Changeset 110

Timestamp:

11/09/09 18:17:33 (10 months ago)

Author:

max

Message:

Modified behavior of automated full page cache invalidation to allow for more graceful handling of potential dogpiling effects.

Files:

• trunk/courant/core/caching/models.py (modified) (2 diffs)

trunk/courant/core/caching/models.py

@@ -6 +6 @@
 from django_extensions.db.fields import ModificationDateTimeField
 from django.conf import settings
+
+# number of seconds to wait before fullpage cache is deleted when expiring a template fragment on that page
+FULLPAGE_CACHE_REFRESH = 10
 
 class CachedObject(models.Model):
@@ -27 +30 @@
                         urls.append(obj_cache.url)
 
-                # delete caches for all marked URLs
-                # since full-page caches don't use anti-dogpiling, we delete the caches themselves
+                # for full page caches, reset them with a short expiration time.
+                # this should hopefully allow for a non-anonymous user to load
+                # the page and create template fragment caches, so that when the
+                # first anonymous user hits the page, it doesn't have to do much
+                # processing to create a new full-page cache (since the fragments are
+                # all cached), and thus avoid potential dogpiling
                 for url in set(urls):
                         key = "%s-%s" % (settings.CACHE_KEY_PREFIX, url)
-                        print "Deleting cache: %s" % key
-                        cache.delete(key)
+                        fullpage_cache = cache.get(key)
+                        if fullpage_cache:
+                                cache.set(key, fullpage_cache, FULLPAGE_CACHE_REFRESH)
         except:
                 pass