[PATCH 1 of 7] ancestors: actually iterate over ancestors in topological order (issue5979)

[Martin von Zweigbergk]

On Fri, Sep 7, 2018 at 8:08 AM Boris Feld <boris.feld at octobus.net> wrote:

> # HG changeset patch
> # User Boris Feld <boris.feld at octobus.net>
> # Date 1536267628 14400
> #      Thu Sep 06 17:00:28 2018 -0400
> # Node ID eb80c721aea9715e23dc35cdd119428aa120ea93
> # Parent  ab452995eafffa69c34e863e4d8c03e163d8f3ad
> # EXP-Topic issue5979
> # Available At https://bitbucket.org/octobus/mercurial-devel/
> #              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r
> eb80c721aea9
> ancestors: actually iterate over ancestors in topological order (issue5979)
>
> This code previously used a dequeue logic, the first ancestors seen were
> the
> first ancestors to be emitted. In branching/merging situations, it can
> result
> in ancestors being yielded before their descendants, breaking the object
> contract.
>
> We got affected by this issue while working on the copy tracing code. At
> about
> the same time, Axel Hecht <axel at mozilla.com> reported the issue and
> provided
> the test case used in this changeset. Thanks Axel.
>
> Running `hg perfancestors` does not show a significant difference between
> the
> old and the new version.
>

In my hg repo, it went from 0.047230 to 0.093331, which is clearly
significant. Maybe you made a last-minute change that made it slower? Or is
my repo just different from yours?
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