FreeTDS Development Group

[Andrew Victor <avictor.za AT gmail.com>]

hi,

I'm busy updating an application from FreeTDS 0.82 to the latest
(0.91.96), and am running into an issue a change to the ct_cancel()
function.

The application is a long-running daemon that makes use of a
connection-pool of persistent connections to a MS-SQL server.  Before
returning a connection back to the pool a ct_cancel(CS_CANCEL_ALL) is
issued to ensure that incomplete commands are terminated, and any
unread result-sets discarded - ie, the server and connection are in a
"known" state.

With FreeTDS 0.91.96, the ct_cancel() call returns but the
"cancel_state" remains in _CS_CANCEL_PENDING state:

      tds_send_cancel(conn->tds_socket);
      tds_process_cancel(conn->tds_socket);
       _ct_initialise_cmd(conn_cmd);
       conn_cmd->cancel_state = _CS_CANCEL_PENDING;


Note: the other types of cs_cancel() don't call tds_process_cancel().


When the connection is later re-used from the pool, the subsequent
calls to ct_send() fails due to this code:

    if (cmd->cancel_state == _CS_CANCEL_PENDING) {
        _ct_cancel_cleanup(cmd);
        return CS_CANCELED;
    }

and _ct_cancel_cleanup() basically just calls:

   tds_process_cancel(con->tds_socket);


Therefore tds_process_cancel() gets called twice, and the
"cancel_state" stays in _CS_CANCEL_PENDING state.


The change seems related to this post on the mailing-list:
   https://lists.ibiblio.org/sympa/arc/freetds/2008q2/023233.html
and this commit:
   
https://gitorious.org/freetds/freetds/commit/96a34d413e02095a4c9c90a6a3936bd57f4d6073


Commenting the two lines:
    conn_cmd->cancel_state = _CS_CANCEL_PENDING;
seems to solve the issue.

I did also try the latest git version.


Regards,
  Andrew Victor