Make maintainer lookup on todo lists fast

This is rather sick to look at. Sorry, Django gives me no other choice.

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

3 files changed, 17 insertions, 5 deletions

diff --git a/main/models.py b/main/models.py
index db456c2..caf36be 100644
--- a/main/models.py
+++ b/main/models.py
@@ -460,12 +460,17 @@ class Todolist(models.Model):
     def __unicode__(self):
         return self.name
 
+    _packages = None
+
     @property
     def packages(self):
-        # select_related() does not use LEFT OUTER JOIN for nullable ForeignKey
-        # fields. That is why we need to explicitly list the ones we want.
-        return TodolistPkg.objects.select_related(
-            'pkg__repo', 'pkg__arch').filter(list=self).order_by('pkg')
+        if not self._packages:
+            # select_related() does not use LEFT OUTER JOIN for nullable
+            # ForeignKey fields. That is why we need to explicitly list the
+            # ones we want.
+            self._packages = TodolistPkg.objects.select_related(
+                'pkg__repo', 'pkg__arch').filter(list=self).order_by('pkg')
+        return self._packages
 
     @property
     def package_names(self):
diff --git a/packages/utils.py b/packages/utils.py
index 0d756a8..4af0f67 100644
--- a/packages/utils.py
+++ b/packages/utils.py
@@ -156,6 +156,7 @@ def attach_maintainers(packages):
     '''Given a queryset or something resembling it of package objects, find all
     the maintainers and attach them to the packages to prevent N+1 query
     cascading.'''
+    packages = list(packages)
     pkgbases = set(p.pkgbase for p in packages)
     rels = PackageRelation.objects.filter(type=PackageRelation.MAINTAINER,
             pkgbase__in=pkgbases).values_list('pkgbase', 'user_id').distinct()
diff --git a/todolists/views.py b/todolists/views.py
index 8ad7be5..585cefd 100644
--- a/todolists/views.py
+++ b/todolists/views.py
@@ -12,6 +12,7 @@ from django.template import Context, loader
 from django.utils import simplejson
 
 from main.models import Todolist, TodolistPkg, Package
+from packages.utils import attach_maintainers
 from .utils import get_annotated_todolists
 
 class TodoListForm(forms.ModelForm):
@@ -49,6 +50,9 @@ def flag(request, listid, pkgid):
 @never_cache
 def view(request, listid):
     todolist = get_object_or_404(Todolist, id=listid)
+    # we don't hold onto the result, but the objects are the same here,
+    # so accessing maintainers in the template is now cheap
+    attach_maintainers(tp.pkg for tp in todolist.packages)
     return direct_to_template(request, 'todolists/view.html', {'list': todolist})
 
 @login_required
@@ -163,8 +167,10 @@ def send_todolist_emails(todo_list, new_packages):
 
 def public_list(request):
     todo_lists = Todolist.objects.incomplete()
+    # total hackjob, but it makes this a lot less query-intensive.
+    all_pkgs = [tp for tl in todo_lists for tp in tl.packages]
+    attach_maintainers([tp.pkg for tp in all_pkgs])
     return direct_to_template(request, "todolists/public_list.html",
             {"todo_lists": todo_lists})
 
-
 # vim: set ts=4 sw=4 et: