| # Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import logging |
| import time |
| import urllib2 |
| |
| |
| class NetworkTimeout(Exception): |
| pass |
| |
| |
| class NetworkTransaction(object): |
| def __init__(self, initial_backoff_seconds=10, grown_factor=1.5, |
| timeout_seconds=(10 * 60)): |
| self._initial_backoff_seconds = initial_backoff_seconds |
| self._backoff_seconds = initial_backoff_seconds |
| self._grown_factor = grown_factor |
| self._timeout_seconds = timeout_seconds |
| self._total_sleep = 0 |
| |
| def run(self, request): |
| self._total_sleep = 0 |
| self._backoff_seconds = self._initial_backoff_seconds |
| while True: |
| try: |
| return request() |
| except urllib2.HTTPError, e: |
| # Don't retry if we aren't getting a 5xx response. |
| if e.code / 100 != 5: |
| raise |
| self._check_for_timeout() |
| logging.warn("Received HTTP status %s loading \"%s\". " |
| "Retrying in %s seconds...", |
| e.code, e.filename, 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 |
