view mercurial/txnutil.py @ 42599:3fb0493812c0

abort: added support for unshelve

This patch adds the support for shelve in `hg abort` plan.

For this the logic to load a `shelvedstate` and the error
handling for it had been shifted to a seperate function
`_loadunshelvedstate()`. This returns a tuple with `state` file
and `opts.`

`hgabortunshelve()` has been created for independent calls.
In case abortion of `unshelve` is called via `hg abort` the
`shelvedstate` needs to be loaded seperately. This has been
ensured by `_loadunshelvedstate()`

`hgabortunshelve()` is then registered as `abortfunc` for state
detection API.

Results are shown as tests.

Differential Revision: https://phab.mercurial-scm.org/D6579

# 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)