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.
> 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
