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SickRage/lib/cachecontrol/adapter.py
2015-02-09 14:09:15 -05:00

80 lines
2.8 KiB
Python

from requests.adapters import HTTPAdapter
from .controller import CacheController
from .cache import DictCache
class CacheControlAdapter(HTTPAdapter):
invalidating_methods = set(['PUT', 'DELETE'])
def __init__(self, cache=None, cache_etags=True, controller_class=None,
serializer=None, *args, **kw):
super(CacheControlAdapter, self).__init__(*args, **kw)
self.cache = cache or DictCache()
controller_factory = controller_class or CacheController
self.controller = controller_factory(
self.cache,
cache_etags=cache_etags,
serializer=serializer,
)
def send(self, request, **kw):
"""
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.
"""
if request.method == 'GET':
cached_response = self.controller.cached_request(request)
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(CacheControlAdapter, self).send(request, **kw)
return resp
def build_response(self, request, response, from_cache=False):
"""
Build a response by making a request or using the cache.
This will end up calling send and returning a potentially
cached response
"""
if not from_cache and request.method == 'GET':
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
response = cached_response
else:
# try to cache the response
try:
self.controller.cache_response(request, response)
except Exception as e:
# Failed to cache the results
pass
resp = super(CacheControlAdapter, self).build_response(
request, response
)
# See if we should invalidate the cache.
if request.method in self.invalidating_methods and resp.ok:
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
return resp