* @return master + port, or null if server has been stopped
*/
private ServerName getMaster() {
ServerName masterServerName = null;
long previousLogTime = 0;
RegionServerStatusProtocol master = null;
boolean refresh = false; // for the first time, use cached data
while (keepLooping() && master == null) {
masterServerName = this.masterAddressManager.getMasterAddress(refresh);
if (masterServerName == null) {
if (!keepLooping()) {