Add waiting list

src/pretix/base/services/waitinglist.py

@@ -0,0 +1,56 @@
+from django.dispatch import receiver
+
+from pretix.base.models import Event, WaitingListEntry
+from pretix.base.models.waitinglist import WaitingListException
+from pretix.base.services.async import ProfiledTask
+from pretix.base.signals import periodic_task
+from pretix.celery_app import app
+
+
+@app.task(base=ProfiledTask)
+def assign_automatically(event_id: int):
+    event = Event.objects.get(id=event_id)
+
+    quota_cache = {}
+    gone = set()
+
+    qs = WaitingListEntry.objects.filter(
+        event=event, voucher__isnull=True
+    ).select_related('item', 'variation').prefetch_related('item__quotas', 'variation__quotas').order_by('created')
+    sent = 0
+
+    for wle in qs:
+        if (wle.item, wle.variation) in gone:
+            continue
+
+        quotas = wle.variation.quotas.all() if wle.variation else wle.item.quotas.all()
+        availability = (
+            wle.variation.check_quotas(count_waitinglist=False, _cache=quota_cache)
+            if wle.variation
+            else wle.item.check_quotas(count_waitinglist=False, _cache=quota_cache)
+        )
+        if availability[1] > 0:
+            try:
+                wle.send_voucher(quota_cache)
+                sent += 1
+            except WaitingListException:  # noqa
+                continue
+
+            # Reduce affected quotas in cache
+            for q in quotas:
+                quota_cache[q.pk] = (
+                    quota_cache[q.pk][0] if quota_cache[q.pk][0] > 1 else 0,
+                    quota_cache[q.pk][1] - 1
+                )
+        else:
+            gone.add((wle.item, wle.variation))
+
+    return sent
+
+
+@receiver(signal=periodic_task)
+def process_waitinglist(sender, **kwargs):
+    qs = Event.objects.prefetch_related('setting_objects', 'organizer__setting_objects').select_related('organizer')
+    for e in qs:
+        if e.settings.waiting_list_enabled and e.settings.waiting_list_auto:
+            assign_automatically.apply_async(args=(e.pk,))