Загрузить файлы в «venv/Lib/site-packages/pip/_vendor/cachecontrol»

venv/Lib/site-packages/pip/_vendor/cachecontrol/__init__.py

@@ -0,0 +1,32 @@
+# SPDX-FileCopyrightText: 2015 Eric Larson
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""CacheControl import Interface.
+
+Make it easy to import from cachecontrol without long namespaces.
+"""
+
+import importlib.metadata
+
+from pip._vendor.cachecontrol.adapter import CacheControlAdapter
+from pip._vendor.cachecontrol.controller import CacheController
+from pip._vendor.cachecontrol.wrapper import CacheControl
+
+__author__ = "Eric Larson"
+__email__ = "eric@ionrock.org"
+# pip patch: this won't work when vendored, so just patch it out as it's unused
+# __version__ = importlib.metadata.version("cachecontrol")
+
+__all__ = [
+    "__author__",
+    "__email__",
+    "__version__",
+    "CacheControlAdapter",
+    "CacheController",
+    "CacheControl",
+]
+
+import logging
+
+logging.getLogger(__name__).addHandler(logging.NullHandler())

venv/Lib/site-packages/pip/_vendor/cachecontrol/_cmd.py

@@ -0,0 +1,70 @@
+# SPDX-FileCopyrightText: 2015 Eric Larson
+#
+# SPDX-License-Identifier: Apache-2.0
+from __future__ import annotations
+
+import logging
+from argparse import ArgumentParser
+from typing import TYPE_CHECKING
+
+from pip._vendor import requests
+
+from pip._vendor.cachecontrol.adapter import CacheControlAdapter
+from pip._vendor.cachecontrol.cache import DictCache
+from pip._vendor.cachecontrol.controller import logger
+
+if TYPE_CHECKING:
+    from argparse import Namespace
+
+    from pip._vendor.cachecontrol.controller import CacheController
+
+
+def setup_logging() -> None:
+    logger.setLevel(logging.DEBUG)
+    handler = logging.StreamHandler()
+    logger.addHandler(handler)
+
+
+def get_session() -> requests.Session:
+    adapter = CacheControlAdapter(
+        DictCache(), cache_etags=True, serializer=None, heuristic=None
+    )
+    sess = requests.Session()
+    sess.mount("http://", adapter)
+    sess.mount("https://", adapter)
+
+    sess.cache_controller = adapter.controller  # type: ignore[attr-defined]
+    return sess
+
+
+def get_args() -> Namespace:
+    parser = ArgumentParser()
+    parser.add_argument("url", help="The URL to try and cache")
+    return parser.parse_args()
+
+
+def main() -> None:
+    args = get_args()
+    sess = get_session()
+
+    # Make a request to get a response
+    resp = sess.get(args.url)
+
+    # Turn on logging
+    setup_logging()
+
+    # try setting the cache
+    cache_controller: CacheController = (
+        sess.cache_controller  # type: ignore[attr-defined]
+    )
+    cache_controller.cache_response(resp.request, resp.raw)
+
+    # Now try to get it
+    if cache_controller.cached_request(resp.request):
+        print("Cached!")
+    else:
+        print("Not cached :(")
+
+
+if __name__ == "__main__":
+    main()

venv/Lib/site-packages/pip/_vendor/cachecontrol/adapter.py

@@ -0,0 +1,167 @@
+# SPDX-FileCopyrightText: 2015 Eric Larson
+#
+# SPDX-License-Identifier: Apache-2.0
+from __future__ import annotations
+
+import functools
+import weakref
+import zlib
+from typing import TYPE_CHECKING, Any, Collection, Mapping
+
+from pip._vendor.requests.adapters import HTTPAdapter
+
+from pip._vendor.cachecontrol.cache import DictCache
+from pip._vendor.cachecontrol.controller import PERMANENT_REDIRECT_STATUSES, CacheController
+from pip._vendor.cachecontrol.filewrapper import CallbackFileWrapper
+
+if TYPE_CHECKING:
+    from pip._vendor.requests import PreparedRequest, Response
+    from pip._vendor.urllib3 import HTTPResponse
+
+    from pip._vendor.cachecontrol.cache import BaseCache
+    from pip._vendor.cachecontrol.heuristics import BaseHeuristic
+    from pip._vendor.cachecontrol.serialize import Serializer
+
+
+class CacheControlAdapter(HTTPAdapter):
+    invalidating_methods = {"PUT", "PATCH", "DELETE"}
+
+    def __init__(
+        self,
+        cache: BaseCache | None = None,
+        cache_etags: bool = True,
+        controller_class: type[CacheController] | None = None,
+        serializer: Serializer | None = None,
+        heuristic: BaseHeuristic | None = None,
+        cacheable_methods: Collection[str] | None = None,
+        *args: Any,
+        **kw: Any,
+    ) -> None:
+        super().__init__(*args, **kw)
+        self.cache = DictCache() if cache is None else cache
+        self.heuristic = heuristic
+        self.cacheable_methods = cacheable_methods or ("GET",)
+
+        controller_factory = controller_class or CacheController
+        self.controller = controller_factory(
+            self.cache, cache_etags=cache_etags, serializer=serializer
+        )
+
+    def send(
+        self,
+        request: PreparedRequest,
+        stream: bool = False,
+        timeout: None | float | tuple[float, float] | tuple[float, None] = None,
+        verify: bool | str = True,
+        cert: (None | bytes | str | tuple[bytes | str, bytes | str]) = None,
+        proxies: Mapping[str, str] | None = None,
+        cacheable_methods: Collection[str] | None = None,
+    ) -> Response:
+        """
+        Send a request. Use the request information to see if it
+        exists in the cache and cache the response if we need to and can.
+        """
+        cacheable = cacheable_methods or self.cacheable_methods
+        if request.method in cacheable:
+            try:
+                cached_response = self.controller.cached_request(request)
+            except zlib.error:
+                cached_response = None
+            if cached_response:
+                return self.build_response(request, cached_response, from_cache=True)
+
+            # check for etags and add headers if appropriate
+            request.headers.update(self.controller.conditional_headers(request))
+
+        resp = super().send(request, stream, timeout, verify, cert, proxies)
+
+        return resp
+
+    def build_response(  # type: ignore[override]
+        self,
+        request: PreparedRequest,
+        response: HTTPResponse,
+        from_cache: bool = False,
+        cacheable_methods: Collection[str] | None = None,
+    ) -> Response:
+        """
+        Build a response by making a request or using the cache.
+
+        This will end up calling send and returning a potentially
+        cached response
+        """
+        cacheable = cacheable_methods or self.cacheable_methods
+        if not from_cache and request.method in cacheable:
+            # Check for any heuristics that might update headers
+            # before trying to cache.
+            if self.heuristic:
+                response = self.heuristic.apply(response)
+
+            # apply any expiration heuristics
+            if response.status == 304:
+                # We must have sent an ETag request. This could mean
+                # that we've been expired already or that we simply
+                # have an etag. In either case, we want to try and
+                # update the cache if that is the case.
+                cached_response = self.controller.update_cached_response(
+                    request, response
+                )
+
+                if cached_response is not response:
+                    from_cache = True
+
+                # We are done with the server response, read a
+                # possible response body (compliant servers will
+                # not return one, but we cannot be 100% sure) and
+                # release the connection back to the pool.
+                response.read(decode_content=False)
+                response.release_conn()
+
+                response = cached_response
+
+            # We always cache the 301 responses
+            elif int(response.status) in PERMANENT_REDIRECT_STATUSES:
+                self.controller.cache_response(request, response)
+            else:
+                # Wrap the response file with a wrapper that will cache the
+                #   response when the stream has been consumed.
+                response._fp = CallbackFileWrapper(  # type: ignore[assignment]
+                    response._fp,  # type: ignore[arg-type]
+                    functools.partial(
+                        self.controller.cache_response, request, weakref.ref(response)
+                    ),
+                )
+                if response.chunked:
+                    super_update_chunk_length = response.__class__._update_chunk_length
+
+                    def _update_chunk_length(
+                        weak_self: weakref.ReferenceType[HTTPResponse],
+                    ) -> None:
+                        self = weak_self()
+                        if self is None:
+                            return
+
+                        super_update_chunk_length(self)
+                        if self.chunk_left == 0:
+                            self._fp._close()  # type: ignore[union-attr]
+
+                    response._update_chunk_length = functools.partial(  # type: ignore[method-assign]
+                        _update_chunk_length, weakref.ref(response)
+                    )
+
+        resp: Response = super().build_response(request, response)
+
+        # See if we should invalidate the cache.
+        if request.method in self.invalidating_methods and resp.ok:
+            assert request.url is not None
+            cache_url = self.controller.cache_url(request.url)
+            self.cache.delete(cache_url)
+
+        # Give the request a from_cache attr to let people use it
+        resp.from_cache = from_cache  # type: ignore[attr-defined]
+
+        return resp
+
+    def close(self) -> None:
+        self.cache.close()
+        super().close()  # type: ignore[no-untyped-call]

venv/Lib/site-packages/pip/_vendor/cachecontrol/cache.py

@@ -0,0 +1,75 @@
+# SPDX-FileCopyrightText: 2015 Eric Larson
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""
+The cache object API for implementing caches. The default is a thread
+safe in-memory dictionary.
+"""
+
+from __future__ import annotations
+
+from threading import Lock
+from typing import IO, TYPE_CHECKING, MutableMapping
+
+if TYPE_CHECKING:
+    from datetime import datetime
+
+
+class BaseCache:
+    def get(self, key: str) -> bytes | None:
+        raise NotImplementedError()
+
+    def set(
+        self, key: str, value: bytes, expires: int | datetime | None = None
+    ) -> None:
+        raise NotImplementedError()
+
+    def delete(self, key: str) -> None:
+        raise NotImplementedError()
+
+    def close(self) -> None:
+        pass
+
+
+class DictCache(BaseCache):
+    def __init__(self, init_dict: MutableMapping[str, bytes] | None = None) -> None:
+        self.lock = Lock()
+        self.data = init_dict or {}
+
+    def get(self, key: str) -> bytes | None:
+        return self.data.get(key, None)
+
+    def set(
+        self, key: str, value: bytes, expires: int | datetime | None = None
+    ) -> None:
+        with self.lock:
+            self.data.update({key: value})
+
+    def delete(self, key: str) -> None:
+        with self.lock:
+            if key in self.data:
+                self.data.pop(key)
+
+
+class SeparateBodyBaseCache(BaseCache):
+    """
+    In this variant, the body is not stored mixed in with the metadata, but is
+    passed in (as a bytes-like object) in a separate call to ``set_body()``.
+
+    That is, the expected interaction pattern is::
+
+        cache.set(key, serialized_metadata)
+        cache.set_body(key)
+
+    Similarly, the body should be loaded separately via ``get_body()``.
+    """
+
+    def set_body(self, key: str, body: bytes) -> None:
+        raise NotImplementedError()
+
+    def get_body(self, key: str) -> IO[bytes] | None:
+        """
+        Return the body as file-like object.
+        """
+        raise NotImplementedError()

venv/Lib/site-packages/pip/_vendor/cachecontrol/controller.py

@@ -0,0 +1,511 @@
+# SPDX-FileCopyrightText: 2015 Eric Larson
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""
+The httplib2 algorithms ported for use with requests.
+"""
+
+from __future__ import annotations
+
+import calendar
+import logging
+import re
+import time
+import weakref
+from email.utils import parsedate_tz
+from typing import TYPE_CHECKING, Collection, Mapping
+
+from pip._vendor.requests.structures import CaseInsensitiveDict
+
+from pip._vendor.cachecontrol.cache import DictCache, SeparateBodyBaseCache
+from pip._vendor.cachecontrol.serialize import Serializer
+
+if TYPE_CHECKING:
+    from typing import Literal
+
+    from pip._vendor.requests import PreparedRequest
+    from pip._vendor.urllib3 import HTTPResponse
+
+    from pip._vendor.cachecontrol.cache import BaseCache
+
+logger = logging.getLogger(__name__)
+
+URI = re.compile(r"^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?")
+
+PERMANENT_REDIRECT_STATUSES = (301, 308)
+
+
+def parse_uri(uri: str) -> tuple[str, str, str, str, str]:
+    """Parses a URI using the regex given in Appendix B of RFC 3986.
+
+    (scheme, authority, path, query, fragment) = parse_uri(uri)
+    """
+    match = URI.match(uri)
+    assert match is not None
+    groups = match.groups()
+    return (groups[1], groups[3], groups[4], groups[6], groups[8])
+
+
+class CacheController:
+    """An interface to see if request should cached or not."""
+
+    def __init__(
+        self,
+        cache: BaseCache | None = None,
+        cache_etags: bool = True,
+        serializer: Serializer | None = None,
+        status_codes: Collection[int] | None = None,
+    ):
+        self.cache = DictCache() if cache is None else cache
+        self.cache_etags = cache_etags
+        self.serializer = serializer or Serializer()
+        self.cacheable_status_codes = status_codes or (200, 203, 300, 301, 308)
+
+    @classmethod
+    def _urlnorm(cls, uri: str) -> str:
+        """Normalize the URL to create a safe key for the cache"""
+        (scheme, authority, path, query, fragment) = parse_uri(uri)
+        if not scheme or not authority:
+            raise Exception("Only absolute URIs are allowed. uri = %s" % uri)
+
+        scheme = scheme.lower()
+        authority = authority.lower()
+
+        if not path:
+            path = "/"
+
+        # Could do syntax based normalization of the URI before
+        # computing the digest. See Section 6.2.2 of Std 66.
+        request_uri = query and "?".join([path, query]) or path
+        defrag_uri = scheme + "://" + authority + request_uri
+
+        return defrag_uri
+
+    @classmethod
+    def cache_url(cls, uri: str) -> str:
+        return cls._urlnorm(uri)
+
+    def parse_cache_control(self, headers: Mapping[str, str]) -> dict[str, int | None]:
+        known_directives = {
+            # https://tools.ietf.org/html/rfc7234#section-5.2
+            "max-age": (int, True),
+            "max-stale": (int, False),
+            "min-fresh": (int, True),
+            "no-cache": (None, False),
+            "no-store": (None, False),
+            "no-transform": (None, False),
+            "only-if-cached": (None, False),
+            "must-revalidate": (None, False),
+            "public": (None, False),
+            "private": (None, False),
+            "proxy-revalidate": (None, False),
+            "s-maxage": (int, True),
+        }
+
+        cc_headers = headers.get("cache-control", headers.get("Cache-Control", ""))
+
+        retval: dict[str, int | None] = {}
+
+        for cc_directive in cc_headers.split(","):
+            if not cc_directive.strip():
+                continue
+
+            parts = cc_directive.split("=", 1)
+            directive = parts[0].strip()
+
+            try:
+                typ, required = known_directives[directive]
+            except KeyError:
+                logger.debug("Ignoring unknown cache-control directive: %s", directive)
+                continue
+
+            if not typ or not required:
+                retval[directive] = None
+            if typ:
+                try:
+                    retval[directive] = typ(parts[1].strip())
+                except IndexError:
+                    if required:
+                        logger.debug(
+                            "Missing value for cache-control " "directive: %s",
+                            directive,
+                        )
+                except ValueError:
+                    logger.debug(
+                        "Invalid value for cache-control directive " "%s, must be %s",
+                        directive,
+                        typ.__name__,
+                    )
+
+        return retval
+
+    def _load_from_cache(self, request: PreparedRequest) -> HTTPResponse | None:
+        """
+        Load a cached response, or return None if it's not available.
+        """
+        # We do not support caching of partial content: so if the request contains a
+        # Range header then we don't want to load anything from the cache.
+        if "Range" in request.headers:
+            return None
+
+        cache_url = request.url
+        assert cache_url is not None
+        cache_data = self.cache.get(cache_url)
+        if cache_data is None:
+            logger.debug("No cache entry available")
+            return None
+
+        if isinstance(self.cache, SeparateBodyBaseCache):
+            body_file = self.cache.get_body(cache_url)
+        else:
+            body_file = None
+
+        result = self.serializer.loads(request, cache_data, body_file)
+        if result is None:
+            logger.warning("Cache entry deserialization failed, entry ignored")
+        return result
+
+    def cached_request(self, request: PreparedRequest) -> HTTPResponse | Literal[False]:
+        """
+        Return a cached response if it exists in the cache, otherwise
+        return False.
+        """
+        assert request.url is not None
+        cache_url = self.cache_url(request.url)
+        logger.debug('Looking up "%s" in the cache', cache_url)
+        cc = self.parse_cache_control(request.headers)
+
+        # Bail out if the request insists on fresh data
+        if "no-cache" in cc:
+            logger.debug('Request header has "no-cache", cache bypassed')
+            return False
+
+        if "max-age" in cc and cc["max-age"] == 0:
+            logger.debug('Request header has "max_age" as 0, cache bypassed')
+            return False
+
+        # Check whether we can load the response from the cache:
+        resp = self._load_from_cache(request)
+        if not resp:
+            return False
+
+        # If we have a cached permanent redirect, return it immediately. We
+        # don't need to test our response for other headers b/c it is
+        # intrinsically "cacheable" as it is Permanent.
+        #
+        # See:
+        #   https://tools.ietf.org/html/rfc7231#section-6.4.2
+        #
+        # Client can try to refresh the value by repeating the request
+        # with cache busting headers as usual (ie no-cache).
+        if int(resp.status) in PERMANENT_REDIRECT_STATUSES:
+            msg = (
+                "Returning cached permanent redirect response "
+                "(ignoring date and etag information)"
+            )
+            logger.debug(msg)
+            return resp
+
+        headers: CaseInsensitiveDict[str] = CaseInsensitiveDict(resp.headers)
+        if not headers or "date" not in headers:
+            if "etag" not in headers:
+                # Without date or etag, the cached response can never be used
+                # and should be deleted.
+                logger.debug("Purging cached response: no date or etag")
+                self.cache.delete(cache_url)
+            logger.debug("Ignoring cached response: no date")
+            return False
+
+        now = time.time()
+        time_tuple = parsedate_tz(headers["date"])
+        assert time_tuple is not None
+        date = calendar.timegm(time_tuple[:6])
+        current_age = max(0, now - date)
+        logger.debug("Current age based on date: %i", current_age)
+
+        # TODO: There is an assumption that the result will be a
+        #       urllib3 response object. This may not be best since we
+        #       could probably avoid instantiating or constructing the
+        #       response until we know we need it.
+        resp_cc = self.parse_cache_control(headers)
+
+        # determine freshness
+        freshness_lifetime = 0
+
+        # Check the max-age pragma in the cache control header
+        max_age = resp_cc.get("max-age")
+        if max_age is not None:
+            freshness_lifetime = max_age
+            logger.debug("Freshness lifetime from max-age: %i", freshness_lifetime)
+
+        # If there isn't a max-age, check for an expires header
+        elif "expires" in headers:
+            expires = parsedate_tz(headers["expires"])
+            if expires is not None:
+                expire_time = calendar.timegm(expires[:6]) - date
+                freshness_lifetime = max(0, expire_time)
+                logger.debug("Freshness lifetime from expires: %i", freshness_lifetime)
+
+        # Determine if we are setting freshness limit in the
+        # request. Note, this overrides what was in the response.
+        max_age = cc.get("max-age")
+        if max_age is not None:
+            freshness_lifetime = max_age
+            logger.debug(
+                "Freshness lifetime from request max-age: %i", freshness_lifetime
+            )
+
+        min_fresh = cc.get("min-fresh")
+        if min_fresh is not None:
+            # adjust our current age by our min fresh
+            current_age += min_fresh
+            logger.debug("Adjusted current age from min-fresh: %i", current_age)
+
+        # Return entry if it is fresh enough
+        if freshness_lifetime > current_age:
+            logger.debug('The response is "fresh", returning cached response')
+            logger.debug("%i > %i", freshness_lifetime, current_age)
+            return resp
+
+        # we're not fresh. If we don't have an Etag, clear it out
+        if "etag" not in headers:
+            logger.debug('The cached response is "stale" with no etag, purging')
+            self.cache.delete(cache_url)
+
+        # return the original handler
+        return False
+
+    def conditional_headers(self, request: PreparedRequest) -> dict[str, str]:
+        resp = self._load_from_cache(request)
+        new_headers = {}
+
+        if resp:
+            headers: CaseInsensitiveDict[str] = CaseInsensitiveDict(resp.headers)
+
+            if "etag" in headers:
+                new_headers["If-None-Match"] = headers["ETag"]
+
+            if "last-modified" in headers:
+                new_headers["If-Modified-Since"] = headers["Last-Modified"]
+
+        return new_headers
+
+    def _cache_set(
+        self,
+        cache_url: str,
+        request: PreparedRequest,
+        response: HTTPResponse,
+        body: bytes | None = None,
+        expires_time: int | None = None,
+    ) -> None:
+        """
+        Store the data in the cache.
+        """
+        if isinstance(self.cache, SeparateBodyBaseCache):
+            # We pass in the body separately; just put a placeholder empty
+            # string in the metadata.
+            self.cache.set(
+                cache_url,
+                self.serializer.dumps(request, response, b""),
+                expires=expires_time,
+            )
+            # body is None can happen when, for example, we're only updating
+            # headers, as is the case in update_cached_response().
+            if body is not None:
+                self.cache.set_body(cache_url, body)
+        else:
+            self.cache.set(
+                cache_url,
+                self.serializer.dumps(request, response, body),
+                expires=expires_time,
+            )
+
+    def cache_response(
+        self,
+        request: PreparedRequest,
+        response_or_ref: HTTPResponse | weakref.ReferenceType[HTTPResponse],
+        body: bytes | None = None,
+        status_codes: Collection[int] | None = None,
+    ) -> None:
+        """
+        Algorithm for caching requests.
+
+        This assumes a requests Response object.
+        """
+        if isinstance(response_or_ref, weakref.ReferenceType):
+            response = response_or_ref()
+            if response is None:
+                # The weakref can be None only in case the user used streamed request
+                # and did not consume or close it, and holds no reference to requests.Response.
+                # In such case, we don't want to cache the response.
+                return
+        else:
+            response = response_or_ref
+
+        # From httplib2: Don't cache 206's since we aren't going to
+        #                handle byte range requests
+        cacheable_status_codes = status_codes or self.cacheable_status_codes
+        if response.status not in cacheable_status_codes:
+            logger.debug(
+                "Status code %s not in %s", response.status, cacheable_status_codes
+            )
+            return
+
+        response_headers: CaseInsensitiveDict[str] = CaseInsensitiveDict(
+            response.headers
+        )
+
+        if "date" in response_headers:
+            time_tuple = parsedate_tz(response_headers["date"])
+            assert time_tuple is not None
+            date = calendar.timegm(time_tuple[:6])
+        else:
+            date = 0
+
+        # If we've been given a body, our response has a Content-Length, that
+        # Content-Length is valid then we can check to see if the body we've
+        # been given matches the expected size, and if it doesn't we'll just
+        # skip trying to cache it.
+        if (
+            body is not None
+            and "content-length" in response_headers
+            and response_headers["content-length"].isdigit()
+            and int(response_headers["content-length"]) != len(body)
+        ):
+            return
+
+        cc_req = self.parse_cache_control(request.headers)
+        cc = self.parse_cache_control(response_headers)
+
+        assert request.url is not None
+        cache_url = self.cache_url(request.url)
+        logger.debug('Updating cache with response from "%s"', cache_url)
+
+        # Delete it from the cache if we happen to have it stored there
+        no_store = False
+        if "no-store" in cc:
+            no_store = True
+            logger.debug('Response header has "no-store"')
+        if "no-store" in cc_req:
+            no_store = True
+            logger.debug('Request header has "no-store"')
+        if no_store and self.cache.get(cache_url):
+            logger.debug('Purging existing cache entry to honor "no-store"')
+            self.cache.delete(cache_url)
+        if no_store:
+            return
+
+        # https://tools.ietf.org/html/rfc7234#section-4.1:
+        # A Vary header field-value of "*" always fails to match.
+        # Storing such a response leads to a deserialization warning
+        # during cache lookup and is not allowed to ever be served,
+        # so storing it can be avoided.
+        if "*" in response_headers.get("vary", ""):
+            logger.debug('Response header has "Vary: *"')
+            return
+
+        # If we've been given an etag, then keep the response
+        if self.cache_etags and "etag" in response_headers:
+            expires_time = 0
+            if response_headers.get("expires"):
+                expires = parsedate_tz(response_headers["expires"])
+                if expires is not None:
+                    expires_time = calendar.timegm(expires[:6]) - date
+
+            expires_time = max(expires_time, 14 * 86400)
+
+            logger.debug(f"etag object cached for {expires_time} seconds")
+            logger.debug("Caching due to etag")
+            self._cache_set(cache_url, request, response, body, expires_time)
+
+        # Add to the cache any permanent redirects. We do this before looking
+        # that the Date headers.
+        elif int(response.status) in PERMANENT_REDIRECT_STATUSES:
+            logger.debug("Caching permanent redirect")
+            self._cache_set(cache_url, request, response, b"")
+
+        # Add to the cache if the response headers demand it. If there
+        # is no date header then we can't do anything about expiring
+        # the cache.
+        elif "date" in response_headers:
+            time_tuple = parsedate_tz(response_headers["date"])
+            assert time_tuple is not None
+            date = calendar.timegm(time_tuple[:6])
+            # cache when there is a max-age > 0
+            max_age = cc.get("max-age")
+            if max_age is not None and max_age > 0:
+                logger.debug("Caching b/c date exists and max-age > 0")
+                expires_time = max_age
+                self._cache_set(
+                    cache_url,
+                    request,
+                    response,
+                    body,
+                    expires_time,
+                )
+
+            # If the request can expire, it means we should cache it
+            # in the meantime.
+            elif "expires" in response_headers:
+                if response_headers["expires"]:
+                    expires = parsedate_tz(response_headers["expires"])
+                    if expires is not None:
+                        expires_time = calendar.timegm(expires[:6]) - date
+                    else:
+                        expires_time = None
+
+                    logger.debug(
+                        "Caching b/c of expires header. expires in {} seconds".format(
+                            expires_time
+                        )
+                    )
+                    self._cache_set(
+                        cache_url,
+                        request,
+                        response,
+                        body,
+                        expires_time,
+                    )
+
+    def update_cached_response(
+        self, request: PreparedRequest, response: HTTPResponse
+    ) -> HTTPResponse:
+        """On a 304 we will get a new set of headers that we want to
+        update our cached value with, assuming we have one.
+
+        This should only ever be called when we've sent an ETag and
+        gotten a 304 as the response.
+        """
+        assert request.url is not None
+        cache_url = self.cache_url(request.url)
+        cached_response = self._load_from_cache(request)
+
+        if not cached_response:
+            # we didn't have a cached response
+            return response
+
+        # Lets update our headers with the headers from the new request:
+        # http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-26#section-4.1
+        #
+        # The server isn't supposed to send headers that would make
+        # the cached body invalid. But... just in case, we'll be sure
+        # to strip out ones we know that might be problematic due to
+        # typical assumptions.
+        excluded_headers = ["content-length"]
+
+        cached_response.headers.update(
+            {
+                k: v
+                for k, v in response.headers.items()
+                if k.lower() not in excluded_headers
+            }
+        )
+
+        # we want a 200 b/c we have content via the cache
+        cached_response.status = 200
+
+        # update our cache
+        self._cache_set(cache_url, request, cached_response)
+
+        return cached_response