ScanRequest request = null;
try {
incRPCcallsMetrics();
request = RequestConverter.buildScanRequest(scannerId, caching, false, nextCallSeq);
ScanResponse response = null;
PayloadCarryingRpcController controller = controllerFactory.newController();
controller.setPriority(getTableName());
controller.setCallTimeout(callTimeout);
try {
response = getStub().scan(controller, request);
// Client and RS maintain a nextCallSeq number during the scan. Every next() call
// from client to server will increment this number in both sides. Client passes this
// number along with the request and at RS side both the incoming nextCallSeq and its
// nextCallSeq will be matched. In case of a timeout this increment at the client side
// should not happen. If at the server side fetching of next batch of data was over,
// there will be mismatch in the nextCallSeq number. Server will throw
// OutOfOrderScannerNextException and then client will reopen the scanner with startrow
// as the last successfully retrieved row.
// See HBASE-5974
nextCallSeq++;
long timestamp = System.currentTimeMillis();
// Results are returned via controller
CellScanner cellScanner = controller.cellScanner();
rrs = ResponseConverter.getResults(cellScanner, response);
if (logScannerActivity) {
long now = System.currentTimeMillis();
if (now - timestamp > logCutOffLatency) {
int rows = rrs == null ? 0 : rrs.length;