view mercurial/txnutil.py @ 41426:02d0a7774882

py3: byteify the LFS blobstore module

This is almost entirely b'' prefixing, with a couple of exceptions forced to
bytes.  Much of this is also borrowed from Augie's code.  There's an
HTTPError.read() that I flagged that I assume needs to be converted to bytes,
but I can't find confirmation.

Handling the deserialized JSON object over several functions made r'' vs b''
accesses confusing, so this assumes that the JSON object will be converted to
bytes immediately.  That will be done in the following commits, so it's not
buried in these trivial changes.

# 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)