protected int loadBlockAndSeekToKey(HFileBlock seekToBlock, ExtendedCell nextIndexedKey,
      boolean rewind, ExtendedCell key, boolean seekBefore) throws IOException {
      if (this.curBlock == null || this.curBlock.getOffset() != seekToBlock.getOffset()) {
        updateCurrentBlock(seekToBlock);
      } else if (rewind) {
        blockBuffer.rewind();
      }
      // Update the nextIndexedKey
      this.nextIndexedKey = nextIndexedKey;
      return blockSeek(key, seekBefore);
    }
Positions this scanner at the start of the file.
@return false if empty file; i.e. a call to next would return false and the current key and
        value are undefined.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderImpl.java