From: Junio C Hamano <gitster@pobox.com>
To: Elijah Newren <newren@gmail.com>
Cc: Derrick Stolee <stolee@gmail.com>,
Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>,
Git Mailing List <git@vger.kernel.org>,
Derrick Stolee <dstolee@microsoft.com>,
Jonathan Tan <jonathantanmy@google.com>,
Taylor Blau <me@ttaylorr.com>, Jeff King <peff@peff.net>
Subject: Re: [PATCH 3/3] diffcore-rename: guide inexact rename detection based on basenames
Date: Mon, 08 Feb 2021 09:37:23 -0800 [thread overview]
Message-ID: <xmqq4kim7964.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <CABPp-BGAgi+ooq==ZY2tWif0--W4Cruz02GDvxueHe6GjQEAXQ@mail.gmail.com> (Elijah Newren's message of "Mon, 8 Feb 2021 00:38:00 -0800")
Elijah Newren <newren@gmail.com> writes:
> idea is still possible. For example, A.txt could have been compared
> to source/some-module/A.txt. And I don't do anything in the final
> "full matrix" stage to avoid re-comparing those two files again.
> However, it is worth noting that A.txt will have been compared to at
> most one other file, not N files.
Sorry, but where does this "at most one other file" come from? "It
is rare to remove source/some-other-module/A.txt at the same time
while the above is happening"? If so, yes, that sounds like a
sensible thing.
> 1) The most expensive comparison is the first one,...
Yes. we keep the spanhash table across comparison.
> 2) This would only save us from at most N comparisons in the N x M
> matrix (since no file in this optimization is compared to more than
> one other)
True, but doesn't rename_src[] and rename_dst[] entries have the
original pathname, where you can see A.txt and some-module/A.txt
share the same filename part cheaply? Is that more expensive than
comparing spanhash tables?
Having asked these, I do think it is not worth pursuing, especially
because I agree with Derrick that this "we see a new file whose name
is the same as the one deleted from a different directory, so if
they are similar enough, let's declare victory and not bother
finding a better match" needs to be used with higher similarity bar
than the normal one. If -M60 says "only consider pairs that are
with at least 60% similarity index", finding one at 60% similarity
and stopping at it only because the pair looks to move a file from
one directory to another directory while retaining the same name,
rejecting other paring, feels a bit too crude a heuristics. And if
we require higher similarity levels to short-circuit, the later full
matrix stage won't be helped with "we must have already rejected"
logic. A.txt and some-module/A.txt may not have been similar enough
to short-circuit and reject others in the earlier part, but the
full-matrix part work at a lower bar, which may consider the pair
good enough to keep as match candidates.
Thanks.
next prev parent reply other threads:[~2021-02-08 17:40 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-06 22:52 [PATCH 0/3] Optimization batch 7: use file basenames to guide rename detection Elijah Newren via GitGitGadget
2021-02-06 22:52 ` [PATCH 1/3] diffcore-rename: compute basenames of all source and dest candidates Elijah Newren via GitGitGadget
2021-02-06 22:52 ` [PATCH 2/3] diffcore-rename: complete find_basename_matches() Elijah Newren via GitGitGadget
2021-02-06 22:52 ` [PATCH 3/3] diffcore-rename: guide inexact rename detection based on basenames Elijah Newren via GitGitGadget
2021-02-07 14:38 ` Derrick Stolee
2021-02-07 19:51 ` Junio C Hamano
2021-02-08 8:38 ` Elijah Newren
2021-02-08 11:43 ` Derrick Stolee
2021-02-08 16:25 ` Elijah Newren
2021-02-08 17:37 ` Junio C Hamano [this message]
2021-02-08 22:00 ` Elijah Newren
2021-02-08 23:43 ` Junio C Hamano
2021-02-08 23:52 ` Elijah Newren
2021-02-08 8:27 ` Elijah Newren
2021-02-08 11:31 ` Derrick Stolee
2021-02-08 16:09 ` Elijah Newren
2021-02-07 5:19 ` [PATCH 0/3] Optimization batch 7: use file basenames to guide rename detection Junio C Hamano
2021-02-07 6:05 ` Elijah Newren
2021-02-09 11:32 ` [PATCH v2 0/4] " Elijah Newren via GitGitGadget
2021-02-09 11:32 ` [PATCH v2 1/4] diffcore-rename: compute basenames of all source and dest candidates Elijah Newren via GitGitGadget
2021-02-09 13:17 ` Derrick Stolee
2021-02-09 16:56 ` Elijah Newren
2021-02-09 17:02 ` Derrick Stolee
2021-02-09 17:42 ` Elijah Newren
2021-02-09 11:32 ` [PATCH v2 2/4] diffcore-rename: complete find_basename_matches() Elijah Newren via GitGitGadget
2021-02-09 13:25 ` Derrick Stolee
2021-02-09 17:17 ` Elijah Newren
2021-02-09 17:34 ` Derrick Stolee
2021-02-09 11:32 ` [PATCH v2 3/4] diffcore-rename: guide inexact rename detection based on basenames Elijah Newren via GitGitGadget
2021-02-09 13:33 ` Derrick Stolee
2021-02-09 17:41 ` Elijah Newren
2021-02-09 18:59 ` Junio C Hamano
2021-02-09 11:32 ` [PATCH v2 4/4] gitdiffcore doc: mention new preliminary step for rename detection Elijah Newren via GitGitGadget
2021-02-09 12:59 ` Derrick Stolee
2021-02-09 17:03 ` Junio C Hamano
2021-02-09 17:44 ` Elijah Newren
2021-02-10 15:15 ` [PATCH v3 0/5] Optimization batch 7: use file basenames to guide " Elijah Newren via GitGitGadget
2021-02-10 15:15 ` [PATCH v3 1/5] t4001: add a test comparing basename similarity and content similarity Elijah Newren via GitGitGadget
2021-02-13 1:15 ` Junio C Hamano
2021-02-13 4:50 ` Elijah Newren
2021-02-13 23:56 ` Junio C Hamano
2021-02-14 1:24 ` Elijah Newren
2021-02-14 1:32 ` Junio C Hamano
2021-02-14 3:14 ` Elijah Newren
2021-02-10 15:15 ` [PATCH v3 2/5] diffcore-rename: compute basenames of all source and dest candidates Elijah Newren via GitGitGadget
2021-02-13 1:32 ` Junio C Hamano
2021-02-10 15:15 ` [PATCH v3 3/5] diffcore-rename: complete find_basename_matches() Elijah Newren via GitGitGadget
2021-02-13 1:48 ` Junio C Hamano
2021-02-13 18:34 ` Elijah Newren
2021-02-13 23:55 ` Junio C Hamano
2021-02-14 3:08 ` Elijah Newren
2021-02-10 15:15 ` [PATCH v3 4/5] diffcore-rename: guide inexact rename detection based on basenames Elijah Newren via GitGitGadget
2021-02-13 1:49 ` Junio C Hamano
2021-02-10 15:15 ` [PATCH v3 5/5] gitdiffcore doc: mention new preliminary step for rename detection Elijah Newren via GitGitGadget
2021-02-10 16:41 ` Junio C Hamano
2021-02-10 17:20 ` Elijah Newren
2021-02-11 8:15 ` [PATCH v4 0/6] Optimization batch 7: use file basenames to guide " Elijah Newren via GitGitGadget
2021-02-11 8:15 ` [PATCH v4 1/6] t4001: add a test comparing basename similarity and content similarity Elijah Newren via GitGitGadget
2021-02-11 8:15 ` [PATCH v4 2/6] diffcore-rename: compute basenames of all source and dest candidates Elijah Newren via GitGitGadget
2021-02-11 8:15 ` [PATCH v4 3/6] diffcore-rename: complete find_basename_matches() Elijah Newren via GitGitGadget
2021-02-11 8:15 ` [PATCH v4 4/6] diffcore-rename: guide inexact rename detection based on basenames Elijah Newren via GitGitGadget
2021-02-11 8:15 ` [PATCH v4 5/6] gitdiffcore doc: mention new preliminary step for rename detection Elijah Newren via GitGitGadget
2021-02-11 8:15 ` [PATCH v4 6/6] merge-ort: call diffcore_rename() directly Elijah Newren via GitGitGadget
2021-02-13 1:53 ` [PATCH v4 0/6] Optimization batch 7: use file basenames to guide rename detection Junio C Hamano
2021-02-14 7:51 ` [PATCH v5 " Elijah Newren via GitGitGadget
2021-02-14 7:51 ` [PATCH v5 1/6] t4001: add a test comparing basename similarity and content similarity Elijah Newren via GitGitGadget
2021-02-14 7:51 ` [PATCH v5 2/6] diffcore-rename: compute basenames of source and dest candidates Elijah Newren via GitGitGadget
2021-02-14 7:51 ` [PATCH v5 3/6] diffcore-rename: complete find_basename_matches() Elijah Newren via GitGitGadget
2021-02-14 7:51 ` [PATCH v5 4/6] diffcore-rename: guide inexact rename detection based on basenames Elijah Newren via GitGitGadget
2021-02-14 7:51 ` [PATCH v5 5/6] gitdiffcore doc: mention new preliminary step for rename detection Elijah Newren via GitGitGadget
2021-02-14 7:51 ` [PATCH v5 6/6] merge-ort: call diffcore_rename() directly Elijah Newren via GitGitGadget
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