author | Sverre Rabbelier <srabbelier@gmail.com> |
Mon, 09 Mar 2009 19:37:56 +0000 | |
changeset 1778 | 660502cad63a |
parent 109 | 620f9b141567 |
permissions | -rwxr-xr-x |
109
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from django.conf import settings |
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from django.core.cache import cache |
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from django.utils.cache import get_cache_key, learn_cache_key, patch_response_headers |
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class CacheMiddleware(object): |
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""" |
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Cache middleware. If this is enabled, each Django-powered page will be |
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cached for CACHE_MIDDLEWARE_SECONDS seconds. Cache is based on URLs. |
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|
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Only parameter-less GET or HEAD-requests with status code 200 are cached. |
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|
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If CACHE_MIDDLEWARE_ANONYMOUS_ONLY is set to True, only anonymous requests |
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(i.e., those node made by a logged-in user) will be cached. This is a |
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simple and effective way of avoiding the caching of the Django admin (and |
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any other user-specific content). |
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|
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This middleware expects that a HEAD request is answered with a response |
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exactly like the corresponding GET request. |
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|
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When a hit occurs, a shallow copy of the original response object is |
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returned from process_request. |
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Pages will be cached based on the contents of the request headers |
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listed in the response's "Vary" header. This means that pages shouldn't |
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change their "Vary" header. |
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This middleware also sets ETag, Last-Modified, Expires and Cache-Control |
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headers on the response object. |
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""" |
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def __init__(self, cache_timeout=None, key_prefix=None, cache_anonymous_only=None): |
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self.cache_timeout = cache_timeout |
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if cache_timeout is None: |
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self.cache_timeout = settings.CACHE_MIDDLEWARE_SECONDS |
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self.key_prefix = key_prefix |
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if key_prefix is None: |
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self.key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX |
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if cache_anonymous_only is None: |
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self.cache_anonymous_only = getattr(settings, 'CACHE_MIDDLEWARE_ANONYMOUS_ONLY', False) |
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else: |
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self.cache_anonymous_only = cache_anonymous_only |
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def process_request(self, request): |
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"Checks whether the page is already cached and returns the cached version if available." |
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if self.cache_anonymous_only: |
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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." |
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if not request.method in ('GET', 'HEAD') or request.GET: |
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request._cache_update_cache = False |
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return None # Don't bother checking the cache. |
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if self.cache_anonymous_only and request.user.is_authenticated(): |
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request._cache_update_cache = False |
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return None # Don't cache requests from authenticated users. |
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cache_key = get_cache_key(request, self.key_prefix) |
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if cache_key is None: |
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request._cache_update_cache = True |
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return None # No cache information available, need to rebuild. |
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response = cache.get(cache_key, None) |
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if response is None: |
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request._cache_update_cache = True |
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return None # No cache information available, need to rebuild. |
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request._cache_update_cache = False |
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return response |
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def process_response(self, request, response): |
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"Sets the cache, if needed." |
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if not hasattr(request, '_cache_update_cache') or not request._cache_update_cache: |
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# We don't need to update the cache, just return. |
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return response |
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if request.method != 'GET': |
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# This is a stronger requirement than above. It is needed |
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# because of interactions between this middleware and the |
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# HTTPMiddleware, which throws the body of a HEAD-request |
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# away before this middleware gets a chance to cache it. |
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return response |
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if not response.status_code == 200: |
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return response |
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patch_response_headers(response, self.cache_timeout) |
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cache_key = learn_cache_key(request, response, self.cache_timeout, self.key_prefix) |
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cache.set(cache_key, response, self.cache_timeout) |
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return response |