view tests/fakedirstatewritetime.py @ 49991:3997c64eff8b

test: use a more direct approach to test racy mutation

The previous test was relying on implementation details and harder to maintain.

The new version is closer to the initial intend : "What happens the file get overwritten from under the current process"

This change is motivated by further changes around the transaction and dirstate
logic that would break the fragile equilibrium that existed before this patch.

Making this change early make it easier to review on its own and remove noise
in future larger changes.

# 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)