Ruud
11 years ago
33 changed files with 1068 additions and 644 deletions
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If you are planning to submit a pull request to requests with any changes in |
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this library do not go any further. These are independent libraries which we |
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vendor into requests. Any changes necessary to these libraries must be made in |
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them and submitted as separate pull requests to those libraries. |
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urllib3 pull requests go here: https://github.com/shazow/urllib3 |
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chardet pull requests go here: https://github.com/chardet/chardet |
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@ -0,0 +1,279 @@ |
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import time |
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import logging |
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from ..exceptions import ( |
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ProtocolError, |
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ConnectTimeoutError, |
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ReadTimeoutError, |
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MaxRetryError, |
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) |
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from ..packages import six |
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log = logging.getLogger(__name__) |
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class Retry(object): |
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""" Retry configuration. |
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Each retry attempt will create a new Retry object with updated values, so |
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they can be safely reused. |
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Retries can be defined as a default for a pool:: |
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retries = Retry(connect=5, read=2, redirect=5) |
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http = PoolManager(retries=retries) |
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response = http.request('GET', 'http://example.com/') |
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Or per-request (which overrides the default for the pool):: |
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response = http.request('GET', 'http://example.com/', retries=Retry(10)) |
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Retries can be disabled by passing ``False``:: |
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response = http.request('GET', 'http://example.com/', retries=False) |
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Errors will be wrapped in :class:`~urllib3.exceptions.MaxRetryError` unless |
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retries are disabled, in which case the causing exception will be raised. |
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:param int total: |
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Total number of retries to allow. Takes precedence over other counts. |
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Set to ``None`` to remove this constraint and fall back on other |
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counts. It's a good idea to set this to some sensibly-high value to |
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account for unexpected edge cases and avoid infinite retry loops. |
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Set to ``0`` to fail on the first retry. |
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Set to ``False`` to disable and imply ``raise_on_redirect=False``. |
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:param int connect: |
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How many connection-related errors to retry on. |
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These are errors raised before the request is sent to the remote server, |
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which we assume has not triggered the server to process the request. |
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Set to ``0`` to fail on the first retry of this type. |
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:param int read: |
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How many times to retry on read errors. |
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These errors are raised after the request was sent to the server, so the |
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request may have side-effects. |
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Set to ``0`` to fail on the first retry of this type. |
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:param int redirect: |
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How many redirects to perform. Limit this to avoid infinite redirect |
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loops. |
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A redirect is a HTTP response with a status code 301, 302, 303, 307 or |
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308. |
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Set to ``0`` to fail on the first retry of this type. |
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Set to ``False`` to disable and imply ``raise_on_redirect=False``. |
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:param iterable method_whitelist: |
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Set of uppercased HTTP method verbs that we should retry on. |
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By default, we only retry on methods which are considered to be |
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indempotent (multiple requests with the same parameters end with the |
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same state). See :attr:`Retry.DEFAULT_METHOD_WHITELIST`. |
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:param iterable status_forcelist: |
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A set of HTTP status codes that we should force a retry on. |
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By default, this is disabled with ``None``. |
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:param float backoff_factor: |
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A backoff factor to apply between attempts. urllib3 will sleep for:: |
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{backoff factor} * (2 ^ ({number of total retries} - 1)) |
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seconds. If the backoff_factor is 0.1, then :func:`.sleep` will sleep |
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for [0.1s, 0.2s, 0.4s, ...] between retries. It will never be longer |
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than :attr:`Retry.MAX_BACKOFF`. |
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By default, backoff is disabled (set to 0). |
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:param bool raise_on_redirect: Whether, if the number of redirects is |
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exhausted, to raise a MaxRetryError, or to return a response with a |
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response code in the 3xx range. |
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""" |
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DEFAULT_METHOD_WHITELIST = frozenset([ |
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'HEAD', 'GET', 'PUT', 'DELETE', 'OPTIONS', 'TRACE']) |
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#: Maximum backoff time. |
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BACKOFF_MAX = 120 |
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def __init__(self, total=10, connect=None, read=None, redirect=None, |
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method_whitelist=DEFAULT_METHOD_WHITELIST, status_forcelist=None, |
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backoff_factor=0, raise_on_redirect=True, _observed_errors=0): |
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self.total = total |
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self.connect = connect |
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self.read = read |
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if redirect is False or total is False: |
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redirect = 0 |
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raise_on_redirect = False |
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self.redirect = redirect |
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self.status_forcelist = status_forcelist or set() |
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self.method_whitelist = method_whitelist |
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self.backoff_factor = backoff_factor |
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self.raise_on_redirect = raise_on_redirect |
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self._observed_errors = _observed_errors # TODO: use .history instead? |
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def new(self, **kw): |
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params = dict( |
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total=self.total, |
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connect=self.connect, read=self.read, redirect=self.redirect, |
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method_whitelist=self.method_whitelist, |
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status_forcelist=self.status_forcelist, |
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backoff_factor=self.backoff_factor, |
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raise_on_redirect=self.raise_on_redirect, |
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_observed_errors=self._observed_errors, |
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) |
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params.update(kw) |
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return type(self)(**params) |
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@classmethod |
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def from_int(cls, retries, redirect=True, default=None): |
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""" Backwards-compatibility for the old retries format.""" |
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if retries is None: |
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retries = default if default is not None else cls.DEFAULT |
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if isinstance(retries, Retry): |
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return retries |
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redirect = bool(redirect) and None |
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new_retries = cls(retries, redirect=redirect) |
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log.debug("Converted retries value: %r -> %r" % (retries, new_retries)) |
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return new_retries |
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def get_backoff_time(self): |
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""" Formula for computing the current backoff |
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:rtype: float |
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""" |
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if self._observed_errors <= 1: |
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return 0 |
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backoff_value = self.backoff_factor * (2 ** (self._observed_errors - 1)) |
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return min(self.BACKOFF_MAX, backoff_value) |
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def sleep(self): |
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""" Sleep between retry attempts using an exponential backoff. |
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By default, the backoff factor is 0 and this method will return |
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immediately. |
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""" |
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backoff = self.get_backoff_time() |
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if backoff <= 0: |
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return |
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time.sleep(backoff) |
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def _is_connection_error(self, err): |
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""" Errors when we're fairly sure that the server did not receive the |
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request, so it should be safe to retry. |
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""" |
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return isinstance(err, ConnectTimeoutError) |
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def _is_read_error(self, err): |
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""" Errors that occur after the request has been started, so we can't |
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assume that the server did not process any of it. |
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""" |
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return isinstance(err, (ReadTimeoutError, ProtocolError)) |
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def is_forced_retry(self, method, status_code): |
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""" Is this method/response retryable? (Based on method/codes whitelists) |
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""" |
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if self.method_whitelist and method.upper() not in self.method_whitelist: |
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return False |
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return self.status_forcelist and status_code in self.status_forcelist |
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def is_exhausted(self): |
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""" Are we out of retries? |
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""" |
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retry_counts = (self.total, self.connect, self.read, self.redirect) |
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retry_counts = list(filter(None, retry_counts)) |
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if not retry_counts: |
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return False |
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return min(retry_counts) < 0 |
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def increment(self, method=None, url=None, response=None, error=None, _pool=None, _stacktrace=None): |
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""" Return a new Retry object with incremented retry counters. |
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:param response: A response object, or None, if the server did not |
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return a response. |
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:type response: :class:`~urllib3.response.HTTPResponse` |
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:param Exception error: An error encountered during the request, or |
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None if the response was received successfully. |
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:return: A new ``Retry`` object. |
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""" |
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if self.total is False and error: |
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# Disabled, indicate to re-raise the error. |
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raise six.reraise(type(error), error, _stacktrace) |
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total = self.total |
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if total is not None: |
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total -= 1 |
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_observed_errors = self._observed_errors |
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connect = self.connect |
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read = self.read |
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redirect = self.redirect |
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if error and self._is_connection_error(error): |
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# Connect retry? |
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if connect is False: |
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raise six.reraise(type(error), error, _stacktrace) |
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elif connect is not None: |
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connect -= 1 |
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_observed_errors += 1 |
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elif error and self._is_read_error(error): |
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# Read retry? |
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if read is False: |
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raise six.reraise(type(error), error, _stacktrace) |
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elif read is not None: |
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read -= 1 |
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_observed_errors += 1 |
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elif response and response.get_redirect_location(): |
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# Redirect retry? |
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if redirect is not None: |
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redirect -= 1 |
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else: |
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# FIXME: Nothing changed, scenario doesn't make sense. |
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_observed_errors += 1 |
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new_retry = self.new( |
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total=total, |
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connect=connect, read=read, redirect=redirect, |
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_observed_errors=_observed_errors) |
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if new_retry.is_exhausted(): |
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raise MaxRetryError(_pool, url, error) |
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log.debug("Incremented Retry for (url='%s'): %r" % (url, new_retry)) |
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return new_retry |
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def __repr__(self): |
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return ('{cls.__name__}(total={self.total}, connect={self.connect}, ' |
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'read={self.read}, redirect={self.redirect})').format( |
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cls=type(self), self=self) |
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# For backwards compatibility (equivalent to pre-v1.9): |
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Retry.DEFAULT = Retry(3) |
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