view mercurial/txnutil.py @ 38998:40374b4a780f

changegroup: track changelog to manifest revision map explicitly

Previously, self._nextclrevtolocalrev was only populated as part
of the changelog lookup callback. But cgpacker._close() was looking
at self._nextclrevtolocalrev on every invocation.

Since self._nextclrevtolocalrev is for communicating the mapping
of changelog revisions to manifest revisions, this commit refactors
the code to make that explicit.

The changelog state now stores this mapping. And after the changelog
group is emitted, we update self._clrevtolocalrev with that dict.
self._nextclrevtolocalrev is unused and has been deleted.

Differential Revision: https://phab.mercurial-scm.org/D4190

# 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)