Fix tracking race condition

apiserver/apiserver/api/views.py

@@ -5,6 +5,7 @@ from django.contrib.auth.models import User, Group
 from django.shortcuts import get_object_or_404, redirect
 from django.db import transaction
 from django.db.models import Max
+from django.db.utils import OperationalError
 from django.http import HttpResponse, Http404, FileResponse
 from django.core.files.base import File
 from django.core.cache import cache
@@ -502,45 +503,50 @@ class StatsViewSet(viewsets.ViewSet, List):
         except KeyError:
             raise exceptions.ValidationError(dict(data='This field is required.'))
 
-    @transaction.atomic
     @action(detail=False, methods=['post'])
     def track(self, request):
-        if 'name' not in request.data:
-            raise exceptions.ValidationError(dict(name='This field is required.'))
+        try:
+            with transaction.atomic():
+                if 'name' not in request.data:
+                    raise exceptions.ValidationError(dict(name='This field is required.'))
 
-        if 'username' not in request.data:
-            raise exceptions.ValidationError(dict(username='This field is required.'))
+                if 'username' not in request.data:
+                    raise exceptions.ValidationError(dict(username='This field is required.'))
 
-        track = cache.get('track', {})
+                track = cache.get('track', {})
 
-        devicename = request.data['name']
-        username = request.data['username']
-        first_name = username.split('.')[0].title()
+                devicename = request.data['name']
+                username = request.data['username']
+                first_name = username.split('.')[0].title()
 
-        track[devicename] = dict(time=time.time(), username=first_name)
-        cache.set('track', track)
+                track[devicename] = dict(time=time.time(), username=first_name)
+                cache.set('track', track)
 
-        # update device usage
-        last_session = models.UsageTrack.objects.filter(devicename=devicename).last()
-        if not last_session or last_session.username != username:
-            try:
-                user = User.objects.get(username__iexact=username)
-            except User.DoesNotExist:
-                logging.error('Username not found: ' + username)
-                user = None
+                # update device usage
+                last_session = models.UsageTrack.objects.filter(devicename=devicename).last()
+                if not last_session or last_session.username != username:
+                    try:
+                        user = User.objects.get(username__iexact=username)
+                    except User.DoesNotExist:
+                        logging.error('Username not found: ' + username)
+                        user = None
 
-            models.UsageTrack.objects.create(
-                user=user,
-                username=username,
-                devicename=devicename,
-                num_seconds=10,
-            )
-            logging.info('New ' + devicename + ' session created for: ' + username)
-        else:
-            last_session.num_seconds += 10
-            last_session.save()
+                    models.UsageTrack.objects.create(
+                        user=user,
+                        username=username,
+                        devicename=devicename,
+                        num_seconds=10,
+                    )
+                    logging.info('New ' + devicename + ' session created for: ' + username)
+                else:
+                    last_session.num_seconds += 10
+                    last_session.save()
 
-        return Response(200)
+            return Response(200)
+
+        # keep trying if we hit a "database locked" error
+        except OperationalError:
+            return self.track(request)
 
 
 class MemberCountViewSet(Base, List):