@Override
  public TimeValuePair currentTimeValuePair() throws IOException {
    return heap.peek().getTimeValuePair();
  }
This class implements {@link IPointReader} for data sources with different priorities.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/read/reader/common/PriorityMergeReader.java