annotate mercurial/ancestor.py @ 45972:8b99c473aae2

copies-rust: move is_ancestor caching within the rust code

Now that the OrdMap merging is fast, smaller things start to matters.

We move the caching of `is_ancestor` call within the Rust code. This avoid
round-trip to Python and help us to shave more time on our slower case:

Repo            Cases                                 Source-Rev   Dest-Rev         Old-Time      New-Time     Difference   Factor
------------------------------------------------------------------------------------------------------------------------------------
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :   2.780174 s,   2.137894 s,  -0.642280 s, × 0.7690
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :   9.843481 s,   8.100385 s,  -1.743096 s, × 0.8229


Note: I would happily have used native code for ancestors computation, however
I failed (did not tried hard) to created a rust version that goes as fast as
the current C version.

Below are full tables for:
- this change compared to the previous change
- this change compared to filelog performance

Repo            Cases                                 Source-Rev   Dest-Rev         Old-Time      New-Time     Difference   Factor
------------------------------------------------------------------------------------------------------------------------------------
mercurial       x_revs_x_added_0_copies               ad6b123de1c7 39cfcef4f463 :   0.000049 s,   0.000047 s,  -0.000002 s, × 0.9592
mercurial       x_revs_x_added_x_copies               2b1c78674230 0c1d10351869 :   0.000182 s,   0.000181 s,  -0.000001 s, × 0.9945
mercurial       x000_revs_x000_added_x_copies         81f8ff2a9bf2 dd3267698d84 :   0.005872 s,   0.005852 s,  -0.000020 s, × 0.9966
pypy            x_revs_x_added_0_copies               aed021ee8ae8 099ed31b181b :   0.000229 s,   0.000229 s,  +0.000000 s, × 1.0000
pypy            x_revs_x000_added_0_copies            4aa4e1f8e19a 359343b9ac0e :   0.000058 s,   0.000058 s,  +0.000000 s, × 1.0000
pypy            x_revs_x_added_x_copies               ac52eb7bbbb0 72e022663155 :   0.000148 s,   0.000146 s,  -0.000002 s, × 0.9865
pypy            x_revs_x00_added_x_copies             c3b14617fbd7 ace7255d9a26 :   0.001205 s,   0.001206 s,  +0.000001 s, × 1.0008
pypy            x_revs_x000_added_x000_copies         df6f7a526b60 a83dc6a2d56f :   0.025662 s,   0.025275 s,  -0.000387 s, × 0.9849
pypy            x000_revs_xx00_added_0_copies         89a76aede314 2f22446ff07e :   0.080113 s,   0.080303 s,  +0.000190 s, × 1.0024
pypy            x000_revs_x000_added_x_copies         8a3b5bfd266e 2c68e87c3efe :   0.153030 s,   0.152641 s,  -0.000389 s, × 0.9975
pypy            x000_revs_x000_added_x000_copies      89a76aede314 7b3dda341c84 :   0.098774 s,   0.099107 s,  +0.000333 s, × 1.0034
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :   2.780174 s,   2.137894 s,  -0.642280 s, × 0.7690
pypy            x0000_revs_xx000_added_0_copies       bf2c629d0071 4ffed77c095c :   0.022218 s,   0.022202 s,  -0.000016 s, × 0.9993
pypy            x0000_revs_xx000_added_x000_copies    08ea3258278e d9fa043f30c0 :   0.252125 s,   0.228946 s,  -0.023179 s, × 0.9081
netbeans        x_revs_x_added_0_copies               fb0955ffcbcd a01e9239f9e7 :   0.000186 s,   0.000186 s,  +0.000000 s, × 1.0000
netbeans        x_revs_x000_added_0_copies            6f360122949f 20eb231cc7d0 :   0.000133 s,   0.000133 s,  +0.000000 s, × 1.0000
netbeans        x_revs_x_added_x_copies               1ada3faf6fb6 5a39d12eecf4 :   0.000320 s,   0.000320 s,  +0.000000 s, × 1.0000
netbeans        x_revs_x00_added_x_copies             35be93ba1e2c 9eec5e90c05f :   0.001336 s,   0.001339 s,  +0.000003 s, × 1.0022
netbeans        x000_revs_xx00_added_0_copies         eac3045b4fdd 51d4ae7f1290 :   0.015573 s,   0.015694 s,  +0.000121 s, × 1.0078
netbeans        x000_revs_x000_added_x_copies         e2063d266acd 6081d72689dc :   0.018667 s,   0.018457 s,  -0.000210 s, × 0.9888
netbeans        x000_revs_x000_added_x000_copies      ff453e9fee32 411350406ec2 :   0.112534 s,   0.111691 s,  -0.000843 s, × 0.9925
netbeans        x0000_revs_xx000_added_x000_copies    588c2d1ced70 1aad62e59ddd :   1.231869 s,   1.166017 s,  -0.065852 s, × 0.9465
mozilla-central x_revs_x_added_0_copies               3697f962bb7b 7015fcdd43a2 :   0.000197 s,   0.000197 s,  +0.000000 s, × 1.0000
mozilla-central x_revs_x000_added_0_copies            dd390860c6c9 40d0c5bed75d :   0.000637 s,   0.000626 s,  -0.000011 s, × 0.9827
mozilla-central x_revs_x_added_x_copies               8d198483ae3b 14207ffc2b2f :   0.000303 s,   0.000303 s,  +0.000000 s, × 1.0000
mozilla-central x_revs_x00_added_x_copies             98cbc58cc6bc 446a150332c3 :   0.001663 s,   0.001679 s,  +0.000016 s, × 1.0096
mozilla-central x_revs_x000_added_x000_copies         3c684b4b8f68 0a5e72d1b479 :   0.007008 s,   0.006947 s,  -0.000061 s, × 0.9913
mozilla-central x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :   0.127385 s,   0.133070 s,  +0.005685 s, × 1.0446
mozilla-central x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :   0.008740 s,   0.008705 s,  -0.000035 s, × 0.9960
mozilla-central x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :   0.005783 s,   0.005913 s,  +0.000130 s, × 1.0225
mozilla-central x000_revs_x000_added_x000_copies      7c97034feb78 4407bd0c6330 :   0.102184 s,   0.101373 s,  -0.000811 s, × 0.9921
mozilla-central x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :   0.046220 s,   0.046526 s,  +0.000306 s, × 1.0066
mozilla-central x0000_revs_xx000_added_x000_copies    f78c615a656c 96a38b690156 :   0.315271 s,   0.313954 s,  -0.001317 s, × 0.9958
mozilla-central x00000_revs_x0000_added_x0000_copies  6832ae71433c 4c222a1d9a00 :   3.478747 s,   3.367395 s,  -0.111352 s, × 0.9680
mozilla-central x00000_revs_x00000_added_x000_copies  76caed42cf7c 1daa622bbe42 :   4.766435 s,   4.691820 s,  -0.074615 s, × 0.9843
mozilla-try     x_revs_x_added_0_copies               aaf6dde0deb8 9790f499805a :   0.001214 s,   0.001199 s,  -0.000015 s, × 0.9876
mozilla-try     x_revs_x000_added_0_copies            d8d0222927b4 5bb8ce8c7450 :   0.001221 s,   0.001216 s,  -0.000005 s, × 0.9959
mozilla-try     x_revs_x_added_x_copies               092fcca11bdb 936255a0384a :   0.000613 s,   0.000613 s,  +0.000000 s, × 1.0000
mozilla-try     x_revs_x00_added_x_copies             b53d2fadbdb5 017afae788ec :   0.001904 s,   0.001906 s,  +0.000002 s, × 1.0011
mozilla-try     x_revs_x000_added_x000_copies         20408ad61ce5 6f0ee96e21ad :   0.093000 s,   0.092766 s,  -0.000234 s, × 0.9975
mozilla-try     x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :   0.132194 s,   0.136074 s,  +0.003880 s, × 1.0294
mozilla-try     x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :   0.009069 s,   0.009067 s,  -0.000002 s, × 0.9998
mozilla-try     x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :   0.006169 s,   0.006243 s,  +0.000074 s, × 1.0120
mozilla-try     x000_revs_x000_added_x000_copies      1346fd0130e4 4c65cbdabc1f :   0.115540 s,   0.114463 s,  -0.001077 s, × 0.9907
mozilla-try     x0000_revs_x_added_0_copies           63519bfd42ee a36a2a865d92 :   0.435381 s,   0.433683 s,  -0.001698 s, × 0.9961
mozilla-try     x0000_revs_x_added_x_copies           9fe69ff0762d bcabf2a78927 :   0.415461 s,   0.411278 s,  -0.004183 s, × 0.9899
mozilla-try     x0000_revs_xx000_added_x_copies       156f6e2674f2 4d0f2c178e66 :   0.155946 s,   0.155133 s,  -0.000813 s, × 0.9948
mozilla-try     x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :   0.048521 s,   0.048933 s,  +0.000412 s, × 1.0085
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :   9.843481 s,   8.100385 s,  -1.743096 s, × 0.8229
mozilla-try     x0000_revs_x0000_added_x0000_copies   e928c65095ed e951f4ad123a :   1.465128 s,   1.446720 s,  -0.018408 s, × 0.9874
mozilla-try     x00000_revs_x00000_added_0_copies     dc8a3ca7010e d16fde900c9c :   1.374283 s,   1.369537 s,  -0.004746 s, × 0.9965
mozilla-try     x00000_revs_x0000_added_x0000_copies  8d3fafa80d4b eb884023b810 :   5.255158 s,   5.186079 s,  -0.069079 s, × 0.9869

Repo            Case                                  Source-Rev   Dest-Rev        filelog     sidedata     Difference    Factor
--------------------------------------------------------------------------------------------------------------------------------------
mercurial       x_revs_x_added_0_copies               ad6b123de1c7 39cfcef4f463 :  0.000892 s, 0.000047 s,  -0.000845 s,    × 0.052691
mercurial       x_revs_x_added_x_copies               2b1c78674230 0c1d10351869 :  0.001823 s, 0.000181 s,  -0.001642 s,    × 0.099287
mercurial       x000_revs_x000_added_x_copies         81f8ff2a9bf2 dd3267698d84 :  0.018063 s, 0.005852 s,  -0.012211 s,    × 0.323977
pypy            x_revs_x_added_0_copies               aed021ee8ae8 099ed31b181b :  0.001505 s, 0.000229 s,  -0.001276 s,    × 0.152159
pypy            x_revs_x000_added_0_copies            4aa4e1f8e19a 359343b9ac0e :  0.205895 s, 0.000058 s,  -0.205837 s,    × 0.000282
pypy            x_revs_x_added_x_copies               ac52eb7bbbb0 72e022663155 :  0.017021 s, 0.000146 s,  -0.016875 s,    × 0.008578
pypy            x_revs_x00_added_x_copies             c3b14617fbd7 ace7255d9a26 :  0.019422 s, 0.001206 s,  -0.018216 s,    × 0.062095
pypy            x_revs_x000_added_x000_copies         df6f7a526b60 a83dc6a2d56f :  0.767740 s, 0.025275 s,  -0.742465 s,    × 0.032921
pypy            x000_revs_xx00_added_0_copies         89a76aede314 2f22446ff07e :  1.188515 s, 0.080303 s,  -1.108212 s,    × 0.067566
pypy            x000_revs_x000_added_x_copies         8a3b5bfd266e 2c68e87c3efe :  1.251968 s, 0.152641 s,  -1.099327 s,    × 0.121921
pypy            x000_revs_x000_added_x000_copies      89a76aede314 7b3dda341c84 :  1.616799 s, 0.099107 s,  -1.517692 s,    × 0.061298
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :  0.001057 s, 2.137894 s,  +2.136837 s, × 2022.605487
pypy            x0000_revs_xx000_added_0_copies       bf2c629d0071 4ffed77c095c :  1.069485 s, 0.022202 s,  -1.047283 s,    × 0.020760
pypy            x0000_revs_xx000_added_x000_copies    08ea3258278e d9fa043f30c0 :  1.350162 s, 0.228946 s,  -1.121216 s,    × 0.169569
netbeans        x_revs_x_added_0_copies               fb0955ffcbcd a01e9239f9e7 :  0.028008 s, 0.000186 s,  -0.027822 s,    × 0.006641
netbeans        x_revs_x000_added_0_copies            6f360122949f 20eb231cc7d0 :  0.132281 s, 0.000133 s,  -0.132148 s,    × 0.001005
netbeans        x_revs_x_added_x_copies               1ada3faf6fb6 5a39d12eecf4 :  0.025311 s, 0.000320 s,  -0.024991 s,    × 0.012643
netbeans        x_revs_x00_added_x_copies             35be93ba1e2c 9eec5e90c05f :  0.052957 s, 0.001339 s,  -0.051618 s,    × 0.025285
netbeans        x000_revs_xx00_added_0_copies         eac3045b4fdd 51d4ae7f1290 :  0.038011 s, 0.015694 s,  -0.022317 s,    × 0.412880
netbeans        x000_revs_x000_added_x_copies         e2063d266acd 6081d72689dc :  0.198639 s, 0.018457 s,  -0.180182 s,    × 0.092917
netbeans        x000_revs_x000_added_x000_copies      ff453e9fee32 411350406ec2 :  0.955713 s, 0.111691 s,  -0.844022 s,    × 0.116867
netbeans        x0000_revs_xx000_added_x000_copies    588c2d1ced70 1aad62e59ddd :  3.838886 s, 1.166017 s,  -2.672869 s,    × 0.303738
mozilla-central x_revs_x_added_0_copies               3697f962bb7b 7015fcdd43a2 :  0.024548 s, 0.000197 s,  -0.024351 s,    × 0.008025
mozilla-central x_revs_x000_added_0_copies            dd390860c6c9 40d0c5bed75d :  0.143394 s, 0.000626 s,  -0.142768 s,    × 0.004366
mozilla-central x_revs_x_added_x_copies               8d198483ae3b 14207ffc2b2f :  0.026046 s, 0.000303 s,  -0.025743 s,    × 0.011633
mozilla-central x_revs_x00_added_x_copies             98cbc58cc6bc 446a150332c3 :  0.085440 s, 0.001679 s,  -0.083761 s,    × 0.019651
mozilla-central x_revs_x000_added_x000_copies         3c684b4b8f68 0a5e72d1b479 :  0.195656 s, 0.006947 s,  -0.188709 s,    × 0.035506
mozilla-central x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :  2.190874 s, 0.133070 s,  -2.057804 s,    × 0.060738
mozilla-central x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :  0.090208 s, 0.008705 s,  -0.081503 s,    × 0.096499
mozilla-central x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :  0.747367 s, 0.005913 s,  -0.741454 s,    × 0.007912
mozilla-central x000_revs_x000_added_x000_copies      7c97034feb78 4407bd0c6330 :  1.152863 s, 0.101373 s,  -1.051490 s,    × 0.087932
mozilla-central x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :  6.598336 s, 0.046526 s,  -6.551810 s,    × 0.007051
mozilla-central x0000_revs_xx000_added_x000_copies    f78c615a656c 96a38b690156 :  3.255015 s, 0.313954 s,  -2.941061 s,    × 0.096452
mozilla-central x00000_revs_x0000_added_x0000_copies  6832ae71433c 4c222a1d9a00 : 15.668041 s, 3.367395 s, -12.300646 s,    × 0.214921
mozilla-central x00000_revs_x00000_added_x000_copies  76caed42cf7c 1daa622bbe42 : 20.439638 s, 4.691820 s, -15.747818 s,    × 0.229545
mozilla-try     x_revs_x_added_0_copies               aaf6dde0deb8 9790f499805a :  0.080923 s, 0.001199 s,  -0.079724 s,    × 0.014817
mozilla-try     x_revs_x000_added_0_copies            d8d0222927b4 5bb8ce8c7450 :  0.498456 s, 0.001216 s,  -0.497240 s,    × 0.002440
mozilla-try     x_revs_x_added_x_copies               092fcca11bdb 936255a0384a :  0.020798 s, 0.000613 s,  -0.020185 s,    × 0.029474
mozilla-try     x_revs_x00_added_x_copies             b53d2fadbdb5 017afae788ec :  0.226930 s, 0.001906 s,  -0.225024 s,    × 0.008399
mozilla-try     x_revs_x000_added_x000_copies         20408ad61ce5 6f0ee96e21ad :  1.113005 s, 0.092766 s,  -1.020239 s,    × 0.083347
mozilla-try     x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :  2.230671 s, 0.136074 s,  -2.094597 s,    × 0.061001
mozilla-try     x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :  0.089672 s, 0.009067 s,  -0.080605 s,    × 0.101113
mozilla-try     x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :  0.740221 s, 0.006243 s,  -0.733978 s,    × 0.008434
mozilla-try     x000_revs_x000_added_x000_copies      1346fd0130e4 4c65cbdabc1f :  1.185881 s, 0.114463 s,  -1.071418 s,    × 0.096521
mozilla-try     x0000_revs_x_added_0_copies           63519bfd42ee a36a2a865d92 :  0.086072 s, 0.433683 s,  +0.347611 s,    × 5.038607
mozilla-try     x0000_revs_x_added_x_copies           9fe69ff0762d bcabf2a78927 :  0.081321 s, 0.411278 s,  +0.329957 s,    × 5.057464
mozilla-try     x0000_revs_xx000_added_x_copies       156f6e2674f2 4d0f2c178e66 :  7.528370 s, 0.155133 s,  -7.373237 s,    × 0.020606
mozilla-try     x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :  6.757368 s, 0.048933 s,  -6.708435 s,    × 0.007241
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :  7.643752 s, 8.100385 s,  +0.456633 s,    × 1.059739
mozilla-try     x0000_revs_x0000_added_x0000_copies   e928c65095ed e951f4ad123a :  9.704242 s, 1.446720 s,  -8.257522 s,    × 0.149081
mozilla-try     x00000_revs_x_added_0_copies          6a320851d377 1ebb79acd503 :  0.092845 s, killed
mozilla-try     x00000_revs_x00000_added_0_copies     dc8a3ca7010e d16fde900c9c : 26.626870 s, 1.369537 s, -25.257333 s,    × 0.051434
mozilla-try     x00000_revs_x_added_x_copies          5173c4b6f97c 95d83ee7242d :  0.092953 s, killed
mozilla-try     x00000_revs_x000_added_x_copies       9126823d0e9c ca82787bb23c :  0.227131 s, killed
mozilla-try     x00000_revs_x0000_added_x0000_copies  8d3fafa80d4b eb884023b810 : 18.884666 s, 5.186079 s, -13.698587 s,    × 0.274619
mozilla-try     x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 21.451622 s, killed
mozilla-try     x00000_revs_x00000_added_x000_copies  9b2a99adc05e 8e29777b48e6 : 25.152558 s, killed

Differential Revision: https://phab.mercurial-scm.org/D9303

# ancestor.py - generic DAG ancestor algorithm for mercurial
#
# Copyright 2006 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import heapq

from .node import nullrev
from . import (
    dagop,
    policy,
    pycompat,
)

parsers = policy.importmod('parsers')


def commonancestorsheads(pfunc, *nodes):
    """Returns a set with the heads of all common ancestors of all nodes,
    heads(::nodes[0] and ::nodes[1] and ...) .

    pfunc must return a list of parent vertices for a given vertex.
    """
    if not isinstance(nodes, set):
        nodes = set(nodes)
    if nullrev in nodes:
        return set()
    if len(nodes) <= 1:
        return nodes

    allseen = (1 << len(nodes)) - 1
    seen = [0] * (max(nodes) + 1)
    for i, n in enumerate(nodes):
        seen[n] = 1 << i
    poison = 1 << (i + 1)

    gca = set()
    interesting = len(nodes)
    nv = len(seen) - 1
    while nv >= 0 and interesting:
        v = nv
        nv -= 1
        if not seen[v]:
            continue
        sv = seen[v]
        if sv < poison:
            interesting -= 1
            if sv == allseen:
                gca.add(v)
                sv |= poison
                if v in nodes:
                    # history is linear
                    return {v}
        if sv < poison:
            for p in pfunc(v):
                sp = seen[p]
                if p == nullrev:
                    continue
                if sp == 0:
                    seen[p] = sv
                    interesting += 1
                elif sp != sv:
                    seen[p] |= sv
        else:
            for p in pfunc(v):
                if p == nullrev:
                    continue
                sp = seen[p]
                if sp and sp < poison:
                    interesting -= 1
                seen[p] = sv
    return gca


def ancestors(pfunc, *orignodes):
    """
    Returns the common ancestors of a and b that are furthest from a
    root (as measured by longest path).

    pfunc must return a list of parent vertices for a given vertex.
    """

    def deepest(nodes):
        interesting = {}
        count = max(nodes) + 1
        depth = [0] * count
        seen = [0] * count
        mapping = []
        for (i, n) in enumerate(sorted(nodes)):
            depth[n] = 1
            b = 1 << i
            seen[n] = b
            interesting[b] = 1
            mapping.append((b, n))
        nv = count - 1
        while nv >= 0 and len(interesting) > 1:
            v = nv
            nv -= 1
            dv = depth[v]
            if dv == 0:
                continue
            sv = seen[v]
            for p in pfunc(v):
                if p == nullrev:
                    continue
                dp = depth[p]
                sp = seen[p]
                if dp <= dv:
                    depth[p] = dv + 1
                    if sp != sv:
                        interesting[sv] += 1
                        seen[p] = sv
                        if sp:
                            interesting[sp] -= 1
                            if interesting[sp] == 0:
                                del interesting[sp]
                elif dv == dp - 1:
                    nsp = sp | sv
                    if nsp == sp:
                        continue
                    seen[p] = nsp
                    interesting.setdefault(nsp, 0)
                    interesting[nsp] += 1
                    interesting[sp] -= 1
                    if interesting[sp] == 0:
                        del interesting[sp]
            interesting[sv] -= 1
            if interesting[sv] == 0:
                del interesting[sv]

        if len(interesting) != 1:
            return []

        k = 0
        for i in interesting:
            k |= i
        return {n for (i, n) in mapping if k & i}

    gca = commonancestorsheads(pfunc, *orignodes)

    if len(gca) <= 1:
        return gca
    return deepest(gca)


class incrementalmissingancestors(object):
    """persistent state used to calculate missing ancestors incrementally

    Although similar in spirit to lazyancestors below, this is a separate class
    because trying to support contains and missingancestors operations with the
    same internal data structures adds needless complexity."""

    def __init__(self, pfunc, bases):
        self.bases = set(bases)
        if not self.bases:
            self.bases.add(nullrev)
        self.pfunc = pfunc

    def hasbases(self):
        '''whether the common set has any non-trivial bases'''
        return self.bases and self.bases != {nullrev}

    def addbases(self, newbases):
        '''grow the ancestor set by adding new bases'''
        self.bases.update(newbases)

    def basesheads(self):
        return dagop.headrevs(self.bases, self.pfunc)

    def removeancestorsfrom(self, revs):
        '''remove all ancestors of bases from the set revs (in place)'''
        bases = self.bases
        pfunc = self.pfunc
        revs.difference_update(bases)
        # nullrev is always an ancestor
        revs.discard(nullrev)
        if not revs:
            return
        # anything in revs > start is definitely not an ancestor of bases
        # revs <= start needs to be investigated
        start = max(bases)
        keepcount = sum(1 for r in revs if r > start)
        if len(revs) == keepcount:
            # no revs to consider
            return

        for curr in pycompat.xrange(start, min(revs) - 1, -1):
            if curr not in bases:
                continue
            revs.discard(curr)
            bases.update(pfunc(curr))
            if len(revs) == keepcount:
                # no more potential revs to discard
                break

    def missingancestors(self, revs):
        """return all the ancestors of revs that are not ancestors of self.bases

        This may include elements from revs.

        Equivalent to the revset (::revs - ::self.bases). Revs are returned in
        revision number order, which is a topological order."""
        revsvisit = set(revs)
        basesvisit = self.bases
        pfunc = self.pfunc
        bothvisit = revsvisit.intersection(basesvisit)
        revsvisit.difference_update(bothvisit)
        if not revsvisit:
            return []

        start = max(max(revsvisit), max(basesvisit))
        # At this point, we hold the invariants that:
        # - revsvisit is the set of nodes we know are an ancestor of at least
        #   one of the nodes in revs
        # - basesvisit is the same for bases
        # - bothvisit is the set of nodes we know are ancestors of at least one
        #   of the nodes in revs and one of the nodes in bases. bothvisit and
        #   revsvisit are mutually exclusive, but bothvisit is a subset of
        #   basesvisit.
        # Now we walk down in reverse topo order, adding parents of nodes
        # already visited to the sets while maintaining the invariants. When a
        # node is found in both revsvisit and basesvisit, it is removed from
        # revsvisit and added to bothvisit. When revsvisit becomes empty, there
        # are no more ancestors of revs that aren't also ancestors of bases, so
        # exit.

        missing = []
        for curr in pycompat.xrange(start, nullrev, -1):
            if not revsvisit:
                break

            if curr in bothvisit:
                bothvisit.remove(curr)
                # curr's parents might have made it into revsvisit through
                # another path
                for p in pfunc(curr):
                    revsvisit.discard(p)
                    basesvisit.add(p)
                    bothvisit.add(p)
                continue

            if curr in revsvisit:
                missing.append(curr)
                revsvisit.remove(curr)
                thisvisit = revsvisit
                othervisit = basesvisit
            elif curr in basesvisit:
                thisvisit = basesvisit
                othervisit = revsvisit
            else:
                # not an ancestor of revs or bases: ignore
                continue

            for p in pfunc(curr):
                if p == nullrev:
                    pass
                elif p in othervisit or p in bothvisit:
                    # p is implicitly in thisvisit. This means p is or should be
                    # in bothvisit
                    revsvisit.discard(p)
                    basesvisit.add(p)
                    bothvisit.add(p)
                else:
                    # visit later
                    thisvisit.add(p)

        missing.reverse()
        return missing


# Extracted from lazyancestors.__iter__ to avoid a reference cycle
def _lazyancestorsiter(parentrevs, initrevs, stoprev, inclusive):
    seen = {nullrev}
    heappush = heapq.heappush
    heappop = heapq.heappop
    heapreplace = heapq.heapreplace
    see = seen.add

    if inclusive:
        visit = [-r for r in initrevs]
        seen.update(initrevs)
        heapq.heapify(visit)
    else:
        visit = []
        heapq.heapify(visit)
        for r in initrevs:
            p1, p2 = parentrevs(r)
            if p1 not in seen:
                heappush(visit, -p1)
                see(p1)
            if p2 not in seen:
                heappush(visit, -p2)
                see(p2)

    while visit:
        current = -visit[0]
        if current < stoprev:
            break
        yield current
        # optimize out heapq operation if p1 is known to be the next highest
        # revision, which is quite common in linear history.
        p1, p2 = parentrevs(current)
        if p1 not in seen:
            if current - p1 == 1:
                visit[0] = -p1
            else:
                heapreplace(visit, -p1)
            see(p1)
        else:
            heappop(visit)
        if p2 not in seen:
            heappush(visit, -p2)
            see(p2)


class lazyancestors(object):
    def __init__(self, pfunc, revs, stoprev=0, inclusive=False):
        """Create a new object generating ancestors for the given revs. Does
        not generate revs lower than stoprev.

        This is computed lazily starting from revs. The object supports
        iteration and membership.

        cl should be a changelog and revs should be an iterable. inclusive is
        a boolean that indicates whether revs should be included. Revs lower
        than stoprev will not be generated.

        Result does not include the null revision."""
        self._parentrevs = pfunc
        self._initrevs = [r for r in revs if r >= stoprev]
        self._stoprev = stoprev
        self._inclusive = inclusive

        self._containsseen = set()
        self._containsiter = _lazyancestorsiter(
            self._parentrevs, self._initrevs, self._stoprev, self._inclusive
        )

    def __nonzero__(self):
        """False if the set is empty, True otherwise."""
        try:
            next(iter(self))
            return True
        except StopIteration:
            return False

    __bool__ = __nonzero__

    def __iter__(self):
        """Generate the ancestors of _initrevs in reverse topological order.

        If inclusive is False, yield a sequence of revision numbers starting
        with the parents of each revision in revs, i.e., each revision is
        *not* considered an ancestor of itself. Results are emitted in reverse
        revision number order. That order is also topological: a child is
        always emitted before its parent.

        If inclusive is True, the source revisions are also yielded. The
        reverse revision number order is still enforced."""
        return _lazyancestorsiter(
            self._parentrevs, self._initrevs, self._stoprev, self._inclusive
        )

    def __contains__(self, target):
        """Test whether target is an ancestor of self._initrevs."""
        seen = self._containsseen
        if target in seen:
            return True
        iter = self._containsiter
        if iter is None:
            # Iterator exhausted
            return False
        # Only integer target is valid, but some callers expect 'None in self'
        # to be False. So we explicitly allow it.
        if target is None:
            return False

        see = seen.add
        try:
            while True:
                rev = next(iter)
                see(rev)
                if rev == target:
                    return True
                if rev < target:
                    return False
        except StopIteration:
            # Set to None to indicate fast-path can be used next time, and to
            # free up memory.
            self._containsiter = None
            return False