org.apache.hadoop.hbase.io.hfile.HFileScanner#seekBefore ( )源码实例Demo

@Override
public Optional<Cell> getLastKey() {
  if (top) {
    return super.getLastKey();
  }
  // Get a scanner that caches the block and that uses pread.
  HFileScanner scanner = getScanner(true, true);
  try {
    if (scanner.seekBefore(this.splitCell)) {
      return Optional.ofNullable(scanner.getKey());
    }
  } catch (IOException e) {
    LOG.warn("Failed seekBefore " + Bytes.toStringBinary(this.splitkey), e);
  } finally {
    if (scanner != null) {
      scanner.close();
    }
  }
  return Optional.empty();
}
 

private Cell doTestOfSeekBefore(Path p, FileSystem fs, Reference bottom, Cell seekBefore,
    CacheConfig cacheConfig) throws IOException {
  ReaderContext context = new ReaderContextBuilder().withFileSystemAndPath(fs, p).build();
  HFileInfo fileInfo = new HFileInfo(context, TEST_UTIL.getConfiguration());
  final HalfStoreFileReader halfreader = new HalfStoreFileReader(context, fileInfo, cacheConfig,
      bottom, new AtomicInteger(0), TEST_UTIL.getConfiguration());
  fileInfo.initMetaAndIndex(halfreader.getHFileReader());
  halfreader.loadFileInfo();
  final HFileScanner scanner = halfreader.getScanner(false, false);
  scanner.seekBefore(seekBefore);
  return scanner.getCell();
}