How to use

hasNext

method

in

org.apache.kylin.metadata.tuple.ITupleIterator

@Override
public boolean moveNext() {
  try {
    if (cursor == null) {
      cursor = queryStorage();
    }
    if (!cursor.hasNext()) {
      return false;
    }
    ITuple tuple = cursor.next();
    if (tuple == null) {
      return false;
    }
    convertCurrentRow(tuple);
    return true;
  } catch (Exception e) {
    try {
      if (cursor != null) {
        cursor.close();
      }
    } catch (Exception ee) {
      logger.info("Error when closing cursor, ignore it", ee);
    }
    throw e;
  }
}

@Test
public void testListAllTables() throws Exception {
  ITupleIterator it = ITupleIterator.EMPTY_TUPLE_ITERATOR;
  assertFalse(it.hasNext());
  assertNull(it.next());
  it.close(); // for coverage
}

@Override
public boolean hasNext() {
  while (!this.tupleIterator.hasNext()) {
    if (this.regionResponsesIterator.hasNext()) {
      this.tupleIterator = new SingleRegionTupleIterator(this.regionResponsesIterator.next());
    } else {
      return false;
    }
  }
  return true;
}

@Override
public ITuple next() {
  ITuple t = null;
  while (hasNext()) {
    if (segmentIterator.hasNext()) {
      t = segmentIterator.next();
      scanCount++;
      break;
    } else {
      segmentIterator.close();
      segmentIterator = segmentIteratorIterator.next();
    }
  }
  return t;
}

@Override
public boolean moveNext() {
  if (cursor == null) {
    cursor = queryStorage();
  }
  if (!cursor.hasNext()) {
    return false;
  }
  ITuple tuple = cursor.next();
  if (tuple == null) {
    return false;
  }
  convertCurrentRow(tuple);
  return true;
}

@Override
public boolean hasNext() {
  // 1. check limit
  if (context.isLimitEnabled() && scanCount >= context.getLimit()) {
    return false;
  }
  // 2. check partial result
  if (context.isAcceptPartialResult() && scanCount > partialResultLimit) {
    context.setPartialResultReturned(true);
    return false;
  }
  // 3. check threshold
  if (scanCount >= context.getThreshold()) {
    throw new ScanOutOfLimitException("Scan row count exceeded threshold: " + context.getThreshold() + ", please add filter condition to narrow down backend scan range, like where clause.");
  }
  // 4. check cube segments
  return segmentIteratorIterator.hasNext() || segmentIterator.hasNext();
}

private int search(List<TblColRef> groups, List<FunctionDesc> aggregations, TupleFilter filter, StorageContext context) {
  int count = 0;
  ITupleIterator iterator = null;
  try {
    SQLDigest sqlDigest = new SQLDigest("default.test_kylin_fact", filter, null, Collections.<TblColRef> emptySet(), groups, Collections.<TblColRef> emptySet(), Collections.<TblColRef> emptySet(), aggregations);
    iterator = storageEngine.search(context, sqlDigest);
    while (iterator.hasNext()) {
      ITuple tuple = iterator.next();
      System.out.println("Tuple = " + tuple);
      count++;
    }
  } catch (Exception e) {
    e.printStackTrace();
  } finally {
    if (iterator != null) {
      iterator.close();
    }
  }
  return count;
}

@Test
public void testListAllTables() throws Exception {
  ITupleIterator it = ITupleIterator.EMPTY_TUPLE_ITERATOR;
  assertFalse(it.hasNext());
  assertNull(it.next());
  it.close(); // for coverage
}

@Override
public boolean moveNext() {
  try {
    if (cursor == null) {
      cursor = queryStorage();
    }
    if (!cursor.hasNext()) {
      return false;
    }
    ITuple tuple = cursor.next();
    if (tuple == null) {
      return false;
    }
    convertCurrentRow(tuple);
    return true;
  } catch (Exception e) {
    try {
      if (cursor != null) {
        cursor.close();
      }
    } catch (Exception ee) {
      logger.info("Error when closing cursor, ignore it", ee);
    }
    throw e;
  }
}