@Override
  public synchronized boolean next(List<? super ExtendedCell> outResults,
    ScannerContext scannerContext) throws IOException {
    if (this.filterClosed) {
      throw new UnknownScannerException("Scanner was closed (timed out?) "
        + "after we renewed it. Could be caused by a very slow scanner "
        + "or a lengthy garbage collection");
    }
    region.startRegionOperation(Operation.SCAN);
    try {
      return nextRaw(outResults, scannerContext);
    } finally {
      region.closeRegionOperation(Operation.SCAN);
    }
  }
Reset both the filter and the old filter.
@throws IOException in case a filter raises an I/O exception.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionScannerImpl.java