view mercurial/txnutil.py @ 42093:edbcf5b239f9

config: read configs from directories in lexicographical order

Mercurial currently reads the .rc files specified in HGRCPATH (and the
system-default paths) in directory order, which is unspecified. My
team at work maintains a set of .rc files. So far there has been no
overlap between them, so we had not noticed this behavior. However, we
would now like to release some common .rc files and then have another
one per plaform with platform-specific overrides. It would be nice if
we can determine the load order by choosing names carefully. This
patch enables that by loading the .rc files in lexicographical order.

Before this patch, the added test case would consistently say "30" on
my file system (whatever I have -- some Linux FS).

Differential Revision: https://phab.mercurial-scm.org/D6193

# 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('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('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)