--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/urllib3/util/retry.py	Sun May 05 23:32:17 2024 -0400
@@ -0,0 +1,529 @@
+from __future__ import annotations
+
+import email
+import logging
+import random
+import re
+import time
+import typing
+from itertools import takewhile
+from types import TracebackType
+
+from ..exceptions import (
+    ConnectTimeoutError,
+    InvalidHeader,
+    MaxRetryError,
+    ProtocolError,
+    ProxyError,
+    ReadTimeoutError,
+    ResponseError,
+)
+from .util import reraise
+
+if typing.TYPE_CHECKING:
+    from ..connectionpool import ConnectionPool
+    from ..response import BaseHTTPResponse
+
+log = logging.getLogger(__name__)
+
+
+# Data structure for representing the metadata of requests that result in a retry.
+class RequestHistory(typing.NamedTuple):
+    method: str | None
+    url: str | None
+    error: Exception | None
+    status: int | None
+    redirect_location: str | None
+
+
+class Retry:
+    """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:
+
+    .. code-block:: python
+
+        retries = Retry(connect=5, read=2, redirect=5)
+        http = PoolManager(retries=retries)
+        response = http.request("GET", "https://example.com/")
+
+    Or per-request (which overrides the default for the pool):
+
+    .. code-block:: python
+
+        response = http.request("GET", "https://example.com/", retries=Retry(10))
+
+    Retries can be disabled by passing ``False``:
+
+    .. code-block:: python
+
+        response = http.request("GET", "https://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.
+
+        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 int other:
+        How many times to retry on other errors.
+
+        Other errors are errors that are not connect, read, redirect or status errors.
+        These errors might be raised after the request was sent to the server, so the
+        request might have side-effects.
+
+        Set to ``0`` to fail on the first retry of this type.
+
+        If ``total`` is not set, it's a good idea to set this to 0 to account
+        for unexpected edge cases and avoid infinite retry loops.
+
+    :param Collection allowed_methods:
+        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_ALLOWED_METHODS`.
+
+        Set to a ``None`` value to retry on any verb.
+
+    :param Collection 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 ``allowed_methods``
+        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 previous retries}))
+
+        seconds. If `backoff_jitter` is non-zero, this sleep is extended by::
+
+            random.uniform(0, {backoff jitter})
+
+        seconds. For example, if the backoff_factor is 0.1, then :func:`Retry.sleep` will
+        sleep for [0.0s, 0.2s, 0.4s, 0.8s, ...] between retries. No backoff will ever
+        be longer than `backoff_max`.
+
+        By default, backoff is disabled (factor 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.
+
+    :param Collection remove_headers_on_redirect:
+        Sequence of headers to remove from the request when a response
+        indicating a redirect is returned before firing off the redirected
+        request.
+    """
+
+    #: Default methods to be used for ``allowed_methods``
+    DEFAULT_ALLOWED_METHODS = frozenset(
+        ["HEAD", "GET", "PUT", "DELETE", "OPTIONS", "TRACE"]
+    )
+
+    #: Default status codes to be used for ``status_forcelist``
+    RETRY_AFTER_STATUS_CODES = frozenset([413, 429, 503])
+
+    #: Default headers to be used for ``remove_headers_on_redirect``
+    DEFAULT_REMOVE_HEADERS_ON_REDIRECT = frozenset(["Cookie", "Authorization"])
+
+    #: Default maximum backoff time.
+    DEFAULT_BACKOFF_MAX = 120
+
+    # Backward compatibility; assigned outside of the class.
+    DEFAULT: typing.ClassVar[Retry]
+
+    def __init__(
+        self,
+        total: bool | int | None = 10,
+        connect: int | None = None,
+        read: int | None = None,
+        redirect: bool | int | None = None,
+        status: int | None = None,
+        other: int | None = None,
+        allowed_methods: typing.Collection[str] | None = DEFAULT_ALLOWED_METHODS,
+        status_forcelist: typing.Collection[int] | None = None,
+        backoff_factor: float = 0,
+        backoff_max: float = DEFAULT_BACKOFF_MAX,
+        raise_on_redirect: bool = True,
+        raise_on_status: bool = True,
+        history: tuple[RequestHistory, ...] | None = None,
+        respect_retry_after_header: bool = True,
+        remove_headers_on_redirect: typing.Collection[
+            str
+        ] = DEFAULT_REMOVE_HEADERS_ON_REDIRECT,
+        backoff_jitter: float = 0.0,
+    ) -> None:
+        self.total = total
+        self.connect = connect
+        self.read = read
+        self.status = status
+        self.other = other
+
+        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.allowed_methods = allowed_methods
+        self.backoff_factor = backoff_factor
+        self.backoff_max = backoff_max
+        self.raise_on_redirect = raise_on_redirect
+        self.raise_on_status = raise_on_status
+        self.history = history or ()
+        self.respect_retry_after_header = respect_retry_after_header
+        self.remove_headers_on_redirect = frozenset(
+            h.lower() for h in remove_headers_on_redirect
+        )
+        self.backoff_jitter = backoff_jitter
+
+    def new(self, **kw: typing.Any) -> Retry:
+        params = dict(
+            total=self.total,
+            connect=self.connect,
+            read=self.read,
+            redirect=self.redirect,
+            status=self.status,
+            other=self.other,
+            allowed_methods=self.allowed_methods,
+            status_forcelist=self.status_forcelist,
+            backoff_factor=self.backoff_factor,
+            backoff_max=self.backoff_max,
+            raise_on_redirect=self.raise_on_redirect,
+            raise_on_status=self.raise_on_status,
+            history=self.history,
+            remove_headers_on_redirect=self.remove_headers_on_redirect,
+            respect_retry_after_header=self.respect_retry_after_header,
+            backoff_jitter=self.backoff_jitter,
+        )
+
+        params.update(kw)
+        return type(self)(**params)  # type: ignore[arg-type]
+
+    @classmethod
+    def from_int(
+        cls,
+        retries: Retry | bool | int | None,
+        redirect: bool | int | None = True,
+        default: Retry | bool | int | None = None,
+    ) -> Retry:
+        """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) -> float:
+        """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))
+        if self.backoff_jitter != 0.0:
+            backoff_value += random.random() * self.backoff_jitter
+        return float(max(0, min(self.backoff_max, backoff_value)))
+
+    def parse_retry_after(self, retry_after: str) -> float:
+        seconds: float
+        # 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_tz(retry_after)
+            if retry_date_tuple is None:
+                raise InvalidHeader(f"Invalid Retry-After header: {retry_after}")
+
+            retry_date = email.utils.mktime_tz(retry_date_tuple)
+            seconds = retry_date - time.time()
+
+        seconds = max(seconds, 0)
+
+        return seconds
+
+    def get_retry_after(self, response: BaseHTTPResponse) -> float | None:
+        """Get the value of Retry-After in seconds."""
+
+        retry_after = response.headers.get("Retry-After")
+
+        if retry_after is None:
+            return None
+
+        return self.parse_retry_after(retry_after)
+
+    def sleep_for_retry(self, response: BaseHTTPResponse) -> bool:
+        retry_after = self.get_retry_after(response)
+        if retry_after:
+            time.sleep(retry_after)
+            return True
+
+        return False
+
+    def _sleep_backoff(self) -> None:
+        backoff = self.get_backoff_time()
+        if backoff <= 0:
+            return
+        time.sleep(backoff)
+
+    def sleep(self, response: BaseHTTPResponse | None = None) -> 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 self.respect_retry_after_header and response:
+            slept = self.sleep_for_retry(response)
+            if slept:
+                return
+
+        self._sleep_backoff()
+
+    def _is_connection_error(self, err: Exception) -> bool:
+        """Errors when we're fairly sure that the server did not receive the
+        request, so it should be safe to retry.
+        """
+        if isinstance(err, ProxyError):
+            err = err.original_error
+        return isinstance(err, ConnectTimeoutError)
+
+    def _is_read_error(self, err: Exception) -> bool:
+        """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: str) -> bool:
+        """Checks if a given HTTP method should be retried upon, depending if
+        it is included in the allowed_methods
+        """
+        if self.allowed_methods and method.upper() not in self.allowed_methods:
+            return False
+        return True
+
+    def is_retry(
+        self, method: str, status_code: int, has_retry_after: bool = False
+    ) -> bool:
+        """Is this method/status code retryable? (Based on allowlists 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 bool(
+            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) -> bool:
+        """Are we out of retries?"""
+        retry_counts = [
+            x
+            for x in (
+                self.total,
+                self.connect,
+                self.read,
+                self.redirect,
+                self.status,
+                self.other,
+            )
+            if x
+        ]
+        if not retry_counts:
+            return False
+
+        return min(retry_counts) < 0
+
+    def increment(
+        self,
+        method: str | None = None,
+        url: str | None = None,
+        response: BaseHTTPResponse | None = None,
+        error: Exception | None = None,
+        _pool: ConnectionPool | None = None,
+        _stacktrace: TracebackType | None = None,
+    ) -> Retry:
+        """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.BaseHTTPResponse`
+        :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 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
+        other = self.other
+        cause = "unknown"
+        status = None
+        redirect_location = None
+
+        if error and self._is_connection_error(error):
+            # Connect retry?
+            if connect is False:
+                raise 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 method is None or not self._is_method_retryable(method):
+                raise reraise(type(error), error, _stacktrace)
+            elif read is not None:
+                read -= 1
+
+        elif error:
+            # Other retry?
+            if other is not None:
+                other -= 1
+
+        elif response and response.get_redirect_location():
+            # Redirect retry?
+            if redirect is not None:
+                redirect -= 1
+            cause = "too many redirects"
+            response_redirect_location = response.get_redirect_location()
+            if response_redirect_location:
+                redirect_location = response_redirect_location
+            status = response.status
+
+        else:
+            # Incrementing because of a server error like a 500 in
+            # status_forcelist and the given method is in the allowed_methods
+            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,
+            other=other,
+            history=history,
+        )
+
+        if new_retry.is_exhausted():
+            reason = error or ResponseError(cause)
+            raise MaxRetryError(_pool, url, reason) from reason  # type: ignore[arg-type]
+
+        log.debug("Incremented Retry for (url='%s'): %r", url, new_retry)
+
+        return new_retry
+
+    def __repr__(self) -> str:
+        return (
+            f"{type(self).__name__}(total={self.total}, connect={self.connect}, "
+            f"read={self.read}, redirect={self.redirect}, status={self.status})"
+        )
+
+
+# For backwards compatibility (equivalent to pre-v1.9):
+Retry.DEFAULT = Retry(3)