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From: Michael Haggerty <mhagger@alum.mit.edu>
To: Jeff King <peff@peff.net>
Cc: "Junio C Hamano" <gitster@pobox.com>,
	"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
	"Stefan Beller" <sbeller@google.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"David Turner" <novalis@novalis.org>,
	"Brandon Williams" <bmwill@google.com>,
	git@vger.kernel.org
Subject: Re: [PATCH v2 28/29] repack_without_refs(): don't lock or unlock the packed refs
Date: Sat, 1 Jul 2017 19:11:37 +0200	[thread overview]
Message-ID: <71e58288-483b-3cfb-00db-523a28c78549@alum.mit.edu> (raw)
In-Reply-To: <20170623195600.cvn26gt7o5rtywy6@sigill.intra.peff.net>

On 06/23/2017 09:56 PM, Jeff King wrote:
> On Fri, Jun 23, 2017 at 09:01:46AM +0200, Michael Haggerty wrote:
> 
>> Change `repack_without_refs()` to expect the packed-refs lock to be
>> held already, and not to release the lock before returning. Change the
>> callers to deal with lock management.
>>
>> This change makes it possible for callers to hold the packed-refs lock
>> for a longer span of time, a possibility that will eventually make it
>> possible to fix some longstanding races.
> 
> This is the sort of clue I was thinking about in my last email. :)

I'll try to be better about that in the future.

And the reason to make `packed_ref_store` fulfill the `ref_store`
interface is mostly indirect at the moment. It was important (to my
sanity, if nothing else) to simplify the interface to the packed-refs
code before rewriting its innards. Since the `ref_store` interface is
familiar and is fairly close to what is needed, it seemed logical to use it.

>> The only semantic change here is that `repack_without_refs()` used to
>> forgot to release the lock in the `if (!removed)` exit path. That
>> omission is now fixed.
> 
> s/used to forgot/previously forgot/ or similar?

Thanks; will fix.

Michael


  reply	other threads:[~2017-07-01 17:11 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-23  7:01 [PATCH v2 00/29] Create a reference backend for packed refs Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 01/29] t1408: add a test of stale packed refs covered by loose refs Michael Haggerty
2017-06-23 18:59   ` Jeff King
2017-06-23 20:22     ` Junio C Hamano
2017-06-23  7:01 ` [PATCH v2 02/29] add_packed_ref(): teach function to overwrite existing refs Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 03/29] packed_ref_store: new struct Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 04/29] packed_ref_store: move `packed_refs_path` here Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 05/29] packed_ref_store: move `packed_refs_lock` member here Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 06/29] clear_packed_ref_cache(): take a `packed_ref_store *` parameter Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 07/29] validate_packed_ref_cache(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 08/29] get_packed_ref_cache(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 09/29] get_packed_refs(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 10/29] add_packed_ref(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 11/29] lock_packed_refs(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 12/29] commit_packed_refs(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 13/29] rollback_packed_refs(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 14/29] get_packed_ref(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 15/29] repack_without_refs(): " Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 16/29] packed_peel_ref(): new function, extracted from `files_peel_ref()` Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 17/29] packed_ref_store: support iteration Michael Haggerty
2017-06-23 19:12   ` Jeff King
2017-06-23  7:01 ` [PATCH v2 18/29] packed_read_raw_ref(): new function, replacing `resolve_packed_ref()` Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 19/29] packed-backend: new module for handling packed references Michael Haggerty
2017-06-23 19:35   ` Jeff King
2017-06-23 19:46     ` Stefan Beller
2017-06-23 21:20     ` Junio C Hamano
2017-06-23  7:01 ` [PATCH v2 20/29] packed_ref_store: make class into a subclass of `ref_store` Michael Haggerty
2017-06-23 19:40   ` Jeff King
2017-06-23  7:01 ` [PATCH v2 21/29] commit_packed_refs(): report errors rather than dying Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 22/29] commit_packed_refs(): use a staging file separate from the lockfile Michael Haggerty
2017-06-23 19:46   ` Jeff King
2017-06-24 11:43     ` Michael Haggerty
2017-06-24 11:57       ` Jeff King
2017-06-23  7:01 ` [PATCH v2 23/29] packed_refs_lock(): function renamed from lock_packed_refs() Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 24/29] packed_refs_lock(): report errors via a `struct strbuf *err` Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 25/29] packed_refs_unlock(), packed_refs_is_locked(): new functions Michael Haggerty
2017-06-23  7:01 ` [PATCH v2 26/29] clear_packed_ref_cache(): don't protest if the lock is held Michael Haggerty
2017-06-23 19:49   ` Jeff King
2017-06-23  7:01 ` [PATCH v2 27/29] commit_packed_refs(): remove call to `packed_refs_unlock()` Michael Haggerty
2017-06-23 19:51   ` Jeff King
2017-06-23  7:01 ` [PATCH v2 28/29] repack_without_refs(): don't lock or unlock the packed refs Michael Haggerty
2017-06-23 19:56   ` Jeff King
2017-07-01 17:11     ` Michael Haggerty [this message]
2017-06-23  7:01 ` [PATCH v2 29/29] read_packed_refs(): die if `packed-refs` contains bogus data Michael Haggerty
2017-06-23 19:58   ` Jeff King
2017-07-01 18:15     ` Michael Haggerty
2017-06-23 19:01 ` [PATCH v2 00/29] Create a reference backend for packed refs Jeff King
2017-06-23 20:00   ` Jeff King
2017-06-23 21:47     ` Junio C Hamano
2017-06-24  1:11       ` Jeff King
2017-06-24 11:14         ` Michael Haggerty
2017-06-23 20:24   ` Junio C Hamano

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