98 lines
4.5 KiB
Python
98 lines
4.5 KiB
Python
from django.conf import settings
|
|
from django.core.cache import cache
|
|
from django.utils.cache import get_cache_key, learn_cache_key, patch_response_headers, get_max_age
|
|
|
|
class CacheMiddleware(object):
|
|
"""
|
|
Cache middleware. If this is enabled, each Django-powered page will be
|
|
cached (based on URLs).
|
|
|
|
Only parameter-less GET or HEAD-requests with status code 200 are cached.
|
|
|
|
The number of seconds each page is stored for is set by the
|
|
"max-age" section of the response's "Cache-Control" header, falling back to
|
|
the CACHE_MIDDLEWARE_SECONDS setting if the section was not found.
|
|
|
|
If CACHE_MIDDLEWARE_ANONYMOUS_ONLY is set to True, only anonymous requests
|
|
(i.e., those not made by a logged-in user) will be cached. This is a
|
|
simple and effective way of avoiding the caching of the Django admin (and
|
|
any other user-specific content).
|
|
|
|
This middleware expects that a HEAD request is answered with a response
|
|
exactly like the corresponding GET request.
|
|
|
|
When a hit occurs, a shallow copy of the original response object is
|
|
returned from process_request.
|
|
|
|
Pages will be cached based on the contents of the request headers
|
|
listed in the response's "Vary" header. This means that pages shouldn't
|
|
change their "Vary" header.
|
|
|
|
This middleware also sets ETag, Last-Modified, Expires and Cache-Control
|
|
headers on the response object.
|
|
"""
|
|
def __init__(self, cache_timeout=None, key_prefix=None, cache_anonymous_only=None):
|
|
self.cache_timeout = cache_timeout
|
|
if cache_timeout is None:
|
|
self.cache_timeout = settings.CACHE_MIDDLEWARE_SECONDS
|
|
self.key_prefix = key_prefix
|
|
if key_prefix is None:
|
|
self.key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
|
|
if cache_anonymous_only is None:
|
|
self.cache_anonymous_only = getattr(settings, 'CACHE_MIDDLEWARE_ANONYMOUS_ONLY', False)
|
|
else:
|
|
self.cache_anonymous_only = cache_anonymous_only
|
|
|
|
def process_request(self, request):
|
|
"Checks whether the page is already cached and returns the cached version if available."
|
|
if self.cache_anonymous_only:
|
|
assert hasattr(request, 'user'), "The Django cache middleware with CACHE_MIDDLEWARE_ANONYMOUS_ONLY=True requires authentication middleware to be installed. Edit your MIDDLEWARE_CLASSES setting to insert 'django.contrib.auth.middleware.AuthenticationMiddleware' before the CacheMiddleware."
|
|
|
|
if not request.method in ('GET', 'HEAD') or request.GET:
|
|
request._cache_update_cache = False
|
|
return None # Don't bother checking the cache.
|
|
|
|
if self.cache_anonymous_only and request.user.is_authenticated():
|
|
request._cache_update_cache = False
|
|
return None # Don't cache requests from authenticated users.
|
|
|
|
cache_key = get_cache_key(request, self.key_prefix)
|
|
if cache_key is None:
|
|
request._cache_update_cache = True
|
|
return None # No cache information available, need to rebuild.
|
|
|
|
response = cache.get(cache_key, None)
|
|
if response is None:
|
|
request._cache_update_cache = True
|
|
return None # No cache information available, need to rebuild.
|
|
|
|
request._cache_update_cache = False
|
|
return response
|
|
|
|
def process_response(self, request, response):
|
|
"Sets the cache, if needed."
|
|
if not hasattr(request, '_cache_update_cache') or not request._cache_update_cache:
|
|
# We don't need to update the cache, just return.
|
|
return response
|
|
if request.method != 'GET':
|
|
# This is a stronger requirement than above. It is needed
|
|
# because of interactions between this middleware and the
|
|
# HTTPMiddleware, which throws the body of a HEAD-request
|
|
# away before this middleware gets a chance to cache it.
|
|
return response
|
|
if not response.status_code == 200:
|
|
return response
|
|
# Try to get the timeout from the "max-age" section of the "Cache-
|
|
# Control" header before reverting to using the default cache_timeout
|
|
# length.
|
|
timeout = get_max_age(response)
|
|
if timeout == None:
|
|
timeout = self.cache_timeout
|
|
elif timeout == 0:
|
|
# max-age was set to 0, don't bother caching.
|
|
return response
|
|
patch_response_headers(response, timeout)
|
|
cache_key = learn_cache_key(request, response, timeout, self.key_prefix)
|
|
cache.set(cache_key, response, timeout)
|
|
return response
|