add a command sentinels (#899)

* 新加scan,sentinels命令

* add command sentinels

StackExchange.Redis/StackExchange/Redis/Interfaces/IServer.cs

-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -646,6 +646,25 @@ public partial interface IServer : IRedis
         /// <remarks>https://redis.io/topics/sentinel</remarks>
         Task SentinelFailoverAsync(string serviceName, CommandFlags flags = CommandFlags.None);
 
+        /// <summary>  
+        /// show a list of sentinels info about a redis master  
+        /// </summary>  
+        /// <param name="serviceName">The sentinel service name.</param>  
+        /// <param name="flags">The command flags to use.</param>  
+        /// <returns>an array of sentinel info KeyValuePair arrays</returns>  
+        /// <remarks>https://redis.io/topics/sentinel</remarks>  
+        KeyValuePair<string, string>[][] SentinelSentinels(string serviceName, CommandFlags flags = CommandFlags.None);  
+   
+        /// <summary>  
+        /// show a list of sentinels info about a redis master  
+        /// </summary>  
+        /// <param name="serviceName">The sentinel service name.</param>  
+        /// <param name="flags">The command flags to use.</param>  
+        /// <returns>an array of sentinel info KeyValuePair arrays</returns>  
+        /// <remarks>https://redis.io/topics/sentinel</remarks>  
+        Task<KeyValuePair<string, string>[][]> SentinelSentinelsAsync(string serviceName, CommandFlags flags = CommandFlags.None);
+
+
         #endregion
     }
 }

StackExchange.Redis/StackExchange/Redis/RedisLiterals.cs

-using System;
+using System;
 using System.Text;
 
 namespace StackExchange.Redis
@@ -66,6 +66,7 @@ public static readonly RedisValue
             GETMASTERADDRBYNAME = "GET-MASTER-ADDR-BY-NAME",
 //            RESET = "RESET",
             FAILOVER = "FAILOVER",
+            Sentinels = "Sentinels",
 
             // Sentinel Literals as of 2.8.4
             MONITOR = "MONITOR",

StackExchange.Redis/StackExchange/Redis/RedisServer.cs

@@ -302,6 +302,7 @@ public IEnumerable<RedisKey> Keys(int database = 0, RedisValue pattern = default
             return ExecuteSync(msg, ResultProcessor.RedisKeyArray);
         }
         
+
         public DateTime LastSave(CommandFlags flags = CommandFlags.None)
         {
             var msg = Message.Create(-1, flags, RedisCommand.LASTSAVE);
@@ -812,6 +813,19 @@ public Task SentinelFailoverAsync(string serviceName, CommandFlags flags = Comma
             return ExecuteAsync(msg, ResultProcessor.SentinelArrayOfArrays);
         }
 
+
+        public KeyValuePair<string, string>[][] SentinelSentinels(string serviceName, CommandFlags flags = CommandFlags.None)
+        {  
+            var msg = Message.Create(-1, flags, RedisCommand.SENTINEL, RedisLiterals.Sentinels, (RedisValue)serviceName);  
+            return ExecuteSync(msg, ResultProcessor.SentinelArrayOfArrays);  
+        }  
+            
+        public Task<KeyValuePair<string, string>[][]> SentinelSentinelsAsync(string serviceName, CommandFlags flags = CommandFlags.None)
+        {  
+            var msg = Message.Create(-1, flags, RedisCommand.SENTINEL, RedisLiterals.Sentinels, (RedisValue)serviceName);  
+            return ExecuteAsync(msg, ResultProcessor.SentinelArrayOfArrays);  
+        }  
+
         #endregion
     }
 }