负载均衡之最小活跃数算法

一、概念

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• 活跃数
  • 集群中各实例未处理的请求数。
• 最小活跃数
  • 集群中各个实例，哪个实例未处理的请求数据最小，就称之为最小活跃数。

二、场景与设计思路

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• 场景
  • 以获取微服务地址为场景。
• 设计思路
  • 初始化微服务地址，并初始化活跃数。
  • 获取字典或集合中活跃数最小的值，如果获取的值有多个，说明活跃数是相同，必须随机出一个地址后，活跃数并且加1。
  • 获取到地址后，必须将该地址的活跃数减1。

三、实现

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• 新建抽象类–AbstractLeastActive

   public abstract class AbstractLeastActive{#region  变量 /// <summary>/// 字典/// </summary>public ConcurrentDictionary<string, int> keyValuePairs = new ConcurrentDictionary<string, int>();/// <summary>/// 相同编号的数据集合 /// </summary>protected List<string> list = new List<string>();#endregion  #region 虚函数/// <summary>/// 筛选最小编号的数据/// </summary>protected void FilterMinValue(){int number = int.MaxValue;foreach (var item in keyValuePairs){if (number >= item.Value){if (number == item.Value){number = item.Value;list.Add(item.Key);continue;}list.Clear();number = item.Value;list.Add(item.Key);}}}/// <summary>/// 随机集合中的数据/// </summary>protected string RandomValue(){Random random = new Random();var num = random.Next(list.Count);return list[num];}/// <summary>/// 活跃数加1/// </summary>/// <param name="key">key值</param>protected void AddActive(string key) {keyValuePairs.TryUpdate(key, keyValuePairs[key]+1, keyValuePairs[key]);}#endregion/// <summary>/// 释放编号/// </summary>/// <param name="key"></param>public abstract void Dispose(string key);/// <summary>/// 获取最小活跃数/// </summary>/// <returns></returns>public abstract string GetValue();
  

• 新建实现类–LeastActive

    public class LeastActive : AbstractLeastActive{/// <summary>/// 获取最小活跃数据/// </summary>/// <returns></returns>public override string GetValue(){string value = "";//筛选数据this.FilterMinValue();if (this.list.Count == 1){value = this.list[0];//活跃数加1this.AddActive(value);return value;}else if (this.list.Count > 1) {value = this.RandomValue();//活跃数加1this.AddActive(value);return value;}return value;}/// <summary>/// 最小活跃数据释放 /// </summary>/// <param name="key"></param>public override void Dispose(string key){keyValuePairs.TryUpdate(key, keyValuePairs[key] - 1, keyValuePairs[key]);}}
  

• 新建单元测试

        private AbstractLeastActive abstractLeastActive = new LeastActive();[Fact]public void Test1(){abstractLeastActive.keyValuePairs.TryAdd("http://localhost:8080", 0); abstractLeastActive.keyValuePairs.TryAdd("http://localhost:8082", 1);abstractLeastActive.keyValuePairs.TryAdd("http://localhost:8081", -1);abstractLeastActive.keyValuePairs.TryAdd("http://localhost:8083", -1);string value = abstractLeastActive.GetValue();abstractLeastActive.Dispose(value);Assert.Equal("http://localhost:8083", value);}
  

四、代码下载

CSDN：https://download.csdn.net/download/Fu_Shi_rong/87435602
Git：https://gitee.com/Fu_Shi_rong/gcnf.algorithm