Fixed #9479 -- Corrected an edge case in bulk queryset deletion that could cause an infinite loop when using MySQL InnoDB.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10913 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/delete_regress/__init__.py

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+

tests/regressiontests/delete_regress/models.py

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+from django.conf import settings
+from django.db import models, backend, connection, transaction
+from django.db.models import sql, query
+from django.test import TransactionTestCase
+
+class Book(models.Model):
+    pagecount = models.IntegerField()
+
+# Can't run this test under SQLite, because you can't
+# get two connections to an in-memory database.
+if settings.DATABASE_ENGINE != 'sqlite3':
+    class DeleteLockingTest(TransactionTestCase):
+        def setUp(self):
+            # Create a second connection to the database
+            self.conn2 = backend.DatabaseWrapper({
+                'DATABASE_HOST': settings.DATABASE_HOST,
+                'DATABASE_NAME': settings.DATABASE_NAME,
+                'DATABASE_OPTIONS': settings.DATABASE_OPTIONS,
+                'DATABASE_PASSWORD': settings.DATABASE_PASSWORD,
+                'DATABASE_PORT': settings.DATABASE_PORT,
+                'DATABASE_USER': settings.DATABASE_USER,
+                'TIME_ZONE': settings.TIME_ZONE,
+            })
+
+            # Put both DB connections into managed transaction mode
+            transaction.enter_transaction_management()
+            transaction.managed(True)
+            self.conn2._enter_transaction_management(True)
+
+        def tearDown(self):
+            # Close down the second connection.
+            transaction.leave_transaction_management()
+            self.conn2.close()
+
+        def test_concurrent_delete(self):
+            "Deletes on concurrent transactions don't collide and lock the database. Regression for #9479"
+
+            # Create some dummy data
+            b1 = Book(id=1, pagecount=100)
+            b2 = Book(id=2, pagecount=200)
+            b3 = Book(id=3, pagecount=300)
+            b1.save()
+            b2.save()
+            b3.save()
+
+            transaction.commit()
+
+            self.assertEquals(3, Book.objects.count())
+
+            # Delete something using connection 2.
+            cursor2 = self.conn2.cursor()
+            cursor2.execute('DELETE from delete_regress_book WHERE id=1')
+            self.conn2._commit();
+
+            # Now perform a queryset delete that covers the object
+            # deleted in connection 2. This causes an infinite loop
+            # under MySQL InnoDB unless we keep track of already
+            # deleted objects.
+            Book.objects.filter(pagecount__lt=250).delete()
+            transaction.commit()
+            self.assertEquals(1, Book.objects.count())