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Differential D9422

copies: iterate over children directly (instead of parents)
ClosedPublic

Authored by marmoute on Nov 27 2020, 11:12 AM.

Details

Reviewers
Alphare
Group Reviewers
hg-reviewers
Commits
rHG294d5aca4ff5: copies: iterate over children directly (instead of parents)
Summary

Before this change we would gather all parent → child edges and iterate on
all parent, gathering copy information for children and aggregating them from
there.

They are not strict requirement for edges to be processed in that specific
order. We could also simply iterate over all "children" revision and aggregate
data from both parents at the same time. This patch does that.

It make various things simpler:

  • since both parents are processed at the same time, we no longer need to cache data for merge (see next changeset for details),
  • we no longer need nested loop to process data,
  • we no longer need to store partial merge data for a rev from distinct loop interaction to another when processing merges,
  • we no longer need to build a full parent -> children mapping (we only rely on a simpler "parent -> number of children" map (for memory efficiency),
  • the data access pattern is now simpler (from lower revisions to higher revisions) and entirely predicable. That predictability open the way to prefetching and parallel processing.

So that new iterations order requires simpler code and open the way to
interesting optimisation.

The effect on performance is quite good. In the worse case, we don't see any
significant negative impact. And in the best case, the reduction of roundtrip
to Python provide us with a significant speed. Some example below:

Repo Case Source-Rev Dest-Rev # of revisions old time new time Difference Factor time per rev

mozilla-try x00000_revs_x00000_added_0_copies dc8a3ca7010e d16fde900c9c : 34414 revs, 0.962867 s, 0.502584 s, -0.460283 s, × 0.5220, 14 µs/rev
mozilla-try x0000_revs_xx000_added_x_copies 156f6e2674f2 4d0f2c178e66 : 8598 revs, 0.110717 s, 0.076323 s, -0.034394 s, × 0.6894, 8 µs/rev

full comparison between the previous changeset and this one

Repo Case Source-Rev Dest-Rev # of revisions old time new time Difference Factor time per rev

mercurial x_revs_x_added_0_copies ad6b123de1c7 39cfcef4f463 : 1 revs, 0.000048 s, 0.000041 s, -0.000007 s, × 0.8542, 41 µs/rev
mercurial x_revs_x_added_x_copies 2b1c78674230 0c1d10351869 : 6 revs, 0.000153 s, 0.000102 s, -0.000051 s, × 0.6667, 17 µs/rev
mercurial x000_revs_x000_added_x_copies 81f8ff2a9bf2 dd3267698d84 : 1032 revs, 0.004209 s, 0.004254 s, +0.000045 s, × 1.0107, 4 µs/rev
pypy x_revs_x_added_0_copies aed021ee8ae8 099ed31b181b : 9 revs, 0.000203 s, 0.000282 s, +0.000079 s, × 1.3892, 31 µs/rev
pypy x_revs_x000_added_0_copies 4aa4e1f8e19a 359343b9ac0e : 1 revs, 0.000059 s, 0.000048 s, -0.000011 s, × 0.8136, 48 µs/rev
pypy x_revs_x_added_x_copies ac52eb7bbbb0 72e022663155 : 7 revs, 0.000194 s, 0.000211 s, +0.000017 s, × 1.0876, 30 µs/rev
pypy x_revs_x00_added_x_copies c3b14617fbd7 ace7255d9a26 : 1 revs, 0.000380 s, 0.000375 s, -0.000005 s, × 0.9868, 375 µs/rev
pypy x_revs_x000_added_x000_copies df6f7a526b60 a83dc6a2d56f : 6 revs, 0.010588 s, 0.010574 s, -0.000014 s, × 0.9987, 1762 µs/rev
pypy x000_revs_xx00_added_0_copies 89a76aede314 2f22446ff07e : 4785 revs, 0.048961 s, 0.049974 s, +0.001013 s, × 1.0207, 10 µs/rev
pypy x000_revs_x000_added_x_copies 8a3b5bfd266e 2c68e87c3efe : 6780 revs, 0.083612 s, 0.084300 s, +0.000688 s, × 1.0082, 12 µs/rev
pypy x000_revs_x000_added_x000_copies 89a76aede314 7b3dda341c84 : 5441 revs, 0.058579 s, 0.060128 s, +0.001549 s, × 1.0264, 11 µs/rev
pypy x0000_revs_x_added_0_copies d1defd0dc478 c9cb1334cc78 : 43645 revs, 0.736783 s, 0.686542 s, -0.050241 s, × 0.9318, 15 µs/rev
pypy x0000_revs_xx000_added_0_copies bf2c629d0071 4ffed77c095c : 2 revs, 0.022050 s, 0.009277 s, -0.012773 s, × 0.4207, 4638 µs/rev
pypy x0000_revs_xx000_added_x000_copies 08ea3258278e d9fa043f30c0 : 11316 revs, 0.120800 s, 0.114733 s, -0.006067 s, × 0.9498, 10 µs/rev
netbeans x_revs_x_added_0_copies fb0955ffcbcd a01e9239f9e7 : 2 revs, 0.000140 s, 0.000081 s, -0.000059 s, × 0.5786, 40 µs/rev
netbeans x_revs_x000_added_0_copies 6f360122949f 20eb231cc7d0 : 2 revs, 0.000114 s, 0.000107 s, -0.000007 s, × 0.9386, 53 µs/rev
netbeans x_revs_x_added_x_copies 1ada3faf6fb6 5a39d12eecf4 : 3 revs, 0.000224 s, 0.000173 s, -0.000051 s, × 0.7723, 57 µs/rev
netbeans x_revs_x00_added_x_copies 35be93ba1e2c 9eec5e90c05f : 9 revs, 0.000723 s, 0.000698 s, -0.000025 s, × 0.9654, 77 µs/rev
netbeans x000_revs_xx00_added_0_copies eac3045b4fdd 51d4ae7f1290 : 1421 revs, 0.009665 s, 0.009248 s, -0.000417 s, × 0.9569, 6 µs/rev
netbeans x000_revs_x000_added_x_copies e2063d266acd 6081d72689dc : 1533 revs, 0.014820 s, 0.015446 s, +0.000626 s, × 1.0422, 10 µs/rev
netbeans x000_revs_x000_added_x000_copies ff453e9fee32 411350406ec2 : 5750 revs, 0.076049 s, 0.074373 s, -0.001676 s, × 0.9780, 12 µs/rev
netbeans x0000_revs_xx000_added_x000_copies 588c2d1ced70 1aad62e59ddd : 66949 revs, 0.683603 s, 0.639870 s, -0.043733 s, × 0.9360, 9 µs/rev
mozilla-central x_revs_x_added_0_copies 3697f962bb7b 7015fcdd43a2 : 2 revs, 0.000161 s, 0.000088 s, -0.000073 s, × 0.5466, 44 µs/rev
mozilla-central x_revs_x000_added_0_copies dd390860c6c9 40d0c5bed75d : 8 revs, 0.000234 s, 0.000199 s, -0.000035 s, × 0.8504, 24 µs/rev
mozilla-central x_revs_x_added_x_copies 8d198483ae3b 14207ffc2b2f : 9 revs, 0.000247 s, 0.000171 s, -0.000076 s, × 0.6923, 19 µs/rev
mozilla-central x_revs_x00_added_x_copies 98cbc58cc6bc 446a150332c3 : 7 revs, 0.000630 s, 0.000592 s, -0.000038 s, × 0.9397, 84 µs/rev
mozilla-central x_revs_x000_added_x000_copies 3c684b4b8f68 0a5e72d1b479 : 3 revs, 0.003286 s, 0.003151 s, -0.000135 s, × 0.9589, 1050 µs/rev
mozilla-central x_revs_x0000_added_x0000_copies effb563bb7e5 c07a39dc4e80 : 6 revs, 0.062441 s, 0.061612 s, -0.000829 s, × 0.9867, 10268 µs/rev
mozilla-central x000_revs_xx00_added_0_copies 6100d773079a 04a55431795e : 1593 revs, 0.005423 s, 0.005381 s, -0.000042 s, × 0.9923, 3 µs/rev
mozilla-central x000_revs_x000_added_x_copies 9f17a6fc04f9 2d37b966abed : 41 revs, 0.005919 s, 0.003742 s, -0.002177 s, × 0.6322, 91 µs/rev
mozilla-central x000_revs_x000_added_x000_copies 7c97034feb78 4407bd0c6330 : 7839 revs, 0.062597 s, 0.061983 s, -0.000614 s, × 0.9902, 7 µs/rev
mozilla-central x0000_revs_xx000_added_0_copies 9eec5917337d 67118cc6dcad : 615 revs, 0.043551 s, 0.019861 s, -0.023690 s, × 0.4560, 32 µs/rev
mozilla-central x0000_revs_xx000_added_x000_copies f78c615a656c 96a38b690156 : 30263 revs, 0.192475 s, 0.188101 s, -0.004374 s, × 0.9773, 6 µs/rev
mozilla-central x00000_revs_x0000_added_x0000_copies 6832ae71433c 4c222a1d9a00 : 153721 revs, 1.955575 s, 1.806696 s, -0.148879 s, × 0.9239, 11 µs/rev
mozilla-central x00000_revs_x00000_added_x000_copies 76caed42cf7c 1daa622bbe42 : 204976 revs, 2.886501 s, 2.682987 s, -0.203514 s, × 0.9295, 13 µs/rev
mozilla-try x_revs_x_added_0_copies aaf6dde0deb8 9790f499805a : 2 revs, 0.001181 s, 0.000852 s, -0.000329 s, × 0.7214, 426 µs/rev
mozilla-try x_revs_x000_added_0_copies d8d0222927b4 5bb8ce8c7450 : 2 revs, 0.001189 s, 0.000859 s, -0.000330 s, × 0.7225, 429 µs/rev
mozilla-try x_revs_x_added_x_copies 092fcca11bdb 936255a0384a : 4 revs, 0.000563 s, 0.000150 s, -0.000413 s, × 0.2664, 37 µs/rev
mozilla-try x_revs_x00_added_x_copies b53d2fadbdb5 017afae788ec : 2 revs, 0.001548 s, 0.001158 s, -0.000390 s, × 0.7481, 579 µs/rev
mozilla-try x_revs_x000_added_x000_copies 20408ad61ce5 6f0ee96e21ad : 1 revs, 0.027782 s, 0.027240 s, -0.000542 s, × 0.9805, 27240 µs/rev
mozilla-try x_revs_x0000_added_x0000_copies effb563bb7e5 c07a39dc4e80 : 6 revs, 0.062781 s, 0.062824 s, +0.000043 s, × 1.0007, 10470 µs/rev
mozilla-try x000_revs_xx00_added_0_copies 6100d773079a 04a55431795e : 1593 revs, 0.005778 s, 0.005463 s, -0.000315 s, × 0.9455, 3 µs/rev
mozilla-try x000_revs_x000_added_x_copies 9f17a6fc04f9 2d37b966abed : 41 revs, 0.006192 s, 0.004238 s, -0.001954 s, × 0.6844, 103 µs/rev
mozilla-try x000_revs_x000_added_x000_copies 1346fd0130e4 4c65cbdabc1f : 6657 revs, 0.065391 s, 0.064113 s, -0.001278 s, × 0.9805, 9 µs/rev
mozilla-try x0000_revs_x_added_0_copies 63519bfd42ee a36a2a865d92 : 40314 revs, 0.317216 s, 0.294063 s, -0.023153 s, × 0.9270, 7 µs/rev
mozilla-try x0000_revs_x_added_x_copies 9fe69ff0762d bcabf2a78927 : 38690 revs, 0.303119 s, 0.281493 s, -0.021626 s, × 0.9287, 7 µs/rev
mozilla-try x0000_revs_xx000_added_x_copies 156f6e2674f2 4d0f2c178e66 : 8598 revs, 0.110717 s, 0.076323 s, -0.034394 s, × 0.6894, 8 µs/rev
mozilla-try x0000_revs_xx000_added_0_copies 9eec5917337d 67118cc6dcad : 615 revs, 0.045739 s, 0.020390 s, -0.025349 s, × 0.4458, 33 µs/rev
mozilla-try x0000_revs_xx000_added_x000_copies 89294cd501d9 7ccb2fc7ccb5 : 97052 revs, 3.098021 s, 3.023879 s, -0.074142 s, × 0.9761, 31 µs/rev
mozilla-try x0000_revs_x0000_added_x0000_copies e928c65095ed e951f4ad123a : 52031 revs, 0.771480 s, 0.735549 s, -0.035931 s, × 0.9534, 14 µs/rev
mozilla-try x00000_revs_x_added_0_copies 6a320851d377 1ebb79acd503 : 363753 revs, 18.813422 s, 18.568900 s, -0.244522 s, × 0.9870, 51 µs/rev
mozilla-try x00000_revs_x00000_added_0_copies dc8a3ca7010e d16fde900c9c : 34414 revs, 0.962867 s, 0.502584 s, -0.460283 s, × 0.5220, 14 µs/rev
mozilla-try x00000_revs_x_added_x_copies 5173c4b6f97c 95d83ee7242d : 362229 revs, 18.684923 s, 18.356645 s, -0.328278 s, × 0.9824, 50 µs/rev
mozilla-try x00000_revs_x000_added_x_copies 9126823d0e9c ca82787bb23c : 359344 revs, 18.296305 s, 18.250393 s, -0.045912 s, × 0.9975, 50 µs/rev
mozilla-try x00000_revs_x0000_added_x0000_copies 8d3fafa80d4b eb884023b810 : 192665 revs, 3.061887 s, 2.792459 s, -0.269428 s, × 0.9120, 14 µs/rev
mozilla-try x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs, 103.869641 s, 107.697264 s, +3.827623 s, × 1.0369, 470 µs/rev
mozilla-try x00000_revs_x00000_added_x000_copies 9b2a99adc05e 8e29777b48e6 : 382065 revs, 64.262957 s, 63.961040 s, -0.301917 s, × 0.9953, 167 µs/rev

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

Alphare created this revision.Nov 27 2020, 11:12 AM
marmoute updated this revision to Diff 23820.Nov 29 2020, 6:13 AM
marmoute updated this revision to Diff 23869.Nov 29 2020, 3:29 PM
marmoute added a reviewer: Alphare.Dec 8 2020, 5:48 AM
marmoute commandeered this revision.
baymax updated this revision to Diff 24115.Dec 8 2020, 6:04 AM

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Alphare added a comment.Dec 8 2020, 11:10 AM

I feel like I will have to get back to this one, I don't seem to have the necessary brainpower to understand the Python code. In the mean time, I have two comments, one of which might help me.

mercurial/copies.py
282

I find the code hard to follow without at least a docstring explaining the point of the algorithm. The Rust code below is more commented.

rust/hg-core/src/copy_tracing.rs
427

This should be called pop_* instead of get_*, I think

baymax updated this revision to Diff 24128.Dec 8 2020, 9:58 PM

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pulkit added a subscriber: pulkit.Dec 12 2020, 3:21 AM
pulkit added inline comments.
mercurial/copies.py
2

Unnecessary change?

362

When *not* using side-data?

589

New comments here and below in this function should be a separate patch.

Alphare added a comment.Dec 14 2020, 3:43 AM

Much clearer with the comments. This looks good, aside from the few comments Pulkit and I have left.

marmoute added inline comments.Dec 14 2020, 5:31 AM
mercurial/copies.py
2

It is necessary because we add some utf-8 character in the docstrings (for clarity)

362

Good catch, thanks.

rust/hg-core/src/copy_tracing.rs
427

Well it only pop the parent_copies if it won't have any other users, so it is a pop_or_get ? or a get_and_clean ?

Alphare added inline comments.Dec 14 2020, 5:35 AM
rust/hg-core/src/copy_tracing.rs
427

get_and_clean is better than get and more correct than pop, I'm fine with that. :)

baymax updated this revision to Diff 24233.Dec 14 2020, 7:06 AM

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Alphare accepted this revision.Dec 14 2020, 8:01 AM
baymax updated this revision to Diff 24351.Dec 17 2020, 3:26 PM

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pulkit added a subscriber: durin42.Dec 18 2020, 3:21 AM
pulkit added inline comments.
mercurial/copies.py
2

I am unable to find any utf8 file in codebase and hence not sure how do we feel about them.

cc: @durin42 what do you think about having utf8 files?

baymax updated this revision to Diff 24380.Dec 18 2020, 8:15 AM

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marmoute added inline comments.Dec 18 2020, 9:27 AM
mercurial/copies.py
2

Actually, we already have some. See mercurial/metadata.py

durin42 added a comment.Dec 18 2020, 12:16 PM

I'm fine with having them I suppose.

marmoute added a commit: rHG294d5aca4ff5: copies: iterate over children directly (instead of parents).Dec 18 2020, 3:05 PM
This revision was not accepted when it landed; it landed in state Needs Review.
Closed by commit rHG294d5aca4ff5: copies: iterate over children directly (instead of parents) (authored by marmoute). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 24422

mercurial/copies.py

# coding: utf8 # coding: utf8
# copies.py - copy detection for Mercurial # copies.py - copy detection for Mercurial
pulkitUnsubmitted
Not Done

Unnecessary change?

pulkit: Unnecessary change?
marmouteAuthorUnsubmitted
Done

It is necessary because we add some utf-8 character in the docstrings (for clarity)

marmoute: It is necessary because we add some utf-8 character in the docstrings (for clarity)
pulkitUnsubmitted
Not Done

I am unable to find any utf8 file in codebase and hence not sure how do we feel about them.

cc: @durin42 what do you think about having utf8 files?

pulkit: I am unable to find any utf8 file in codebase and hence not sure how do we feel about them. cc…
marmouteAuthorUnsubmitted
Done

Actually, we already have some. See mercurial/metadata.py

marmoute: Actually, we already have some. See `mercurial/metadata.py`
# #
# Copyright 2008 Matt Mackall <mpm@selenic.com> # Copyright 2008 Matt Mackall <mpm@selenic.com>
# #
# This software may be used and distributed according to the terms of the # This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version. # GNU General Public License version 2 or any later version.
from __future__ import absolute_import from __future__ import absolute_import
ret = cache.get(key) ret = cache.get(key)
if ret is None: if ret is None:
ret = cache[key] = is_ancestor(anc, desc) ret = cache[key] = is_ancestor(anc, desc)
return ret return ret
return _is_ancestor return _is_ancestor
def _changesetforwardcopies(a, b, match): def _changesetforwardcopies(a, b, match):
AlphareUnsubmitted
Not Done

I find the code hard to follow without at least a docstring explaining the point of the algorithm. The Rust code below is more commented.

Alphare: I find the code hard to follow without at least a docstring explaining the point of the…
if a.rev() in (nullrev, b.rev()): if a.rev() in (nullrev, b.rev()):
return {} return {}
repo = a.repo().unfiltered() repo = a.repo().unfiltered()
children = {} children = {}
cl = repo.changelog cl = repo.changelog
isancestor = cl.isancestorrev isancestor = cl.isancestorrev
missingrevs = cl.findmissingrevs(common=[a.rev()], heads=[b.rev()])
mrset = set(missingrevs) # To track rename from "A" to B, we need to gather all parent → children
# edges that are contains in `::B` but not in `::A`.
#
#
# To do so, we need to gather all revisions exclusive¹ to "B" (ie¹: `::b -
# ::a`) and also all the "roots point", ie the parents of the exclusive set
# that belong to ::a. These are exactly all the revisions needed to express
# the parent → children we need to combine.
#
# [1] actually, we need to gather all the edges within `(::a)::b`, ie:
# excluding paths that leads to roots that are not ancestors of `a`. We
# keep this out of the explanation because it is hard enough without this special case..
parents = cl._uncheckedparentrevs
graph_roots = (nullrev, nullrev)
ancestors = cl.ancestors([a.rev()], inclusive=True)
revs = cl.findmissingrevs(common=[a.rev()], heads=[b.rev()])
roots = set() roots = set()
for r in missingrevs: has_graph_roots = False
for p in cl.parentrevs(r):
if p == nullrev: # iterate over `only(B, A)`
continue for r in revs:
if p not in children: ps = parents(r)
children[p] = [r] if ps == graph_roots:
has_graph_roots = True
else: else:
children[p].append(r) p1, p2 = ps
if p not in mrset:
roots.add(p) # find all the "root points" (see larger comment above)
if p1 != nullrev and p1 in ancestors:
roots.add(p1)
if p2 != nullrev and p2 in ancestors:
roots.add(p2)
if not roots: if not roots:
# no common revision to track copies from # no common revision to track copies from
return {} return {}
min_root = min(roots) if has_graph_roots:
# this deal with the special case mentionned in the [1] footnotes. We
from_head = set( # must filter out revisions that leads to non-common graphroots.
cl.reachableroots(min_root, [b.rev()], list(roots), includepath=True) roots = list(roots)
) m = min(roots)
h = [b.rev()]
iterrevs = set(from_head) roots_to_head = cl.reachableroots(m, h, roots, includepath=True)
iterrevs &= mrset roots_to_head = set(roots_to_head)
iterrevs.update(roots) revs = [r for r in revs if r in roots_to_head]
iterrevs.remove(b.rev())
revs = sorted(iterrevs)
if repo.filecopiesmode == b'changeset-sidedata': if repo.filecopiesmode == b'changeset-sidedata':
# When using side-data, we will process the edges "from" the children.
# We iterate over the childre, gathering previous collected data for
# the parents. Do know when the parents data is no longer necessary, we
# keep a counter of how many children each revision has.
#
# An interresting property of `children_count` is that it only contains
# revision that will be relevant for a edge of the graph. So if a
# children has parent not in `children_count`, that edges should not be
# processed.
children_count = dict((r, 0) for r in roots)
for r in revs:
for p in cl.parentrevs(r):
if p == nullrev:
continue
children_count[r] = 0
if p in children_count:
children_count[p] += 1
revinfo = _revinfo_getter(repo, match) revinfo = _revinfo_getter(repo, match)
return _combine_changeset_copies( return _combine_changeset_copies(
revs, children, b.rev(), revinfo, match, isancestor revs, children_count, b.rev(), revinfo, match, isancestor
) )
else: else:
# When not using side-data, we will process the edges "from" the parent.
pulkitUnsubmitted
Not Done

When *not* using side-data?

pulkit: When *not* using side-data?
marmouteAuthorUnsubmitted
Done

Good catch, thanks.

marmoute: Good catch, thanks.
# so we need a full mapping of the parent -> children relation.
children = dict((r, []) for r in roots)
for r in revs:
for p in cl.parentrevs(r):
if p == nullrev:
continue
children[r] = []
if p in children:
children[p].append(r)
x = revs.pop()
assert x == b.rev()
revs.extend(roots)
revs.sort()
revinfo = _revinfo_getter_extra(repo) revinfo = _revinfo_getter_extra(repo)
return _combine_changeset_copies_extra( return _combine_changeset_copies_extra(
revs, children, b.rev(), revinfo, match, isancestor revs, children, b.rev(), revinfo, match, isancestor
) )
def _combine_changeset_copies( def _combine_changeset_copies(
revs, children, targetrev, revinfo, match, isancestor revs, children_count, targetrev, revinfo, match, isancestor
): ):
"""combine the copies information for each item of iterrevs """combine the copies information for each item of iterrevs
revs: sorted iterable of revision to visit revs: sorted iterable of revision to visit
children: a {parent: [children]} mapping. children_count: a {parent: <number-of-relevant-children>} mapping.
targetrev: the final copies destination revision (not in iterrevs) targetrev: the final copies destination revision (not in iterrevs)
revinfo(rev): a function that return (p1, p2, p1copies, p2copies, removed) revinfo(rev): a function that return (p1, p2, p1copies, p2copies, removed)
match: a matcher match: a matcher
It returns the aggregated copies information for `targetrev`. It returns the aggregated copies information for `targetrev`.
""" """
alwaysmatch = match.always() alwaysmatch = match.always()
if rustmod is not None and alwaysmatch: if rustmod is not None and alwaysmatch:
return rustmod.combine_changeset_copies( return rustmod.combine_changeset_copies(
list(revs), children, targetrev, revinfo, isancestor list(revs), children_count, targetrev, revinfo, isancestor
) )
isancestor = cached_is_ancestor(isancestor) isancestor = cached_is_ancestor(isancestor)
all_copies = {} all_copies = {}
# iterate over all the "parent" side of copy tracing "edge" # iterate over all the "children" side of copy tracing "edge"
for r in revs: for current_rev in revs:
# fetch potential previously computed data for that parent p1, p2, changes = revinfo(current_rev)
copies = all_copies.pop(r, None) current_copies = None
# iterate over all parents to chain the existing data with the
# data from the parent → child edge.
for parent, parent_rev in ((1, p1), (2, p2)):
if parent_rev == nullrev:
continue
remaining_children = children_count.get(parent_rev)
if remaining_children is None:
continue
remaining_children -= 1
children_count[parent_rev] = remaining_children
if remaining_children:
copies = all_copies.get(parent_rev, None)
else:
copies = all_copies.pop(parent_rev, None)
if copies is None: if copies is None:
# this is a root # this is a root
copies = {} copies = {}
# iterate over all known children to chain the existing data with the newcopies = copies
# data from the parent → child edge. # chain the data in the edge with the existing data
for i, c in enumerate(children[r]):
p1, p2, changes = revinfo(c)
childcopies = {}
# select the right parent → child edge
if r == p1:
parent = 1
if changes is not None: if changes is not None:
childcopies = {}
if parent == 1:
childcopies = changes.copied_from_p1 childcopies = changes.copied_from_p1
else: elif parent == 2:
assert r == p2
parent = 2
if changes is not None:
childcopies = changes.copied_from_p2 childcopies = changes.copied_from_p2
if not alwaysmatch: if not alwaysmatch:
childcopies = { childcopies = {
dst: src for dst, src in childcopies.items() if match(dst) dst: src
for dst, src in childcopies.items()
if match(dst)
} }
# chain the data in the edge with the existing data
newcopies = copies
if childcopies: if childcopies:
newcopies = copies.copy() newcopies = copies.copy()
for dest, source in pycompat.iteritems(childcopies): for dest, source in pycompat.iteritems(childcopies):
prev = copies.get(source) prev = copies.get(source)
if prev is not None and prev[1] is not None: if prev is not None and prev[1] is not None:
source = prev[1] source = prev[1]
newcopies[dest] = (c, source) newcopies[dest] = (current_rev, source)
assert newcopies is not copies assert newcopies is not copies
if changes is not None and changes.removed: if changes.removed:
if newcopies is copies: if newcopies is copies:
newcopies = copies.copy() newcopies = copies.copy()
for f in changes.removed: for f in changes.removed:
if f in newcopies: if f in newcopies:
if newcopies is copies: if newcopies is copies:
# copy on write to avoid affecting potential other # copy on write to avoid affecting potential other
# branches. when there are no other branches, this # branches. when there are no other branches, this
# could be avoided. # could be avoided.
newcopies = copies.copy() newcopies = copies.copy()
newcopies[f] = (c, None) newcopies[f] = (current_rev, None)
# check potential need to combine the data from another parent (for # check potential need to combine the data from another parent (for
# that child). See comment below for details. # that child). See comment below for details.
othercopies = all_copies.get(c) if current_copies is None:
if othercopies is None: current_copies = newcopies
all_copies[c] = newcopies elif current_copies is newcopies:
elif newcopies is othercopies:
# nothing to merge: # nothing to merge:
pass pass
else: else:
# we are the second parent to work on c, we need to merge our # we are the second parent to work on c, we need to merge our
# work with the other. # work with the other.
# #
# In case of conflict, parent 1 take precedence over parent 2. # In case of conflict, parent 1 take precedence over parent 2.
# This is an arbitrary choice made anew when implementing # This is an arbitrary choice made anew when implementing
# changeset based copies. It was made without regards with # changeset based copies. It was made without regards with
# potential filelog related behavior. # potential filelog related behavior.
if parent == 1: assert parent == 2
if newcopies is copies: current_copies = _merge_copies_dict(
newcopies = copies.copy() newcopies, current_copies, isancestor, changes
minor, major = othercopies, newcopies )
else: all_copies[current_rev] = current_copies
# we do not know if the other dict is a copy or not, so we
# need to blindly copy it. Future change should make this
# unnecessary.
minor, major = newcopies, othercopies.copy()
copies = _merge_copies_dict(minor, major, isancestor, changes)
all_copies[c] = copies
# filter out internal details and return a {dest: source mapping} # filter out internal details and return a {dest: source mapping}
final_copies = {} final_copies = {}
for dest, (tt, source) in all_copies[targetrev].items(): for dest, (tt, source) in all_copies[targetrev].items():
if source is not None: if source is not None:
final_copies[dest] = source final_copies[dest] = source
return final_copies return final_copies
def _combine_changeset_copies_extra( def _combine_changeset_copies_extra(
revs, children, targetrev, revinfo, match, isancestor revs, children, targetrev, revinfo, match, isancestor
): ):
"""version of `_combine_changeset_copies` that works with the Google """version of `_combine_changeset_copies` that works with the Google
specific "extra" based storage for copy information""" specific "extra" based storage for copy information"""
all_copies = {} all_copies = {}
alwaysmatch = match.always() alwaysmatch = match.always()
for r in revs: for r in revs:
pulkitUnsubmitted
Not Done

New comments here and below in this function should be a separate patch.

pulkit: New comments here and below in this function should be a separate patch.
copies = all_copies.pop(r, None) copies = all_copies.pop(r, None)
if copies is None: if copies is None:
# this is a root # this is a root
copies = {} copies = {}
for i, c in enumerate(children[r]): for i, c in enumerate(children[r]):
p1, p2, p1copies, p2copies, removed, ismerged = revinfo(c) p1, p2, p1copies, p2copies, removed, ismerged = revinfo(c)
if r == p1: if r == p1:
parent = 1 parent = 1

rust/hg-core/src/copy_tracing.rs

use crate::utils::hg_path::HgPath; use crate::utils::hg_path::HgPath;
use crate::utils::hg_path::HgPathBuf; use crate::utils::hg_path::HgPathBuf;
use crate::Revision; use crate::Revision;
use crate::NULL_REVISION;
use im_rc::ordmap::DiffItem; use im_rc::ordmap::DiffItem;
use im_rc::ordmap::OrdMap; use im_rc::ordmap::OrdMap;
use std::cmp::Ordering; use std::cmp::Ordering;
use std::collections::HashMap; use std::collections::HashMap;
use std::convert::TryInto; use std::convert::TryInto;
/// rev_info(rev): callback to get revision information: /// rev_info(rev): callback to get revision information:
/// * first parent /// * first parent
/// * second parent /// * second parent
/// * ChangedFiles /// * ChangedFiles
/// isancestors(low_rev, high_rev): callback to check if a revision is an /// isancestors(low_rev, high_rev): callback to check if a revision is an
/// ancestor of another /// ancestor of another
pub fn combine_changeset_copies<A: Fn(Revision, Revision) -> bool, D>( pub fn combine_changeset_copies<A: Fn(Revision, Revision) -> bool, D>(
revs: Vec<Revision>, revs: Vec<Revision>,
children: HashMap<Revision, Vec<Revision>>, mut children_count: HashMap<Revision, usize>,
target_rev: Revision, target_rev: Revision,
rev_info: RevInfoMaker<D>, rev_info: RevInfoMaker<D>,
is_ancestor: &A, is_ancestor: &A,
) -> PathCopies { ) -> PathCopies {
let mut all_copies = HashMap::new(); let mut all_copies = HashMap::new();
let mut oracle = AncestorOracle::new(is_ancestor); let mut oracle = AncestorOracle::new(is_ancestor);
for rev in revs { for rev in revs {
// Retrieve data computed in a previous iteration
let copies = all_copies.remove(&rev);
let copies = match copies {
Some(c) => c,
None => TimeStampedPathCopies::default(), // root of the walked set
};
let current_children = match children.get(&rev) {
Some(c) => c,
None => panic!("inconsistent `revs` and `children`"),
};
for child in current_children {
// We will chain the copies information accumulated for `rev` with
// the individual copies information for each of its children.
// Creating a new PathCopies for each `rev` → `children` vertex.
let mut d: DataHolder<D> = DataHolder { data: None }; let mut d: DataHolder<D> = DataHolder { data: None };
let (p1, p2, changes) = rev_info(*child, &mut d); let (p1, p2, changes) = rev_info(rev, &mut d);
let parent = if rev == p1 { // We will chain the copies information accumulated for the parent with
Parent::FirstParent // the individual copies information the curent revision. Creating a
} else { // new TimeStampedPath for each `rev` → `children` vertex.
assert_eq!(rev, p2); let mut copies: Option<TimeStampedPathCopies> = None;
Parent::SecondParent if p1 != NULL_REVISION {
}; // Retrieve data computed in a previous iteration
let new_copies = let parent_copies = get_and_clean_parent_copies(
add_from_changes(&copies, &changes, parent, *child); &mut all_copies,
&mut children_count,
p1,
);
if let Some(parent_copies) = parent_copies {
// combine it with data for that revision
let vertex_copies = add_from_changes(
&parent_copies,
&changes,
Parent::FirstParent,
rev,
);
// keep that data around for potential later combination
copies = Some(vertex_copies);
}
}
if p2 != NULL_REVISION {
// Retrieve data computed in a previous iteration
let parent_copies = get_and_clean_parent_copies(
&mut all_copies,
&mut children_count,
p2,
);
if let Some(parent_copies) = parent_copies {
// combine it with data for that revision
let vertex_copies = add_from_changes(
&parent_copies,
&changes,
Parent::SecondParent,
rev,
);
// Merge has two parents needs to combines their copy information. copies = match copies {
None => Some(vertex_copies),
// Merge has two parents needs to combines their copy
// information.
// //
// If the vertex from the other parent was already processed, we // If we got data from both parents, We need to combine
// will have a value for the child ready to be used. We need to // them.
// grab it and combine it with the one we already Some(copies) => Some(merge_copies_dict(
// computed. If not we can simply store the newly vertex_copies,
// computed data. The processing happening at copies,
// the time of the second parent will take care of combining the &changes,
// two TimeStampedPathCopies instance. &mut oracle,
match all_copies.remove(child) { )),
None => {
all_copies.insert(child, new_copies);
}
Some(other_copies) => {
let (minor, major) = match parent {
Parent::FirstParent => (other_copies, new_copies),
Parent::SecondParent => (new_copies, other_copies),
};
let merged_copies =
merge_copies_dict(minor, major, &changes, &mut oracle);
all_copies.insert(child, merged_copies);
}
}; };
} }
} }
match copies {
Some(copies) => {
all_copies.insert(rev, copies);
}
_ => {}
}
}
// Drop internal information (like the timestamp) and return the final // Drop internal information (like the timestamp) and return the final
// mapping. // mapping.
let tt_result = all_copies let tt_result = all_copies
.remove(&target_rev) .remove(&target_rev)
.expect("target revision was not processed"); .expect("target revision was not processed");
let mut result = PathCopies::default(); let mut result = PathCopies::default();
for (dest, tt_source) in tt_result { for (dest, tt_source) in tt_result {
if let Some(path) = tt_source.path { if let Some(path) = tt_source.path {
result.insert(dest, path); result.insert(dest, path);
} }
} }
result result
} }
/// fetch previous computed information
///
/// If no other children are expected to need this information, we drop it from
/// the cache.
///
/// If parent is not part of the set we are expected to walk, return None.
fn get_and_clean_parent_copies(
AlphareUnsubmitted
Not Done

This should be called pop_* instead of get_*, I think

Alphare: This should be called `pop_*` instead of `get_*`, I think
marmouteAuthorUnsubmitted
Done

Well it only pop the parent_copies if it won't have any other users, so it is a pop_or_get ? or a get_and_clean ?

marmoute: Well it only pop the parent_copies if it won't have any other users, so it is a `pop_or_get` ?
AlphareUnsubmitted
Not Done

get_and_clean is better than get and more correct than pop, I'm fine with that. :)

Alphare: `get_and_clean` is better than `get` and more correct than `pop`, I'm fine with that. :)
all_copies: &mut HashMap<Revision, TimeStampedPathCopies>,
children_count: &mut HashMap<Revision, usize>,
parent_rev: Revision,
) -> Option<TimeStampedPathCopies> {
let count = children_count.get_mut(&parent_rev)?;
*count -= 1;
if *count == 0 {
match all_copies.remove(&parent_rev) {
Some(c) => Some(c),
None => Some(TimeStampedPathCopies::default()),
}
} else {
match all_copies.get(&parent_rev) {
Some(c) => Some(c.clone()),
None => Some(TimeStampedPathCopies::default()),
}
}
}
/// Combine ChangedFiles with some existing PathCopies information and return /// Combine ChangedFiles with some existing PathCopies information and return
/// the result /// the result
fn add_from_changes( fn add_from_changes(
base_copies: &TimeStampedPathCopies, base_copies: &TimeStampedPathCopies,
changes: &ChangedFiles, changes: &ChangedFiles,
parent: Parent, parent: Parent,
current_rev: Revision, current_rev: Revision,
) -> TimeStampedPathCopies { ) -> TimeStampedPathCopies {

rust/hg-cpython/src/copy_tracing.rs

/// Combines copies information contained into revision `revs` to build a copy /// Combines copies information contained into revision `revs` to build a copy
/// map. /// map.
/// ///
/// See mercurial/copies.py for details /// See mercurial/copies.py for details
pub fn combine_changeset_copies_wrapper( pub fn combine_changeset_copies_wrapper(
py: Python, py: Python,
revs: PyList, revs: PyList,
children: PyDict, children_count: PyDict,
target_rev: Revision, target_rev: Revision,
rev_info: PyObject, rev_info: PyObject,
is_ancestor: PyObject, is_ancestor: PyObject,
) -> PyResult<PyDict> { ) -> PyResult<PyDict> {
let revs: PyResult<_> = let revs: PyResult<_> =
revs.iter(py).map(|r| Ok(r.extract(py)?)).collect(); revs.iter(py).map(|r| Ok(r.extract(py)?)).collect();
// Wrap the `is_ancestor` python callback as a Rust closure // Wrap the `is_ancestor` python callback as a Rust closure
ChangedFiles::new(addrs) ChangedFiles::new(addrs)
} }
// value was presumably None, meaning they was no copy data. // value was presumably None, meaning they was no copy data.
Err(_) => ChangedFiles::new_empty(), Err(_) => ChangedFiles::new_empty(),
}; };
(p1, p2, files) (p1, p2, files)
}); });
let children: PyResult<_> = children let children_count: PyResult<_> = children_count
.items(py) .items(py)
.iter() .iter()
.map(|(k, v)| { .map(|(k, v)| Ok((k.extract(py)?, v.extract(py)?)))
let v: &PyList = v.cast_as(py)?;
let v: PyResult<_> =
v.iter(py).map(|child| Ok(child.extract(py)?)).collect();
Ok((k.extract(py)?, v?))
})
.collect(); .collect();
let res = combine_changeset_copies( let res = combine_changeset_copies(
revs?, revs?,
children?, children_count?,
target_rev, target_rev,
rev_info_maker, rev_info_maker,
&is_ancestor_wrap, &is_ancestor_wrap,
); );
let out = PyDict::new(py); let out = PyDict::new(py);
for (dest, source) in res.into_iter() { for (dest, source) in res.into_iter() {
out.set_item( out.set_item(
py, py,