From: Phillip Wood <phillip.wood123@gmail.com>
To: Jeff King <peff@peff.net>,
Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Phillip Wood <phillip.wood@dunelm.org.uk>,
Derrick Stolee <stolee@gmail.com>,
Phillip Wood via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org
Subject: Re: [PATCH 1/3] diff histogram: intern strings
Date: Fri, 19 Nov 2021 10:05:32 +0000 [thread overview]
Message-ID: <86d38148-7b97-76aa-148b-346cc179615a@gmail.com> (raw)
In-Reply-To: <YZZ0e7CCGW5QbQlW@coredump.intra.peff.net>
On 18/11/2021 15:42, Jeff King wrote:
> On Thu, Nov 18, 2021 at 04:35:48PM +0100, Johannes Schindelin wrote:
>
>> I think the really important thing to point out is that
>> `xdl_classify_record()` ensures that the `ha` attribute is different for
>> different text. AFAIR it even "linearizes" the `ha` values, i.e. they
>> won't be all over the place but start at 0 (or 1).
>>
>> So no, I'm not worried about collisions. That would be a bug in
>> `xdl_classify_record()` and I think we would have caught this bug by now.
>
> Ah, thanks for that explanation. That addresses my collision concern from
> earlier in the thread completely.
Yes, thanks for clarifying I should have been clearer in my reply to
Stolee. The reason I was waffling on about file sizes is that there can
only be a collision if there are more than 2^32 unique lines. I think
the minimum file size where that happens is just below 10GB when one
side of the diff has 2^31 lines and the other has 2^31 + 1 lines and all
the lines are unique.
Best Wishes
Phillip
next prev parent reply other threads:[~2021-11-19 10:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-17 11:20 [PATCH 0/3] xdiff: speedup histogram diff Phillip Wood via GitGitGadget
2021-11-17 11:20 ` [PATCH 1/3] diff histogram: intern strings Phillip Wood via GitGitGadget
2021-11-17 15:55 ` Derrick Stolee
2021-11-17 16:46 ` Jeff King
2021-11-17 16:52 ` Phillip Wood
2021-11-18 15:35 ` Johannes Schindelin
2021-11-18 15:42 ` Jeff King
2021-11-19 10:05 ` Phillip Wood [this message]
2021-11-19 14:45 ` Jeff King
2021-11-19 21:22 ` Ævar Arnfjörð Bjarmason
2021-11-19 22:19 ` Jeff King
2021-11-19 15:49 ` Johannes Schindelin
2021-11-17 11:20 ` [PATCH 2/3] xdiff: avoid unnecessary memory allocations Phillip Wood via GitGitGadget
2021-11-17 11:20 ` [PATCH 3/3] xdiff: simplify comparison Phillip Wood via GitGitGadget
2021-11-18 15:40 ` [PATCH 0/3] xdiff: speedup histogram diff Johannes Schindelin
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