view mercurial/txnutil.py @ 39989:c9026e9297e3

identify: only query remote bookmarks if needed

Instead of all the time when operating on a remote repo. This
perf regression was introduced in 15a79ac823e8, in 4.3.

This datahint method returns nothing for -Tjson, -Tpickle, -Tdebug
--config ui.formatdebug=true and --config ui.formatjson, so the
bookmarks won't show up. I don't know what these formatters are for.
plainformatter and templateformatter work properly, and the few other
uses of datahint should have the same kind of problem.

There is further weirdness where "--template '{node}'" is not enough
to avoid querying the bookmarks, you also need to pass --id or -q.

Differential Revision: https://phab.mercurial-scm.org/D4819

# 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)