D623: copytrace: move fast heuristic copytracing algorithm to core

[yuja (Yuya Nishihara)]

yuja requested changes to this revision.
yuja added a comment.
This revision now requires changes to proceed.


  I don't think we can just swap c1 and c2 because what we're calculating
  is the copy from c1 to c2, which is directed. Instead, maybe we can simply
  fall back to the "full" algorithm if base isn't in the c2 branch.
  
    while ctx.rev() > base.rev():
        ...
    if ctx != base:
        switch to full copytracing

INLINE COMMENTS

> copies.py:634
> +    changedfiles = set()
> +    mdst = c1.manifest()
> +    # Tell whether the base is ancestor of c2 or not

Nit: s/mdst/m1/

> copies.py:639
> +    baserev = base.rev()
> +    if c2rev < baserev and len(repo.revs('%s::%s' % (c2rev, baserev))) == 0:
> +        baseancestor = False

- `len(smartset)` might be expensive, just evaluate it as boolean
- `repo.revs('%d::%d', c2rev, baserev)` should be safer

> copies.py:646
> +    if not baseancestor:
> +        c1, c2 = c2, c1
> +

I don't think we can do that, but if we could, we should swap
m1 and m2, too.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D623

To: pulkit, #hg-reviewers, yuja
Cc: yuja, mercurial-devel