view mercurial/txnutil.py @ 33702:033484935391

exchange: access requirements on repo instead of peer

As part of formalizing the peer interface, I audited for attribute
accesses for non-internal names to find API violations. This
uncovered the code changed in this commit.

localpeer.requirements is just an alias to the repo's requirements
attribute. So, change the code to get the data from the source
instead of relying on a one-off attribute in the localpeer type.

Differential Revision: https://phab.mercurial-scm.org/D265

# 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)