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From: Jeff King <peff@peff.net>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, Chris Torek <chris.torek@gmail.com>,
	Derrick Stolee <derrickstolee@github.com>,
	Junio C Hamano <gitster@pobox.com>,
	Patrick Steinhardt <ps@pks.im>
Subject: Re: [PATCH v4 15/16] upload-pack.c: avoid enumerating hidden refs where possible
Date: Mon, 3 Jul 2023 02:26:44 -0400	[thread overview]
Message-ID: <20230703062644.GI3502534@coredump.intra.peff.net> (raw)
In-Reply-To: <19bf4a52d696b4789e6ab9c62f51d0ba955b7b6a.1687270849.git.me@ttaylorr.com>

On Tue, Jun 20, 2023 at 10:22:17AM -0400, Taylor Blau wrote:

> In a similar fashion as a previous commit, teach `upload-pack` to avoid
> enumerating hidden references where possible.
> 
> Note, however, that there are certain cases where cannot avoid
> enumerating even hidden references, in particular when either of:
> 
>   - `uploadpack.allowTipSHA1InWant`, or
>   - `uploadpack.allowReachableSHA1InWant`
> 
> are set, corresponding to `ALLOW_TIP_SHA1` and `ALLOW_REACHABLE_SHA1`,
> respectively.
> 
> When either of these bits are set, upload-pack's `is_our_ref()` function
> needs to consider the `HIDDEN_REF` bit of the referent's object flags.
> So we must visit all references, including the hidden ones, in order to
> mark their referents with the `HIDDEN_REF` bit.
> 
> When neither `ALLOW_TIP_SHA1` nor `ALLOW_REACHABLE_SHA1` are set, the
> `is_our_ref()` function considers only the `OUR_REF` bit, and not the
> `HIDDEN_REF` one. `OUR_REF` is applied via `mark_our_ref()`, and only
> to objects at the tips of non-hidden references, so we do not need to
> visit hidden references in this case.

Both of these are noops if uploadpack.allowAnySHA1InWant is set, or if
we are using the v2 protocol. Setting both allowAny and allowTip is
sufficiently stupid that I don't care much that they lose out on an
optimization. But I could see somebody setting one of those for the
benefit of v0 clients, but then also serving v2 clients (which
effectively ignore those restrictions).

I guess v2 clients don't hit this code at all (they are handled by
ls-refs, which comes in the next patch). So that just leaves the case
that allowAny is set. By itself the optimization should kick in (good).
With allowTip or allowReachable it would not, but that is the "this is
stupid" case in which it is OK to fall back to the existing behavior
(even though we _could_ enable the optimization). OTOH, it would be easy
to check it, as it's just another bit in allow_uor.

I'm OK going either way.

-Peff

  reply	other threads:[~2023-07-03  6:26 UTC|newest]

Thread overview: 149+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-08 21:59 [PATCH 00/15] refs: implement skip lists for packed backend Taylor Blau
2023-05-08 21:59 ` [PATCH 01/15] refs.c: rename `ref_filter` Taylor Blau
2023-05-08 21:59 ` [PATCH 02/15] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-05-08 21:59 ` [PATCH 03/15] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-05-08 21:59 ` [PATCH 04/15] ref-filter: add ref_filter_clear() Taylor Blau
2023-05-08 22:29   ` Junio C Hamano
2023-05-08 22:33     ` Taylor Blau
2023-05-09 15:14   ` Patrick Steinhardt
2023-05-09 19:11     ` Taylor Blau
2023-05-08 21:59 ` [PATCH 05/15] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-05-08 22:36   ` Junio C Hamano
2023-05-09 20:13     ` Taylor Blau
2023-05-08 21:59 ` [PATCH 06/15] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-05-08 23:22   ` Junio C Hamano
2023-05-09 20:22     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 07/15] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-05-09 15:14   ` Patrick Steinhardt
2023-05-09 20:23     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 08/15] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-05-08 23:56   ` Junio C Hamano
2023-05-09 20:29     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 09/15] refs/packed-backend.c: implement skip lists to avoid excluded pattern(s) Taylor Blau
2023-05-09  0:10   ` Chris Torek
2023-05-09 20:39     ` Taylor Blau
2023-05-09 15:15   ` Patrick Steinhardt
2023-05-09 20:55     ` Taylor Blau
2023-05-09 21:15       ` Taylor Blau
2023-05-10  7:25       ` Patrick Steinhardt
2023-05-09 23:40   ` Junio C Hamano
2023-05-10  2:30     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 10/15] refs/packed-backend.c: add trace2 counters for skip list Taylor Blau
2023-05-08 22:00 ` [PATCH 11/15] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-05-08 22:00 ` [PATCH 12/15] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-05-08 22:00 ` [PATCH 13/15] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-05-08 22:00 ` [PATCH 14/15] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-05-09 15:15   ` Patrick Steinhardt
2023-05-09 21:34     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 15/15] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-05-15 19:23 ` [PATCH v2 00/16] refs: implement jump lists for packed backend Taylor Blau
2023-05-15 19:23   ` [PATCH v2 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-05-15 19:23   ` [PATCH v2 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-05-15 19:23   ` [PATCH v2 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-05-15 19:23   ` [PATCH v2 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-05-15 19:23   ` [PATCH v2 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-06-06  7:00     ` Patrick Steinhardt
2023-06-20 12:15       ` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-05-15 19:23   ` [PATCH v2 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-06-06  7:00     ` Patrick Steinhardt
2023-06-20 12:16       ` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 12/16] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-05-15 19:23   ` [PATCH v2 13/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-06-06  7:01     ` Patrick Steinhardt
2023-06-20 12:18       ` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-05-15 19:23   ` [PATCH v2 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-05-15 19:23   ` [PATCH v2 16/16] ls-refs.c: " Taylor Blau
2023-06-06  7:01   ` [PATCH v2 00/16] refs: implement jump lists for packed backend Patrick Steinhardt
2023-06-20 12:22     ` Taylor Blau
2023-06-07 10:40 ` [PATCH v3 " Taylor Blau
2023-06-07 10:40   ` [PATCH v3 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-06-13 22:19     ` Junio C Hamano
2023-06-07 10:40   ` [PATCH v3 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-06-07 10:41   ` [PATCH v3 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-06-13 22:37     ` Junio C Hamano
2023-06-07 10:41   ` [PATCH v3 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-06-07 10:41   ` [PATCH v3 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-06-13 23:42     ` Junio C Hamano
2023-06-20 11:52       ` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-06-14  0:27     ` Junio C Hamano
2023-06-20 12:05       ` Taylor Blau
2023-06-20 18:49         ` Junio C Hamano
2023-06-07 10:41   ` [PATCH v3 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-06-14  0:32     ` Junio C Hamano
2023-06-20 12:08       ` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 12/16] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-06-14  0:40     ` Junio C Hamano
2023-06-07 10:41   ` [PATCH v3 13/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-06-07 10:42   ` [PATCH v3 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-06-07 10:42   ` [PATCH v3 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-06-07 10:42   ` [PATCH v3 16/16] ls-refs.c: " Taylor Blau
2023-06-12 21:05   ` [PATCH v3 00/16] refs: implement jump lists for packed backend Junio C Hamano
2023-06-20 14:20 ` [PATCH v4 " Taylor Blau
2023-06-20 14:21   ` [PATCH v4 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-07-03  5:13     ` Jeff King
2023-06-20 14:21   ` [PATCH v4 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-07-03  5:15     ` Jeff King
2023-07-03 17:07       ` Taylor Blau
2023-06-20 14:21   ` [PATCH v4 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-07-03  5:16     ` Jeff King
2023-06-20 14:21   ` [PATCH v4 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-07-03  5:19     ` Jeff King
2023-07-03 17:13       ` Taylor Blau
2023-07-03 17:32         ` Jeff King
2023-06-20 14:21   ` [PATCH v4 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-07-03  5:27     ` Jeff King
2023-07-03 17:18       ` Taylor Blau
2023-07-03 17:22         ` Taylor Blau
2023-07-03 17:33           ` Jeff King
2023-06-20 14:21   ` [PATCH v4 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-06-20 14:21   ` [PATCH v4 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-06-20 14:21   ` [PATCH v4 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-06-20 14:21   ` [PATCH v4 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-07-03  5:56     ` Jeff King
2023-07-03 17:38       ` Taylor Blau
2023-06-20 14:21   ` [PATCH v4 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-06-20 14:21   ` [PATCH v4 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-07-03  5:59     ` Jeff King
2023-06-20 14:22   ` [PATCH v4 12/16] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-07-03  6:18     ` Jeff King
2023-07-04 18:22       ` Taylor Blau
2023-06-20 14:22   ` [PATCH v4 13/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-06-20 14:22   ` [PATCH v4 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-06-20 14:22   ` [PATCH v4 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-07-03  6:26     ` Jeff King [this message]
2023-07-04 18:43       ` Taylor Blau
2023-06-20 14:22   ` [PATCH v4 16/16] ls-refs.c: " Taylor Blau
2023-07-03  6:27     ` Jeff King
2023-07-03  6:29   ` [PATCH v4 00/16] refs: implement jump lists for packed backend Jeff King
2023-07-10 21:12 ` [PATCH v5 " Taylor Blau
2023-07-10 21:12   ` [PATCH v5 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-07-10 21:12   ` [PATCH v5 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-07-10 21:12   ` [PATCH v5 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-07-10 21:12   ` [PATCH v5 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-07-10 21:12   ` [PATCH v5 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-07-10 21:12   ` [PATCH v5 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-07-10 21:12   ` [PATCH v5 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 12/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-07-10 21:12   ` [PATCH v5 13/16] refs.h: implement `hidden_refs_to_excludes()` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-07-10 21:12   ` [PATCH v5 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-07-10 21:12   ` [PATCH v5 16/16] ls-refs.c: " Taylor Blau
2023-07-10 22:35   ` [PATCH v5 00/16] refs: implement jump lists for packed backend Junio C Hamano
2023-07-11  9:37     ` Patrick Steinhardt
2023-07-11 15:56       ` Junio C Hamano
2023-07-11 17:19         ` Taylor Blau

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