Multiplexing incorrectly disabled after reuse a mysql_connection with auto_increment

[ahaha-zhang]

Hi Rene:
Version v1.4.16
I find that if a new connection reuses the mysql_connection with auto_increment, multiplexing is incorrectly disabled.
Since auto_increment_delay_token of the mysql_connection with auto_increment is not reset to zero when the mysql_connection is pushed back to ConnectionsFree list. Then new session which reuses the connection will be multiplexing disabled since MySQL_Connection::MultiplexDisabled() returns true.

Reproduce:
1.create a new session and back end connection:A.
2.insert into xxxx with auto_increment, thus,auto_increment_delay_token is set to 5 by default.
3.disconnect and connection A is pushed back to ConnectionsFree list.
4.create a new session and will reuse connection:A. The new session is multiplexing disabled.

Fix:
Reset connection->auto_increment_delay_token to zero when get new back end connection
MySQL_Connection * MySQL_HostGroups_Manager::get_MyConn_from_pool(unsigned int _hid, MySQL_Session *sess, bool ff) {
MySQL_Connection * conn=NULL;
wrlock();
status.myconnpoll_get++;
MyHGC *myhgc=MyHGC_lookup(_hid);
MySrvC *mysrvc=myhgc->get_random_MySrvC();
if (mysrvc) { // a MySrvC exists. If not, we return NULL = no targets
conn=mysrvc->ConnectionsFree->get_random_MyConn(sess, ff);
if (conn) {
mysrvc->ConnectionsUsed->add(conn);
++conn->auto_increment_delay_token = 0;//reset auto_increment_delay_token of mysql_connection
status.myconnpoll_get_ok++;
}
}
wrunlock();
proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 7, "Returning MySQL Connection %p, server %s:%d\n", conn, (conn ? conn->parent->address : "") , (conn ? conn->parent->port : 0 ));
return conn;
}

Thank you!

[renecannao]

Thank you for the report.
Fixed in both 1.4.16 and 2.0.4 .
Note that the solution implemented is different than the suggested one.
auto_increment_delay_token is being reset to 0 in MySQL_Connection::reset() .

[ahaha-zhang]

OK, thx :)