Ticket #13105: django-1.1.1-thread-safe.patch

db/models/fields/related.py

@@ -10 +10 @@
 from django.utils.functional import curry
 from django.core import exceptions
 from django import forms
+from threading import Lock
 
 try:
     set
@@ -408 +409 @@
         def __init__(self, model=None, core_filters=None, instance=None, symmetrical=None,
                 join_table=None, source_col_name=None, target_col_name=None):
             super(ManyRelatedManager, self).__init__()
+            self._lock = model.objects._lock # using the model's manager lock
             self.core_filters = core_filters
             self.model = model
             self.symmetrical = symmetrical
@@ -488 +490 @@
                         raise TypeError, "'%s' instance expected" % self.model._meta.object_name
                     else:
                         new_ids.add(obj)
-                # Add the newly created or already existing objects to the join table.
-                # First find out which items are already added, to avoid adding them twice
-                cursor = connection.cursor()
-                cursor.execute("SELECT %s FROM %s WHERE %s = %%s AND %s IN (%s)" % \
-                    (target_col_name, self.join_table, source_col_name,
-                    target_col_name, ",".join(['%s'] * len(new_ids))),
-                    [self._pk_val] + list(new_ids))
-                existing_ids = set([row[0] for row in cursor.fetchall()])
-
-                # Add the ones that aren't there already
-                for obj_id in (new_ids - existing_ids):
-                    cursor.execute("INSERT INTO %s (%s, %s) VALUES (%%s, %%s)" % \
-                        (self.join_table, source_col_name, target_col_name),
-                        [self._pk_val, obj_id])
-                transaction.commit_unless_managed()
+
+                self._lock.acquire()
+                try:
+                    # Add the newly created or already existing objects to the join table.
+                    # First find out which items are already added, to avoid adding them twice
+                    cursor = connection.cursor()
+                    cursor.execute("SELECT %s FROM %s WHERE %s = %%s AND %s IN (%s)" % \
+                        (target_col_name, self.join_table, source_col_name,
+                        target_col_name, ",".join(['%s'] * len(new_ids))),
+                        [self._pk_val] + list(new_ids))
+                    existing_ids = set([row[0] for row in cursor.fetchall()])
+
+                    # Add the ones that aren't there already
+                    for obj_id in (new_ids - existing_ids):
+                        cursor.execute("INSERT INTO %s (%s, %s) VALUES (%%s, %%s)" % \
+                            (self.join_table, source_col_name, target_col_name),
+                            [self._pk_val, obj_id])
+                    transaction.commit_unless_managed()
+                finally: self._lock.release()
 
         def _remove_items(self, source_col_name, target_col_name, *objs):
             # source_col_name: the PK colname in join_table for the source object

db/models/manager.py

@@ -3 +3 @@
 from django.db.models.query import QuerySet, EmptyQuerySet, insert_query
 from django.db.models import signals
 from django.db.models.fields import FieldDoesNotExist
+from threading import Lock
 
 def ensure_default_manager(sender, **kwargs):
     """
@@ -47 +48 @@
 
     def __init__(self):
         super(Manager, self).__init__()
+        self._lock = Lock()
         self._set_creation_counter()
         self.model = None
         self._inherited = False
@@ -120 +122 @@
         return self.get_query_set().get(*args, **kwargs)
 
     def get_or_create(self, **kwargs):
-        return self.get_query_set().get_or_create(**kwargs)
+        self._lock.acquire()
+        try: result = self.get_query_set().get_or_create(**kwargs)
+        finally: self._lock.release()
+        return result
 
     def create(self, **kwargs):
         return self.get_query_set().create(**kwargs)