From: Phillip Wood <firstname.lastname@example.org> To: Johannes Schindelin <Johannes.Schindelin@gmx.de>, Elijah Newren <email@example.com> Cc: Elijah Newren via GitGitGadget <firstname.lastname@example.org>, Git Mailing List <email@example.com>, Philip Oakley <firstname.lastname@example.org> Subject: Re: unifying sequencer's options persisting, was Re: [PATCH v2] sequencer: fix edit handling for cherry-pick and revert messages Date: Fri, 2 Apr 2021 14:10:16 +0100 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> one more thought below... On 02/04/2021 12:28, Phillip Wood wrote: > Hi Dscho and Elijah > > On 31/03/2021 14:48, Johannes Schindelin wrote: >> Hi, >> >> On Tue, 30 Mar 2021, Elijah Newren wrote: >> >>> On Tue, Mar 30, 2021 at 3:13 AM Johannes Schindelin >>> <Johannes.Schindelin@gmx.de> wrote: >>> >>>> I'll allow myself one tangent: the subject of the sequencer's Unix >>>> shell script heritage seems to come up with an increasing frequency, >>>> in particular the awful "let's write out one file per setting" >>>> strategy. >>>> >>>> I would _love_ for `save_opts()` to write a JSON instead (or an INI >>>> via the `git_config_*()` family of functions, as is done already by >>>> the cherry-pick/revert stuff), now that we no longer have any shell >>>> script backend (apart from `--preserve-merges`, but that one is on its >>>> way out anyway). >>>> >>>> The one thing that concerns me with this idea is that I know for a >>>> fact that some enterprisey users play games with those files inside >>>> `<GIT_DIR>/rebase-merge` that should be considered internal >>>> implementation details. Not sure how to deprecate that properly, I >>>> don't think we have a sane way to detect whether users rely on these >>>> implementation details other than breaking their expectations, which >>>> is not really a gentle way to ask them to update their scripts. > > I think it depends if users are just reading the files or writing to > them. If they are reading them (which my scripts do) then we could > continue to write the important files along side the new single-file > that git actually reads. I think there is a distinction between the > files such as git-rebase-todo which hold state and the one-line files > which hold the options passed by the user. For example I have scripts > that read git-rebase-todo, rewritten-pending, rewritten-list, amend-head > and check that author-script exists. If a script starts a rebase then it > should know what options are in effect without reading them from > .git/rebase-merge. > >>> Ooh, I'm glad you took this tangent. May I follow it for a second? >>> I'd really, really like this too, for three reasons: >>> >>> 1) I constantly get confused about the massive duplication and >>> difference in control structures and which ones affect which type of >>> operations in sequencer.c. Having them both use an ini-file would >>> allow us to remove lots of that duplication. I'm sure there'll still >>> be some rebase-specific or cherry-pick-specific options, but we don't >>> need a separate parallel structure for every piece of config. One thing to bear in mind is that you can cherry-pick or revert a sequence of commits while rebasing - I think that means we need to store the state for rebase in a separate location to that for cherry-pick/revert Best Wishes Phillip >>> 2) In my merge-ort optimization work, rebasing 35 commits in linux.git >>> across a massive set of 26K upstream renames has dropped rename >>> detection time from the top spot. And it also dropped several other >>> things in the merge machinery from their spots as well. Do you know >>> what's the slowest now? Wasted time from sequencer.c: the unnecessary >>> process forking and all the useless disk writing (which I suspect is >>> mostly updating the index and working directory but also writing all >>> the individual control files under .git/rebase-merge/). And this >>> stuff from sequencer.c is not just barely the slowest part, it's the >>> slowest by a wide margin. > > I think we do a lot of needless writing which is unrelated to whether we > write to one file or may files. For example from memory picking a commit > involves writing the 'message', 'author-script', 'rewritten-pending' > (which is often immediately deleted), 'rewritten-list' (we append to > that one) 'CHERRY_PICK_HEAD' (which is immediately deleted unless the > pick has become empty), 'git-rebase-todo' is completely rewritten, and > 'done' is appended to. None of this is necessary. For rewording and > merges the only thing that needs to be written is the commit message for > the external process to use. Fixup and squash add a couple more files > into the mix. > > I think we would save a lot by only syncing the state to disk when we > stop or run an exec command (the state needs to be synced so exec > commands can alter the todo list). In those cases we need to write the > index and possibly run an external process so writing a couple of files > is probably insignificant. > > Where I think we can usefully consolidate is the one-line files which > store the options rather than state - these are read an written much > less frequently so I don't think they have much of a performance hit but > it would be much nicer to just serialize the options to a single file. > >>> >>> 3) I also want to allow cherry-picking or rebasing branches that >>> aren't even checked out (assuming no conflicts are triggered; >>> otherwise an error can be shown with the user asked to repeat with the >>> operation connected to an active working directory). > > Exciting! > >>> For such an >>> operation, the difference between "cherry-pick" and "rebase" is nearly >>> irrelevant so you'd expect the code to be the same; every time I look >>> at the code, though, it seems that the control structures are >>> separating these two types of operations in more areas than just the >>> reading and writing of the config. > > Yes this can be confusing, for example rebase and cherry-pick handle the > todo list differently. Rebase removes the command before trying to pick > the commit and adds it back if the pick fails for a non-conflict reason, > cherry-pick only removes the command if the pick is successful. > > Best Wishes > > Phillip > >> Excellent, we're in agreement, then. >> >> The remaining question is: how do we want to go about it? Do we just want >> to codify the notion that these are internal details that are nobody's >> business, and if they are using the exact file system layout of the >> current sequencer, then it's their responsibility to adapt? >> >> Ciao, >> Dscho >> >
next prev parent reply other threads:[~2021-04-02 13:10 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-26 7:16 [PATCH] " Elijah Newren via GitGitGadget 2021-03-26 12:27 ` Philip Oakley 2021-03-26 15:12 ` Elijah Newren 2021-03-28 1:30 ` Junio C Hamano 2021-03-29 9:23 ` Phillip Wood 2021-03-29 20:52 ` Junio C Hamano 2021-03-29 21:25 ` Elijah Newren 2021-03-30 2:09 ` [PATCH v2] " Elijah Newren via GitGitGadget 2021-03-30 10:13 ` Johannes Schindelin 2021-03-30 18:47 ` Junio C Hamano 2021-03-30 20:16 ` Elijah Newren 2021-03-31 17:36 ` Ævar Arnfjörð Bjarmason 2021-03-31 17:52 ` Elijah Newren 2021-03-31 18:01 ` Junio C Hamano 2021-04-01 16:31 ` Elijah Newren 2021-03-30 19:37 ` Elijah Newren 2021-03-31 13:48 ` unifying sequencer's options persisting, was " Johannes Schindelin 2021-04-02 11:28 ` Phillip Wood 2021-04-02 13:10 ` Phillip Wood [this message] 2021-04-02 21:01 ` Junio C Hamano 2021-04-02 22:18 ` Elijah Newren 2021-04-02 22:27 ` Junio C Hamano 2021-04-08 2:40 ` Johannes Schindelin 2021-04-08 17:45 ` Junio C Hamano 2021-04-08 19:58 ` Christian Couder 2021-04-09 13:53 ` Johannes Schindelin 2021-03-31 6:52 ` [PATCH v3] " Elijah Newren via GitGitGadget 2021-03-31 14:38 ` Johannes Schindelin 2021-04-02 11:40 unifying sequencer's options persisting, was Re: [PATCH v2] " Gabriel Young
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style List information: http://vger.kernel.org/majordomo-info.html * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --email@example.com \ --firstname.lastname@example.org \ --cc=Johannes.Schindelin@gmx.de \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --subject='Re: unifying sequencer'\''s options persisting, was Re: [PATCH v2] sequencer: fix edit handling for cherry-pick and revert messages' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Code repositories for project(s) associated with this inbox: https://80x24.org/mirrors/git.git This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).