hgdemandimport/tracing.py

parsers: drop one extra argument to PyErr_Format

GCC gave the following warning during `make local`:

mercurial/cext/parsers.c: In function 'dirstate_item_from_v1_data':
mercurial/cext/parsers.c:413:30: warning: too many arguments for format [-Wformat-extra-args]
  413 |                              "unknown state: `%c` (%d, %d, %d)", state, mode,
      |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To reproduce, you might need to add the -Wformat-extra-args flag, because it
isn't present for me when building for the default python3. But I can see this
warning while simply building 6.1 with `make PYTHON=python2 clean local`.

I don't think this NULL was useful, because other instances of PyErr_Format()
don't have any NULLs as the final argument, but keep in mind that I don't know
python's C API.

# 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.

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