from lib.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