/**
* Counts the rows from the {@code scanner} until exhaustion. It doesn't require the scanner to be
* new, so it can be used to finish scanning a previously-started scan.
*/
protected static int countRowsInScan(AsyncKuduScanner scanner) throws Exception {
final AtomicInteger counter = new AtomicInteger();
Callback<Object, RowResultIterator> cb =
new Callback<Object, RowResultIterator>() {
@Override
public Object call(RowResultIterator arg) throws Exception {
if (arg == null) return null;
counter.addAndGet(arg.getNumRows());
return null;
}
};
while (scanner.hasMoreRows()) {
Deferred<RowResultIterator> data = scanner.nextRows();
data.addCallbacks(cb, defaultErrorCB);
data.join(DEFAULT_SLEEP);
}
Deferred<RowResultIterator> closer = scanner.close();
closer.addCallbacks(cb, defaultErrorCB);
closer.join(DEFAULT_SLEEP);
return counter.get();
}
/**
* Scans a number of rows.
*
* <p>Once this method returns {@code null} once (which indicates that this {@code Scanner} is
* done scanning), calling it again leads to an undefined behavior.
*
* @return a list of rows.
*/
public RowResultIterator nextRows() throws Exception {
Deferred<RowResultIterator> d = asyncScanner.nextRows();
return d.join(asyncScanner.scanRequestTimeout);
}
