95 lines
3.0 KiB
Python
95 lines
3.0 KiB
Python
# Copyright 2015 gRPC authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Utilities for working with callables."""
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from abc import ABC
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import collections
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import enum
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import functools
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import logging
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_LOGGER = logging.getLogger(__name__)
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class Outcome(ABC):
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"""A sum type describing the outcome of some call.
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Attributes:
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kind: One of Kind.RETURNED or Kind.RAISED respectively indicating that the
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call returned a value or raised an exception.
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return_value: The value returned by the call. Must be present if kind is
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Kind.RETURNED.
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exception: The exception raised by the call. Must be present if kind is
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Kind.RAISED.
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"""
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@enum.unique
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class Kind(enum.Enum):
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"""Identifies the general kind of the outcome of some call."""
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RETURNED = object()
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RAISED = object()
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class _EasyOutcome(
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collections.namedtuple('_EasyOutcome',
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['kind', 'return_value', 'exception']), Outcome):
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"""A trivial implementation of Outcome."""
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def _call_logging_exceptions(behavior, message, *args, **kwargs):
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try:
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return _EasyOutcome(Outcome.Kind.RETURNED, behavior(*args, **kwargs),
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None)
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except Exception as e: # pylint: disable=broad-except
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_LOGGER.exception(message)
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return _EasyOutcome(Outcome.Kind.RAISED, None, e)
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def with_exceptions_logged(behavior, message):
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"""Wraps a callable in a try-except that logs any exceptions it raises.
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Args:
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behavior: Any callable.
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message: A string to log if the behavior raises an exception.
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Returns:
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A callable that when executed invokes the given behavior. The returned
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callable takes the same arguments as the given behavior but returns a
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future.Outcome describing whether the given behavior returned a value or
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raised an exception.
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"""
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@functools.wraps(behavior)
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def wrapped_behavior(*args, **kwargs):
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return _call_logging_exceptions(behavior, message, *args, **kwargs)
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return wrapped_behavior
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def call_logging_exceptions(behavior, message, *args, **kwargs):
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"""Calls a behavior in a try-except that logs any exceptions it raises.
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Args:
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behavior: Any callable.
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message: A string to log if the behavior raises an exception.
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*args: Positional arguments to pass to the given behavior.
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**kwargs: Keyword arguments to pass to the given behavior.
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Returns:
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An Outcome describing whether the given behavior returned a value or raised
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an exception.
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"""
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return _call_logging_exceptions(behavior, message, *args, **kwargs)
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