mercurial/txnutil.py

formatting: byteify all mercurial/ and hgext/ string literals

Done with

    python3.7 contrib/byteify-strings.py -i $(hg files 'set:mercurial/**.py - mercurial/thirdparty/** + hgext/**.py - hgext/fsmonitor/pywatchman/** - mercurial/__init__.py')
    black -l 80 -t py33 -S $(hg files 'set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**" - hgext/fsmonitor/pywatchman/**')

# skip-blame mass-reformatting only

Differential Revision: https://phab.mercurial-scm.org/D6972

# 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)