view mercurial/txnutil.py @ 42172:71d8b4d91616 stable

setup: properly package distutils in py2exe virtualenv builds

Our in-repo py2exe packaging code uses virtualenvs for managing
dependencies. An advantage of this is that packaging is more
deterministic and reproducible. Without virtualenvs, we need to
install packages in the system Python install. Packages installed
by other consumers of the system Python could leak into the Mercurial
package.

A regression from this change was that py2exe packages contained
the virtualenv's hacked distutils modules instead of the original
distutils modules. (virtualenv installs a hacked distutils module
because distutils uses relative path lookups that fail when running
from a virtualenv.)

This commit introduces a workaround so py2exe packaging uses the
original distutils modules when running from a virtualenv.

With this change, `import distutils` no longer fails from py2exe
builds produced from a virtualenv. This fixes the regression.
Furthermore, we now include all distutils modules. Before, py2exe's
module finding would only find modules there were explicitly
referenced in code. So, we now package a complete copy of distutils
instead of a partial one. This is even better than before.

# no-check-commit foo_bar function name

# 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)