view mercurial/txnutil.py @ 33764:297d1b70685c

wireproto: properly implement batchable checking

remoteiterbatcher (unlike remotebatcher) only supports batchable
commands. This claim can be validated by comparing their
implementations of submit() and noting how remoteiterbatcher assumes
the invoked method has a "batchable" attribute, which is set by
@peer.batchable.

remoteiterbatcher has a custom __getitem__ that was trying to
validate that only batchable methods are called. However, it was only
validating that the called method exists, not that it is batchable.

This wasn't a big deal since remoteiterbatcher.submit() would raise
an AttributeError attempting to `mtd.batchable(...)`.

Let's fix the check and convert it to ProgrammingError, which may
not have been around when this was originally implemented.

Differential Revision: https://phab.mercurial-scm.org/D317

# 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)