Fewer db requests on bda tirage.

bda.algorithm
- use iterator to find max_groups, instead of a db request

bda.views.do_tirage
- select_related() are now focused on some relationships (they were
  taking useless relationships)
- bda-revente filling takes 1 request (each save and add was issuing
  1 request)

bda/algorithm.py

@@ -22,8 +22,7 @@ class Algorithm(object):
               show.requests
             - on crée des tables de demandes pour chaque personne, afin de
               pouvoir modifier les rankings"""
-        self.max_group = \
-            2 * choices.aggregate(Max('priority'))['priority__max']
+        self.max_group = 2*max(choice.priority for choice in choices)
         self.shows = []
         showdict = {}
         for show in shows:

bda/views.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+from collections import defaultdict
 from functools import partial
 import random
 import hashlib
@@ -262,9 +263,9 @@ def do_tirage(tirage_elt, token):
     # Initialisation du dictionnaire data qui va contenir les résultats
     start = time.time()
     data = {
-        'shows': tirage_elt.spectacle_set.select_related().all(),
+        'shows': tirage_elt.spectacle_set.select_related('location'),
         'token': token,
-        'members': tirage_elt.participant_set.all(),
+        'members': tirage_elt.participant_set.select_related('user'),
         'total_slots': 0,
         'total_losers': 0,
         'total_sold': 0,
@@ -277,7 +278,7 @@ def do_tirage(tirage_elt, token):
         ChoixSpectacle.objects
         .filter(spectacle__tirage=tirage_elt)
         .order_by('participant', 'priority')
-        .select_related().all()
+        .select_related('participant', 'participant__user', 'spectacle')
     )
     results = Algorithm(data['shows'], data['members'], choices)(token)
 
@@ -334,10 +335,18 @@ def do_tirage(tirage_elt, token):
     ])
 
     # On inscrit à BdA-Revente ceux qui n'ont pas eu les places voulues
-    for (show, _, losers) in results:
-        for (loser, _, _, _) in losers:
-            loser.choicesrevente.add(show)
-            loser.save()
+    ChoixRevente = Participant.choicesrevente.through
+
+    lost_by = defaultdict(set)
+    for show, _, losers in results:
+        for loser, _, _, _ in losers:
+            lost_by[loser].add(show)
+
+    ChoixRevente.objects.bulk_create(
+        ChoixRevente(participant=member, spectacle=show)
+        for member, shows in lost_by.items()
+        for show in shows
+    )
 
     data["duration"] = time.time() - start
     data["results"] = results