Add support to mapping between internal and external IP's and Validate fileds from 'SENTINEL sentinels' command

.gitignore

@@ -158,3 +158,6 @@ $RECYCLE.BIN/
 .DS_Store
 *.nupkg
 /ctstone.Redis/nuget-pack-push.cmd
+
+# Visual studio stuff
+.vs/

CSRedis/RedisSentinelManager.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Threading.Tasks;
 
 // http://redis.io/topics/sentinel-clients
@@ -13,10 +14,13 @@ namespace CSRedis
     public class RedisSentinelManager : IDisposable
     {
         const int DefaultPort = 26379;
+        private const int NUMBER_OF_CONNECTIONS = 10;
         readonly LinkedList<Tuple<string, int>> _sentinels;
         string _masterName;
         int _connectTimeout;
+        LinkedList<Tuple<string, RedisConnectionPool>> _pools;
         RedisClient _redisClient;
+        Dictionary<string, string> _hostMapping;
 
         /// <summary>
         /// Occurs when the master connection has sucessfully connected
@@ -30,13 +34,45 @@ public class RedisSentinelManager : IDisposable
         public RedisSentinelManager(params string[] sentinels)
         {
             _sentinels = new LinkedList<Tuple<string, int>>();
+            _pools = new LinkedList<Tuple<string, RedisConnectionPool>>();
             foreach (var host in sentinels)
             {
                 string[] parts = host.Split(':');
                 string hostname = parts[0].Trim();
                 int port = Int32.Parse(parts[1]);
                 Add(hostname, port);
             }
+
+        }
+
+        /// <summary>
+        /// Return a client from the connection pool
+        /// </summary>
+        /// <returns>a master redis client</returns>
+        public RedisClient GetClient()
+        {
+            RedisClient client;
+            client = GetClientFromPool();
+            if (!IsMaster(client))
+            {
+                Connect(_masterName, _connectTimeout);
+                client = GetClientFromPool();
+            }
+
+            return client;
+        }
+
+        // return true if client is master
+        private bool IsMaster(RedisClient client) => client != null && client.Info("role") == "master";
+
+        private RedisClient GetClientFromPool()
+        {
+            var first = _pools.FirstOrDefault();
+            if (first != null)
+            {
+                return first.Item2.GetClient();
+            }
+            return null;
         }
 
         /// <summary>
@@ -48,6 +84,22 @@ public void Add(string host)
             Add(host, DefaultPort);
         }
 
+        /// <summary>
+        /// Add host mapping for the internal IP returned by Sentinel to the external IP
+        /// </summary>
+        /// <param name="hostMapping">Dictionary of sentinel host mapping between internal and external IPs</param>
+        public void AddHostMapping(Dictionary<string, string> hostMapping)
+        {
+            _hostMapping = hostMapping;
+        }
+
+        private string MapHost(string host)
+        {
+            if (_hostMapping != null && _hostMapping.ContainsKey(host))
+                return _hostMapping[host];
+            return host;
+        }
+
         /// <summary>
         /// Add a new sentinel host
         /// </summary>
@@ -79,6 +131,14 @@ public string Connect(string masterName, int timeout = 200)
                 throw new IOException("Could not connect to sentinel or master");
 
             _redisClient.ReconnectAttempts = 0;
+            if(!_pools.Any(c=>c.Item1 == sentinel))
+                _pools.AddFirst(Tuple.Create(sentinel, new RedisConnectionPool(_redisClient.Host, _redisClient.Port, NUMBER_OF_CONNECTIONS)));
+            else
+            {
+                var pool = _pools.Where(c => c.Item1 == sentinel).First();
+                _pools.Remove(pool);
+                _pools.AddFirst(pool);
+            }
             return sentinel;
         }
 
@@ -137,7 +197,7 @@ string SetMaster(string name, int timeout)
                     if (master == null)
                         continue;
 
-                    _redisClient = new RedisClient(master.Item1, master.Item2);
+                    _redisClient = new RedisClient(MapHost(master.Item1), master.Item2);
                     _redisClient.Connected += OnConnectionConnected;
                     if (!_redisClient.Connect(timeout))
                         continue;

CSRedis/Types.cs

@@ -403,12 +403,26 @@ public RedisServerInfo(SerializationInfo info, StreamingContext context)
             Port = info.GetInt32("port");
             RunId = info.GetString("runid");
             Flags = info.GetString("flags").Split(',');
-            PendingCommands = info.GetInt64("pending-commands");
+            PendingCommands = Exists(info, "pending-commands")? info.GetInt64("pending-commands"): info.GetInt64("link-pending-commands");
             LastOkPingReply = info.GetInt64("last-ok-ping-reply");
             LastPingReply = info.GetInt64("last-ping-reply");
             DownAfterMilliseconds = info.GetInt64("down-after-milliseconds");
         }
 
+        /// <summary>
+        /// Check if key exists in SerializationInfo
+        /// </summary>
+        /// <param name="info">SerializationInfo object</param>
+        /// <param name="key">The key to check</param>
+        /// <returns>Return true if key exists in SerializationInfo object</returns>
+        protected static bool Exists(SerializationInfo info, string key)
+        {
+            foreach(var entry in info)
+                if (entry.Name == key)
+                    return true;
+            return false;
+        }
+
         /// <summary>
         /// Get or set Redis server name
         /// </summary>
@@ -618,7 +632,8 @@ public class RedisSentinelInfo : RedisServerInfo
         public RedisSentinelInfo(SerializationInfo info, StreamingContext context)
             : base(info, context)
         {
-            SDownTime = info.GetInt64("s-down-time");
+            if(Exists(info, "s-down-time"))
+                SDownTime = info.GetInt64("s-down-time");
             LastHelloMessage = info.GetInt64("last-hello-message");
             VotedLeader = info.GetString("voted-leader");
             VotedLeaderEpoch = info.GetInt64("voted-leader-epoch");