StackExchange.Redis 之 操作Redis链接字符串配置（链接Redis集群）

参考文档：

https://blog.csdn.net/smj20170417/article/details/79928228

https://www.jianshu.com/p/0b3be884d2f5

Redis链接字符串可以提出来放到 Config文件当中：

  <connectionStrings>
    <add name="Connection_Redis" connectionString="127.0.0.1:6379,127.0.0.1:6380,127.0.0.1:6381,127.0.0.1:6382,password=123456,abortConnect=false" />
  </connectionStrings>

当有多个Redis实例时，可以设置链接多个实例，中间用逗号分隔即可（比如：使用Redis集群）。

    public class RedisCacheHelper
    {
        private readonly Logger _log = LogManager.GetCurrentClassLogger();

        /// <summary>
        /// 连接字符串
        /// </summary>
        private static string _connectionString;

        /// <summary>
        /// redis 连接对象
        /// </summary>
        private static IConnectionMultiplexer _connMultiplexer;

        /// <summary>
        /// 实例化对象
        /// </summary>
        private static RedisCacheHelper _cacheHelper;
        /// <summary>
        /// 实例
        /// </summary>
        private static RedisCacheHelper _instance;

        /// <summary>
        /// 锁
        /// </summary>
        private static readonly object Locker = new object();

        /// <summary>
        /// 数据库
        /// </summary>
        private IDatabase _db;


        /// <summary>
        /// 默认链接实例
        /// </summary>
        private RedisCacheHelper()
        {
            _connectionString = ConfigurationManager.ConnectionStrings["Connection_Redis"].ConnectionString;
            _connMultiplexer = ConnectionMultiplexer.Connect(_connectionString);
            //添加注册事件
            AddRegisterEvent();
        }

        /// <summary>
        /// 获取 Redis 连接对象
        /// </summary>
        private IConnectionMultiplexer Connnection
        {
            get
            {
                if (_connMultiplexer == null || !_connMultiplexer.IsConnected)
                {
                    lock (Locker)
                    {
                        if (_connMultiplexer == null || !_connMultiplexer.IsConnected)
                        {
                            _connMultiplexer = ConnectionMultiplexer.Connect(_connectionString);
                        }
                    }
                }
                return _connMultiplexer;
            }
        }

        /// <summary>
        /// 获取指定db，默认不指定
        /// </summary>
        /// <param name="db"></param>
        /// <returns></returns>
        private IDatabase GetDatabase(int db = -1)
        {
            return Connnection.GetDatabase(db);
        }

        /// <summary>
        /// 调用实例，通过该实例调用Redis
        /// </summary>
        public static RedisCacheHelper Instance
        {
            get
            {
                if (_cacheHelper != null) return _cacheHelper;
                lock (Locker)
                {
                    if (_cacheHelper != null) return _cacheHelper;
                    _cacheHelper = new RedisCacheHelper();
                }
                return _cacheHelper;
            }
        }

        #region 注册事件

        /// <summary>
        /// 添加注册事件
        /// </summary>
        private void AddRegisterEvent()
        {
            _connMultiplexer.ConnectionRestored += ConnMultiplexer_ConnectionRestored;
            _connMultiplexer.ConnectionFailed += ConnMultiplexer_ConnectionFailed;
            _connMultiplexer.ErrorMessage += ConnMultiplexer_ErrorMessage;
            _connMultiplexer.ConfigurationChanged += ConnMultiplexer_ConfigurationChanged;
            _connMultiplexer.HashSlotMoved += ConnMultiplexer_HashSlotMoved;
            _connMultiplexer.InternalError += ConnMultiplexer_InternalError;
            _connMultiplexer.ConfigurationChangedBroadcast += ConnMultiplexer_ConfigurationChangedBroadcast;
        }

        /// <summary>
        /// 重新配置广播时（通常意味着主从同步更改）
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_ConfigurationChangedBroadcast(object sender, EndPointEventArgs e)
        {
            _log.Info($"{nameof(ConnMultiplexer_ConfigurationChangedBroadcast)}: {e.EndPoint}");
        }

        /// <summary>
        /// 发生内部错误时（主要用于调试）
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_InternalError(object sender, InternalErrorEventArgs e)
        {
            _log.Error($"{nameof(ConnMultiplexer_InternalError)}: {e.Exception}");
        }

        /// <summary>
        /// 更改集群时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_HashSlotMoved(object sender, HashSlotMovedEventArgs e)
        {
            _log.Info(
                $"{nameof(ConnMultiplexer_HashSlotMoved)}: {nameof(e.OldEndPoint)}-{e.OldEndPoint} To {nameof(e.NewEndPoint)}-{e.NewEndPoint}");
        }

        /// <summary>
        /// 配置更改时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_ConfigurationChanged(object sender, EndPointEventArgs e)
        {
            _log.Info($"{nameof(ConnMultiplexer_ConfigurationChanged)}: {e.EndPoint}");
        }

        /// <summary>
        /// 发生错误时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_ErrorMessage(object sender, RedisErrorEventArgs e)
        {
            _log.Error($"{nameof(ConnMultiplexer_ErrorMessage)}: {e.Message}");
        }

        /// <summary>
        /// 物理连接失败时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_ConnectionFailed(object sender, ConnectionFailedEventArgs e)
        {
            _log.Fatal($"{nameof(ConnMultiplexer_ConnectionFailed)}: {e.Exception}");
        }

        /// <summary>
        /// 建立物理连接时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ConnMultiplexer_ConnectionRestored(object sender, ConnectionFailedEventArgs e)
        {
            _log.Info($"{nameof(ConnMultiplexer_ConnectionRestored)}: {e.Exception}");
        }

        #endregion
    }

以上Redis链接就配置好了，使用方式如下：首先在把集群中的主从服务都开启，3主、3从

然后在代码中进行操作验证，向缓存中插入一条数据，然后循环读写数据，循环的时候手动任意关闭Redis服务当中的 1~2个 服务器

            while (true)
            {
                //设置age
                RedisCacheHelper.Instance.Set("age", "10", new TimeSpan(0, 5, 0));

                //获取age
                var getage = RedisCacheHelper.Instance.Get("age");
                Console.WriteLine(DateTime.Now.ToString("HH:mm:ss.fff") + "：" + getage);

                Thread.Sleep(1000); // 等待1s
            }

成功将缓存存入到服务器当中，运行效果如下：

此时查看Redis集群，发现主从实例都有数据了，接下来我们把其中任意1个 Redis实例关掉 (上边运行的循环代码程序不要关闭)

发现程序正常运行：

但是上边的步骤，我经过多次测试，在任意关闭某个实例的时候，偶尔会报如下错误：集群挂了

我们把写的方法注释掉，只保留读取的代码，同样会偶尔报异常。

但是大部分情况下，关掉其中一个实例，程序都正常运行：