Connect post_save signals where they will always be triggered

We need to do this in the models.py files, otherwise the post_save signal
might not be connected right away on launch of the application. Move them
over there, add a dispatch_uid so it only gets hooked up once, and do some
other function moving around so we don't have circular imports.

Signed-off-by: Dan McGee <dan@archlinux.org>

4 files changed, 37 insertions, 24 deletions

diff --git a/feeds.py b/feeds.py
index 9d1418b..e7462bc 100644
--- a/feeds.py
+++ b/feeds.py
@@ -4,19 +4,14 @@ from decimal import Decimal, ROUND_HALF_DOWN
 from django.contrib.syndication.views import Feed
 from django.core.cache import cache
 from django.db.models import Q
-from django.db.models.signals import post_save
 from django.utils.hashcompat import md5_constructor
 from django.views.decorators.http import condition
 
 from main.models import Arch, Repo, Package
+from main.utils import CACHE_TIMEOUT, INVALIDATE_TIMEOUT
+from main.utils import CACHE_PACKAGE_KEY, CACHE_NEWS_KEY
 from news.models import News
 
-CACHE_TIMEOUT = 1800
-INVALIDATE_TIMEOUT = 15
-
-CACHE_PACKAGE_KEY = 'cache_package_latest'
-CACHE_NEWS_KEY = 'cache_news_latest'
-
 def utc_offset():
     '''Calculate the UTC offset from local time. Useful for converting values
     stored in local time to things like cache last modifed headers.'''
@@ -47,14 +42,6 @@ def retrieve_package_latest():
         pass
     return None
 
-def refresh_package_latest(**kwargs):
-    # We could delete the value, but that could open a race condition
-    # where the new data wouldn't have been committed yet by the calling
-    # thread. Instead, explicitly set it to None for a short amount of time.
-    # Hopefully by the time it expires we will have committed, and the cache
-    # will be valid again. See "Scaling Django" by Mike Malone, slide 30.
-    cache.set(CACHE_PACKAGE_KEY, None, INVALIDATE_TIMEOUT)
-
 def package_etag(request, *args, **kwargs):
     latest = retrieve_package_latest()
     if latest:
@@ -134,10 +121,6 @@ def retrieve_news_latest():
         pass
     return None
 
-def refresh_news_latest(**kwargs):
-    # same thoughts apply as in refresh_package_latest
-    cache.set(CACHE_NEWS_KEY, None, INVALIDATE_TIMEOUT)
-
 def news_etag(request, *args, **kwargs):
     latest = retrieve_news_latest()
     if latest:
@@ -168,8 +151,4 @@ class NewsFeed(Feed):
     def item_author_name(self, item):
         return item.author.get_full_name()
 
-# connect signals needed to keep cache in line with reality
-post_save.connect(refresh_package_latest, sender=Package)
-post_save.connect(refresh_news_latest, sender=News)
-
 # vim: set ts=4 sw=4 et:
diff --git a/main/models.py b/main/models.py
index dc700fb..888f0b8 100644
--- a/main/models.py
+++ b/main/models.py
@@ -325,4 +325,10 @@ class TodolistPkg(models.Model):
         db_table = 'todolist_pkgs'
         unique_together = (('list','pkg'),)
 
+# connect signals needed to keep cache in line with reality
+from main.utils import refresh_package_latest
+from django.db.models.signals import post_save
+post_save.connect(refresh_package_latest, sender=Package,
+        dispatch_uid="main.models")
+
 # vim: set ts=4 sw=4 et:
diff --git a/main/utils.py b/main/utils.py
index ae446ab..d7681cb 100644
--- a/main/utils.py
+++ b/main/utils.py
@@ -5,6 +5,12 @@ except ImportError:
 from django.core.cache import cache
 from django.utils.hashcompat import md5_constructor
 
+CACHE_TIMEOUT = 1800
+INVALIDATE_TIMEOUT = 15
+
+CACHE_PACKAGE_KEY = 'cache_package_latest'
+CACHE_NEWS_KEY = 'cache_news_latest'
+
 def cache_function_key(func, args, kwargs):
     raw = [func.__name__, func.__module__, args, kwargs]
     pickled = pickle.dumps(raw, protocol=pickle.HIGHEST_PROTOCOL)
@@ -40,7 +46,23 @@ def clear_cache_function(func, args, kwargs):
     key = cache_function_key(func, args, kwargs)
     cache.delete(key)
 
-#utility to make a pair of django choices
+# utility to make a pair of django choices
 make_choice = lambda l: [(str(m), str(m)) for m in l]
 
+# These are in here because we would be jumping around in some import circles
+# and hoops otherwise. The only thing currently using these keys is the feed
+# caching stuff.
+
+def refresh_package_latest(**kwargs):
+    # We could delete the value, but that could open a race condition
+    # where the new data wouldn't have been committed yet by the calling
+    # thread. Instead, explicitly set it to None for a short amount of time.
+    # Hopefully by the time it expires we will have committed, and the cache
+    # will be valid again. See "Scaling Django" by Mike Malone, slide 30.
+    cache.set(CACHE_PACKAGE_KEY, None, INVALIDATE_TIMEOUT)
+
+def refresh_news_latest(**kwargs):
+    # same thoughts apply as in refresh_package_latest
+    cache.set(CACHE_NEWS_KEY, None, INVALIDATE_TIMEOUT)
+
 # vim: set ts=4 sw=4 et:
diff --git a/news/models.py b/news/models.py
index 6c8a703..e2486c9 100644
--- a/news/models.py
+++ b/news/models.py
@@ -23,4 +23,10 @@ class News(models.Model):
         get_latest_by = 'postdate'
         ordering = ['-postdate']
 
+# connect signals needed to keep cache in line with reality
+from main.utils import refresh_news_latest
+from django.db.models.signals import post_save
+post_save.connect(refresh_news_latest, sender=News,
+        dispatch_uid="news.models")
+
 # vim: set ts=4 sw=4 et: