[IMP] sql_db: add event handlers for post-commit and post-rollback

openerp/sql_db.py

@@ -173,6 +173,9 @@ class Cursor(object):
 
         self.cache = {}
 
+        # event handlers, see method after() below
+        self._event_handlers = {'commit': [], 'rollback': []}
+
     def __build_dict(self, row):
         return {d.name: row[i] for i, d in enumerate(self._obj.description)}
     def dictfetchone(self):
@@ -337,17 +340,45 @@ class Cursor(object):
                 else ISOLATION_LEVEL_READ_COMMITTED
         self._cnx.set_isolation_level(isolation_level)
 
+    @check
+    def after(self, event, func):
+        """ Register an event handler.
+
+            :param event: the event, either `'commit'` or `'rollback'`
+            :param func: a callable object, called with no argument after the
+                event occurs
+
+            Be careful when coding an event handler, since any operation on the
+            cursor that was just committed/rolled back will take place in the
+            next transaction that has already begun, and may still be rolled
+            back or committed independently. You may consider the use of a
+            dedicated temporary cursor to do some database operation.
+        """
+        self._event_handlers[event].append(func)
+
+    def _pop_event_handlers(self):
+        # return the current handlers, and reset them on self
+        result = self._event_handlers
+        self._event_handlers = {'commit': [], 'rollback': []}
+        return result
+
     @check
     def commit(self):
         """ Perform an SQL `COMMIT`
         """
-        return self._cnx.commit()
+        result = self._cnx.commit()
+        for func in self._pop_event_handlers()['commit']:
+            func()
+        return result
 
     @check
     def rollback(self):
         """ Perform an SQL `ROLLBACK`
         """
-        return self._cnx.rollback()
+        result = self._cnx.rollback()
+        for func in self._pop_event_handlers()['rollback']:
+            func()
+        return result
 
     def __enter__(self):
         """ Using the cursor as a contextmanager automatically commits and