revlog: add a small cache of unfiltered chunk
This can provides a massive boost to the reading of multiple revision and the
computation of a valid delta chain.
This greatly help operation like `hg log --patch`, delta computation (helping
pull/unbundle), linkrev adjustment (helping copy tracing).
A first round of benchmark for `hg log --patch --limit 1000` shows improvement
in the 10-20% range on "small" repository like pypy or mercurial and large
improvements (about 33%) for more complex ones like netbeans and mozilla's.
These speeds up are consistent with the improvement to `hg pull` (from a server
sending poor deltas) I saw benchmarking this last year. Further benchmark will
be run during the freeze.
I added some configuration in the experimental space to be able to further test
the effect of various tuning for now. This feature should fit well in the
"usage/resource profile" configuration that we should land next cycle.
When it does not provides a benefit the overhead of the cache seem to be around
2%, a small price for the big improvement. In addition I believe we could shave
most of this overhead with a more efficent lru implementation.
[fix]
clang-format:command = clang-format --style file
clang-format:pattern = set:(**.c or **.cc or **.h) and not "include:contrib/clang-format-ignorelist"
rustfmt:command = rustfmt +nightly
rustfmt:pattern = set:"**.rs" - "mercurial/thirdparty/**"
black:command = black --config=pyproject.toml -
black:pattern = set:**.py - mercurial/thirdparty/**
# Mercurial doesn't have any Go code, but if we did this is how we
# would configure `hg fix` for Go:
go:command = gofmt
go:pattern = set:**.go