Subject: Re: [PATCH 3/3] revision: insert unsorted, then sort in prepare_revision_walk()

From: Martin Fick <[email-masked]>
Date: Mon, 2 Apr 2012 17:16:22 -0600

On Monday, April 02, 2012 02:37:28 pm Jeff King wrote:
> On Mon, Apr 02, 2012 at 09:51:21AM -0700, Shawn O. Pearce 
wrote:
> > Probably. But we tend to hate caches in Git because
> > they can get stale and need to be rebuilt, and are
> > redundant with the base data. The mythical "pack v4"
> > work was going to approach this problem by storing the
> > commit timestamps uncompressed in a more machine
> > friendly format. Unfortunately the work has been
> > stalled for years.
...

> So it's sort-of a cache, in that it's redundant with the
> actual data. But staleness and writing issues are a lot
> simpler, since it only gets updated when we index the
> pack (and the pack index in general is a similar
> concept; 
...
except that in the case of timestamps, it never even gets 
stale, it simply misses some entries or keeps entries around 
which should go away.  So even if the pack files are rebuilt 
and someone forgets to update the timestamp index, it 
shouldn't cause any problems:  the timestamps which are 
there should still work and likely will still be useful,

-Martin

-- 
Employee of Qualcomm Innovation Center, Inc. which is a 
member of Code Aurora Forum