From: Elijah Newren <newren@gmail.com>
To: Derrick Stolee <stolee@gmail.com>
Cc: 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>
Subject: Re: [PATCH v2 06/13] merge-ort: add data structures for in-memory caching of rename detection
Date: Mon, 17 May 2021 20:55:07 -0700 [thread overview]
Message-ID: <CABPp-BFOSBVP-9A6BQegpaPRA+iU=ZQCiJYrTEkq0H9b+xRjEQ@mail.gmail.com> (raw)
In-Reply-To: <b9bb5b44-47ce-8198-c546-8f07d03ef863@gmail.com>
On Mon, May 17, 2021 at 6:41 AM Derrick Stolee <stolee@gmail.com> wrote:
>
> On 5/3/21 10:12 PM, Elijah Newren via GitGitGadget wrote:
> > From: Elijah Newren <newren@gmail.com>
> >
> > When there are many renames between the old base of a series of commits
> > and the new base for a series of commits, the sequence of merges
> > employed to transplant those commits (from a cherry-pick or rebase
> > operation) will repeatedly detect the exact same renames. This is
> > wasted effort.
> >
> > Add data structures which will be used to cache rename detection
> > results, along with the initialization and deallocation of these data
> > structures. Future commits will populate these caches, detect the
> > appropriate circumstances when they can be used, and employ them to
> > avoid re-detecting the same renames repeatedly.
>
> I appreciate the definitions and boilerplate for these data
> structures being isolated to their own patch.
>
> > @@ -140,6 +140,37 @@ struct rename_info {
> > int callback_data_nr, callback_data_alloc;
> > char *callback_data_traverse_path;
> >
> > + /*
> > + * cached_pairs: Caching of renames and deletions.
> > + *
> > + * These are mappings recording renames and deletions of individual
> > + * files (not directories). They are thus a map from an old
> > + * filename to either NULL (for deletions) or a new filename (for
> > + * renames).
> > + */
> > + struct strmap cached_pairs[3];
> > +
> > + /*
> > + * cached_target_names: just the destinations from cached_pairs
> > + *
> > + * We sometimes want a fast lookup to determine if a given filename
> > + * is one of the destinations in cached_pairs. cached_target_names
> > + * is thus duplicative information, but it provides a fast lookup.
> > + */
> > + struct strset cached_target_names[3];
>
> These two work well together. Very clear.
>
> > + /*
> > + * cached_irrelevant: Caching of rename_sources that aren't relevant.
> > + *
> > + * cached_pairs records both renames and deletes. Sometimes we
> > + * do not know if a path is a rename or a delete because we pass
> > + * RELEVANT_LOCATION to diffcore_rename_extended() and based on
> > + * various optimizations it returns without detecting whether that
> > + * path is actually a rename or a delete. We need to cache such
> > + * paths too, but separately from cached_pairs.
> > + */
> > + struct strset cached_irrelevant[3];
>
> I'm having a hard time parsing what these "irrelevant" paths will be.
> It seems like diffcore_rename_extended() will report something other
> than "rename" or "delete" for some paths. Could we explicitly mark
> that state as "irrelevant"?
The state is better known as RELEVANT_NO_MORE, yes.
> /*
> * cached_irrelevant: Caching of rename_sources that aren't relevant.
> *
> * cached_pairs records both renames and deletes. Sometimes we
> * do not know if a path is a rename or a delete because we pass
> * RELEVANT_LOCATION to diffcore_rename_extended() which might
> * describe a path as "irrelevant" instead of as a "rename" or "delete".
> * We need to cache such paths too, but separately from cached_pairs.
> */
>
> Does this make sense? diffcore_rename_extended() might need an update
> to match this extra, explicit state.
Hmm, let's flesh out the description a bit and try to be more
explicit. How about:
/*
* cached_irrelevant: Caching of rename_sources that aren't relevant.
*
* If we try to detect a rename for a source path and succeed, it's
* part of a rename. If we try to detect a rename for a source path
* and fail, then it's a delete. If we do not try to detect a rename
* for a path, then we don't know if it's a rename or a delete. If
* merge-ort doesn't think the path is relevant, then we just won't
* cache anything for that path. But there's a slight problem in
* that merge-ort can think a path is RELEVANT_LOCATION, but due to
* commit 9bd342137e ("diffcore-rename: determine which
* relevant_sources are no longer relevant", 2021-03-13),
* diffcore-rename can downgrade the path to RELEVANT_NO_MORE. To
* avoid excessive calls to diffcore_rename_extended() we still need
* to cache such paths, though we cannot record them as either
* renames or deletes. So we cache them here as a "turned out to be
* irrelevant *for this commit*" as they are often also irrelevant
* for subsequent commits, though we will have to do some extra
* checking to see whether such paths become relevant for rename
* detection when cherry-picking/rebasing subsequent commits.
*/
next prev parent reply other threads:[~2021-05-18 3:55 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-24 21:32 [PATCH 0/7] Optimization batch 11: avoid repeatedly detecting same renames Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 1/7] merge-ort: add data structures for in-memory caching of rename detection Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 2/7] merge-ort: populate caches of rename detection results Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 3/7] merge-ort: add code to check for whether cached renames can be reused Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 4/7] merge-ort: avoid accidental API mis-use Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 5/7] merge-ort: preserve cached renames for the appropriate side Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 6/7] merge-ort: add helper functions for using cached renames Elijah Newren via GitGitGadget
2021-03-24 21:32 ` [PATCH 7/7] merge-ort, diffcore-rename: employ cached renames when possible Elijah Newren via GitGitGadget
2021-03-24 22:04 ` [PATCH 0/7] Optimization batch 11: avoid repeatedly detecting same renames Junio C Hamano
2021-03-24 23:25 ` Elijah Newren
2021-03-25 18:59 ` Junio C Hamano
2021-03-29 22:34 ` Elijah Newren
2021-03-30 12:07 ` Derrick Stolee
2021-05-04 2:12 ` [PATCH v2 00/13] " Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 01/13] t6423: rename file within directory that other side renamed Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 02/13] Documentation/technical: describe remembering renames optimization Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 03/13] fast-rebase: change assert() to BUG() Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 04/13] fast-rebase: write conflict state to working tree, index, and HEAD Elijah Newren via GitGitGadget
2021-05-17 13:32 ` Derrick Stolee
2021-05-18 3:42 ` Elijah Newren
2021-05-18 13:54 ` Derrick Stolee
2021-05-04 2:12 ` [PATCH v2 05/13] t6429: testcases for remembering renames Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 06/13] merge-ort: add data structures for in-memory caching of rename detection Elijah Newren via GitGitGadget
2021-05-17 13:41 ` Derrick Stolee
2021-05-18 3:55 ` Elijah Newren [this message]
2021-05-18 13:57 ` Derrick Stolee
2021-05-04 2:12 ` [PATCH v2 07/13] merge-ort: populate caches of rename detection results Elijah Newren via GitGitGadget
2021-05-17 13:51 ` Derrick Stolee
2021-05-20 0:48 ` Elijah Newren
2021-05-04 2:12 ` [PATCH v2 08/13] merge-ort: add code to check for whether cached renames can be reused Elijah Newren via GitGitGadget
2021-05-17 14:01 ` Derrick Stolee
2021-05-04 2:12 ` [PATCH v2 09/13] merge-ort: avoid accidental API mis-use Elijah Newren via GitGitGadget
2021-05-17 14:10 ` Derrick Stolee
2021-05-04 2:12 ` [PATCH v2 10/13] merge-ort: preserve cached renames for the appropriate side Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 11/13] merge-ort: add helper functions for using cached renames Elijah Newren via GitGitGadget
2021-05-04 2:12 ` [PATCH v2 12/13] merge-ort: handle interactions of caching and rename/rename(1to1) cases Elijah Newren via GitGitGadget
2021-05-17 14:16 ` Derrick Stolee
2021-05-04 2:12 ` [PATCH v2 13/13] merge-ort, diffcore-rename: employ cached renames when possible Elijah Newren via GitGitGadget
2021-05-17 14:23 ` Derrick Stolee
2021-05-20 0:36 ` Elijah Newren
2021-05-22 11:17 ` Derrick Stolee
2021-05-14 17:37 ` [PATCH v2 00/13] Optimization batch 11: avoid repeatedly detecting same renames Elijah Newren
2021-05-14 21:04 ` Derrick Stolee
2021-05-20 6:09 ` [PATCH v3 " Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 01/13] t6423: rename file within directory that other side renamed Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 02/13] Documentation/technical: describe remembering renames optimization Elijah Newren via GitGitGadget
2021-05-20 11:32 ` Bagas Sanjaya
2021-05-20 15:14 ` Kerry, Richard
2021-05-20 16:34 ` Elijah Newren
2021-05-20 6:09 ` [PATCH v3 03/13] fast-rebase: change assert() to BUG() Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 04/13] fast-rebase: write conflict state to working tree, index, and HEAD Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 05/13] t6429: testcases for remembering renames Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 06/13] merge-ort: add data structures for in-memory caching of rename detection Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 07/13] merge-ort: populate caches of rename detection results Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 08/13] merge-ort: add code to check for whether cached renames can be reused Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 09/13] merge-ort: avoid accidental API mis-use Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 10/13] merge-ort: preserve cached renames for the appropriate side Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 11/13] merge-ort: add helper functions for using cached renames Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 12/13] merge-ort: handle interactions of caching and rename/rename(1to1) cases Elijah Newren via GitGitGadget
2021-05-20 6:09 ` [PATCH v3 13/13] merge-ort, diffcore-rename: employ cached renames when possible Elijah Newren via GitGitGadget
2021-05-22 11:17 ` [PATCH v3 00/13] Optimization batch 11: avoid repeatedly detecting same renames Derrick Stolee
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CABPp-BFOSBVP-9A6BQegpaPRA+iU=ZQCiJYrTEkq0H9b+xRjEQ@mail.gmail.com' \
--to=newren@gmail.com \
--cc=dstolee@microsoft.com \
--cc=git@vger.kernel.org \
--cc=gitgitgadget@gmail.com \
--cc=jonathantanmy@google.com \
--cc=me@ttaylorr.com \
--cc=stolee@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).