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+# SPDX-License-Identifier: MIT
+from __future__ import absolute_import
+import time
+import logging
+from collections import namedtuple
+from itertools import takewhile
+import email
+import re
+
+from ..exceptions import (
+ ConnectTimeoutError,
+ MaxRetryError,
+ ProtocolError,
+ ReadTimeoutError,
+ ResponseError,
+ InvalidHeader,
+)
+from ..packages import six
+
+
+log = logging.getLogger(__name__)
+
+# Data structure for representing the metadata of requests that result in a retry.
+RequestHistory = namedtuple('RequestHistory', ["method", "url", "error",
+ "status", "redirect_location"])
+
+
+class Retry(object):
+ """ Retry configuration.
+
+ Each retry attempt will create a new Retry object with updated values, so
+ they can be safely reused.
+
+ Retries can be defined as a default for a pool::
+
+ retries = Retry(connect=5, read=2, redirect=5)
+ http = PoolManager(retries=retries)
+ response = http.request('GET', 'http://example.com/')
+
+ Or per-request (which overrides the default for the pool)::
+
+ response = http.request('GET', 'http://example.com/', retries=Retry(10))
+
+ Retries can be disabled by passing ``False``::
+
+ response = http.request('GET', 'http://example.com/', retries=False)
+
+ Errors will be wrapped in :class:`~urllib3.exceptions.MaxRetryError` unless
+ retries are disabled, in which case the causing exception will be raised.
+
+ :param int total:
+ Total number of retries to allow. Takes precedence over other counts.
+
+ Set to ``None`` to remove this constraint and fall back on other
+ counts. It's a good idea to set this to some sensibly-high value to
+ account for unexpected edge cases and avoid infinite retry loops.
+
+ Set to ``0`` to fail on the first retry.
+
+ Set to ``False`` to disable and imply ``raise_on_redirect=False``.
+
+ :param int connect:
+ How many connection-related errors to retry on.
+
+ These are errors raised before the request is sent to the remote server,
+ which we assume has not triggered the server to process the request.
+
+ Set to ``0`` to fail on the first retry of this type.
+
+ :param int read:
+ How many times to retry on read errors.
+
+ These errors are raised after the request was sent to the server, so the
+ request may have side-effects.
+
+ Set to ``0`` to fail on the first retry of this type.
+
+ :param int redirect:
+ How many redirects to perform. Limit this to avoid infinite redirect
+ loops.
+
+ A redirect is a HTTP response with a status code 301, 302, 303, 307 or
+ 308.
+
+ Set to ``0`` to fail on the first retry of this type.
+
+ Set to ``False`` to disable and imply ``raise_on_redirect=False``.
+
+ :param int status:
+ How many times to retry on bad status codes.
+
+ These are retries made on responses, where status code matches
+ ``status_forcelist``.
+
+ Set to ``0`` to fail on the first retry of this type.
+
+ :param iterable method_whitelist:
+ Set of uppercased HTTP method verbs that we should retry on.
+
+ By default, we only retry on methods which are considered to be
+ idempotent (multiple requests with the same parameters end with the
+ same state). See :attr:`Retry.DEFAULT_METHOD_WHITELIST`.
+
+ Set to a ``False`` value to retry on any verb.
+
+ :param iterable status_forcelist:
+ A set of integer HTTP status codes that we should force a retry on.
+ A retry is initiated if the request method is in ``method_whitelist``
+ and the response status code is in ``status_forcelist``.
+
+ By default, this is disabled with ``None``.
+
+ :param float backoff_factor:
+ A backoff factor to apply between attempts after the second try
+ (most errors are resolved immediately by a second try without a
+ delay). urllib3 will sleep for::
+
+ {backoff factor} * (2 ^ ({number of total retries} - 1))
+
+ seconds. If the backoff_factor is 0.1, then :func:`.sleep` will sleep
+ for [0.0s, 0.2s, 0.4s, ...] between retries. It will never be longer
+ than :attr:`Retry.BACKOFF_MAX`.
+
+ By default, backoff is disabled (set to 0).
+
+ :param bool raise_on_redirect: Whether, if the number of redirects is
+ exhausted, to raise a MaxRetryError, or to return a response with a
+ response code in the 3xx range.
+
+ :param bool raise_on_status: Similar meaning to ``raise_on_redirect``:
+ whether we should raise an exception, or return a response,
+ if status falls in ``status_forcelist`` range and retries have
+ been exhausted.
+
+ :param tuple history: The history of the request encountered during
+ each call to :meth:`~Retry.increment`. The list is in the order
+ the requests occurred. Each list item is of class :class:`RequestHistory`.
+
+ :param bool respect_retry_after_header:
+ Whether to respect Retry-After header on status codes defined as
+ :attr:`Retry.RETRY_AFTER_STATUS_CODES` or not.
+
+ """
+
+ DEFAULT_METHOD_WHITELIST = frozenset([
+ 'HEAD', 'GET', 'PUT', 'DELETE', 'OPTIONS', 'TRACE'])
+
+ RETRY_AFTER_STATUS_CODES = frozenset([413, 429, 503])
+
+ #: Maximum backoff time.
+ BACKOFF_MAX = 120
+
+ def __init__(self, total=10, connect=None, read=None, redirect=None, status=None,
+ method_whitelist=DEFAULT_METHOD_WHITELIST, status_forcelist=None,
+ backoff_factor=0, raise_on_redirect=True, raise_on_status=True,
+ history=None, respect_retry_after_header=True):
+
+ self.total = total
+ self.connect = connect
+ self.read = read
+ self.status = status
+
+ if redirect is False or total is False:
+ redirect = 0
+ raise_on_redirect = False
+
+ self.redirect = redirect
+ self.status_forcelist = status_forcelist or set()
+ self.method_whitelist = method_whitelist
+ self.backoff_factor = backoff_factor
+ self.raise_on_redirect = raise_on_redirect
+ self.raise_on_status = raise_on_status
+ self.history = history or tuple()
+ self.respect_retry_after_header = respect_retry_after_header
+
+ def new(self, **kw):
+ params = dict(
+ total=self.total,
+ connect=self.connect, read=self.read, redirect=self.redirect, status=self.status,
+ method_whitelist=self.method_whitelist,
+ status_forcelist=self.status_forcelist,
+ backoff_factor=self.backoff_factor,
+ raise_on_redirect=self.raise_on_redirect,
+ raise_on_status=self.raise_on_status,
+ history=self.history,
+ )
+ params.update(kw)
+ return type(self)(**params)
+
+ @classmethod
+ def from_int(cls, retries, redirect=True, default=None):
+ """ Backwards-compatibility for the old retries format."""
+ if retries is None:
+ retries = default if default is not None else cls.DEFAULT
+
+ if isinstance(retries, Retry):
+ return retries
+
+ redirect = bool(redirect) and None
+ new_retries = cls(retries, redirect=redirect)
+ log.debug("Converted retries value: %r -> %r", retries, new_retries)
+ return new_retries
+
+ def get_backoff_time(self):
+ """ Formula for computing the current backoff
+
+ :rtype: float
+ """
+ # We want to consider only the last consecutive errors sequence (Ignore redirects).
+ consecutive_errors_len = len(list(takewhile(lambda x: x.redirect_location is None,
+ reversed(self.history))))
+ if consecutive_errors_len <= 1:
+ return 0
+
+ backoff_value = self.backoff_factor * (2 ** (consecutive_errors_len - 1))
+ return min(self.BACKOFF_MAX, backoff_value)
+
+ def parse_retry_after(self, retry_after):
+ # Whitespace: https://tools.ietf.org/html/rfc7230#section-3.2.4
+ if re.match(r"^\s*[0-9]+\s*$", retry_after):
+ seconds = int(retry_after)
+ else:
+ retry_date_tuple = email.utils.parsedate(retry_after)
+ if retry_date_tuple is None:
+ raise InvalidHeader("Invalid Retry-After header: %s" % retry_after)
+ retry_date = time.mktime(retry_date_tuple)
+ seconds = retry_date - time.time()
+
+ if seconds < 0:
+ seconds = 0
+
+ return seconds
+
+ def get_retry_after(self, response):
+ """ Get the value of Retry-After in seconds. """
+
+ retry_after = response.getheader("Retry-After")
+
+ if retry_after is None:
+ return None
+
+ return self.parse_retry_after(retry_after)
+
+ def sleep_for_retry(self, response=None):
+ retry_after = self.get_retry_after(response)
+ if retry_after:
+ time.sleep(retry_after)
+ return True
+
+ return False
+
+ def _sleep_backoff(self):
+ backoff = self.get_backoff_time()
+ if backoff <= 0:
+ return
+ time.sleep(backoff)
+
+ def sleep(self, response=None):
+ """ Sleep between retry attempts.
+
+ This method will respect a server's ``Retry-After`` response header
+ and sleep the duration of the time requested. If that is not present, it
+ will use an exponential backoff. By default, the backoff factor is 0 and
+ this method will return immediately.
+ """
+
+ if response:
+ slept = self.sleep_for_retry(response)
+ if slept:
+ return
+
+ self._sleep_backoff()
+
+ def _is_connection_error(self, err):
+ """ Errors when we're fairly sure that the server did not receive the
+ request, so it should be safe to retry.
+ """
+ return isinstance(err, ConnectTimeoutError)
+
+ def _is_read_error(self, err):
+ """ Errors that occur after the request has been started, so we should
+ assume that the server began processing it.
+ """
+ return isinstance(err, (ReadTimeoutError, ProtocolError))
+
+ def _is_method_retryable(self, method):
+ """ Checks if a given HTTP method should be retried upon, depending if
+ it is included on the method whitelist.
+ """
+ if self.method_whitelist and method.upper() not in self.method_whitelist:
+ return False
+
+ return True
+
+ def is_retry(self, method, status_code, has_retry_after=False):
+ """ Is this method/status code retryable? (Based on whitelists and control
+ variables such as the number of total retries to allow, whether to
+ respect the Retry-After header, whether this header is present, and
+ whether the returned status code is on the list of status codes to
+ be retried upon on the presence of the aforementioned header)
+ """
+ if not self._is_method_retryable(method):
+ return False
+
+ if self.status_forcelist and status_code in self.status_forcelist:
+ return True
+
+ return (self.total and self.respect_retry_after_header and
+ has_retry_after and (status_code in self.RETRY_AFTER_STATUS_CODES))
+
+ def is_exhausted(self):
+ """ Are we out of retries? """
+ retry_counts = (self.total, self.connect, self.read, self.redirect, self.status)
+ retry_counts = list(filter(None, retry_counts))
+ if not retry_counts:
+ return False
+
+ return min(retry_counts) < 0
+
+ def increment(self, method=None, url=None, response=None, error=None,
+ _pool=None, _stacktrace=None):
+ """ Return a new Retry object with incremented retry counters.
+
+ :param response: A response object, or None, if the server did not
+ return a response.
+ :type response: :class:`~urllib3.response.HTTPResponse`
+ :param Exception error: An error encountered during the request, or
+ None if the response was received successfully.
+
+ :return: A new ``Retry`` object.
+ """
+ if self.total is False and error:
+ # Disabled, indicate to re-raise the error.
+ raise six.reraise(type(error), error, _stacktrace)
+
+ total = self.total
+ if total is not None:
+ total -= 1
+
+ connect = self.connect
+ read = self.read
+ redirect = self.redirect
+ status_count = self.status
+ cause = 'unknown'
+ status = None
+ redirect_location = None
+
+ if error and self._is_connection_error(error):
+ # Connect retry?
+ if connect is False:
+ raise six.reraise(type(error), error, _stacktrace)
+ elif connect is not None:
+ connect -= 1
+
+ elif error and self._is_read_error(error):
+ # Read retry?
+ if read is False or not self._is_method_retryable(method):
+ raise six.reraise(type(error), error, _stacktrace)
+ elif read is not None:
+ read -= 1
+
+ elif response and response.get_redirect_location():
+ # Redirect retry?
+ if redirect is not None:
+ redirect -= 1
+ cause = 'too many redirects'
+ redirect_location = response.get_redirect_location()
+ status = response.status
+
+ else:
+ # Incrementing because of a server error like a 500 in
+ # status_forcelist and a the given method is in the whitelist
+ cause = ResponseError.GENERIC_ERROR
+ if response and response.status:
+ if status_count is not None:
+ status_count -= 1
+ cause = ResponseError.SPECIFIC_ERROR.format(
+ status_code=response.status)
+ status = response.status
+
+ history = self.history + (RequestHistory(method, url, error, status, redirect_location),)
+
+ new_retry = self.new(
+ total=total,
+ connect=connect, read=read, redirect=redirect, status=status_count,
+ history=history)
+
+ if new_retry.is_exhausted():
+ raise MaxRetryError(_pool, url, error or ResponseError(cause))
+
+ log.debug("Incremented Retry for (url='%s'): %r", url, new_retry)
+
+ return new_retry
+
+ def __repr__(self):
+ return ('{cls.__name__}(total={self.total}, connect={self.connect}, '
+ 'read={self.read}, redirect={self.redirect}, status={self.status})').format(
+ cls=type(self), self=self)
+
+
+# For backwards compatibility (equivalent to pre-v1.9):
+Retry.DEFAULT = Retry(3)