copies: iterate over children directly (instead of parents) 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 Differential Revision: https://phab.mercurial-scm.org/D9422

     1

# coding: utf8

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# copies.py - copy detection for Mercurial

     3

#

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# Copyright 2008 Matt Mackall <mpm@selenic.com>

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#

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# This software may be used and distributed according to the terms of the

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# GNU General Public License version 2 or any later version.

     8

     9

from __future__ import absolute_import

    10

    11

import collections

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import os

    13

    14

from .i18n import _

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from .node import (

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    nullid,

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    nullrev,

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)

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from . import (

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    match as matchmod,

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    pathutil,

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    policy,

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    pycompat,

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    util,

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)

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    28

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from .utils import stringutil

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from .revlogutils import (

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    flagutil,

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    sidedata as sidedatamod,

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)

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rustmod = policy.importrust("copy_tracing")

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    38

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def _filter(src, dst, t):

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    """filters out invalid copies after chaining"""

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    # When _chain()'ing copies in 'a' (from 'src' via some other commit 'mid')

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    # with copies in 'b' (from 'mid' to 'dst'), we can get the different cases

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    # in the following table (not including trivial cases). For example, case 2

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    # is where a file existed in 'src' and remained under that name in 'mid' and

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    # then was renamed between 'mid' and 'dst'.

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    #

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    # case src mid dst result

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    #   1   x   y   -    -

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    #   2   x   y   y   x->y

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    #   3   x   y   x    -

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    #   4   x   y   z   x->z

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    #   5   -   x   y    -

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    #   6   x   x   y   x->y

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    #

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    # _chain() takes care of chaining the copies in 'a' and 'b', but it

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    # cannot tell the difference between cases 1 and 2, between 3 and 4, or

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    # between 5 and 6, so it includes all cases in its result.

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    # Cases 1, 3, and 5 are then removed by _filter().

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    for k, v in list(t.items()):

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        # remove copies from files that didn't exist

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        if v not in src:

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            del t[k]

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        # remove criss-crossed copies

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        elif k in src and v in dst:

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            del t[k]

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        # remove copies to files that were then removed

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        elif k not in dst:

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            del t[k]

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    72

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def _chain(prefix, suffix):

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    """chain two sets of copies 'prefix' and 'suffix'"""

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    result = prefix.copy()

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    for key, value in pycompat.iteritems(suffix):

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        result[key] = prefix.get(value, value)

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    return result

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    80

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def _tracefile(fctx, am, basemf):

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    """return file context that is the ancestor of fctx present in ancestor

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    manifest am

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    Note: we used to try and stop after a given limit, however checking if that

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    limit is reached turned out to be very expensive. we are better off

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    disabling that feature."""

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    for f in fctx.ancestors():

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        path = f.path()

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        if am.get(path, None) == f.filenode():

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            return path

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        if basemf and basemf.get(path, None) == f.filenode():

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            return path

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    96

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def _dirstatecopies(repo, match=None):

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    ds = repo.dirstate

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    c = ds.copies().copy()

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    for k in list(c):

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        if ds[k] not in b'anm' or (match and not match(k)):

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            del c[k]

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    return c

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def _computeforwardmissing(a, b, match=None):

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    """Computes which files are in b but not a.

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    This is its own function so extensions can easily wrap this call to see what

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    files _forwardcopies is about to process.

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    """

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    ma = a.manifest()

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    mb = b.manifest()

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    return mb.filesnotin(ma, match=match)

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def usechangesetcentricalgo(repo):

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    """Checks if we should use changeset-centric copy algorithms"""

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    if repo.filecopiesmode == b'changeset-sidedata':

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        return True

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    readfrom = repo.ui.config(b'experimental', b'copies.read-from')

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    changesetsource = (b'changeset-only', b'compatibility')

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    return readfrom in changesetsource

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   124

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def _committedforwardcopies(a, b, base, match):

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    """Like _forwardcopies(), but b.rev() cannot be None (working copy)"""

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    # files might have to be traced back to the fctx parent of the last

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    # one-side-only changeset, but not further back than that

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    repo = a._repo

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   131

    if usechangesetcentricalgo(repo):

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        return _changesetforwardcopies(a, b, match)

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    debug = repo.ui.debugflag and repo.ui.configbool(b'devel', b'debug.copies')

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    dbg = repo.ui.debug

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    if debug:

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        dbg(b'debug.copies:    looking into rename from %s to %s\n' % (a, b))

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    am = a.manifest()

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    basemf = None if base is None else base.manifest()

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    # find where new files came from

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    # we currently don't try to find where old files went, too expensive

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    # this means we can miss a case like 'hg rm b; hg cp a b'

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    cm = {}

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    # Computing the forward missing is quite expensive on large manifests, since

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    # it compares the entire manifests. We can optimize it in the common use

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    # case of computing what copies are in a commit versus its parent (like

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    # during a rebase or histedit). Note, we exclude merge commits from this

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    # optimization, since the ctx.files() for a merge commit is not correct for

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    # this comparison.

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    forwardmissingmatch = match

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    if b.p1() == a and b.p2().node() == nullid:

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        filesmatcher = matchmod.exact(b.files())

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        forwardmissingmatch = matchmod.intersectmatchers(match, filesmatcher)

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    missing = _computeforwardmissing(a, b, match=forwardmissingmatch)

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   158

    ancestrycontext = a._repo.changelog.ancestors([b.rev()], inclusive=True)

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   160

    if debug:

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        dbg(b'debug.copies:      missing files to search: %d\n' % len(missing))

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    for f in sorted(missing):

   164

        if debug:

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            dbg(b'debug.copies:        tracing file: %s\n' % f)

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        fctx = b[f]

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        fctx._ancestrycontext = ancestrycontext

   168

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        if debug:

   170

            start = util.timer()

   171

        opath = _tracefile(fctx, am, basemf)

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        if opath:

   173

            if debug:

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                dbg(b'debug.copies:          rename of: %s\n' % opath)

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            cm[f] = opath

   176

        if debug:

   177

            dbg(

   178

                b'debug.copies:          time: %f seconds\n'

   179

                % (util.timer() - start)

   180

            )

   181

    return cm

   182

   183

   184

def _revinfo_getter(repo, match):

   185

    """returns a function that returns the following data given a <rev>"

   186

   187

    * p1: revision number of first parent

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    * p2: revision number of first parent

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    * changes: a ChangingFiles object

   190

    """

   191

    cl = repo.changelog

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    parents = cl.parentrevs

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    flags = cl.flags

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   195

    HASCOPIESINFO = flagutil.REVIDX_HASCOPIESINFO

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   197

    changelogrevision = cl.changelogrevision

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   199

    # A small cache to avoid doing the work twice for merges

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    #

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    # In the vast majority of cases, if we ask information for a revision

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    # about 1 parent, we'll later ask it for the other. So it make sense to

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    # keep the information around when reaching the first parent of a merge

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    # and dropping it after it was provided for the second parents.

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    #

   206

    # It exists cases were only one parent of the merge will be walked. It

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    # happens when the "destination" the copy tracing is descendant from a

   208

    # new root, not common with the "source". In that case, we will only walk

   209

    # through merge parents that are descendant of changesets common

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    # between "source" and "destination".

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    #

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    # With the current case implementation if such changesets have a copy

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    # information, we'll keep them in memory until the end of

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    # _changesetforwardcopies. We don't expect the case to be frequent

   215

    # enough to matters.

   216

    #

   217

    # In addition, it would be possible to reach pathological case, were

   218

    # many first parent are met before any second parent is reached. In

   219

    # that case the cache could grow. If this even become an issue one can

   220

    # safely introduce a maximum cache size. This would trade extra CPU/IO

   221

    # time to save memory.

   222

    merge_caches = {}

   223

   224

    alwaysmatch = match.always()

   225

   226

    if rustmod is not None and alwaysmatch:

   227

   228

        def revinfo(rev):

   229

            p1, p2 = parents(rev)

   230

            value = None

   231

            e = merge_caches.pop(rev, None)

   232

            if e is not None:

   233

                return e

   234

            if flags(rev) & HASCOPIESINFO:

   235

                raw = changelogrevision(rev)._sidedata.get(sidedatamod.SD_FILES)

   236

            else:

   237

                raw = None

   238

            value = (p1, p2, raw)

   239

            if p1 != nullrev and p2 != nullrev:

   240

                # XXX some case we over cache, IGNORE

   241

                merge_caches[rev] = value

   242

            return value

   243

   244

    else:

   245

   246

        def revinfo(rev):

   247

            p1, p2 = parents(rev)

   248

            value = None

   249

            e = merge_caches.pop(rev, None)

   250

            if e is not None:

   251

                return e

   252

            changes = None

   253

            if flags(rev) & HASCOPIESINFO:

   254

                changes = changelogrevision(rev).changes

   255

            value = (p1, p2, changes)

   256

            if p1 != nullrev and p2 != nullrev:

   257

                # XXX some case we over cache, IGNORE

   258

                merge_caches[rev] = value

   259

            return value

   260

   261

    return revinfo

   262

   263

   264

def cached_is_ancestor(is_ancestor):

   265

    """return a cached version of is_ancestor"""

   266

    cache = {}

   267

   268

    def _is_ancestor(anc, desc):

   269

        if anc > desc:

   270

            return False

   271

        elif anc == desc:

   272

            return True

   273

        key = (anc, desc)

   274

        ret = cache.get(key)

   275

        if ret is None:

   276

            ret = cache[key] = is_ancestor(anc, desc)

   277

        return ret

   278

   279

    return _is_ancestor

   280

   281

   282

def _changesetforwardcopies(a, b, match):

   283

    if a.rev() in (nullrev, b.rev()):

   284

        return {}

   285

   286

    repo = a.repo().unfiltered()

   287

    children = {}

   288

   289

    cl = repo.changelog

   290

    isancestor = cl.isancestorrev

   291

   292

    # To track rename from "A" to B, we need to gather all parent → children

   293

    # edges that are contains in `::B` but not in `::A`.

   294

    #

   295

    #

   296

    # To do so, we need to gather all revisions exclusive¹ to "B" (ie¹: `::b -

   297

    # ::a`) and also all the "roots point", ie the parents of the exclusive set

   298

    # that belong to ::a. These are exactly all the revisions needed to express

   299

    # the parent → children we need to combine.

   300

    #

   301

    # [1] actually, we need to gather all the edges within `(::a)::b`, ie:

   302

    # excluding paths that leads to roots that are not ancestors of `a`. We

   303

    # keep this out of the explanation because it is hard enough without this special case..

   304

   305

    parents = cl._uncheckedparentrevs

   306

    graph_roots = (nullrev, nullrev)

   307

   308

    ancestors = cl.ancestors([a.rev()], inclusive=True)

   309

    revs = cl.findmissingrevs(common=[a.rev()], heads=[b.rev()])

   310

    roots = set()

   311

    has_graph_roots = False

   312

   313

    # iterate over `only(B, A)`

   314

    for r in revs:

   315

        ps = parents(r)

   316

        if ps == graph_roots:

   317

            has_graph_roots = True

   318

        else:

   319

            p1, p2 = ps

   320

   321

            # find all the "root points" (see larger comment above)

   322

            if p1 != nullrev and p1 in ancestors:

   323

                roots.add(p1)

   324

            if p2 != nullrev and p2 in ancestors:

   325

                roots.add(p2)

   326

    if not roots:

   327

        # no common revision to track copies from

   328

        return {}

   329

    if has_graph_roots:

   330

        # this deal with the special case mentionned in the [1] footnotes. We

   331

        # must filter out revisions that leads to non-common graphroots.

   332

        roots = list(roots)

   333

        m = min(roots)

   334

        h = [b.rev()]

   335

        roots_to_head = cl.reachableroots(m, h, roots, includepath=True)

   336

        roots_to_head = set(roots_to_head)

   337

        revs = [r for r in revs if r in roots_to_head]

   338

   339

    if repo.filecopiesmode == b'changeset-sidedata':

   340

        # When using side-data, we will process the edges "from" the children.

   341

        # We iterate over the childre, gathering previous collected data for

   342

        # the parents. Do know when the parents data is no longer necessary, we

   343

        # keep a counter of how many children each revision has.

   344

        #

   345

        # An interresting property of `children_count` is that it only contains

   346

        # revision that will be relevant for a edge of the graph. So if a

   347

        # children has parent not in `children_count`, that edges should not be

   348

        # processed.

   349

        children_count = dict((r, 0) for r in roots)

   350

        for r in revs:

   351

            for p in cl.parentrevs(r):

   352

                if p == nullrev:

   353

                    continue

   354

                children_count[r] = 0

   355

                if p in children_count:

   356

                    children_count[p] += 1

   357

        revinfo = _revinfo_getter(repo, match)

   358

        return _combine_changeset_copies(

   359

            revs, children_count, b.rev(), revinfo, match, isancestor

   360

        )

   361

    else:

   362

        # When not using side-data, we will process the edges "from" the parent.

   363

        # so we need a full mapping of the parent -> children relation.

   364

        children = dict((r, []) for r in roots)

   365

        for r in revs:

   366

            for p in cl.parentrevs(r):

   367

                if p == nullrev:

   368

                    continue

   369

                children[r] = []

   370

                if p in children:

   371

                    children[p].append(r)

   372

        x = revs.pop()

   373

        assert x == b.rev()

   374

        revs.extend(roots)

   375

        revs.sort()

   376

   377

        revinfo = _revinfo_getter_extra(repo)

   378

        return _combine_changeset_copies_extra(

   379

            revs, children, b.rev(), revinfo, match, isancestor

   380

        )

   381

   382

   383

def _combine_changeset_copies(

   384

    revs, children_count, targetrev, revinfo, match, isancestor

   385

):

   386

    """combine the copies information for each item of iterrevs

   387

   388

    revs: sorted iterable of revision to visit

   389

    children_count: a {parent: <number-of-relevant-children>} mapping.

   390

    targetrev: the final copies destination revision (not in iterrevs)

   391

    revinfo(rev): a function that return (p1, p2, p1copies, p2copies, removed)

   392

    match: a matcher

   393

   394

    It returns the aggregated copies information for `targetrev`.

   395

    """

   396

   397

    alwaysmatch = match.always()