Re: Protecting old temporary objects being reused from concurrent "git gc"?
- From
Jeff King <peff@peff.net>
- Date
- Nov 15, 2016, 17:40 UTC
- Message-ID
- <20161115174028.zvohfcw4jse3jrmm@sigill.intra.peff.net>
- In-Reply-To
- <1479231184.2406.88.camel@mattmccutchen.net>
On Tue, Nov 15, 2016 at 12:33:04PM -0500, Matt McCutchen wrote:
Show 8 quoted lines
> On Tue, 2016-11-15 at 12:06 -0500, Jeff King wrote: > > - when an object write is optimized out because we already have the > > object, git will update the mtime on the file (loose object or > > packfile) to freshen it > > FWIW, I am not seeing this happen when I do "git read-tree --prefix" > followed by "git write-tree" using the current master (3ab2281). See > the attached test script.
The optimization I'm thinking about is the one from write_sha1_file(), which learned to freshen in 33d4221c7 (write_sha1_file: freshen existing objects, 2014-10-15).
I suspect the issue is that read-tree populates the cache-tree index extension, and then write-tree omits the object write before it even gets to write_sha1_file(). The solution is that it should probably be calling one of the freshen() functions (possibly just replacing has_sha1_file() with check_and_freshen(), but I haven't looked).
I'd definitely welcome patches in this area.
> OK. I'll write a patch to add a summary of this information to the > git-gc man page.
Sounds like a good idea. Thanks.
-Peff