view hgdemandimport/tracing.py @ 44810:62435a5b46fe

revisions: parse "x123" as "nodeid starting with 123" without prefixhexnode

`experimental.revisions.prefixhexnode` makes it so the template
function `shortest()` uses an "x" prefix to disambiguate between short
nodeids and revnums. That config has so far also been used for
enabling parsing of "x123" unambiguously as a nodeid. That makes it a
little annoying for people who have prefixhexnode=yes to share such
nodeids with people who have prefixhexnode=no ("x123" will be
considered invalid for them). There seems to be little harm in
allowing that parsing for everyone. We still let e.g. bookmark names
like "x123" take precedence over the nodeid, so that's not a
concern. The only thing I can think of is that people get used to the
"x" prefix being valid, making it impossible for us to change to a
different prefix if we wanted to do that when graduating the feature.

Differential Revision: https://phab.mercurial-scm.org/D8514

# Support code for event tracing in Mercurial. Lives in demandimport
# so it can also be used in demandimport.
#
# Copyright 2018 Google LLC.
#
# 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 contextlib
import os

_pipe = None
_checked = False
_session = 'none'


def _isactive():
    global _pipe, _session, _checked
    if _pipe is None:
        if _checked:
            return False
        _checked = True
        if 'HGCATAPULTSERVERPIPE' not in os.environ:
            return False
        _pipe = open(os.environ['HGCATAPULTSERVERPIPE'], 'w', 1)
        _session = os.environ.get('HGCATAPULTSESSION', 'none')
    return True


@contextlib.contextmanager
def log(whencefmt, *whenceargs):
    if not _isactive():
        yield
        return
    whence = whencefmt % whenceargs
    try:
        # Both writes to the pipe are wrapped in try/except to ignore
        # errors, as we can see mysterious errors in here if the pager
        # is active. Presumably other conditions could trigger
        # problems too.
        try:
            _pipe.write('START %s %s\n' % (_session, whence))
        except IOError:
            pass
        yield
    finally:
        try:
            _pipe.write('END %s %s\n' % (_session, whence))
        except IOError:
            pass


def counter(label, amount, *labelargs):
    if not _isactive():
        return
    l = label % labelargs
    # See above in log() for why this is in a try/except.
    try:
        _pipe.write('COUNTER %s %d %s\n' % (_session, amount, l))
    except IOError:
        pass