upstream/mercurial-mirror Files · mercurial/policy.py

worker: ignore meaningless exit status indication returned by os.waitpid()...

worker: ignore meaningless exit status indication returned by os.waitpid() Before this patch, worker implementation assumes that os.waitpid() with os.WNOHANG returns '(0, 0)' for still running child process. This is explicitly specified as below in Python API document. os.WNOHANG The option for waitpid() to return immediately if no child process status is available immediately. The function returns (0, 0) in this case. On the other hand, POSIX specification doesn't define the "stat_loc" value returned by waitpid() with WNOHANG for such child process. http://pubs.opengroup.org/onlinepubs/9699919799/functions/waitpid.html CPython implementation for os.waitpid() on POSIX doesn't take any care of this gap, and this may cause unexpected "exit status indication" even on POSIX conformance platform. For example, os.waitpid() with os.WNOHANG returns non-zero "exit status indication" on FreeBSD. This implies os.kill() with own pid or sys.exit() with non-zero exit code, even if no child process fails. To ignore meaningless exit status indication returned by os.waitpid(), this patch skips subsequent steps forcibly, if os.waitpid() returns 0 as pid. This patch also arranges examination of 'p' value for readability. FYI, there are some issues below about this behavior reported for CPython. https://bugs.python.org/issue21791 https://bugs.python.org/issue27808

Maciej Fijalkowski - - Load All Authors

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      # 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

      # Rules for how modules can be loaded. Values are:

      #

      #    c - require C extensions

      #    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, require the C extensions for performance reasons.

      policy = 'c'

      policynoc = ('cffi', 'cffi-allow', 'py')

      policynocffi = ('c', 'py')

      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 = 'cffi'

      # Our C extensions aren't yet compatible with Python 3. So use pure Python

      # on Python 3 for now.

      if sys.version_info[0] >= 3:

          policy = 'py'

      # Environment variable can always force settings.

      policy = os.environ.get('HGMODULEPOLICY', policy)

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				# 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

				# Rules for how modules can be loaded. Values are:
				#
				# c - require C extensions
				# 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, require the C extensions for performance reasons.
				policy = 'c'
				policynoc = ('cffi', 'cffi-allow', 'py')
				policynocffi = ('c', 'py')

				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 = 'cffi'

				# Our C extensions aren't yet compatible with Python 3. So use pure Python
				# on Python 3 for now.
				if sys.version_info[0] >= 3:
				policy = 'py'

				# Environment variable can always force settings.
				policy = os.environ.get('HGMODULEPOLICY', policy)