + index-v2 and index-v5. >>>> + >>>> + For index-v2 it simply changes the filter_opts, so >>>> + for_each_index_entry uses the changed index_opts, to iterate >>>> + over a different set of cache entries. >>>> + >>>> + For index-v5 it refreshes the index if the filter_opts have >>>> + changed and sets the new filter_opts in the index state, again >>>> + to iterate over a different set of cache entries as with >>>> + index-v2. >>>> + >>>> + This has some optimization potential, in the case that the >>>> + opts get stricter (less of the index should be read) it >>>> + doesn't have to reload anything, but currently does. >>> >>> The only use case I see so far is converting a partial index_state >>> back to a full one. Apart from doing so in order to write the new >>> index, I think some operation (like rename tracking in diff or >>> unpack-trees) may expect full index. I think we should support that. I >>> doubt we need to change pathspec to something different than the one >>> we used to load the index. When a user passes a pathspec to a command, >>> the user expects the command to operate on that set only, not outside. >> >> One application was in ls-files, where we strip the trailing slash from >> the pathspecs for submodules. But when we let the caller filter the >> rest out it's not needed anymore. We load all entries without the >> trailing slash anyway. > > That submodule trailing slash stripping code will be moved away soon > (I've been working on it for some time now). There's similar code in > pathspec.c. I hope by the time this series becomes a candidate for > 'next', those pathspec manipulation is already gone. For > strip_trailing_slash_from_submodules, peeking in index file for a few > entries is probably ok. For check_path_for_gitlink, full index is > loaded until we figure out a clever way. Ah great, for now I'll just not use the for_each_index_entry function in ls-files, and then change the code later once the stripping code is moved away. >>> Some thoughts about the writing api. >>> >>> In think we should avoid automatically converting partial index into a >>> full one before writing. Push that back to the caller and die() when >>> asked to update partial index. They know at what point the index may >>> be updated and even what part of it may be updated. I think all >>> commands fall into two categories, tree-wide updates (merge, >>> checkout...) and limited by the user-given pathspec. "what part to be >>> updated" is not so hard to determine. >> >> Hrm this is only true if index entries are added or removed, not if they >> are only changed. If they are only changed we can write a partially >> read index once we have partial writing. > > Yep. We can detect if changes are updates only, no additions nor > removals. If so do partial write, else full write. These little > details are hidden from the user, as long as they keep their promise > about read/write regions. > >> For now it would make sense to just die() though, until we have that in place. > > Agreed. > -- > Duy