branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
# Test the config layer generated by environment variables
import os
from mercurial import (
encoding,
extensions,
rcutil,
ui as uimod,
util,
)
from mercurial.utils import procutil
testtmp = encoding.environ[b'TESTTMP']
# prepare hgrc files
def join(name):
return os.path.join(testtmp, name)
with open(join(b'sysrc'), 'wb') as f:
f.write(b'[ui]\neditor=e0\n[pager]\npager=p0\n')
with open(join(b'userrc'), 'wb') as f:
f.write(b'[ui]\neditor=e1')
# replace rcpath functions so they point to the files above
def systemrcpath():
return [join(b'sysrc')]
def userrcpath():
return [join(b'userrc')]
extensions.wrapfunction(rcutil, 'default_rc_resources', lambda orig: [])
rcutil.systemrcpath = systemrcpath
rcutil.userrcpath = userrcpath
# utility to print configs
def printconfigs(env):
encoding.environ = env
rcutil._rccomponents = None # reset cache
ui = uimod.ui.load()
for section, name, value in ui.walkconfig():
source = ui.configsource(section, name)
procutil.stdout.write(
b'%s.%s=%s # %s\n' % (section, name, value, util.pconvert(source))
)
procutil.stdout.write(b'\n')
# environment variable overrides
printconfigs({})
printconfigs({b'EDITOR': b'e2', b'PAGER': b'p2'})