这篇来讲如何利用memcached实现一级缓存,以及如何让一级缓存组件支持在企业库,memcached或者其它第三方实施方案之间的切换。memcached本人并没有太多经验,如果文中有说的不对的地方,还希望批评指出,且文中关于memcached的代码大多来自网络。
创建memcached实现类MemcachedWebCacheProvider,由它来继承缓存提供者接口IWebCacheProvider,主里memcached客户端我采用.NET memcached client library ,这个类库很久没有更新这过了,没有和java版同步,有部分功能目前没有实现。
1:初始化memcached服务,这段初始化代码在程序中保证执行一次就够,一般可以放在gloabl文件中,或者是设置一个静态变量来存储服务的状态。
- private void Setup()
- {
- String serverlist = { "127.0.0.1:11211" };
- this._pool = SockIOPool.GetInstance("default");
- this._pool.SetServers(serverlist); //设置服务器列
- //各服务器之间负载均衡的设置
- this._pool.SetWeights(new int { 1 });
- //socket pool设置
- this._pool.InitConnections = 5; //初始化时创建的连接数
- this._pool.MinConnections = 5; //最小连接数
- this._pool.MaxConnections = 250; //最大连接数
- //连接的最大空闲时间,下面设置为6个小时(单位ms),超过这个设置时间,连接会被释放掉
- this._pool.MaxIdle = 1000 * 60 * 60 * 6;
- //通讯的超时时间,下面设置为3秒(单位ms),.NET版本没有实现
- this._pool.SocketTimeout = 1000 * 3;
- //socket连接的超时时间,下面设置表示连接不超时,即一直保持连接状态
- this._pool.SocketConnectTimeout = 0;
- this._pool.Nagle = false; //是否对TCP/IP通讯使用Nalgle算法,.NET版本没有实现
- //维护线程的间隔激活时间,下面设置为60秒(单位s),设置为0表示不启用维护线程
- this._pool.MaintenanceSleep = 60;
- //socket单次任务的最大时间,超过这个时间socket会被强行中断掉(当前任务失败)
- this._pool.MaxBusy = 1000 * 10;
- this._pool.Initialize();
- }
2:获取一个memcached客户端。
- private MemcachedClient GetClient()
- {
- MemcachedClient client = new MemcachedClient();
- client.PoolName = "default";
- return client;
- }
3:根据memcached提供的功能实现IWebCacheProvider,代码就不贴了,大家可以自己去试试。
到此我们就利用memcached实现了一级缓存,由于.NET memcached client library 实现了分布式,我们只需要在多台服务器上安装上memcached服务,在初始化memcached代码中增加了服务器相关配置即可。String serverlist = { "127.0.0.1:11211" };
如何让一级缓存组件支持多实现方案之间的切换。
MyWebCacheServiceClient:客户端缓存组件实例,它来完成一级缓存与二级缓存之间的联系,以及根据配置文件来选择一级缓存的实施方案。
第一:CacheServiceMode,根据它就可以决定缓存是只缓存二级缓存还是两级都缓存。
1:LocalCacheOnlyMode,只启用web server上的二级缓存。
2:BufferedLCacheServerMode,即启用web server上的二级缓存也启用cache server上的缓存。
3:Off,关闭缓存功能。
第二:IWebCacheProvider service = this .GetPrimaryCacheProvider(hashKey);方式决定了一级缓存的实施方案。
- /// <summary>
- /// 获取一级缓存
- /// </summary>
- /// <param name="hashKey"></param>
- /// <param name="configFilePath"></param>
- /// <returns></returns>
- private IWebCacheProvider GetPrimaryCacheProvider(uint hashKey)
- {
- IWebCacheProvider provider = null;
- string cacheType = WebConfig.ChannelConfig["CacheType"].ToString().ToLower();
- switch (cacheType)
- {
- case "memcached":
- provider = WebCacheProviderFactory.GetMemcachedWebCacheProvider(configFilePath);
- break;
- case "entlib":
- provider = servicePool.GetServiceClient(hashKey) as IWebCacheProvider;
- break;
- }
- return provider;
- }
插入缓存的逻辑:原理就是根据配置文件中的CacheMode来完成缓存级别的判定以及一级缓存的方案。
- public void Insert(string key, object value, string region, string subRegion, CacheItemConfig cacheItemConfig)
- {
- if (string.IsNullOrEmpty(key) || value == null)
- return;
- //关闭模式,不使用缓存
- if (Options.CacheServiceMode == ECacheServiceMode.Off)
- {
- return;
- }
- else if (Options.CacheServiceMode == ECacheServiceMode.BufferedLCacheServerMode
- || Options.CacheServiceMode == ECacheServiceMode.LocalAndCacheServerAndSql
- || Options.CacheServiceMode == ECacheServiceMode.LocalCacheOnlyMode)
- {//使用带缓冲的模式
- if (Options.BufferType == ECacheDependencyType.SlidingTime)
- {
- SecondaryCacheProvider.Insert(key, value, region, subRegion, MyCacheItemPriority.Normal, Options.BufferSlidingTime);
- }
- else if (Options.BufferType == ECacheDependencyType.AbsoluteTime)
- {
- SecondaryCacheProvider.Insert(key, value, region, subRegion, MyCacheItemPriority.Normal, Options.BufferAbsoluteTime);
- }
- if (Options.CacheServiceMode == ECacheServiceMode.LocalCacheOnlyMode)
- {//只使用本地缓存
- return;
- }
- }
- checkKey(key);
- uint hashKey = hash(key);
- try
- {
- if (Options.CacheServiceMode == ECacheServiceMode.CacheServerMode
- || Options.CacheServiceMode == ECacheServiceMode.BufferedLCacheServerMode
- || Options.CacheServiceMode == ECacheServiceMode.CacheServerAndSql
- || Options.CacheServiceMode == ECacheServiceMode.LocalAndCacheServerAndSql)
- {//CacheServer模式使用Cache服务器保存Cache
- IWebCacheProvider service = this .GetPrimaryCacheProvider(hashKey);
- byte byteValue = SerializationHelper.SaveToBinaryBytes(value);
- var cachePriority = ModelConverter.ToRefClass(cacheItemConfig.CachePriority);
- if (cacheItemConfig.CacheType == ECacheDependencyType.AbsoluteTime)
- {
- AbsoluteTimeCacheDependency absTime = new AbsoluteTimeCacheDependency();
- absTime.AbsoluteTime = DateTime.Now.AddMinutes(cacheItemConfig.CacheTimeMinutes);
- service.Insert(key, byteValue, region, subRegion, cachePriority, absTime);
- }
- else if (cacheItemConfig.CacheType == ECacheDependencyType.SlidingTime)
- {
- SlidingTimeCacheDependency slTime = new SlidingTimeCacheDependency();
- slTime.SlidingTime = new TimeSpan(0, cacheItemConfig.CacheTimeMinutes, 0);
- service.Insert(key, byteValue, region, subRegion, cachePriority, slTime);
- }
- }
- }
- catch (Exception ex)
- {//出现异常,保存到数据库中
- servicePool.ReplaceServiceClient(hashKey);
- this.SendLogEmail(ex);
- }
- }
客户端调用代码:为了调用方便,创建一个CacheHelper来帮助完成:
- public class CacheHelper
- {
- /// <summary>
- /// 主分区
- /// </summary>
- public const string REGION = "MyBlog";
- /// <summary>
- /// 子分区
- /// </summary>
- public const string SUB_REGION = "default";
- public const string BlogListConfigKey = "BlogListConfigKey";
- #region 页面间数据传递
- /// <summary>
- /// 新增页面间传递数据到WebCache
- /// </summary>
- /// <returns>返回PageKeyID,用于页面间传递的键值</returns>
- public static string InsertPageParams(string configKey, object obj,string pageKey)
- {
- string result = null;
- MyWebCacheServiceClient cacheClient = CacheClientFactory.GetWebCacheServiceClient(REGION, SUB_REGION, configKey);
- cacheClient.Insert(
- MyWebCacheServiceClient.BuildKey(configKey,pageKey),
- obj,
- REGION,
- SUB_REGION);
- return result;
- }
- /// <summary>
- /// 从Cache里获取页面传递Cache
- /// </summary>
- /// <param name="key">FlightCacheKey里的常量</param>
- /// <param name="pageKeyID">页面传递的键值</param>
- public static object GetPageParams(string configKey, string pageKey)
- {
- object result = null;
- MyWebCacheServiceClient cacheClient = CacheClientFactory.GetWebCacheServiceClient(REGION,
- SUB_REGION, configKey);
- result = cacheClient.Get(
- MyWebCacheServiceClient.BuildKey(configKey, pageKey),
- REGION,
- SUB_REGION);
- return result;
- }
- #endregion
- }
两级缓存类结构图:
以上代码贴出来看起来有点乱,这里贴出网站两级缓存类结构图: