How to use the apsw.BusyError function in apsw

# Call do_update if this is an update type.
            # Otherwise we insert.

            if static:
                txn.execute("DELETE FROM '%s';" % tablename)
                rowcount = self.do_insert_table(txn, table)

            else:
                if update:
                    rowcount = self.do_update_table(txn, table, identity)
                else:
                    rowcount = self.do_insert_table(txn, table)

            txn.execute("COMMIT;")

        except apsw.BusyError as e:
            # This should only happen if we exceed the busy timeout.
            logging.info("SqlConnections: Warning: Lock contention for adding table '%s': %s for %s", tablename, str(e), identity)

            try:
                txn.execute("ROLLBACK;")
            except:
                pass

            # Should we try again?
            if table.test_retry():
                logging.info("SqlConnections: ERROR: Retries failed for table '%s'", tablename)
                return 0

            # Place this request back on the event queue for a retry.
            self.async_add_table_data(table, identity)

def backup_database(self, path):
        dest_db = apsw.Connection(path)
        with dest_db.backup('main', self.conn, 'main') as b:
            while not b.done:
                try:
                    b.step(100)
                except apsw.BusyError:
                    pass
        dest_db.cursor().execute('DELETE FROM metadata_dirtied; VACUUM;')
        dest_db.close()

step = 1
        #log.debug(statement)
        while True:
            curtime = time.time()
            try:
                if bindings is not None:
                    return cur.execute(statement, newbindings)
                else:
                    return cur.execute(statement)
            except apsw.LockedError:
                if waited > self.retrytime:
                    raise # We don't wait any longer 
                time.sleep(step / 1000)
                waited += step
                step = randrange(step+1, 2*(step+1), 1)
            except apsw.BusyError:
                if time.time() - curtime < self.retrytime/1000:
                    log.warn('SQLite detected deadlock condition!')
                raise

def backup_database(self, path):
        dest_db = apsw.Connection(path)
        with dest_db.backup('main', self.conn, 'main') as b:
            while not b.done:
                try:
                    b.step(100)
                except apsw.BusyError:
                    pass
        dest_db.cursor().execute('DELETE FROM metadata_dirtied; VACUUM;')
        dest_db.close()