commandserver: handle IOError related to flushing of streams
After dispatch, without chg we have handling of flushing of streams and
exception handling related to it. The exception handling part is important
because there can be exceptions when flushing fout or ferr.
One such case is in `test-basic.t` which was failing on python3+chg without this
patch as this handling was missing from chg.
Failure can be seen at
https://foss.heptapod.net/octobus/mercurial-devel/-/jobs/128399
Honestly I am not sure which one of `chgserver.py` or `commandserver.py` the
change should go in.
Differential Revision: https://phab.mercurial-scm.org/D9517
# policy.py - module policy logic for Mercurial.
#
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
#
# 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 os
import sys
from .pycompat import getattr
# Rules for how modules can be loaded. Values are:
#
# c - require C extensions
# rust+c - require Rust and C extensions
# rust+c-allow - allow Rust and C extensions with fallback to pure Python
# for each
# allow - allow pure Python implementation when C loading fails
# cffi - required cffi versions (implemented within pure module)
# cffi-allow - allow pure Python implementation if cffi version is missing
# py - only load pure Python modules
#
# By default, fall back to the pure modules so the in-place build can
# run without recompiling the C extensions. This will be overridden by
# __modulepolicy__ generated by setup.py.
policy = b'allow'
_packageprefs = {
# policy: (versioned package, pure package)
b'c': ('cext', None),
b'allow': ('cext', 'pure'),
b'cffi': ('cffi', None),
b'cffi-allow': ('cffi', 'pure'),
b'py': (None, 'pure'),
# For now, rust policies impact importrust only
b'rust+c': ('cext', None),
b'rust+c-allow': ('cext', 'pure'),
}
try:
from . import __modulepolicy__
policy = __modulepolicy__.modulepolicy
except ImportError:
pass
# PyPy doesn't load C extensions.
#
# The canonical way to do this is to test platform.python_implementation().
# But we don't import platform and don't bloat for it here.
if '__pypy__' in sys.builtin_module_names:
policy = b'cffi'
# Environment variable can always force settings.
if sys.version_info[0] >= 3:
if 'HGMODULEPOLICY' in os.environ:
policy = os.environ['HGMODULEPOLICY'].encode('utf-8')
else:
policy = os.environ.get('HGMODULEPOLICY', policy)
def _importfrom(pkgname, modname):
# from .<pkgname> import <modname> (where . is looked through this module)
fakelocals = {}
pkg = __import__(pkgname, globals(), fakelocals, [modname], level=1)
try:
fakelocals[modname] = mod = getattr(pkg, modname)
except AttributeError:
raise ImportError('cannot import name %s' % modname)
# force import; fakelocals[modname] may be replaced with the real module
getattr(mod, '__doc__', None)
return fakelocals[modname]
# keep in sync with "version" in C modules
_cextversions = {
('cext', 'base85'): 1,
('cext', 'bdiff'): 3,
('cext', 'mpatch'): 1,
('cext', 'osutil'): 4,
('cext', 'parsers'): 17,
}
# map import request to other package or module
_modredirects = {
('cext', 'charencode'): ('cext', 'parsers'),
('cffi', 'base85'): ('pure', 'base85'),
('cffi', 'charencode'): ('pure', 'charencode'),
('cffi', 'parsers'): ('pure', 'parsers'),
}
def _checkmod(pkgname, modname, mod):
expected = _cextversions.get((pkgname, modname))
actual = getattr(mod, 'version', None)
if actual != expected:
raise ImportError(
'cannot import module %s.%s '
'(expected version: %d, actual: %r)'
% (pkgname, modname, expected, actual)
)
def importmod(modname):
"""Import module according to policy and check API version"""
try:
verpkg, purepkg = _packageprefs[policy]
except KeyError:
raise ImportError('invalid HGMODULEPOLICY %r' % policy)
assert verpkg or purepkg
if verpkg:
pn, mn = _modredirects.get((verpkg, modname), (verpkg, modname))
try:
mod = _importfrom(pn, mn)
if pn == verpkg:
_checkmod(pn, mn, mod)
return mod
except ImportError:
if not purepkg:
raise
pn, mn = _modredirects.get((purepkg, modname), (purepkg, modname))
return _importfrom(pn, mn)
def _isrustpermissive():
"""Assuming the policy is a Rust one, tell if it's permissive."""
return policy.endswith(b'-allow')
def importrust(modname, member=None, default=None):
"""Import Rust module according to policy and availability.
If policy isn't a Rust one, this returns `default`.
If either the module or its member is not available, this returns `default`
if policy is permissive and raises `ImportError` if not.
"""
if not policy.startswith(b'rust'):
return default
try:
mod = _importfrom('rustext', modname)
except ImportError:
if _isrustpermissive():
return default
raise
if member is None:
return mod
try:
return getattr(mod, member)
except AttributeError:
if _isrustpermissive():
return default
raise ImportError("Cannot import name %s" % member)