tests/fakedirstatewritetime.py

repository: teach addgroup() to receive data with missing parents

The way the narrow extension works today, the server rewrites
outgoing changegroup data to lie about parents when the parents
data is missing. It adds the ellipsis flag to the revision so
it can be recorded as such in the revlog.

In the new wire protocol, such rewriting does not occur on
the server (at least not yet anyway). Instead, it is up to the
client to recognize when it has received a revision without its
parents. This means rewriting will be performed on the client.

Furthermore, the mechanism for storing a shallow revision may
differ from store to store. For example, the revlog store uses
the ellipsis flag to denote a revision's parents have been
rewritten. But a non-revlog store may wish to store things
differently. And, some stores may not even support receiving
shallow revision data!

Therefore, it makes sense for the store itself to be making
decisions about what to do when they receive revision data
without their parents.

This commit teaches the addgroup() bulk insert method to accept
a boolean argument that indicates whether the incoming data may
lack parent revisions. This flag can be set when receiving
"shallow" data from a remote.

The revlog implementation of this method has been taught to rewrite
the missing parent(s) to nullid and to add the ellipsis flag to
the revision when a missing parent is encountered. But it only
does this if ellipsis flags are enabled on the repo and the
incoming data is marked as possibly shallow. An error occurs
otherwise.

Differential Revision: https://phab.mercurial-scm.org/D5165

# 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,
    registrar,
)
from mercurial.utils import dateutil

configtable = {}
configitem = registrar.configitem(configtable)

configitem(b'fakedirstatewritetime', b'fakenow',
    default=None,
)

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.items():
        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(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]

    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)