mercurial/txnutil.py

manifest: remove _repo from manifestctx objects

We were storing the repo on the manifestctx objects so that they could access
the manifestlog via repo.manifestlog, which would refresh the structure if it
became out of date. This caused probems however when we want to have multiple
manifest logs in memory at once, like when transitioning to tree manifest from
flat manifests, since a tree manifest would try to access sub-trees via
repo.manifestlog[node], which was the flat manifest.

The solution is to just not store the repo, and instead store the manifestlog
that created this context. This removes the invalidation when the in memory
manifestlog becomes out of date, but people should probably not be keeping ctx's
around that long anyway.

# 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)