def check_cache(self, request):
"""
Checks whether the page is already cached and returns the cached
version if available.
"""
if not request.method in ('GET', 'HEAD'):
request._cache_update_cache = False
return None # Don't bother checking the cache.
# if request said no-cache in header then don't return from cache
if request.headers.has_key('Cache-Control') and request.headers['Cache-Control'] == 'no-cache':
request._cache_update_cache = True
return None
# try and get the cached GET response
cache_key = get_cache_key(request, self.key_prefix, 'GET', cache=self.cache)
if cache_key is None:
request._cache_update_cache = True
return None # No cache information available, need to rebuild.
response = self.cache.get(cache_key, None)
# if it wasn't found and we are looking for a HEAD, try looking just for that
if response is None and request.method == 'HEAD':
cache_key = get_cache_key(request, self.key_prefix, 'HEAD', cache=self.cache)
response = self.cache.get(cache_key, None)
if response is None:
request._cache_update_cache = True
return None # No cache information available, need to rebuild.
# hit, return cached response
request._cache_update_cache = False
return response
def process_304_response(self, request, response):
cache_key = get_cache_key(request, LONG_TERM_CACHE_KEY_PREFIX+self.key_prefix, 'GET', cache=self.cache)
if cache_key is None:
return None
cached_response = self.cache.get(cache_key, None)
if cached_response is None:
return None
else:
response._content = cached_response.content
return response
def patch_if_none_match_header(self, request):
"""
Add 'If-None-Match' header to request if:
1. request does not have 'If-None-Match' already, and
2. Previous response has 'ETag' header.
"""
if 'If-None-Match' not in request.headers:
cache_key = get_cache_key(request, LONG_TERM_CACHE_KEY_PREFIX+self.key_prefix, 'GET', cache=self.cache)
if cache_key is not None:
response = self.cache.get(cache_key, None)
if response is not None:
if response.has_header('ETag'):
request.headers['If-None-Match'] = response['ETag']
def patch_if_modified_since_header(self, request):
"""
Add 'If-Modified-Since' header to request if:
1. request does not have 'If-Modified-Since' already, and
2. Previous response has 'Last-Modified' header.
"""
if 'If-Modified-Since' not in request.headers:
cache_key = get_cache_key(request, LONG_TERM_CACHE_KEY_PREFIX+self.key_prefix, 'GET', cache=self.cache)
if cache_key is not None:
response = self.cache.get(cache_key, None)
if response is not None:
if response.has_header('Last-Modified'):
request.headers['If-Modified-Since'] = response['Last-Modified']