private void removeBlockFromFreeList(FreeList freeList, int headerIx, int ix) {
      int bOffset = offsetFromHeaderIndex(headerIx),
          bpHeaderIx = getPrevFreeListItem(bOffset), bnHeaderIx = getNextFreeListItem(bOffset);
      CasLog.logRemoveFromList(arenaIx, headerIx, ix, freeList.listHead);
      if (freeList.listHead == headerIx) {
        assert bpHeaderIx == -1;
        freeList.listHead = bnHeaderIx;
      }
      // Unnecessary: data.putInt(bOffset, -1); data.putInt(bOffset + 4, -1);
      if (bpHeaderIx != -1) {
        data.putInt(offsetFromHeaderIndex(bpHeaderIx) + 4, bnHeaderIx);
      }
      if (bnHeaderIx != -1) {
        data.putInt(offsetFromHeaderIndex(bnHeaderIx), bpHeaderIx);
      }
    }
Unsets the headers (meaning this does not refer to a buffer).
llap-server/src/java/org/apache/hadoop/hive/llap/cache/BuddyAllocator.java