revlog: add a C implementation of `headrevsdiff`
Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.
Even the average case of this Python implementation is still
noticeable in the profiles.
This patch makes the computation much much faster by doing it in C.
#require test-repo pylint
Run pylint for known rules we care about.
-----------------------------------------
There should be no recorded failures; fix the codebase before introducing a
new check.
Current checks:
- W0102: no mutable default argument
- C0321: only one statement on a single line
$ touch $TESTTMP/fakerc
$ pylint --rcfile=$TESTTMP/fakerc --disable=all \
> --enable=W0102,C0321 \
> --reports=no \
> --ignore=thirdparty \
> mercurial hgdemandimport hgext hgext3rd | sed 's/\r$//'
Using config file *fakerc (glob) (?)
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------------------------------------* (glob) (?)
Your code has been rated at 10.00/10* (glob) (?)
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