Merge pull request #409 from edx/multi-tenancy/delete-baskets-in-batches

Batching basket deletions

ecommerce/extensions/basket/management/commands/delete_ordered_baskets.py

@@ -5,6 +5,7 @@ These baskets don't have much value once the order is placed, and unnecessarily
 """
 from __future__ import unicode_literals
 from django.core.management import BaseCommand
+from django.db import transaction
 from oscar.core.loading import get_model
 
 Basket = get_model('basket', 'Basket')
@@ -14,6 +15,12 @@ class Command(BaseCommand):
     help = 'Delete baskets for which orders have been placed.'
 
     def add_arguments(self, parser):
+        parser.add_argument('-b', '--batch-size',
+                            action='store',
+                            dest='batch_size',
+                            default=1000,
+                            type=int,
+                            help='Size of each batch of baskets to be deleted.')
         parser.add_argument('--commit',
                             action='store_true',
                             dest='commit',
@@ -25,9 +32,19 @@ class Command(BaseCommand):
         count = queryset.count()
 
         if options['commit']:
-            self.stderr.write('Deleting [{}] baskets...'.format(count))
-            queryset.delete()
-            self.stderr.write('Done.')
+            if count:
+                self.stderr.write('Deleting [{}] baskets...'.format(count))
+                batch_size = options['batch_size']
+                max_id = queryset.order_by('-id')[0].id
+                for start in range(0, max_id, batch_size):
+                    end = min(start + batch_size, max_id)
+                    self.stderr.write('...deleting baskets [{start}] through [{end}]...'.format(start=start, end=end))
+                    with transaction.atomic():
+                        queryset.filter(pk__gte=start, pk__lte=end).delete()
+
+                self.stderr.write('Done.')
+            else:
+                self.stderr.write('No baskets to delete.')
         else:
             msg = 'This is a dry run. Had the --commit flag been included, [{}] baskets would have been deleted.'. \
                 format(count)

ecommerce/extensions/basket/tests/test_commands.py

@@ -31,7 +31,7 @@ class DeleteOrderedBasketsCommandTests(TestCase):
         self.assertEqual(Basket.objects.count(), expected)
 
         # Verify the number of baskets expected to be deleted was printed to stderr
-        expected = 'This is a dry run. Had the --commit flag been included, [{}] baskets would have been deleted.'.\
+        expected = 'This is a dry run. Had the --commit flag been included, [{}] baskets would have been deleted.'. \
             format(len(self.orders))
         self.assertEqual(out.getvalue().strip(), expected)
 
@@ -48,5 +48,17 @@ class DeleteOrderedBasketsCommandTests(TestCase):
         self.assertEqual(list(Basket.objects.all()), self.unordered_baskets)
 
         # Verify info was output to stderr
-        expected = 'Deleting [{}] baskets...\nDone.'.format(len(self.orders))
-        self.assertEqual(out.getvalue().strip(), expected)
+        actual = out.getvalue().strip()
+        self.assertTrue(actual.startswith('Deleting [{}] baskets...'.format(len(self.orders))))
+        self.assertTrue(actual.endswith('Done.'))
+
+    def test_commit_without_baskets(self):
+        """ Verify the command does nothing if there are no baskets to delete. """
+        # Delete all baskets
+        Basket.objects.all().delete()
+
+        # Call the command with the commit flag
+        out = StringIO()
+        call_command(self.command, commit=True, stderr=out)
+
+        self.assertEqual(out.getvalue().strip(), 'No baskets to delete.')