branchmap: Save changectx creation during update
The newly introduced `branchmap` function allows us to skip the
creation of changectx objects. This speeds up the construction of
the branchmap.
On the mozilla repository (117293 changesets, 15490 mutable)
Before:
! impactable 19.9
! mutable 0.576
! unserved 3.16
After:
! impactable 7.03 (2.8x faster)
! mutable 0.352 (1.6x)
! unserved 1.15 (2.7x)
On the cpython repository (81418 changesets, 6418 mutable)
Before:
! impactable 15.9
! mutable 0.451
! unserved 0.861
After:
! impactable 6.55 (2.4x faster)
! mutable 0.170 (2.6x faster)
! unserved 0.289 (2.9x faster)
On the pypy repository (58852 changesets)
Before:
! impactable 13.6
After:
! impactable 6.17 (2.2x faster)
On my Mercurial repository (18295 changesets, 2210 mutable)
Before:
! impactable 23.9
! mutable 0.368
! unserved 0.057
After:
! impactable 1.31 (18x faster)
! mutable 0.042 (8.7x)
! unserved 0.025 (2.2x)
syntax: glob
*.elc
*.orig
*.rej
*~
*.mergebackup
*.o
*.so
*.dll
*.exe
*.pyd
*.pyc
*.pyo
*$py.class
*.swp
*.prof
*.zip
\#*\#
.\#*
tests/.coverage*
tests/annotated
tests/*.err
tests/htmlcov
build
contrib/hgsh/hgsh
dist
doc/*.[0-9]
doc/*.[0-9].gendoc.txt
doc/*.[0-9].{x,ht}ml
MANIFEST
MANIFEST.in
patches
mercurial/__version__.py
mercurial/hgpythonlib.h
mercurial.egg-info
.DS_Store
tags
cscope.*
i18n/hg.pot
locale/*/LC_MESSAGES/hg.mo
hgext/__index__.py
# files installed with a local --pure build
mercurial/base85.py
mercurial/bdiff.py
mercurial/diffhelpers.py
mercurial/mpatch.py
mercurial/osutil.py
mercurial/parsers.py
syntax: regexp
^\.pc/
^\.(pydev)?project
# hackable windows distribution additions
^hg-python
^hg.py$