DBClientConnection* DBClientReplicaSet::selectNodeUsingTags(
shared_ptr<ReadPreferenceSetting> readPref) {
if (!shouldReevaluate() && checkLastHost(readPref.get())) {
LOG( 3 ) << "dbclient_rs selecting compatible last used node " << _lastSlaveOkHost
<< endl;
return _lastSlaveOkConn.get();
}
ReplicaSetMonitorPtr monitor = _getMonitor();
_lastSlaveOkHost = monitor->getHostOrRefresh(*readPref);
if ( _lastSlaveOkHost.empty() ){
LOG( 3 ) << "dbclient_rs no compatible node found" << endl;
return NULL;
}
_lastReadPref = readPref;
// Primary connection is special because it is the only connection that is
// versioned in mongos. Therefore, we have to make sure that this object
// maintains only one connection to the primary and use that connection
// every time we need to talk to the primary.
if (monitor->isPrimary(_lastSlaveOkHost)) {
checkMaster();
_lastSlaveOkConn = _master;
_lastSlaveOkHost = _masterHost; // implied, but still assign just to be safe
LOG( 3 ) << "dbclient_rs selecting primary node " << _lastSlaveOkHost << endl;
return _master.get();
}
string errmsg;
ConnectionString connStr(_lastSlaveOkHost);
// Needs to perform a dynamic_cast because we need to set the replSet
// callback. We should eventually not need this after we remove the
// callback.
DBClientConnection* newConn = dynamic_cast<DBClientConnection*>(
connStr.connect(errmsg, _so_timeout));
// Assert here instead of returning NULL since the contract of this method is such
// that returning NULL means none of the nodes were good, which is not the case here.
uassert(16532, str::stream() << "Failed to connect to " << _lastSlaveOkHost.toString(),
newConn != NULL);
_lastSlaveOkConn.reset(newConn);
_lastSlaveOkConn->setReplSetClientCallback(this);
_lastSlaveOkConn->setRunCommandHook(_runCommandHook);
_lastSlaveOkConn->setPostRunCommandHook(_postRunCommandHook);
_auth(_lastSlaveOkConn.get());
LOG( 3 ) << "dbclient_rs selecting node " << _lastSlaveOkHost << endl;
return _lastSlaveOkConn.get();
}
