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From: Eric Sunshine <sunshine@sunshineco.com>
To: Jeff King <peff@peff.net>
Cc: Git List <git@vger.kernel.org>
Subject: Re: [PATCH 1/2] pack-revindex: drop hash table
Date: Mon, 21 Dec 2015 02:06:59 -0500	[thread overview]
Message-ID: <CAPig+cTD+qknnZ3rH7skcTxZA16AL0BPbLT5ZaJdwwu_d-i=Jw@mail.gmail.com> (raw)
In-Reply-To: <20151221061948.GA25763@sigill.intra.peff.net>

On Mon, Dec 21, 2015 at 1:19 AM, Jeff King <peff@peff.net> wrote:
> The main entry point to the pack-revindex code is
> find_pack_revindex(). This calls revindex_for_pack(), which
> lazily computes and caches the revindex for the pack.
>
> We store the cache in a very simple hash table. It's created
> by init_pack_revindex(), which inserts an entry for every
> packfile we know about, and we never grow or shrink the
> hash. If we ever need the revindex for a pack that isn't in
> the hash, we die() with an internal error.
>
> This can lead to a race, because we may load more packs
> after having called init_pack_revindex(). For example,
> imagine we have one process which needs to look at the
> revindex for a variety of objects (e.g., cat-file's
> "%(objectsize:disk)" format).  Simultaneously, git-gc is
> running, which is doing a `git repack -ad` is running. We
> might hit a sequence like:

Probably want to drop one of the "is running"s...

  parent reply	other threads:[~2015-12-21  7:07 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-21  6:19 [PATCH 1/2] pack-revindex: drop hash table Jeff King
2015-12-21  6:20 ` [PATCH 2/2] pack-revindex: store entries directly in packed_git Jeff King
2015-12-21  7:06 ` Eric Sunshine [this message]
2015-12-21  7:08   ` [PATCH 1/2] pack-revindex: drop hash table Jeff King

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