141 lines
4.6 KiB
Python
Executable File
141 lines
4.6 KiB
Python
Executable File
# Protocol Buffers - Google's data interchange format
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# Copyright 2008 Google Inc. All rights reserved.
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#
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# Use of this source code is governed by a BSD-style
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# license that can be found in the LICENSE file or at
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# https://developers.google.com/open-source/licenses/bsd
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"""Determine which implementation of the protobuf API is used in this process.
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"""
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import importlib
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import os
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import sys
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import warnings
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def _ApiVersionToImplementationType(api_version):
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if api_version == 2:
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return 'cpp'
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if api_version == 1:
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raise ValueError('api_version=1 is no longer supported.')
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if api_version == 0:
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return 'python'
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return None
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_implementation_type = None
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try:
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# pylint: disable=g-import-not-at-top
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from google.protobuf.internal import _api_implementation
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# The compile-time constants in the _api_implementation module can be used to
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# switch to a certain implementation of the Python API at build time.
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_implementation_type = _ApiVersionToImplementationType(
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_api_implementation.api_version)
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except ImportError:
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pass # Unspecified by compiler flags.
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def _CanImport(mod_name):
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try:
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mod = importlib.import_module(mod_name)
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# Work around a known issue in the classic bootstrap .par import hook.
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if not mod:
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raise ImportError(mod_name + ' import succeeded but was None')
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return True
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except ImportError:
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return False
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if _implementation_type is None:
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if _CanImport('google._upb._message'):
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_implementation_type = 'upb'
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elif _CanImport('google.protobuf.pyext._message'):
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_implementation_type = 'cpp'
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else:
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_implementation_type = 'python'
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# This environment variable can be used to switch to a certain implementation
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# of the Python API, overriding the compile-time constants in the
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# _api_implementation module. Right now only 'python', 'cpp' and 'upb' are
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# valid values. Any other value will raise error.
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_implementation_type = os.getenv('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION',
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_implementation_type)
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if _implementation_type not in ('python', 'cpp', 'upb'):
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raise ValueError('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION {0} is not '
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'supported. Please set to \'python\', \'cpp\' or '
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'\'upb\'.'.format(_implementation_type))
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if 'PyPy' in sys.version and _implementation_type == 'cpp':
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warnings.warn('PyPy does not work yet with cpp protocol buffers. '
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'Falling back to the python implementation.')
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_implementation_type = 'python'
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_c_module = None
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if _implementation_type == 'cpp':
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try:
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# pylint: disable=g-import-not-at-top
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from google.protobuf.pyext import _message
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sys.modules['google3.net.proto2.python.internal.cpp._message'] = _message
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_c_module = _message
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del _message
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except ImportError:
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# TODO: fail back to python
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warnings.warn(
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'Selected implementation cpp is not available.')
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pass
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if _implementation_type == 'upb':
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try:
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# pylint: disable=g-import-not-at-top
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from google._upb import _message
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_c_module = _message
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del _message
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except ImportError:
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warnings.warn('Selected implementation upb is not available. '
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'Falling back to the python implementation.')
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_implementation_type = 'python'
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pass
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# Detect if serialization should be deterministic by default
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try:
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# The presence of this module in a build allows the proto implementation to
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# be upgraded merely via build deps.
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#
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# NOTE: Merely importing this automatically enables deterministic proto
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# serialization for C++ code, but we still need to export it as a boolean so
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# that we can do the same for `_implementation_type == 'python'`.
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#
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# NOTE2: It is possible for C++ code to enable deterministic serialization by
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# default _without_ affecting Python code, if the C++ implementation is not in
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# use by this module. That is intended behavior, so we don't actually expose
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# this boolean outside of this module.
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#
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# pylint: disable=g-import-not-at-top,unused-import
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from google.protobuf import enable_deterministic_proto_serialization
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_python_deterministic_proto_serialization = True
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except ImportError:
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_python_deterministic_proto_serialization = False
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# Usage of this function is discouraged. Clients shouldn't care which
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# implementation of the API is in use. Note that there is no guarantee
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# that differences between APIs will be maintained.
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# Please don't use this function if possible.
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def Type():
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return _implementation_type
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# See comment on 'Type' above.
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# TODO: Remove the API, it returns a constant. b/228102101
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def Version():
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return 2
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# For internal use only
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def IsPythonDefaultSerializationDeterministic():
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return _python_deterministic_proto_serialization
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