Ticket #5815: add_cache_clear_feature.diff

django/utils/cache.py

@@ -158 +158 @@
     cache as the pages themselves. If the cache ages some data out of the
     cache, this just means that we have to build the response once to get at
     the Vary header and so at the list of headers to use for the cache key.
+    
+    Also, another key (hashes) is added to the cache, to keep track of every
+    page hash that matches the same request path.
     """
     if key_prefix is None:
         key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
     if cache_timeout is None:
         cache_timeout = settings.CACHE_MIDDLEWARE_SECONDS
-    cache_key = 'views.decorators.cache.cache_header.%s.%s' % (key_prefix, iri_to_uri(request.path))
+    header_key = 'views.decorators.cache.cache_header.%s.%s' % (key_prefix, iri_to_uri(request.path))
     if response.has_header('Vary'):
         headerlist = ['HTTP_'+header.upper().replace('-', '_') for header in vary_delim_re.split(response['Vary'])]
-        cache.set(cache_key, headerlist, cache_timeout)
-        return _generate_cache_key(request, headerlist, key_prefix)
     else:
-        # if there is no Vary header, we still need a cache key
-        # for the request.path
-        cache.set(cache_key, [], cache_timeout)
-        return _generate_cache_key(request, [], key_prefix)
+        headerlist = []
+
+    cache.set(header_key, headerlist, cache_timeout)
+    cache_key = _generate_cache_key(request, headerlist, key_prefix)
+
+    hashes_key = 'views.decorators.cache.cache_hashes.%s.%s' % (key_prefix, iri_to_uri(request.path))
+    hashes = cache.get(hashes_key, [])
+    page_hash = cache_key.split('.')[-1]
+    if not page_hash in hashes:
+        hashes.append(page_hash)
+        cache.set(hashes_key, hashes, cache_timeout)
+
+    return cache_key
+
+def clear_cache_for_path(path, key_prefix=None):
+    """
+    Given a request path, every cache entry related to it gets deleted,
+    specifically, the following keys get deleted:
+        views.decorators.cache.cache_hashes.`key_prefix`.`path`
+        views.decorators.cache.cache_header.`key_prefix`.`path`
+        views.decorators.cache.cache_page.`key_prefix`.`path`.*
+    """
+    if key_prefix is None:
+        key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
+    hashes_key = 'views.decorators.cache.cache_hashes.%s.%s' % (key_prefix, iri_to_uri(path))
+    hashes = cache.get(hashes_key, None)
+    if hashes:
+        for page_hash in hashes:
+            page_key = 'views.decorators.cache.cache_page.%s.%s.%s' \
+                           % (key_prefix, iri_to_uri(path), page_hash)
+            cache.delete(page_key)
+        header_key = 'views.decorators.cache.cache_header.%s.%s' % (key_prefix, iri_to_uri(path))
+        cache.delete(header_key)
+    cache.delete(hashes_key)
+

docs/cache.txt

@@ -574 +574 @@
 
 .. _`Cache-Control spec`: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9
 
+Cache refreshing
+================
+
+It is possible to clear the cache for an specific view, to achieve that, you 
+should tell your view's url path (and optionally, a key_prefix) to 
+``clear_cache_for_path(path, key_prefix=None)``.
+
+    from django.utils.cache import clear_cache_for_path
+    
+    # clear the all cached data for path '/blog/posts/2/'
+    clear_cache_for_path('/blog/posts/2/')
+    
+Note that it will delete every page cached from matching this path, ``Vary`` headers
+doesn't matter.
+
 Other optimizations
 ===================