private int allocateFast(int freeListIx, MemoryBuffer[] dest, long[] destHeaders,
        int destIx, int destCount, int allocSize) {
      if (data == null) return -1; // not allocated yet
      FreeList freeList = freeLists[freeListIx];
      if (!freeList.lock.tryLock()) return destIx;
      try {
        return allocateFromFreeListUnderLock(
            freeList, freeListIx, dest, destHeaders, destIx, destCount, allocSize);
      } finally {
        freeList.lock.unlock();
      }
    }
Unsets the headers (meaning this does not refer to a buffer).
llap-server/src/java/org/apache/hadoop/hive/llap/cache/BuddyAllocator.java