view hgdemandimport/tracing.py @ 42612:3c16b9c0b099

continue: added logic for hg continue

This is part of GSoC19 project `Implement abort and
continue commands`. This patch is part of the continue plan.

This adds the basic logic for hg continue. This command
aborts an multistep operation like graft, histedit, rebase,
transplant and unshelve if they are in an unfinished state.

The first part of the logic is determining the unfinished
operation from the state detection API under statemod.
This API is extended to support hg continue by adding a method
to register the abort logic as a function (here continuefunc).

Once the unfinished operation is determined the registered
logic is used to resume the command in case it is interrupted.
The benefit of this kind of framework is that any new extension
developed can support hg continue by registering the command
and logic under statedetection API.

hg continue currently supports --dry-run/-n flag only.
It is used to dry run hg abort

Differential Revision: https://phab.mercurial-scm.org/D6645

# 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

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