private void rebuildRecentFeed(Integer uid){
        TreeMap<Long,Integer> topFeed=new TreeMap<>();
        TreeSet<Integer> subscribeList=subscribeMap.get(uid);
        for(Integer userId : subscribeList){
            TreeMap<Long,Integer> treeMap=postFeedMap.get(userId);
            topFeed=mergeRecentFeed(topFeed,treeMap==null?new TreeMap():treeMap);
        }
        TreeMap<Long,Integer> treeMap=postFeedMap.get(uid);
        topFeed=mergeRecentFeed(topFeed,treeMap==null?new TreeMap():treeMap);

        LinkedList<Integer> linkedList=new LinkedList<>();
        for(Map.Entry<Long,Integer> entry: topFeed.entrySet()){
            linkedList.add(0,entry.getValue());
        }
        recentFeedMap.put(uid,linkedList);
    }