tests/fakedirstatewritetime.py

test: add test-transaction-rollback-on-sigpipe.t demonstrating py3 regression

When an hg push is interrupted with C-c, the remote [hg serve] command
receives SIGPIPE.

If a pretxnchangegroup hook fails, the remote hg then tries to
rollback the transaction. It begins by printing "transaction
abort!\n". This returns EPIPE, but ui.py ignores that error.

In python3 (but not python2), this "transaction abort!\n" message
stays in a buffer, so future flushes of stderr will try to print the
message again, and so those flushes will also hit EPIPE.

This test demonstrates such a case where this EPIPE causes the
transaction rollback to fail, leaving behind an abandoned transaction.

Differential Revision: https://phab.mercurial-scm.org/D9151

# 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

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')
rustmod = policy.importrust('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]

    if rustmod is not None:
        # The Rust implementation does not use public parse/pack dirstate
        # to prevent conversion round-trips
        orig_dirstatemap_write = dirstate.dirstatemap.write
        wrapper = lambda self, st, now: orig_dirstatemap_write(
            self, st, fakenow
        )
        dirstate.dirstatemap.write = wrapper

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

    orig_module = parsers
    orig_pack_dirstate = parsers.pack_dirstate

    orig_module.pack_dirstate = wrapper
    dirstate._getfsnow = lambda *args: fakenow
    try:
        return func()
    finally:
        orig_module.pack_dirstate = orig_pack_dirstate
        dirstate._getfsnow = orig_dirstate_getfsnow
        if rustmod is not None:
            dirstate.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)