private void setHeaderFree(int headerIndex, int freeListIx, CasLog.Src src) {
      headers[headerIndex] = makeHeader(freeListIx, false);
      buffers[headerIndex] = null;
      CasLog.logSetFree(src, arenaIx, headerIndex, allocSizeFromFreeList(freeListIx));
    }
Sets the header at an index to refer to free space in a certain free list.
llap-server/src/java/org/apache/hadoop/hive/llap/cache/BuddyAllocator.java