private byte readNextByte(Position readPos) {
    // This method is inefficient. It's only used when something crosses buffer boundaries.
    ponderNextBufferToRead(readPos);
    return readPos.buffer[readPos.offset++];
  }
THIS METHOD IS NOT THREAD-SAFE. Use only at load time (or be mindful of thread safety).
serde/src/java/org/apache/hadoop/hive/serde2/WriteBuffers.java