[PATCH 4 of 4] copy: add flag for disabling copy tracing

[Augie Fackler]

On Mon, Feb 02, 2015 at 07:20:02PM -0800, Durham Goode wrote:
> # HG changeset patch
> # User Durham Goode <durham at fb.com>
> # Date 1422386787 28800
> #      Tue Jan 27 11:26:27 2015 -0800
> # Node ID 39427c27d17d5d13bbe24367d458705dd9a6d64a
> # Parent  7c2e0203750f9372d77c374ce931e0bb87a54f0f
> copy: add flag for disabling copy tracing

I like the spirit of the series. First three are queued.

>
> Copy tracing can be up to 50% of rebase time when rebasing medium sized stacks
> of commits (~12 commits) in large repos (hundreds of thousands of files).
> This provides the option of turning off the majority of copy tracing. It
> does not turn off _forwardcopies() since that is used to carry copy
> information inside a commit across a rebase.
>
> This will affect the situation where a user edits a file, then rebases on top of
> commits that have moved that file. The move will not be detected and the user
> will have to manually resolve the issue.
>
> Once the lazymanifest work goes in, we can make this smarter by only disabling
> copy detection when we know all the target files exist in the destination (since
> we will be able to cheaply detect this with lazymanifest.diff).
>
> This takes a 12 commit rebase from 70s to 45s. Future patches will bring this
> down further to 27s.
>
> diff --git a/mercurial/copies.py b/mercurial/copies.py
> --- a/mercurial/copies.py
> +++ b/mercurial/copies.py
> @@ -192,6 +192,9 @@ def _forwardcopies(a, b):
>      return cm
>
>  def _backwardrenames(a, b):
> +    if a._repo.ui.config('ui', 'copytracemode') == 'disabled':

I don't have a constructive suggestion, but [ui] is the wrong section
for this. I know marmoute has strong opinions about config sections,
maybe he'll have a better idea?

> +        return {}
> +
>      # Even though we're not taking copies into account, 1:n rename situations
>      # can still exist (e.g. hg cp a b; hg mv a c). In those cases we
>      # arbitrarily pick one of the renames.
> @@ -261,6 +264,13 @@ def mergecopies(repo, c1, c2, ca):
>      if c2.node() is None and c1.node() == repo.dirstate.p1():
>          return repo.dirstate.copies(), {}, {}, {}
>
> +    if repo.ui.config('ui', 'copytracemode') == 'disabled':
> +        # If we're just tracking against the parent, do a simple check.
> +        # This is necessary to ensure copies survive rebasing.
> +        if ca in c2.parents():
> +            return pathcopies(ca, c2), {}, {}, {}
> +        return {}, {}, {}, {}
> +
>      limit = _findlimit(repo, c1.rev(), c2.rev())
>      if limit is None:
>          # no common ancestor, no copies
> diff --git a/tests/test-copy-move-merge.t b/tests/test-copy-move-merge.t
> --- a/tests/test-copy-move-merge.t
> +++ b/tests/test-copy-move-merge.t
> @@ -61,4 +61,45 @@ file c
>    1
>    2
>
> +Verify disabling copy tracing loses copy info
> +
> +  $ hg up -qC 2
> +  $ hg rebase --keep -d 1 -b 2 --config extensions.rebase=
> +  rebasing 2:add3f11052fa "other" (tip)
> +  merging b and a to b
> +  merging c and a to c
> +
> +  $ test -f a
> +  [1]
> +
> +  $ cat b
> +  0
> +  1
> +  2
> +
> +  $ cat c
> +  0
> +  1
> +  2
> +
> +  $ hg strip -r . --config extensions.strip=
> +  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
> +  saved backup bundle to $TESTTMP/t/.hg/strip-backup/550bd84c0cd3-fc575957-backup.hg (glob)
> +  $ hg up -qC 2
> +  $ hg rebase --keep -d 1 -b 2 --config extensions.rebase= --config ui.copytracemode=disabled
> +  rebasing 2:add3f11052fa "other" (tip)
> +  remote changed a which local deleted
> +  use (c)hanged version or leave (d)eleted? c
> +  $ cat a
> +  0
> +  1
> +
> +  $ cat b
> +  1
> +  2
> +
> +  $ cat c
> +  1
> +  2
> +
>    $ cd ..
> _______________________________________________
> Mercurial-devel mailing list
> Mercurial-devel at selenic.com
> http://selenic.com/mailman/listinfo/mercurial-devel