merge: use constants for actions
We finish up establishing named constants in this file with
actions.
I remember scratching my head trying to figure out what this
code was doing as part of addressing a recent security issue with
subrepos. Having the named constants in place definitely makes
things easier to read.
I'm not convinced the new constants have the best names (I'm not
an expert in this code). But they can be changed easily enough.
Also, since these constants are internal only, we might want
to change their values to something more human readable to
facilitate debugging. Or maybe we could employ an enum type
some day...
Differential Revision: https://phab.mercurial-scm.org/D2701
# txnutil.py - transaction related utilities
#
# Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> 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)