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# Copyright 2015 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""A thread pool that logs exceptions raised by tasks executed within it."""
import logging
from concurrent import futures
_LOGGER = logging.getLogger(__name__)
_LOGGER.addHandler(logging.NullHandler())
def _wrap(behavior):
"""Wraps an arbitrary callable behavior in exception-logging."""
def _wrapping(*args, **kwargs):
try:
return behavior(*args, **kwargs)
except Exception:
_LOGGER.exception(
'Unexpected exception from %s executed in logging pool!',
behavior)
raise
return _wrapping
class _LoggingPool(object):
"""An exception-logging futures.ThreadPoolExecutor-compatible thread pool."""
def __init__(self, backing_pool):
self._backing_pool = backing_pool
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self._backing_pool.shutdown(wait=True)
def submit(self, fn, *args, **kwargs):
return self._backing_pool.submit(_wrap(fn), *args, **kwargs)
def map(self, func, *iterables, **kwargs):
return self._backing_pool.map(
_wrap(func), *iterables, timeout=kwargs.get('timeout', None))
def shutdown(self, wait=True):
self._backing_pool.shutdown(wait=wait)
def pool(max_workers):
"""Creates a thread pool that logs exceptions raised by the tasks within it.
Args:
max_workers: The maximum number of worker threads to allow the pool.
Returns:
A futures.ThreadPoolExecutor-compatible thread pool that logs exceptions
raised by the tasks executed within it.
"""
return _LoggingPool(futures.ThreadPoolExecutor(max_workers))
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