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

django/db/models/query_utils.py

@@ -32,11 +32,21 @@ class CollectedObjects(object):
 
     This is used for the database object deletion routines so that we can
     calculate the 'leaf' objects which should be deleted first.
+
+    previously_seen is an optional argument. It must be a CollectedObjects
+    instance itself; any previously_seen collected object will be blocked from
+    being added to this instance.
     """
 
-    def __init__(self):
+    def __init__(self, previously_seen=None):
         self.data = {}
         self.children = {}
+        if previously_seen:
+            self.blocked = previously_seen.blocked
+            for cls, seen in previously_seen.data.items():
+                self.blocked.setdefault(cls, SortedDict()).update(seen)
+        else:
+            self.blocked = {}
 
     def add(self, model, pk, obj, parent_model, nullable=False):
         """
@@ -53,6 +63,9 @@ class CollectedObjects(object):
         Returns True if the item already existed in the structure and
         False otherwise.
         """
+        if pk in self.blocked.get(model, {}):
+            return True
+
         d = self.data.setdefault(model, SortedDict())
         retval = pk in d
         d[pk] = obj