[PATCH 2/2] dim: Try to gc the rr-cache

[Daniel Vetter]

On Fri, Jul 14, 2017 at 12:57:23PM +0300, Jani Nikula wrote:
> On Thu, 13 Jul 2017, Sean Paul <seanpaul at chromium.org> wrote:
> > On Wed, Jul 12, 2017 at 02:12:24PM +0200, Daniel Vetter wrote:
> >> The problem is that we have a distributed cache - every committer has
> >> a copy. Which means even just a slight clock skew will make sure that
> >> a naive gc algorithm results in lots of thrashing around.
> >> 
> >> To fix this add a huge hysteresis: Only add files newer than 1 day,
> >> and only remove them when older than 60 days. As long as people have
> >> reasonable accurate clocks on their machines this should work.
> >> 
> >> A different problem is that we can't use filesystem timestamps (and
> >> hence can't use git rerere gc): When someone comes back from vacations
> >> and updates git rerere, all the files will have current timestamps,
> >> even when they've been pushed out weeks ago. To fix that, use the git
> >> log to judge old files to remove. Also, remove old files before adding
> >> new ones, to avoid confusion.
> >> 
> >> Also, we need to teach the cp -r to preserve timestamps, otherwise
> >> this won't work.
> >> 
> >> v2: Use git log to remove old files.
> >> 
> >> v3: Remove the debug uncommenting (Sean).
> >> 
> >> v4: Split out code movement and explain better what's going on (Jani).
> >
> > Yeah, much easier to digest with the split.
> >
> > Reviewed-by: Sean Paul <seanpaul at chromium.org>
> 
> I'll trust that and hope for the best. ;)

Pushed and asked everyone I managed to ping over irc to upgrade. Let's see
how often we have to push out a revert until the old stuff is dead for
good (I already screwed up twice locally ...).
-Daniel

> 
> BR,
> Jani.
> 
> 
> >
> >> 
> >> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> >> ---
> >>  dim | 10 ++++++++--
> >>  1 file changed, 8 insertions(+), 2 deletions(-)
> >> 
> >> diff --git a/dim b/dim
> >> index b788edd29653..79d616cbf354 100755
> >> --- a/dim
> >> +++ b/dim
> >> @@ -513,9 +513,15 @@ function commit_rerere_cache
> >>  
> >>  		git pull >& /dev/null
> >>  		rm $(rr_cache_dir)/rr-cache -Rf &> /dev/null || true
> >> -		cp $(rr_cache_dir)/* rr-cache -r
> >> +		cp $(rr_cache_dir)/* rr-cache -r --preserve=timestamps
> >>  		git add ./*.patch >& /dev/null || true
> >> -		git add rr-cache/* > /dev/null
> >> +		for file  in $(git ls-files); do
> >> +			if ! git log --since="60 days ago" --name-only -- $file | grep $file &> /dev/null; then
> >> +				git rm $file &> /dev/null
> >> +				echo deleting $file
> >> +			fi
> >> +		done
> >> +		find rr-cache/ -ctime -1 -type f -print0 | xargs -0 git add > /dev/null
> >>  		git rm rr-cache/rr-cache &> /dev/null || true
> >>  		if git commit -m "$time: $integration_branch rerere cache update" >& /dev/null; then
> >>  			echo -n "New commit. "
> >> -- 
> >> 2.13.2
> >> 
> >> _______________________________________________
> >> dri-devel mailing list
> >> dri-devel at lists.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch