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# Copyright 2016 Tesora Inc.
# All Rights Reserved.
#
# 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.
import time
from functools import wraps
from oslo_log import log as logging
LOG = logging.getLogger(__name__)
def retry(expected_exception_cls, retries=3, delay_fun=lambda n: 3 * n):
"""Retry decorator.
Executes the decorated function N times with a variable timeout
on a given exception(s).
:param expected_exception_cls: Handled exception classes.
:type expected_exception_cls: class or tuple of classes
:param delay_fun: The time delay in sec as a function of the
number of attempts (n) already executed.
:type delay_fun: callable
"""
def retry_deco(f):
@wraps(f)
def wrapper(*args, **kwargs):
remaining_attempts = retries
while remaining_attempts > 1:
try:
return f(*args, **kwargs)
except expected_exception_cls:
remaining_attempts -= 1
delay = delay_fun(retries - remaining_attempts)
LOG.exception(
"Retrying in %(delay)d seconds "
"(remaining attempts: %(remaining)d)..." %
{'delay': delay, 'remaining': remaining_attempts})
time.sleep(delay)
return f(*args, **kwargs)
return wrapper
return retry_deco
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