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# Copyright 2020 Google LLC
#
# 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.
"""Retry decorator. Copied from ClusterFuzz source."""
import functools
import inspect
import logging
import sys
import time
# pylint: disable=too-many-arguments,broad-except
def sleep(seconds):
"""Invoke time.sleep. This is to avoid the flakiness of time.sleep. See:
crbug.com/770375"""
time.sleep(seconds)
def get_delay(num_try, delay, backoff):
"""Compute backoff delay."""
return delay * (backoff**(num_try - 1))
def wrap(retries,
delay,
backoff=2,
exception_type=Exception,
retry_on_false=False):
"""Retry decorator for a function."""
assert delay > 0
assert backoff >= 1
assert retries >= 0
def decorator(func):
"""Decorator for the given function."""
tries = retries + 1
is_generator = inspect.isgeneratorfunction(func)
function_with_type = func.__qualname__
if is_generator:
function_with_type += ' (generator)'
def handle_retry(num_try, exception=None):
"""Handle retry."""
if (exception is None or
isinstance(exception, exception_type)) and num_try < tries:
logging.info('Retrying on %s failed with %s. Retrying again.',
function_with_type,
sys.exc_info()[1])
sleep(get_delay(num_try, delay, backoff))
return True
logging.error('Retrying on %s failed with %s. Raise.', function_with_type,
sys.exc_info()[1])
return False
@functools.wraps(func)
def _wrapper(*args, **kwargs):
"""Regular function wrapper."""
for num_try in range(1, tries + 1):
try:
result = func(*args, **kwargs)
if retry_on_false and not result:
if not handle_retry(num_try):
return result
continue
return result
except Exception as error:
if not handle_retry(num_try, exception=error):
raise
@functools.wraps(func)
def _generator_wrapper(*args, **kwargs):
"""Generator function wrapper."""
# This argument is not applicable for generator functions.
assert not retry_on_false
already_yielded_element_count = 0
for num_try in range(1, tries + 1):
try:
for index, result in enumerate(func(*args, **kwargs)):
if index >= already_yielded_element_count:
yield result
already_yielded_element_count += 1
break
except Exception as error:
if not handle_retry(num_try, exception=error):
raise
if is_generator:
return _generator_wrapper
return _wrapper
return decorator
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