tests/fakedirstatewritetime.py

dirstate: expose a sparse matcher on dirstate (API)

The sparse extension performs a lot of monkeypatching of dirstate
to make it sparse aware. Essentially, various operations need to
take the active sparse config into account. They do this by obtaining
a matcher representing the sparse config and filtering paths through
it.

The monkeypatching is done by stuffing a reference to a repo on
dirstate and calling sparse.matcher() (which takes a repo instance)
during each function call. The reason this function takes a repo
instance is because resolving the sparse config may require resolving
file contents from filelogs, and that requires a repo. (If the
current sparse config references "profile" files, the contents of
those files from the dirstate's parent revisions is resolved.)

I seem to recall people having strong opinions that the dirstate
object not have a reference to a repo. So copying what the sparse
extension does probably won't fly in core. Plus, the dirstate
modifications shouldn't require a full repo: they only need a matcher.
So there's no good reason to stuff a reference to the repo in
dirstate.

This commit exposes a sparse matcher to dirstate via a property that
when looked up will call a function that eventually calls
sparse.matcher(). The repo instance is bound in a closure, so it
isn't exposed to dirstate.

This approach is functionally similar to what the sparse extension does
today, except it hides the repo instance from dirstate. The approach
is not optimal because we have to call a proxy function and
sparse.matcher() on every property lookup. There is room to cache
the matcher instance in dirstate. After all, the matcher only changes
if the dirstate's parents change or if the sparse config changes. It
feels like we should be able to detect both events and update the
matcher when this occurs. But for now we preserve the existing
semantics so we can move the dirstate sparseness bits into core. Once
in core, refactoring becomes a bit easier since it will be clearer how
all these components interact.

The sparse extension has been updated to use the new property.
Because all references to the repo on dirstate have been removed,
the code for setting it has been removed.

# 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 __future__ import absolute_import

from mercurial import (
    context,
    dirstate,
    extensions,
    policy,
    util,
)

parsers = policy.importmod(r'parsers')

def pack_dirstate(fakenow, orig, dmap, copymap, pl, now):
    # execute what original parsers.pack_dirstate should do actually
    # for consistency
    actualnow = int(now)
    for f, e in dmap.iteritems():
        if e[0] == 'n' and e[3] == actualnow:
            e = parsers.dirstatetuple(e[0], e[1], e[2], -1)
            dmap[f] = e

    return orig(dmap, copymap, pl, fakenow)

def fakewrite(ui, func):
    # fake "now" of 'pack_dirstate' only if it is invoked while 'func'

    fakenow = ui.config('fakedirstatewritetime', '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 = util.parsedate(fakenow, ['%Y%m%d%H%M'])[0]

    orig_pack_dirstate = parsers.pack_dirstate
    orig_dirstate_getfsnow = dirstate._getfsnow
    wrapper = lambda *args: pack_dirstate(fakenow, orig_pack_dirstate, *args)

    parsers.pack_dirstate = wrapper
    dirstate._getfsnow = lambda *args: fakenow
    try:
        return func()
    finally:
        parsers.pack_dirstate = orig_pack_dirstate
        dirstate._getfsnow = orig_dirstate_getfsnow

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.committablectx, 'markcommitted',
                            markcommitted)