# Copyright (C) 2010 Google Inc. All rights reserved.

# 

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# modification, are permitted provided that the following conditions are

# met:

# 

#     * Redistributions of source code must retain the above copyright

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# in the documentation and/or other materials provided with the

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# 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

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import logging

import time

from webkitpy.thirdparty.autoinstalled.mechanize import HTTPError

from webkitpy.common.system.deprecated_logging import log

_log = logging.getLogger(__name__)

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._grown_factor = grown_factor

        self._timeout_seconds = timeout_seconds

    def run(self, request):

        self._total_sleep = 0

        self._backoff_seconds = self._initial_backoff_seconds

        while True:

            try:

                return request()

            except HTTPError, e:

                self._check_for_timeout()

                _log.warn("Received HTTP status %s from server.  Retrying in "

                          "%s seconds..." % (e.code, 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