80 lines
2.8 KiB
Python
80 lines
2.8 KiB
Python
from requests.adapters import HTTPAdapter
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from .controller import CacheController
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from .cache import DictCache
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class CacheControlAdapter(HTTPAdapter):
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invalidating_methods = set(['PUT', 'DELETE'])
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def __init__(self, cache=None, cache_etags=True, controller_class=None,
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serializer=None, *args, **kw):
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super(CacheControlAdapter, self).__init__(*args, **kw)
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self.cache = cache or DictCache()
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controller_factory = controller_class or CacheController
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self.controller = controller_factory(
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self.cache,
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cache_etags=cache_etags,
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serializer=serializer,
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)
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def send(self, request, **kw):
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"""
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Send a request. Use the request information to see if it
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exists in the cache and cache the response if we need to and can.
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"""
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if request.method == 'GET':
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cached_response = self.controller.cached_request(request)
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if cached_response:
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return self.build_response(request, cached_response, from_cache=True)
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# check for etags and add headers if appropriate
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request.headers.update(self.controller.conditional_headers(request))
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resp = super(CacheControlAdapter, self).send(request, **kw)
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return resp
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def build_response(self, request, response, from_cache=False):
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"""
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Build a response by making a request or using the cache.
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This will end up calling send and returning a potentially
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cached response
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"""
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if not from_cache and request.method == 'GET':
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if response.status == 304:
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# We must have sent an ETag request. This could mean
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# that we've been expired already or that we simply
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# have an etag. In either case, we want to try and
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# update the cache if that is the case.
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cached_response = self.controller.update_cached_response(
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request, response
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)
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if cached_response is not response:
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from_cache = True
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response = cached_response
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else:
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# try to cache the response
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try:
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self.controller.cache_response(request, response)
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except Exception as e:
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# Failed to cache the results
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pass
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resp = super(CacheControlAdapter, self).build_response(
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request, response
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)
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# See if we should invalidate the cache.
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if request.method in self.invalidating_methods and resp.ok:
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cache_url = self.controller.cache_url(request.url)
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self.cache.delete(cache_url)
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# Give the request a from_cache attr to let people use it
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resp.from_cache = from_cache
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return resp
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