From c80afa08c7aec23984e84bfb3ab5683c9c392115 Mon Sep 17 00:00:00 2001
From: Dan McGee <dan@archlinux.org>
Date: Wed, 17 Aug 2011 09:01:07 -0500
Subject: releng: refactor results overview page for performance

Use some annotation stuff and trickeration to reduce the number of
queries we need on the results overview page by quite a bit.

Signed-off-by: Dan McGee <dan@archlinux.org>
---
 releng/models.py | 26 --------------------------
 releng/views.py  | 49 +++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/releng/models.py b/releng/models.py
index 3afef55e..a958288b 100644
--- a/releng/models.py
+++ b/releng/models.py
@@ -10,36 +10,10 @@ class IsoOption(models.Model):
     def __unicode__(self):
         return self.name
 
-    def get_test_result(self, success):
-        try:
-            return self.test_set.filter(success=success).select_related(
-                    'iso').latest('iso__id').iso
-        except Test.DoesNotExist:
-            return None
-
-    def get_last_success(self):
-        return self.get_test_result(True)
-
-    def get_last_failure(self):
-        return self.get_test_result(False)
-
     class Meta:
         abstract = True
 
 class RollbackOption(IsoOption):
-    def get_rollback_test_result(self, success):
-        try:
-            return self.rollback_test_set.filter(success=success).select_related(
-                    'iso').latest('iso__id').iso
-        except Test.DoesNotExist:
-            return None
-
-    def get_last_rollback_success(self):
-        return self.get_rollback_test_result(True)
-
-    def get_last_rollback_failure(self):
-        return self.get_rollback_test_result(False)
-
     class Meta:
         abstract = True
 
diff --git a/releng/views.py b/releng/views.py
index 796fc044..7f895a45 100644
--- a/releng/views.py
+++ b/releng/views.py
@@ -1,6 +1,6 @@
 from django import forms
 from django.conf import settings
-from django.db.models import Count
+from django.db.models import Count, Max
 from django.http import Http404
 from django.shortcuts import get_object_or_404, redirect
 from django.views.generic.simple import direct_to_template
@@ -85,18 +85,49 @@ def calculate_option_overview(field_name):
         'is_rollback': is_rollback,
         'values': []
     }
+    if not is_rollback:
+        successes = dict(model.objects.values_list('pk').filter(
+            test__success=True).annotate(latest=Max('test__iso__id')))
+        failures = dict(model.objects.values_list('pk').filter(
+            test__success=False).annotate(latest=Max('test__iso__id')))
+    else:
+        successes = dict(model.objects.values_list('pk').filter(
+            rollback_test_set__success=True).annotate(
+                latest=Max('rollback_test_set__iso__id')))
+        failures = dict(model.objects.values_list('pk').filter(
+            rollback_test_set__success=False).annotate(
+                latest=Max('rollback_test_set__iso__id')))
+
     for value in model.objects.all():
-        data = { 'value': value }
-        if is_rollback:
-            data['success'] = value.get_last_rollback_success()
-            data['failure'] = value.get_last_rollback_failure()
-        else:
-            data['success'] = value.get_last_success()
-            data['failure'] = value.get_last_failure()
+        data = {
+            'value': value,
+            'success': successes.get(value.pk),
+            'failure': failures.get(value.pk),
+        }
         option['values'].append(data)
 
     return option
 
+def options_fetch_iso(options):
+    '''Replaces the Iso PK with a full Iso model object in a list of options
+    used on the overview page. We do it this way to only have to query the Iso
+    table once rather than once per option.'''
+    # collect all necessary Iso PKs
+    all_pks = set()
+    for option in options:
+        all_pks.update(v['success'] for v in option['values'])
+        all_pks.update(v['failure'] for v in option['values'])
+
+    all_pks.discard(None)
+    all_isos = Iso.objects.in_bulk(all_pks)
+
+    for option in options:
+        for value in option['values']:
+            value['success'] = all_isos.get(value['success'])
+            value['failure'] = all_isos.get(value['failure'])
+
+    return options
+
 def test_results_overview(request):
     # data structure produced:
     # [ { option, name, is_rollback, values: [ { value, success, failure } ... ] } ... ]
@@ -107,6 +138,8 @@ def test_results_overview(request):
     for field in fields:
         all_options.append(calculate_option_overview(field))
 
+    all_options = options_fetch_iso(all_options)
+
     context = {
             'options': all_options,
             'iso_url': settings.ISO_LIST_URL,
-- 
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