blob: 45ef346b2af40f0992bc44824df5ea6f8d70a43b [file] [log] [blame]
# Copyright (C) 2010 Google Inc. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import logging
import sys
import time
if sys.version_info > (3, 0):
from urllib.error import HTTPError, URLError
else:
from urllib2 import HTTPError, URLError
_log = logging.getLogger(__name__)
class NetworkTimeout(Exception):
def __str__(self):
return 'NetworkTimeout'
class NetworkTransaction(object):
def __init__(self, initial_backoff_seconds=10, grown_factor=1.5, timeout_seconds=(10 * 60), convert_404_to_None=False):
self._initial_backoff_seconds = initial_backoff_seconds
self._grown_factor = grown_factor
self._timeout_seconds = timeout_seconds
self._convert_404_to_None = convert_404_to_None
def run(self, request, url=None):
self._total_sleep = 0
self._backoff_seconds = self._initial_backoff_seconds
while True:
try:
return request()
except HTTPError as e:
if self._convert_404_to_None and e.code == 404:
return None
self._check_for_timeout()
_log.warn("Received HTTP status %s loading \"%s\". Retrying in %s seconds..." % (e.code, e.filename, self._backoff_seconds))
self._sleep()
except URLError as e:
self._check_for_timeout()
_log.warn('Received URLError: "{}" while loading {}. Retrying in {} seconds...'.format(e.reason, url, self._backoff_seconds))
self._sleep()
def _check_for_timeout(self):
if self._total_sleep + self._backoff_seconds > self._timeout_seconds:
raise NetworkTimeout()
def _sleep(self):
time.sleep(self._backoff_seconds)
self._total_sleep += self._backoff_seconds
self._backoff_seconds *= self._grown_factor