[PATCH 2 of 6 V2] hidden: use _domainancestors to compute revs revealed by dynamic blocker

[Gregory Szorc]

On Tue, May 23, 2017 at 1:02 PM, Pierre-Yves David <
pierre-yves.david at ens-lyon.org> wrote:

> # HG changeset patch
> # User Pierre-Yves David <pierre-yves.david at octobus.net>
> # Date 1495373721 -7200
> #      Sun May 21 15:35:21 2017 +0200
> # Node ID e72ddd1a53c4c6321e7ecd686cd24c2a8c8914bc
> # Parent  5f964af88a0fae242ce24b0478c676d2056e0dc6
> # EXP-Topic fast-compute-hidden
> # Available At https://www.mercurial-scm.org/
> repo/users/marmoute/mercurial/
> #              hg pull https://www.mercurial-scm.org/
> repo/users/marmoute/mercurial/ -r e72ddd1a53c4
> hidden: use _domainancestors to compute revs revealed by dynamic blocker
>
> The complexity of computing the revealed changesets is now 'O(revealed)'.
> This massively speeds up the computation on large repository. Moving it to
> the
> millisecond range.
>
> Below are timing from two Mozilla repositories with different contents:
>
> 1) mozilla repository with:
>  * 400667 changesets
>  * 35 hidden changesets (first rev-268334)
>  * 288 visible drafts
>  * obsolete working copy (dynamicblockers),
>
> Before:
> ! visible
> ! wall 0.030247 comb 0.030000 user 0.030000 sys 0.000000 (best of 100)
>
> After:
> ! visible
> ! wall 0.000585 comb 0.000000 user 0.000000 sys 0.000000 (best of 4221)
>
> The timing above include the computation of obsolete changeset:
> ! obsolete
> ! wall 0.000396 comb 0.000000 user 0.000000 sys 0.000000 (best of 6816)
>
> So adjusted time give 30ms before versus 0.2ms after. A 150x speedup.
>
> 2) mozilla repository with:
>  * 405645 changesets
>  * 4312 hidden changesets (first rev-326004)
>  * 264 visible drafts
>  * obsolete working copy (dynamicblockers),
>
> Before:
> ! visible
> ! wall 0.168658 comb 0.170000 user 0.170000 sys 0.000000 (best of 48)
>
> After
> ! visible
> ! wall 0.008612 comb 0.010000 user 0.010000 sys 0.000000 (best of 325)
>
> The timing above include the computation of obsolete changeset:
> ! obsolete
> ! wall 0.006408 comb 0.010000 user 0.010000 sys 0.000000 (best of 404)
>
> So adjusted time give 160ms before versus 2ms after. A 75x speedup.
>
> diff --git a/mercurial/repoview.py b/mercurial/repoview.py
> --- a/mercurial/repoview.py
> +++ b/mercurial/repoview.py
> @@ -212,8 +212,10 @@ def computehidden(repo):
>          # changesets and remove those.
>          dynamic = hidden & revealedrevs(repo)
>          if dynamic:
> -            blocked = cl.ancestors(dynamic, inclusive=True)
> -            hidden = frozenset(r for r in hidden if r not in blocked)
>

An obvious problem with this old code is that the "r not in blocked" bit is
an O(n) list lookup. Out of curiosity, how does the perf of "blocked =
set(cl.ancestors(dynamic, inclusive=True))" compare to the new code using
_domainancestors()?


> +            pfunc = cl.parentrevs
> +            mutablephases = (phases.draft, phases.secret)
> +            mutable = repo._phasecache.getrevset(repo, mutablephases)
> +            hidden = hidden - _domainancestors(pfunc, dynamic, mutable)
>      return hidden
>
>  def computeunserved(repo):
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