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From: Junio C Hamano <gitster@pobox.com>
To: Derrick Stolee <derrickstolee@github.com>
Cc: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org, me@ttaylorr.com, vdye@github.com,
	avarab@gmail.com, steadmon@google.com, chooglen@google.com
Subject: Re: [PATCH v2 01/10] bundle: optionally skip reachability walk
Date: Mon, 23 Jan 2023 12:13:33 -0800	[thread overview]
Message-ID: <xmqqilgxm2ky.fsf@gitster.g> (raw)
In-Reply-To: <eae85534-89c9-6eff-69d5-7d4b2be85fb6@github.com> (Derrick Stolee's message of "Mon, 23 Jan 2023 13:24:26 -0500")

Derrick Stolee <derrickstolee@github.com> writes:

> We are specifically removing the requirement that the objects are
> reachable from refs, we still check that the objects are in the
> object store. Thus, we can only be in a bad state afterwards if
> the required objects for a bundle were in the object store,
> previously unreachable, and one of these two things happened:
>
> 1. Some objects reachable from those required commits were already
>    missing in the repository (so the repo's object store was broken
>    but only for some unreachable objects).

A repository having some unreachable objects floating in the object
store is not corrupt.  As long as all the objects reachable from refs
are connected, that is a perfectly sane state.

But allowing unbundling with the sanity check loosened WILL corrupt
it, at the moment you point some objects from the bundle with refs.

> I think we should trust the repository to not be in the first state,

So, I think this line of thought is simply mistaken.

>> I am OK as long as we check the assumption holds true at the end;
>> this looks like a good optimization.
>  
> So are you recommending that we verify all objects reachable from
> the new refs/bundles/* are present after unbundling?

Making sure that prerequisites are connected will reduce the span of
the DAG we would need to verify.  After unbundling all bundles, but
before updating the refs to point at the tips in the bundles, if we
can make sure that these prerequisite objects named in the bundles
are reachable from the tips recorded in the bundles, while stopping
the traversal at the tips of original refs (remember: we have only
updated objects in the object store, but haven't updated the refs from
the bundles), that would allow us to make sure that the updates to
refs proposed by the bundles will not corrupt the repository.


  reply	other threads:[~2023-01-23 20:13 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-06 20:36 [PATCH 0/8] Bundle URIs V: creationToken heuristic for incremental fetches Derrick Stolee via GitGitGadget
2023-01-06 20:36 ` [PATCH 1/8] t5558: add tests for creationToken heuristic Derrick Stolee via GitGitGadget
2023-01-17 18:17   ` Victoria Dye
2023-01-17 21:00     ` Derrick Stolee
2023-01-06 20:36 ` [PATCH 2/8] bundle-uri: parse bundle.heuristic=creationToken Derrick Stolee via GitGitGadget
2023-01-09  2:38   ` Junio C Hamano
2023-01-09 14:20     ` Derrick Stolee
2023-01-17 19:13   ` Victoria Dye
2023-01-06 20:36 ` [PATCH 3/8] bundle-uri: parse bundle.<id>.creationToken values Derrick Stolee via GitGitGadget
2023-01-09  3:08   ` Junio C Hamano
2023-01-09 14:41     ` Derrick Stolee
2023-01-17 19:24   ` Victoria Dye
2023-01-06 20:36 ` [PATCH 4/8] bundle-uri: download in creationToken order Derrick Stolee via GitGitGadget
2023-01-09  3:22   ` Junio C Hamano
2023-01-09 14:58     ` Derrick Stolee
2023-01-19 18:32   ` Victoria Dye
2023-01-20 14:56     ` Derrick Stolee
2023-01-06 20:36 ` [PATCH 5/8] clone: set fetch.bundleURI if appropriate Derrick Stolee via GitGitGadget
2023-01-19 19:42   ` Victoria Dye
2023-01-20 15:42     ` Derrick Stolee
2023-01-06 20:36 ` [PATCH 6/8] bundle-uri: drop bundle.flag from design doc Derrick Stolee via GitGitGadget
2023-01-19 19:44   ` Victoria Dye
2023-01-06 20:36 ` [PATCH 7/8] fetch: fetch from an external bundle URI Derrick Stolee via GitGitGadget
2023-01-19 20:34   ` Victoria Dye
2023-01-20 15:47     ` Derrick Stolee
2023-01-06 20:36 ` [PATCH 8/8] bundle-uri: store fetch.bundleCreationToken Derrick Stolee via GitGitGadget
2023-01-19 22:24   ` Victoria Dye
2023-01-20 15:53     ` Derrick Stolee
2023-01-23 15:21 ` [PATCH v2 00/10] Bundle URIs V: creationToken heuristic for incremental fetches Derrick Stolee via GitGitGadget
2023-01-23 15:21   ` [PATCH v2 01/10] bundle: optionally skip reachability walk Derrick Stolee via GitGitGadget
2023-01-23 18:03     ` Junio C Hamano
2023-01-23 18:24       ` Derrick Stolee
2023-01-23 20:13         ` Junio C Hamano [this message]
2023-01-23 22:30           ` Junio C Hamano
2023-01-24 12:27             ` Derrick Stolee
2023-01-24 14:14               ` [PATCH v2.5 01/11] bundle: test unbundling with incomplete history Derrick Stolee
2023-01-24 17:16                 ` Junio C Hamano
2023-01-24 14:16               ` [PATCH v2.5 02/11] bundle: verify using connected() Derrick Stolee
2023-01-24 17:33                 ` Junio C Hamano
2023-01-24 18:46                   ` Derrick Stolee
2023-01-24 20:41                     ` Junio C Hamano
2023-01-24 15:22               ` [PATCH v2 01/10] bundle: optionally skip reachability walk Junio C Hamano
2023-01-23 21:08         ` Junio C Hamano
2023-01-23 15:21   ` [PATCH v2 02/10] t5558: add tests for creationToken heuristic Derrick Stolee via GitGitGadget
2023-01-27 19:15     ` Victoria Dye
2023-01-23 15:21   ` [PATCH v2 03/10] bundle-uri: parse bundle.heuristic=creationToken Derrick Stolee via GitGitGadget
2023-01-23 15:21   ` [PATCH v2 04/10] bundle-uri: parse bundle.<id>.creationToken values Derrick Stolee via GitGitGadget
2023-01-23 15:21   ` [PATCH v2 05/10] bundle-uri: download in creationToken order Derrick Stolee via GitGitGadget
2023-01-27 19:17     ` Victoria Dye
2023-01-27 19:32       ` Junio C Hamano
2023-01-30 18:43         ` Derrick Stolee
2023-01-30 19:02           ` Junio C Hamano
2023-01-30 19:12             ` Derrick Stolee
2023-01-23 15:21   ` [PATCH v2 06/10] clone: set fetch.bundleURI if appropriate Derrick Stolee via GitGitGadget
2023-01-23 15:21   ` [PATCH v2 07/10] bundle-uri: drop bundle.flag from design doc Derrick Stolee via GitGitGadget
2023-01-23 15:21   ` [PATCH v2 08/10] fetch: fetch from an external bundle URI Derrick Stolee via GitGitGadget
2023-01-27 19:18     ` Victoria Dye
2023-01-23 15:21   ` [PATCH v2 09/10] bundle-uri: store fetch.bundleCreationToken Derrick Stolee via GitGitGadget
2023-01-23 15:21   ` [PATCH v2 10/10] bundle-uri: test missing bundles with heuristic Derrick Stolee via GitGitGadget
2023-01-27 19:21     ` Victoria Dye
2023-01-30 18:47       ` Derrick Stolee
2023-01-27 19:28   ` [PATCH v2 00/10] Bundle URIs V: creationToken heuristic for incremental fetches Victoria Dye
2023-01-31 13:29   ` [PATCH v3 00/11] " Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 01/11] bundle: test unbundling with incomplete history Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 02/11] bundle: verify using check_connected() Derrick Stolee via GitGitGadget
2023-01-31 17:35       ` Junio C Hamano
2023-01-31 19:31         ` Derrick Stolee
2023-01-31 19:36           ` Junio C Hamano
2023-01-31 13:29     ` [PATCH v3 03/11] t5558: add tests for creationToken heuristic Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 04/11] bundle-uri: parse bundle.heuristic=creationToken Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 05/11] bundle-uri: parse bundle.<id>.creationToken values Derrick Stolee via GitGitGadget
2023-01-31 21:22       ` Junio C Hamano
2023-01-31 13:29     ` [PATCH v3 06/11] bundle-uri: download in creationToken order Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 07/11] clone: set fetch.bundleURI if appropriate Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 08/11] bundle-uri: drop bundle.flag from design doc Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 09/11] fetch: fetch from an external bundle URI Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 10/11] bundle-uri: store fetch.bundleCreationToken Derrick Stolee via GitGitGadget
2023-01-31 13:29     ` [PATCH v3 11/11] bundle-uri: test missing bundles with heuristic Derrick Stolee via GitGitGadget
2023-01-31 22:01     ` [PATCH v3 00/11] Bundle URIs V: creationToken heuristic for incremental fetches Junio C Hamano

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