view mercurial/txnutil.py @ 46604:ad107ed7a4aa

ci: test real dependency installation for pip

In the past, the pip smoke test inhibited actual dependency
installation, but that fails in different environments for setuptools
itself. Since it isn't what we actually want to test (which is pip
install), allow this to call home, if HGTESTS_ALLOW_NETIO=1 is set
in the environment.

Differential Revision: https://phab.mercurial-scm.org/D9950

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

from . import encoding


def mayhavepending(root):
    """return whether 'root' may have pending changes, which are
    visible to this process.
    """
    return root == encoding.environ.get(b'HG_PENDING')


def trypending(root, vfs, filename, **kwargs):
    """Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    """
    if mayhavepending(root):
        try:
            return (vfs(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)