codekingpro/portable-devtools

1# Protocol Buffers - Google's data interchange format2# Copyright 2008 Google Inc.  All rights reserved.3#4# Use of this source code is governed by a BSD-style5# license that can be found in the LICENSE file or at6# https://developers.google.com/open-source/licenses/bsd7 8"""Determine which implementation of the protobuf API is used in this process.9"""10 11import importlib12import os13import sys14import warnings15 16_GOOGLE3_PYTHON_UPB_DEFAULT = True17 18 19def _ApiVersionToImplementationType(api_version):20  if api_version == 2:21    return 'cpp'22  if api_version == 1:23    raise ValueError('api_version=1 is no longer supported.')24  if api_version == 0:25    return 'python'26  return None27 28 29_implementation_type = None30try:31  # pylint: disable=g-import-not-at-top32  from google.protobuf.internal import _api_implementation33  # The compile-time constants in the _api_implementation module can be used to34  # switch to a certain implementation of the Python API at build time.35  _implementation_type = _ApiVersionToImplementationType(36      _api_implementation.api_version)37except ImportError:38  pass  # Unspecified by compiler flags.39 40 41def _CanImport(mod_name):42  try:43    mod = importlib.import_module(mod_name)44    # Work around a known issue in the classic bootstrap .par import hook.45    if not mod:46      raise ImportError(mod_name + ' import succeeded but was None')47    return True48  except ImportError:49    return False50 51 52if _implementation_type is None:53  if _CanImport('google._upb._message'):54    _implementation_type = 'upb'55  elif _CanImport('google.protobuf.pyext._message'):56    _implementation_type = 'cpp'57  else:58    _implementation_type = 'python'59 60 61# This environment variable can be used to switch to a certain implementation62# of the Python API, overriding the compile-time constants in the63# _api_implementation module. Right now only 'python', 'cpp' and 'upb' are64# valid values. Any other value will raise error.65_implementation_type = os.getenv('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION',66                                 _implementation_type)67 68if _implementation_type not in ('python', 'cpp', 'upb'):69  raise ValueError('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION {0} is not '70                   'supported. Please set to \'python\', \'cpp\' or '71                   '\'upb\'.'.format(_implementation_type))72 73if 'PyPy' in sys.version and _implementation_type == 'cpp':74  warnings.warn('PyPy does not work yet with cpp protocol buffers. '75                'Falling back to the python implementation.')76  _implementation_type = 'python'77 78_c_module = None79 80if _implementation_type == 'cpp':81  try:82    # pylint: disable=g-import-not-at-top83    from google.protobuf.pyext import _message84    sys.modules['google3.net.proto2.python.internal.cpp._message'] = _message85    _c_module = _message86    del _message87  except ImportError:88    # TODO: fail back to python89    warnings.warn(90        'Selected implementation cpp is not available.')91    pass92 93if _implementation_type == 'upb':94  try:95    # pylint: disable=g-import-not-at-top96    from google._upb import _message97    _c_module = _message98    del _message99  except ImportError:100    warnings.warn('Selected implementation upb is not available. '101                  'Falling back to the python implementation.')102    _implementation_type = 'python'103    pass104 105# Detect if serialization should be deterministic by default106try:107  # The presence of this module in a build allows the proto implementation to108  # be upgraded merely via build deps.109  #110  # NOTE: Merely importing this automatically enables deterministic proto111  # serialization for C++ code, but we still need to export it as a boolean so112  # that we can do the same for `_implementation_type == 'python'`.113  #114  # NOTE2: It is possible for C++ code to enable deterministic serialization by115  # default _without_ affecting Python code, if the C++ implementation is not in116  # use by this module.  That is intended behavior, so we don't actually expose117  # this boolean outside of this module.118  #119  # pylint: disable=g-import-not-at-top,unused-import120  from google.protobuf import enable_deterministic_proto_serialization121  _python_deterministic_proto_serialization = True122except ImportError:123  _python_deterministic_proto_serialization = False124 125 126# Usage of this function is discouraged. Clients shouldn't care which127# implementation of the API is in use. Note that there is no guarantee128# that differences between APIs will be maintained.129# Please don't use this function if possible.130def Type():131  return _implementation_type132 133 134# For internal use only135def IsPythonDefaultSerializationDeterministic():136  return _python_deterministic_proto_serialization137