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From: Jonathan Tan <jonathantanmy@google.com>
To: steadmon@google.com
Cc: git@vger.kernel.org, Jonathan Tan <jonathantanmy@google.com>
Subject: Re: [PATCH] clone: do faster object check for partial clones
Date: Wed,  3 Apr 2019 11:58:10 -0700	[thread overview]
Message-ID: <20190403185810.8787-1-jonathantanmy@google.com> (raw)
In-Reply-To: <6de682d5e48186970644569586fc6613763d5caa.1554312374.git.steadmon@google.com>

> For partial clones, doing a full connectivity check is wasteful; we skip
> promisor objects (which, for a partial clone, is all known objects), and
> excluding them all from the connectivity check can take a significant
> amount of time on large repos.

Instead of "excluding them all", I would word this as "enumerating them
all so that we can exclude them" - the enumerating is the slow part, not
the excluding (which actually makes things faster).

> +	if (opt->check_refs_only) {
> +		/*
> +		 * For partial clones, we don't want to walk the full commit
> +		 * graph because we're skipping promisor objects anyway. We
> +		 * should just check that objects referenced by wanted refs were
> +		 * transferred.

The enumeration of promisor objects to be excluded is done through
for_each_packed_object() (see is_promisor_object()), not through walking
the commit graph. Maybe reword this comment to be similar to what I've
suggested for the commit message.

> @@ -46,6 +46,14 @@ struct check_connected_options {
>  	 * during a fetch.
>  	 */
>  	unsigned is_deepening_fetch : 1;
> +
> +	/*
> +	 * If non-zero, only check the top-level objects referenced by the
> +	 * wanted refs (passed in as cb_data). This is useful for partial
> +	 * clones, where this can be much faster than excluding all promisor
> +	 * objects prior to walking the commit graph.
> +	 */
> +	unsigned check_refs_only : 1;
>  };

Same enumerating vs excluding comment as before.

Aside from that: thinking from scratch, we want something that tells
check_connected() to avoid anything that enumerates the list of promised
objects, since the objects that we're checking are all promisor objects,
and thus any outgoing links are automatically promised. I would include
some of this explanation in the comment, but in the interest of trying
to avoid a bikeshedding discussion, I don't consider this necessary.

  reply	other threads:[~2019-04-03 18:58 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-03 17:27 [PATCH] clone: do faster object check for partial clones Josh Steadmon
2019-04-03 18:58 ` Jonathan Tan [this message]
2019-04-03 19:41 ` Jeff King
2019-04-03 20:57   ` Jonathan Tan
2019-04-04  0:21     ` Josh Steadmon
2019-04-04  1:33     ` Jeff King
2019-04-04 22:53 ` [PATCH v2] rev-list: exclude promisor objects at walk time Josh Steadmon
2019-04-04 23:08   ` Jeff King
2019-04-04 23:47     ` Josh Steadmon
2019-04-05  0:00       ` Jeff King
2019-04-05  0:09         ` Josh Steadmon
2019-04-08 20:59           ` Josh Steadmon
2019-04-08 21:06 ` [PATCH v3] " Josh Steadmon
2019-04-08 22:23   ` Christian Couder
2019-04-08 23:12     ` Josh Steadmon
2019-04-09 15:14   ` Junio C Hamano
2019-04-09 15:15     ` Jeff King
2019-04-09 15:43       ` Junio C Hamano
2019-04-09 16:35         ` Josh Steadmon
2019-04-09 18:04   ` SZEDER Gábor
2019-04-09 23:42     ` Josh Steadmon
2019-04-11  4:06       ` Jeff King
2019-04-12 22:38         ` Josh Steadmon
2019-04-13  5:34           ` Jeff King
2019-04-19 20:26             ` Josh Steadmon
2019-04-19 21:00 ` [PATCH v4] clone: do faster object check for partial clones Josh Steadmon
2019-04-22 21:31   ` Jeff King

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