content: package com.platform.rpc.remoting.invoker.route.impl;
  
  import com.platform.rpc.remoting.invoker.route.XxlRpcLoadBalance;
  
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  public class XxlRpcLoadBalanceLFUStrategy extends XxlRpcLoadBalance {
  
      private ConcurrentMap<String, HashMap<String, Integer>> jobLfuMap = new ConcurrentHashMap<String, HashMap<String, Integer>>();
      private long CACHE_VALID_TIME = 0;
  
      public String doRoute(String serviceKey, TreeSet<String> addressSet) {
  
          // cache clear
          if (System.currentTimeMillis() > CACHE_VALID_TIME) {
              jobLfuMap.clear();
              CACHE_VALID_TIME = System.currentTimeMillis() + 1000*60*60*24;
          }
  
          // lfu item init
          HashMap<String, Integer> lfuItemMap = jobLfuMap.get(serviceKey);     // Key排序可以用TreeMap+构造入参Compare；Value排序暂时只能通过ArrayList；
          if (lfuItemMap == null) {
              lfuItemMap = new HashMap<String, Integer>();
              jobLfuMap.putIfAbsent(serviceKey, lfuItemMap);   // 避免重复覆盖
          }
  
          // put new
          for (String address: addressSet) {
              if (!lfuItemMap.containsKey(address) || lfuItemMap.get(address) >1000000 ) {
                  lfuItemMap.put(address, 0);
              }
          }
  
          // remove old
          List<String> delKeys = new ArrayList<>();
          for (String existKey: lfuItemMap.keySet()) {
              if (!addressSet.contains(existKey)) {
                  delKeys.add(existKey);
              }
          }
          if (delKeys.size() > 0) {
              for (String delKey: delKeys) {
                  lfuItemMap.remove(delKey);
              }
          }
  
          // load least userd count address
          List<Map.Entry<String, Integer>> lfuItemList = new ArrayList<Map.Entry<String, Integer>>(lfuItemMap.entrySet());
          Collections.sort(lfuItemList, new Comparator<Map.Entry<String, Integer>>() {
              @Override
              public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
                  return o1.getValue().compareTo(o2.getValue());
              }
          });
  
          Map.Entry<String, Integer> addressItem = lfuItemList.get(0);
          String minAddress = addressItem.getKey();
          addressItem.setValue(addressItem.getValue() + 1);
  
          return minAddress;
      }
  
      @Override
      public String route(String serviceKey, TreeSet<String> addressSet) {
          String finalAddress = doRoute(serviceKey, addressSet);
          return finalAddress;
      }
  
  }
  