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.
# extension to emulate invoking 'dirstate.write()' at the time
# specified by '[fakedirstatewritetime] fakenow', only when
# 'dirstate.write()' is invoked via functions below:
#
# - 'workingctx._poststatusfixup()' (= 'repo.status()')
# - 'committablectx.markcommitted()'
from mercurial import (
context,
dirstatemap as dirstatemapmod,
extensions,
policy,
registrar,
)
from mercurial.dirstateutils import timestamp
from mercurial.utils import dateutil
try:
from mercurial import rustext
rustext.__name__ # force actual import (see hgdemandimport)
except ImportError:
rustext = None
configtable = {}
configitem = registrar.configitem(configtable)
configitem(
b'fakedirstatewritetime',
b'fakenow',
default=None,
)
parsers = policy.importmod('parsers')
has_rust_dirstate = policy.importrust('dirstate') is not None
def pack_dirstate(orig, dmap, copymap, pl):
return orig(dmap, copymap, pl)
def fakewrite(ui, func):
# fake "now" of 'pack_dirstate' only if it is invoked while 'func'
fakenow = ui.config(b'fakedirstatewritetime', b'fakenow')
if not fakenow:
# Execute original one, if fakenow isn't configured. This is
# useful to prevent subrepos from executing replaced one,
# because replacing 'parsers.pack_dirstate' is also effective
# in subrepos.
return func()
# parsing 'fakenow' in YYYYmmddHHMM format makes comparison between
# 'fakenow' value and 'touch -t YYYYmmddHHMM' argument easy
fakenow = dateutil.parsedate(fakenow, [b'%Y%m%d%H%M'])[0]
fakenow = timestamp.timestamp((fakenow, 0, False))
if has_rust_dirstate:
# The Rust implementation does not use public parse/pack dirstate
# to prevent conversion round-trips
orig_dirstatemap_write = dirstatemapmod.dirstatemap.write
wrapper = lambda self, tr, st: orig_dirstatemap_write(self, tr, st)
dirstatemapmod.dirstatemap.write = wrapper
orig_get_fs_now = timestamp.get_fs_now
wrapper = lambda *args: pack_dirstate(orig_pack_dirstate, *args)
orig_module = parsers
orig_pack_dirstate = parsers.pack_dirstate
orig_module.pack_dirstate = wrapper
timestamp.get_fs_now = (
lambda *args: fakenow
) # XXX useless for this purpose now
try:
return func()
finally:
orig_module.pack_dirstate = orig_pack_dirstate
timestamp.get_fs_now = orig_get_fs_now
if has_rust_dirstate:
dirstatemapmod.dirstatemap.write = orig_dirstatemap_write
def _poststatusfixup(orig, workingctx, status, fixup):
ui = workingctx.repo().ui
return fakewrite(ui, lambda: orig(workingctx, status, fixup))
def markcommitted(orig, committablectx, node):
ui = committablectx.repo().ui
return fakewrite(ui, lambda: orig(committablectx, node))
def extsetup(ui):
extensions.wrapfunction(
context.workingctx, '_poststatusfixup', _poststatusfixup
)
extensions.wrapfunction(context.workingctx, 'markcommitted', markcommitted)