view mercurial/txnutil.py @ 44305:d8d4fa9a7f18

rust-re2: add wrapper for calling Re2 from Rust This assumes that Re2 is installed following Google's guide. I am not sure how we want to integrate it in the project, but I think a follow-up patch would be more appropriate for such work. As it stands, *not* having Re2 installed results in a compilation error, which is a problem as it breaks install compatibility. Hence, this is gated behind a non-default `with-re2` compilation feature. Differential Revision: https://phab.mercurial-scm.org/D7910
author Raphaël Gomès <rgomes@octobus.net>
date Thu, 16 Jan 2020 13:34:04 +0100
parents 687b865b95ad
children 89a2afe31e82
line wrap: on
line source

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> 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)