phases: rework the logic of _pushdiscoveryphase to bound complexity This rework the various graph traversal in _pushdiscoveryphase to keep the complexity in check. This is done though a couple of things: - first, limiting the space we have to explore, for example, if we are not in publishing push, we don't need to consider remote draft roots that are also draft locally, as there is nothing to be moved there. - avoid unbounded descendant computation, and use the faster "rev between" computation. This provide a massive boost to performance when exchanging with repository with a massive amount of draft, like mozilla-try: ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # benchmark.name = hg.command.push # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.explicit-rev = all-out-heads # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.reuse-external-delta-parent = default ## benchmark.variants.revs = any-1-extra-rev before: 20.346590 seconds after: 11.232059 seconds (-38.15%, -7.48 seconds) ## benchmark.variants.revs = any-100-extra-rev before: 24.752051 seconds after: 15.367412 seconds (-37.91%, -9.38 seconds) After this changes, the push operation is still quite too slow. Some of this can be attributed to general phases slowness (reading all the roots from disk for example) and other know slowness (not using persistent-nodemap, branchmap, tags, etc. We are also working on them, but with this series, phase discovery during push no longer showing up in profile and this is a pretty nice and bit low-hanging fruit out of the way. ### (same case as the above) # benchmark.variants.revs = any-1-extra-rev pre-%ln-change: 44.235070 this-changeset: 11.232059 seconds (-74.61%, -33.00 seconds) # benchmark.variants.revs = any-100-extra-rev pre-%ln-change: 49.234697 this-changeset: 15.367412 seconds (-68.79%, -33.87 seconds) Note that with this change, the `hg push` performance is now much closer to the `hg pull` performance, even it still lagging behind a bit. (and the overall performance are still too slow). ### data-env-vars.name = mozilla-try-2023-03-22-ds2-pnm # benchmark.variants.explicit-rev = all-out-heads # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.pulled-delta-reuse-policy = default # bin-env-vars.hg.flavor = rust ## benchmark.variants.revs = any-1-extra-rev hg.command.pull: 6.517450 hg.command.push: 11.219888 ## benchmark.variants.revs = any-100-extra-rev hg.command.pull: 10.160991 hg.command.push: 14.251107 ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # bin-env-vars.hg.py-re2-module = default # benchmark.variants.explicit-rev = all-out-heads # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.pulled-delta-reuse-policy = default ## bin-env-vars.hg.flavor = default ## benchmark.variants.revs = any-1-extra-rev hg.command.pull: 8.577772 hg.command.push: 11.232059 ## bin-env-vars.hg.flavor = default ## benchmark.variants.revs = any-100-extra-rev hg.command.pull: 13.152976 hg.command.push: 15.367412 ## bin-env-vars.hg.flavor = rust ## benchmark.variants.revs = any-1-extra-rev hg.command.pull: 8.731982 hg.command.push: 11.178751 ## bin-env-vars.hg.flavor = rust ## benchmark.variants.revs = any-100-extra-rev hg.command.pull: 13.184236 hg.command.push: 15.620843

     1

  $ hg init a

     2

  $ cd a

     3

  $ touch empty1

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  $ hg add empty1

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  $ hg commit -m 'add empty1'

     6

     7

  $ touch empty2

     8

  $ hg add empty2

     9

  $ hg commit -m 'add empty2'

    10

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  $ hg up -C 0

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  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

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  $ touch empty3

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  $ hg add empty3

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  $ hg commit -m 'add empty3'

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  created new head

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  $ hg heads

    19

  changeset:   2:a1cb177e0d44

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  tag:         tip

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  parent:      0:1e1d9c4e5b64

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  user:        test

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  date:        Thu Jan 01 00:00:00 1970 +0000

    24

  summary:     add empty3

    25

    26

  changeset:   1:097d2b0e17f6

    27

  user:        test

    28

  date:        Thu Jan 01 00:00:00 1970 +0000

    29

  summary:     add empty2

    30

    31

    32

  $ hg merge 1

    33

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

    34

  (branch merge, don't forget to commit)

    35

    36

Before changeset 05257fd28591, we didn't notice the

    37

empty file that came from rev 1:

    38

    39

  $ hg status

    40

  M empty2

    41

  $ hg commit -m merge

    42

  $ hg manifest --debug tip

    43

  b80de5d138758541c5f05265ad144ab9fa86d1db 644   empty1

    44

  b80de5d138758541c5f05265ad144ab9fa86d1db 644   empty2

    45

  b80de5d138758541c5f05265ad144ab9fa86d1db 644   empty3

    46

    47

  $ cd ..