private void reset(final long timestamp, final T value) {
    upperDoor = Double.MIN_VALUE;
    lowerDoor = Double.MAX_VALUE;

    lastStoredTimestamp = timestamp;
    lastStoredValue = value;
  }
The last stored time and value we compare current point against lastReadTimestamp and
lastReadValue
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/processor/downsampling/sdt/SwingingDoorTrendingFilter.java