public int isActive(int uid){
		//if active return -1 
		//else return 0
		int actualIdx = memberIdxs.get(uid);
		int shardIdx = myMemberObjs[actualIdx].get_shardIdx();
		int idxInShard = myMemberObjs[actualIdx].get_idxInShard();

		try {
			uStatSemaphores[shardIdx].acquire();
			if (userStatusShards[shardIdx][idxInShard] == 'a'){
				//user is active
				uStatSemaphores[shardIdx].release();
				return -1;
			}else{
				//user is not active
				//activate it
				userStatusShards[shardIdx][idxInShard] = 'a';
				uStatSemaphores[shardIdx].release();
				return 0;
			}	
		} catch (Exception e) {
			System.out.println("Error-Cant activate any user");
			e.printStackTrace(System.out);
			System.exit(-1);
		}
		return -1;
	}