| import time |
| import logging |
| |
| from ..exceptions import ( |
| ConnectTimeoutError, |
| MaxRetryError, |
| ProtocolError, |
| ReadTimeoutError, |
| ResponseError, |
| ) |
| from ..packages import six |
| |
| |
| log = logging.getLogger(__name__) |
| |
| |
| 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 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 |
| indempotent (multiple requests with the same parameters end with the |
| same state). See :attr:`Retry.DEFAULT_METHOD_WHITELIST`. |
| |
| :param iterable status_forcelist: |
| A set of HTTP status codes that we should force a retry on. |
| |
| By default, this is disabled with ``None``. |
| |
| :param float backoff_factor: |
| A backoff factor to apply between attempts. 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 [0.1s, 0.2s, 0.4s, ...] between retries. It will never be longer |
| than :attr:`Retry.MAX_BACKOFF`. |
| |
| 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. |
| """ |
| |
| DEFAULT_METHOD_WHITELIST = frozenset([ |
| 'HEAD', 'GET', 'PUT', 'DELETE', 'OPTIONS', 'TRACE']) |
| |
| #: Maximum backoff time. |
| BACKOFF_MAX = 120 |
| |
| def __init__(self, total=10, connect=None, read=None, redirect=None, |
| method_whitelist=DEFAULT_METHOD_WHITELIST, status_forcelist=None, |
| backoff_factor=0, raise_on_redirect=True, _observed_errors=0): |
| |
| self.total = total |
| self.connect = connect |
| self.read = read |
| |
| 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._observed_errors = _observed_errors # TODO: use .history instead? |
| |
| def new(self, **kw): |
| params = dict( |
| total=self.total, |
| connect=self.connect, read=self.read, redirect=self.redirect, |
| method_whitelist=self.method_whitelist, |
| status_forcelist=self.status_forcelist, |
| backoff_factor=self.backoff_factor, |
| raise_on_redirect=self.raise_on_redirect, |
| _observed_errors=self._observed_errors, |
| ) |
| 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 |
| """ |
| if self._observed_errors <= 1: |
| return 0 |
| |
| backoff_value = self.backoff_factor * (2 ** (self._observed_errors - 1)) |
| return min(self.BACKOFF_MAX, backoff_value) |
| |
| def sleep(self): |
| """ Sleep between retry attempts using an exponential backoff. |
| |
| By default, the backoff factor is 0 and this method will return |
| immediately. |
| """ |
| backoff = self.get_backoff_time() |
| if backoff <= 0: |
| return |
| time.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_forced_retry(self, method, status_code): |
| """ Is this method/status code retryable? (Based on method/codes whitelists) |
| """ |
| if self.method_whitelist and method.upper() not in self.method_whitelist: |
| return False |
| |
| return self.status_forcelist and status_code in self.status_forcelist |
| |
| def is_exhausted(self): |
| """ Are we out of retries? """ |
| retry_counts = (self.total, self.connect, self.read, self.redirect) |
| 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 |
| |
| _observed_errors = self._observed_errors |
| connect = self.connect |
| read = self.read |
| redirect = self.redirect |
| cause = 'unknown' |
| |
| 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 |
| _observed_errors += 1 |
| |
| elif error and self._is_read_error(error): |
| # Read retry? |
| if read is False: |
| raise six.reraise(type(error), error, _stacktrace) |
| elif read is not None: |
| read -= 1 |
| _observed_errors += 1 |
| |
| elif response and response.get_redirect_location(): |
| # Redirect retry? |
| if redirect is not None: |
| redirect -= 1 |
| cause = 'too many redirects' |
| |
| else: |
| # Incrementing because of a server error like a 500 in |
| # status_forcelist and a the given method is in the whitelist |
| _observed_errors += 1 |
| cause = ResponseError.GENERIC_ERROR |
| if response and response.status: |
| cause = ResponseError.SPECIFIC_ERROR.format( |
| status_code=response.status) |
| |
| new_retry = self.new( |
| total=total, |
| connect=connect, read=read, redirect=redirect, |
| _observed_errors=_observed_errors) |
| |
| 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})').format( |
| cls=type(self), self=self) |
| |
| |
| # For backwards compatibility (equivalent to pre-v1.9): |
| Retry.DEFAULT = Retry(3) |
