From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Jonathan Tan <jonathantanmy@google.com>,
git@vger.kernel.org, stolee@gmail.com
Subject: Re: [PATCH on master v2] revision: use commit graph in get_reference()
Date: Tue, 11 Dec 2018 05:54:40 -0500 [thread overview]
Message-ID: <20181211105439.GA8452@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqwooj5xpr.fsf@gitster-ct.c.googlers.com>
On Sun, Dec 09, 2018 at 09:51:28AM +0900, Junio C Hamano wrote:
> > -static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item)
> > +static struct commit *parse_commit_in_graph_one(struct repository *r,
> > + struct commit_graph *g,
> > + struct commit *shell,
> > + const struct object_id *oid)
>
> Now the complexity of the behaviour of this function deserves to be
> documented in a comment in front. Let me see if I can get it
> correctly without such a comment by explaining the function aloud.
>
> The caller may or may not have already obtained an in-core commit
> object for a given object name, so shell could be NULL but otherwise
> it could be used for optimization. When shell==NULL, the function
> looks up the commit object using the oid parameter instead. The
> returned in-core commit has the parents etc. filled as if we ran
> parse_commit() on it. If the commit is not yet in the graph, the
> caller may get a NULL even if the commit exists.
Yeah, this was the part that took me a bit to figure out, as well. The
optimization here is really just avoiding a call to lookup_commit(),
which will do a single hash-table lookup. I wonder if that's actually
worth this more complex interface (as opposed to just always taking an
oid and then always returning a "struct commit", which could be old or
new).
-Peff
next prev parent reply other threads:[~2018-12-11 10:55 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 22:42 [PATCH on sb/more-repo-in-api] revision: use commit graph in get_reference() Jonathan Tan
2018-12-04 23:12 ` Stefan Beller
2018-12-06 23:36 ` Jonathan Tan
2018-12-07 13:49 ` Derrick Stolee
2018-12-05 4:54 ` Jeff King
2018-12-06 23:54 ` Jonathan Tan
2018-12-07 8:53 ` Jeff King
2018-12-05 23:15 ` Junio C Hamano
2018-12-07 21:50 ` [PATCH on master v2] " Jonathan Tan
2018-12-09 0:51 ` Junio C Hamano
2018-12-09 1:49 ` Junio C Hamano
2018-12-11 10:54 ` Jeff King [this message]
2018-12-12 19:58 ` Jonathan Tan
2018-12-13 1:27 ` Jeff King
2018-12-13 16:20 ` Derrick Stolee
2018-12-13 18:54 ` [PATCH v3] " Jonathan Tan
2018-12-14 3:20 ` Junio C Hamano
2018-12-14 8:45 ` Jeff King
2019-01-25 15:33 ` Regression in: [PATCH on sb/more-repo-in-api] " SZEDER Gábor
2019-01-25 19:56 ` Stefan Beller
2019-01-25 22:01 ` Jonathan Tan
2019-01-25 22:14 ` SZEDER Gábor
2019-01-25 22:21 ` SZEDER Gábor
2019-01-27 13:08 ` [PATCH] object_as_type: initialize commit-graph-related fields of 'struct commit' SZEDER Gábor
2019-01-27 13:28 ` SZEDER Gábor
2019-01-27 18:40 ` Derrick Stolee
2019-01-28 16:15 ` Jeff King
2019-01-28 16:57 ` Jonathan Tan
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