Cache bounce

Author: milesmcc

shynet/analytics/migrations/0008_session_is_bounce.py

@@ -0,0 +1,24 @@
+# Generated by Django 3.1.7 on 2021-03-28 21:38
+
+from django.db.models.expressions import F
+from ..models import Session, Hit
+from django.db import migrations, models
+from django.db.models import Subquery, OuterRef
+
+def update_bounce_stats(_a, _b):
+    Session.objects.all().annotate(hit_count=models.Count("hit")).filter(hit_count__gt=1).update(is_bounce=False)
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('analytics', '0007_auto_20210328_1634'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='session',
+            name='is_bounce',
+            field=models.BooleanField(db_index=True, default=True),
+        ),
+        migrations.RunPython(update_bounce_stats, lambda: ()),
+    ]

shynet/analytics/models.py

@@ -49,6 +49,8 @@ class Session(models.Model):
     latitude = models.FloatField(null=True)
     time_zone = models.TextField(blank=True)
 
+    is_bounce = models.BooleanField(default=True, db_index=True)
+
     class Meta:
         ordering = ["-start_time"]
         indexes = [
@@ -76,6 +78,12 @@ def get_absolute_url(self):
             kwargs={"pk": self.service.pk, "session_pk": self.uuid},
         )
 
+    def recalculate_bounce(self):
+        bounce = self.hit_set.count() == 1
+        if bounce != self.is_bounce:
+            self.is_bounce = bounce
+            self.save()
+
 
 class Hit(models.Model):
     session = models.ForeignKey(Session, on_delete=models.CASCADE, db_index=True)

shynet/analytics/tasks.py

@@ -186,6 +186,10 @@ def ingress_request(
                 last_seen=time,
                 service=service
             )
+
+            # Recalculate whether the session is a bounce
+            session.recalculate_bounce()
+
             # Set idempotency (if applicable)
             if idempotency is not None:
                 cache.set(

shynet/core/models.py

@@ -133,7 +133,7 @@ def get_relative_stats(self, start_time, end_time):
         )
         hit_count = hits.count()
 
-        bounces = sessions.annotate(hit_count=models.Count("hit")).filter(hit_count=1)
+        bounces = sessions.filter(is_bounce=True)
         bounce_count = bounces.count()
 
         locations = (