perf: add a new `perfmergecopies` command
This command benchmark calls to `mercurial.copies.mergecopies`
perf: factor selection of revisions involved in the merge out
We will introduce more performance command around merge. As a first step we
factor out pieces of `perfmergecalculate` that can be reused.
perf: allow to specify the base of the merge in perfmergecalculate
We can now test the rebase case.
perf: add a --from flag to perfmergecalculate
Before this change, `perfmergecalculate` was always benchmarking the merge of
the working copy with another revision. We can now benchmark the
`mergecalculate` call for any arbitrary pair of revision.
py3: fix test-narrow* which started failing because of recent changes
#skip-blame because just r'' prefix
Differential Revision: https://phab.mercurial-scm.org/D6447
manifest: add some documentation to _lazymanifest python code
It was not particularly easy figuring out the design of this class and keeping
track of how the pieces work. So might as well write some of it down for the
next person.
manifest: avoid corruption by dropping removed files with pure (
issue5801)
Previously, removed files would simply be marked by overwriting the first byte
with NUL and dropping their entry in `self.position`. But no effort was made to
ignore them when compacting the dictionary into text form. This allowed them to
slip into the manifest revision, since the code seems to be trying to minimize
the string operations by copying as large a chunk as possible. As part of this,
compact() walks the existing text based on entries in the `positions` list, and
consumed everything up to the next position entry. This typically resulted in
a ValueError complaining about unsorted manifest entries.
Sometimes it seems that files do get dropped in large repos- it seems to
correspond to there being a new entry that would take the same slot. A much
more trivial problem is that if the only changes were removals, `_compact()`
didn't even run because `__delitem__` doesn't add anything to `self.extradata`.
Now there's an explicit variable to flag this, both to allow `_compact()` to
run, and to avoid searching the manifest in cases where there are no removals.
In practice, this behavior was mostly obscured by the check in fastdelta() which
takes a different path that explicitly drops removed files if there are fewer
than 1000 changes. However, timeless has a repo where after rebasing tens of
commits, a totally different path[1] is taken that bypasses the change count
check and hits this problem.
[1] https://www.mercurial-scm.org/repo/hg/file/
2338bdea4474/mercurial/manifest.py#l1511
tests: demonstrate broken manifest generation with the pure module
This will be fixed next. But I don't fully understand how 'b.txt' is actually
removed properly in the second test, given what's broken. Also, I'm not sure
why 'bb.txt' is flagged as not being in the manifest, when it clearly appears
to be.
tests: add test for {file_mods}, {file_adds}, {file_dels} on merge commit
Differential Revision: https://phab.mercurial-scm.org/D6368