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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Pratyush Yadav <me@yadavpratyush.com>
Cc: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org, Bert Wesarg <bert.wesarg@googlemail.com>
Subject: Re: [PATCH v4 1/1] Make gitdir work with worktrees, respect core.hooksPath, etc
Date: Mon, 14 Oct 2019 00:18:51 +0200 (CEST)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.1910140015500.46@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <20191013185540.fwyn4ox5dbyxgvnh@yadavpratyush.com>

Hi Pratyush,

On Mon, 14 Oct 2019, Pratyush Yadav wrote:

> On 12/10/19 11:24PM, Johannes Schindelin wrote:
> > Hi Pratyush,
> >
> > On Sat, 12 Oct 2019, Pratyush Yadav wrote:
> >
> > > On 08/10/19 04:33AM, Johannes Schindelin via GitGitGadget wrote:
> > >
> > > > @@ -1453,10 +1501,16 @@ proc rescan {after {honor_trustmtime 1}} {
> > > >  	global HEAD PARENT MERGE_HEAD commit_type
> > > >  	global ui_index ui_workdir ui_comm
> > > >  	global rescan_active file_states
> > > > -	global repo_config
> > > > +	global repo_config _gitdir_cache
> > > >
> > > >  	if {$rescan_active > 0 || ![lock_index read]} return
> > > >
> > > > +	# Only re-prime gitdir cache on a full rescan
> > > > +	if {$after ne "ui_ready"} {
> > >
> > > What do you mean by a "full rescan"? I assume you use it as the
> > > differentiator between `ui_do_rescan` (called when you hit F5 or choose
> > > rescan from the menu) and `do_rescan` (called when you revert a line or
> > > hunk), and a "full rescan" refers to `ui_do_rescan`.
> > >
> > > Well in that case, this check is incorrect. `do_rescan` passes only
> > > "ui_ready" and `ui_do_rescan` passes "force_first_diff ui_ready".
> > >
> > > But either way, I'm not a big fan of this. This check makes assumptions
> > > about the behaviour of its callers based on what they pass to $after.
> > > The way I see it, $after should be a black box to `rescan`, and it
> > > should make absolutely no assumptions about it.
> > >
> > > Doing it this way is really brittle, and would break as soon as someone
> > > changes the behaviour of `ui_do_rescan`. If someone in the future passes
> > > a different value in $after, this would stop working as intended and
> > > would not refresh the cached list on a rescan.
> > >
> > > So, I think a better place for this if statement would be in
> > > `ui_do_rescan`. This would mean adding a new function that does this.
> > > But if we unset _gitdir_cache in prime_gitdir_cache (I see no reason not
> > > to), we can get away with just something like:
> > >
> > >   proc ui_do_rescan {} {
> > >   	rescan {prime_gitdir_cache; ui_ready}
> > >   }
> > >
> > > Though since `prime_gitdir_cache` does not really depend on the rescan
> > > being finished, something like this would also work fine:
> > >
> > >   proc ui_do_rescan {} {
> > >   	rescan ui_ready
> > >   	prime_gitdir_cache
> > >   }
> >
> > That was my first attempt. However, there is a very important piece of
> > code that is even still quoted above: that `if {$rescan_active > 0 ||
> > ![lock_index read]} return` part.
> >
> > I do _not_ want to interfere with an actively-going-on rescan. If there
> > is an active one, I don't want to re-prime the `_gitdir` cache.
>
> Good catch! In that case I suppose refreshing the cache in $after would
> be the way to go (IOW, the former of my two suggestions). Anything
> $after won't get executed if we return early from that check.

The obvious problem with that solution is that the `_gitdir` is reset
_after_ the rescan. In my solution, it is reset _before_, as I have no
idea how often the `_gitdir` values are used during a rescan (and if
none of they were, I would like to be very cautious to prepare for a
future where any of those `_gitdir` values _are_ used during a rescan).

So I am afraid that I find way too serious problems with both of your
proposed alternatives.

Ciao,
Johannes

>
> > That was the reason why I put the additional code into `rescan` rather
> > than into `ui_do_rescan()`.
> >
> > Ciao,
> > Johannes
> >
> > >
> > > This would allow us to do these two things in parallel since `rescan` is
> > > asynchronous. But that would also mean it is possible that the status
> > > bar would show "Ready" while `prime_gitdir_cache` is still executing.
> > >
> > > I can't really make up my mind on what is better. I'm inclining on using
> > > the latter way, effectively trading a bit of UI inconsistency for
> > > performance (at least in theory).
> > >
> > > Thoughts?
> > >
> > > > +		array unset _gitdir_cache
> > > > +		prime_gitdir_cache
> > > > +	}
> > > > +
> > > >  	repository_state newType newHEAD newMERGE_HEAD
> > > >  	if {[string match amend* $commit_type]
> > > >  		&& $newType eq {normal}
>
> --
> Regards,
> Pratyush Yadav
>
>

  reply	other threads:[~2019-10-13 22:19 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-26 21:17 [PATCH 0/1] git-gui: respect core.hooksPath, falling back to .git/hooks Johannes Schindelin via GitGitGadget
2019-09-26 21:17 ` [PATCH 1/1] " Johannes Schindelin via GitGitGadget
2019-09-26 22:36   ` Pratyush Yadav
2019-09-27  6:10     ` Bert Wesarg
2019-09-27 13:05       ` Pratyush Yadav
2019-09-30  9:42         ` Johannes Schindelin
2019-10-01 13:31           ` Pratyush Yadav
2019-10-01 17:38             ` Johannes Schindelin
2019-10-04 16:48               ` Pratyush Yadav
2019-10-04 19:56                 ` Johannes Schindelin
2019-09-30  9:45 ` [PATCH v2 0/1] git-gui: " Johannes Schindelin via GitGitGadget
2019-09-30  9:45   ` [PATCH v2 1/1] " Johannes Schindelin via GitGitGadget
2019-10-04 21:41   ` [PATCH v3 0/1] git-gui: " Johannes Schindelin via GitGitGadget
2019-10-04 21:41     ` [PATCH v3 1/1] Fix gitdir e.g. to respect core.hooksPath Johannes Schindelin via GitGitGadget
2019-10-08  0:29       ` Pratyush Yadav
2019-10-08 11:30         ` Johannes Schindelin
2019-10-08 11:33     ` [PATCH v4 0/1] git-gui: respect core.hooksPath, falling back to .git/hooks Johannes Schindelin via GitGitGadget
2019-10-08 11:33       ` [PATCH v4 1/1] Make gitdir work with worktrees, respect core.hooksPath, etc Johannes Schindelin via GitGitGadget
2019-10-11 22:26         ` Pratyush Yadav
2019-10-12 21:24           ` Johannes Schindelin
2019-10-13 18:55             ` Pratyush Yadav
2019-10-13 22:18               ` Johannes Schindelin [this message]
2019-10-17 18:34                 ` Pratyush Yadav
2019-10-14  8:14               ` Johannes Schindelin

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