Sets a session variable specifying the lag time for ignoring a slave server.
function db_ignore_slave() {
$connection_info = Database::getConnectionInfo();
// Only set ignore_slave_server if there are slave servers being used, which
// is assumed if there are more than one.
if (count($connection_info) > 1) {
// Five minutes is long enough to allow the slave to break and resume
// interrupted replication without causing problems on the Drupal site from
// the old data.
$duration = variable_get('maximum_replication_lag', 300);
// Set session variable with amount of time to delay before using slave.
$_SESSION['ignore_slave_server'] = REQUEST_TIME + $duration;
}
}