push: rework the computation of fallbackheads to be correct
The previous computation tried to be smart but ended up being wrong. This was
caught by phase movement test while reworking the phase discovery logic to be
faster.
The previous logic was failing to catch case where the pushed set was not based
on a common heads (i.e. when the discovery seemed to have "over discovered"
content, outside the pushed set)
In the following graph, `e` is a common head and we `hg push -r f`. We need to
detect `c` as a fallback heads and we previous failed to do so::
e
|
d f
|/
c
|
b
|
a
The performance impact of the change seems minimal. On the most impacted
repository at hand (mozilla-try), the slowdown seems mostly mixed in the
overall noise `hg push` but seems to be in the hundred of milliseconds order of
magnitude. When using rust, we seems to be a bit faster, probably because we
leverage more accelaratd internals.
I added a couple of performance related common for further investigation later
on.
# 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)