StackExchange.Redis 實現SetNx

　　今天有同事指出如何在StackExchange.Redis 實現Redis的原生命令。

 ConnectionMultiplexer redis = ConnectionMultiplexer.Connect(options);
            var db=redis.GetDatabase();
            bool flag = db.StringSet("InvQty222", "111", TimeSpan.FromSeconds(900), When.NotExists, CommandFlags.None);
            Console.WriteLine(flag);
            Console.ReadKey();
        }

　　 部分源碼如下：

   if (expiry == null || expiry.Value == TimeSpan.MaxValue)
            { // no expiry
                switch (when)
                {
                    case When.Always: return Message.Create(Database, flags, RedisCommand.SET, key, value);
                    case When.NotExists: return Message.Create(Database, flags, RedisCommand.SETNX, key, value);
                    case When.Exists: return Message.Create(Database, flags, RedisCommand.SET, key, value, RedisLiterals.XX);
                }
            }