view mercurial/txnutil.py @ 37282:009d0283de5f

debugcommands: drop base revision from debugindex

Revlog index data consists of generic index metadata that will
likely be implemented across all storage engines and revlog-specifc
metadata.

Most tests printing index data only care about the generic fields.

This commit drops the printing of the base revision from
`hg debugindex`. This value is an implementation detail of
revlogs / delta chains. If tests are interested in verifying this
implementation detail, `hg debugdeltachain` is a better command.

Most tests were skipping over this field anyway. Tests that weren't
looked like they were newer. So my guess is we forgot to make them
skip the field to match the style of the older tests. This reinforces
my belief that the base revision is not worth having in
`hg debugindex`.

Differential Revision: https://phab.mercurial-scm.org/D3027

# 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)