Redis作為緩存服務器

 

　　1、ICache的Redis實現沒有放在'Framework.Cache/Logic'中。如果是以前，我會認為這樣不好。我會這樣做，'Framework.Cache'項目引用Redis項目或直接從Nuget安裝Redis，

把實現定義在‘Framework.Cache/Logic’中，這樣結構看起來很順眼，‘這算是高內聚么！！！’。不過自從接觸了IOC后，現在這樣的結構似乎也很合理，沒什么違和感。

這就好似把‘IRepository’和‘Repositories’，一個放在Domain，一個放在Infrastructure

　　2、當前比較穩定的Redis客戶端（開源的程序包）有ServiceStack.Redis 和 StackExchange.Redis。我都用了一下，ServiceStatck的

比較好用，不過我感覺后者的性能應該會稍好點

　　3、關於ServiceStack.Redis中的接口，IRedisClient，ICacheClient，IRedisTypedClient<T>，IEntityStore<T>，IEntityStore。

這些“亂七八糟”的接口和CRUD都有關系，中的有些方法看似好像是重復的，后續希望能整理出一篇結合源碼，理論點的文章

　　

一、Framework.Cache

接口ICache，定義緩存操作開放的方法

    public interface ICache
    {
        /// <summary>
        /// Gets all entries in the cache
        /// </summary>
        IEnumerable<KeyValuePair<string, object>> Entries { get; }

        /// <summary>
        /// Gets a cache item associated with the specified key or adds the item
        /// if it doesn't exist in the cache.
        /// </summary>
        /// <typeparam name="T">The type of the item to get or add</typeparam>
        /// <param name="key">The cache item key</param>
        /// <param name="baseMethod">Func which returns value to be added to the cache</param>
        /// <returns>Cached item value</returns>
        T Get<T>(string key, Func<T> baseMethod);

        /// <summary>
        /// Gets a cache item associated with the specified key or adds the item
        /// if it doesn't exist in the cache.
        /// </summary>
        /// <typeparam name="T">The type of the item to get or add</typeparam>
        /// <param name="key">The cache item key</param>
        /// <param name="baseMethod">Func which returns value to be added to the cache</param>
        /// <param name="cacheTime">Expiration time in minutes</param>
        /// <returns>Cached item value</returns>
        T Get<T>(string key, Func<T> baseMethod, int cacheTime);

        /// <summary>
        /// Gets a value indicating whether an item associated with the specified key exists in the cache
        /// </summary>
        /// <param name="key">key</param>
        /// <returns>Result</returns>
        bool Contains(string key);

        /// <summary>
        /// Removes the value with the specified key from the cache
        /// </summary>
        /// <param name="key">/key</param>
        void Remove(string key);
    }

 

二、基於‘ServiceStack.Redis’的緩存實現

public class SSRedisCache : ICache
    {
        private const string REGION_NAME = "$#SSRedisCache#$";
        private const int _DefaultCacheTime = 30;
        private readonly static object s_lock = new object();

        private IRedisClient GetClient()
        {
            return RedisManager.GetClient();
        }

        private IRedisClient GetReadOnlyClient()
        {
            return RedisManager.GetReadOnlyClient();
        }

        public IEnumerable<KeyValuePair<string, object>> Entries
        {
            get { throw new NotImplementedException(); }
        }

        public T Get<T>(string key, Func<T> baseMethod)
        {
            return Get<T>(key, baseMethod, _DefaultCacheTime);
        }

        public T Get<T>(string key, Func<T> baseMethod, int cacheTime)
        {
            using (var redisClient = GetClient())
            {
                key = BuildKey(key);

                if (redisClient.ContainsKey(key))
                {
                    return redisClient.Get<T>(key);
                }
                else
                {
                    lock (s_lock)
                    {
                        if (!redisClient.ContainsKey(key))
                        {
                            var value = baseMethod();
                            if (value != null) //請區別null與String.Empty
                            {
                                redisClient.Set<T>(key, value, TimeSpan.FromMinutes(cacheTime));
                                //redisClient.Save();
                            }
                            return value;
                        }
                        return redisClient.Get<T>(key);
                    }
                }
            }
        }

        public bool Contains(string key)
        {
            using (var redisClient = GetReadOnlyClient())
            {
                return redisClient.ContainsKey(BuildKey(key));
            }
        }

        public void Remove(string key)
        {
            using (var redisClient = GetClient())
            {
                redisClient.Remove(BuildKey(key));
            }
        }

        private string BuildKey(string key)
        {
            return string.IsNullOrEmpty(key) ? null : REGION_NAME + key;
        }

    }

 

三、基於‘StackExchange.Redis’的緩存實現

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="MsgPack.Cli" version="0.6.8" targetFramework="net45" />
  <package id="StackExchange.Redis" version="1.0.488" targetFramework="net45" />
  <package id="StackExchange.Redis.Extensions.Core" version="1.3.2.0" targetFramework="net45" />
  <package id="StackExchange.Redis.Extensions.MsgPack" version="1.3.2.0" targetFramework="net45" />
</packages>

public class SERedisCache : ICache
    {
        private const string REGION_NAME = "$#SERedisCache#$";
        private const int _DefaultCacheTime = 30;
        private readonly static object s_lock = new object();

        private StackExchangeRedisCacheClient GetClient()
        {
            return new StackExchangeRedisCacheClient(RedisServer.Connection, new MsgPackObjectSerializer());
        }

        public IEnumerable<KeyValuePair<string, object>> Entries
        {
            get { throw new NotImplementedException(); }
        }

        public T Get<T>(string key, Func<T> baseMethod)
        {
            return Get(key, baseMethod, _DefaultCacheTime);
        }

        public T Get<T>(string key, Func<T> baseMethod, int cacheTime)
        {
            using (var cacheClient = GetClient())
            {
                key = BuildKey(key);

                if (cacheClient.Exists(key))
                {
                    return cacheClient.Get<T>(key);
                }
                else
                {
                    lock (s_lock)
                    {
                        if (!cacheClient.Exists(key))
                        {
                            var value = baseMethod();
                            if (value != null) //請區別null與String.Empty
                            {
                                cacheClient.Add<T>(key, value, TimeSpan.FromMinutes(cacheTime));
                            }
                            return value;
                        }
                        return cacheClient.Get<T>(key);
                    }
                }
            }
        }

        public bool Contains(string key)
        {
            using (var cacheClient = GetClient())
            {
                return cacheClient.Exists(BuildKey(key));
            }
        }

        public void Remove(string key)
        {
            using (var cacheClient = GetClient())
            {
                cacheClient.Remove(BuildKey(key));
            }
        }

        private string BuildKey(string key)
        {
            return string.IsNullOrEmpty(key) ? null : REGION_NAME + key;
        }

    }

 

完整代碼（稍后） 會在另一篇文章關於Web API中附上