为了提高一个系统或网站的性能和IO吞吐量,我们一般都会采用缓存技术。当然NopCommerce也不例外,本文我们就来给大家分析一下nop中Cache缓存相关类设计、核心源码及实现原理。
一、Nop.Core.Caching.ICacheManager
Nop首先抽象出了一个缓存存储和读取相关管理接口Nop.Core.Caching.ICacheManager。
namespaceNop.Core.Caching { /// <summary> ///Cache manager interface /// </summary> public interfaceICacheManager { /// <summary> ///Gets or sets the value associated with the specified key. /// </summary> /// <typeparam name="T">Type</typeparam> /// <param name="key">The key of the value to get.</param> /// <returns>The value associated with the specified key.</returns> T Get<T>(stringkey); /// <summary> ///Adds the specified key and object to the cache. /// </summary> /// <param name="key">key</param> /// <param name="data">Data</param> /// <param name="cacheTime">Cache time</param> void Set(string key, object data, intcacheTime); /// <summary> ///Gets a value indicating whether the value associated with the specified key is cached /// </summary> /// <param name="key">key</param> /// <returns>Result</returns> bool IsSet(stringkey); /// <summary> ///Removes the value with the specified key from the cache /// </summary> /// <param name="key">/key</param> void Remove(stringkey); /// <summary> ///Removes items by pattern /// </summary> /// <param name="pattern">pattern</param> void RemoveByPattern(stringpattern); /// <summary> ///Clear all cache data /// </summary> voidClear(); } } 二、Nop.Core.Caching.MemoryCacheManager 接口ICacheManager具体实现是在类Nop.Core.Caching.MemoryCacheManager: usingSystem; usingSystem.Collections.Generic; usingSystem.Runtime.Caching; usingSystem.Text.RegularExpressions; namespaceNop.Core.Caching { /// <summary> ///Represents a manager for caching between HTTP requests (long term caching) /// </summary> public partial classMemoryCacheManager : ICacheManager { protectedObjectCache Cache { get{ returnMemoryCache.Default; } } /// <summary> ///Gets or sets the value associated with the specified key. /// </summary> /// <typeparam name="T">Type</typeparam> /// <param name="key">The key of the value to get.</param> /// <returns>The value associated with the specified key.</returns> public virtual T Get<T>(stringkey) { return(T)Cache[key]; } /// <summary> ///Adds the specified key and object to the cache. /// </summary> /// <param name="key">key</param> /// <param name="data">Data</param> /// <param name="cacheTime">Cache time</param> public virtual void Set(string key, object data, intcacheTime) { if (data == null) return; var policy = newCacheItemPolicy(); policy.AbsoluteExpiration = DateTime.Now +TimeSpan.FromMinutes(cacheTime); Cache.Add(newCacheItem(key, data), policy); } /// <summary> ///Gets a value indicating whether the value associated with the specified key is cached /// </summary> /// <param name="key">key</param> /// <returns>Result</returns> public virtual bool IsSet(stringkey) { return(Cache.Contains(key)); } /// <summary> ///Removes the value with the specified key from the cache /// </summary> /// <param name="key">/key</param> public virtual void Remove(stringkey) { Cache.Remove(key); } /// <summary> ///Removes items by pattern /// </summary> /// <param name="pattern">pattern</param> public virtual void RemoveByPattern(stringpattern) { var regex = new Regex(pattern, RegexOptions.Singleline | RegexOptions.Compiled |RegexOptions.IgnoreCase); var keysToRemove = new List<String>(); foreach (var item inCache) if(regex.IsMatch(item.Key)) keysToRemove.Add(item.Key); foreach (string key inkeysToRemove) { Remove(key); } } /// <summary> ///Clear all cache data /// </summary> public virtual voidClear() { foreach (var item inCache) Remove(item.Key); } } }
可以看到上面Nop的缓存数据是使用的的MemoryCache.Default来存储的,MemoryCache.Default是获取对默认 System.Runtime.Caching.MemoryCache 实例的引用,缓存的默认实例,也就是程序运行的内存中。
Nop除了提供了一个MemoryCacheManager,还有一个Nop.Core.Caching.PerRequestCacheManager类,它提供的是MemoryCacheManager相同的功能,不过它是把数据存在HttpContextBase.Items中,如下:
usingSystem; usingSystem.Collections; usingSystem.Collections.Generic; usingSystem.Text.RegularExpressions; usingSystem.Web; namespaceNop.Core.Caching { /// <summary> ///Represents a manager for caching during an HTTP request (short term caching) /// </summary> public partial classPerRequestCacheManager : ICacheManager { private readonlyHttpContextBase _context; /// <summary> ///Ctor /// </summary> /// <param name="context">Context</param> publicPerRequestCacheManager(HttpContextBase context) { this._context =context; } /// <summary> ///Creates a new instance of the NopRequestCache class /// </summary> protected virtualIDictionary GetItems() { if (_context != null) return_context.Items; return null; } //省略其它代码.... } }
三、缓存接口ICacheManager依赖注入
缓存接口ICacheManager使用了依赖注入,我们在Nop.Web.Framework.DependencyRegistrar类中就能找到对ICacheManager的注册代码:
//cache manager builder.RegisterType<MemoryCacheManager>().As<ICacheManager>().Named<ICacheManager>("nop_cache_static").SingleInstance(); builder.RegisterType<PerRequestCacheManager>().As<ICacheManager>().Named<ICacheManager>("nop_cache_per_request").InstancePerLifetimeScope(); //pass MemoryCacheManager as cacheManager (cache settings between requests) builder.RegisterType<ProductTagService>().As<IProductTagService>() .WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_static")) .InstancePerLifetimeScope(); //pass MemoryCacheManager as cacheManager (cache settings between requests) builder.RegisterType<PermissionService>().As<IPermissionService>() .WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_static")) .InstancePerLifetimeScope(); //pass MemoryCacheManager as cacheManager (cache settings between requests) builder.RegisterType<AclService>().As<IAclService>() .WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_static")) .InstancePerLifetimeScope(); //pass MemoryCacheManager as cacheManager (cache settings between requests) builder.RegisterType<PriceCalculationService>().As<IPriceCalculationService>() .WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_static")) .InstancePerLifetimeScope(); //pass MemoryCacheManager as cacheManager (cache settings between requests) builder.RegisterType<CustomerActivityService>().As<ICustomerActivityService>() .WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_static")) .InstancePerLifetimeScope();
上面最开始对接口ICacheManager两实现分别是MemoryCacheManager和PerRequestCacheManager并通过.Named来区分。Autofac高级特性--注册Named命名和Key Service服务
接下来可以配置不同的Service依赖不同的ICacheManager的实现:.WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_static"))或者.WithParameter(ResolvedParameter.ForNamed<ICacheManager>("nop_cache_per_request"))。
四、具体实例BlogController
下面我们来举例看一下怎么使用这个缓存的。我们就以Nop.Web.Controllers.BlogController的方法BlogTags为例:
[ChildActionOnly] publicActionResult BlogTags() { if (!_blogSettings.Enabled) return Content(""); var cacheKey = string.Format(ModelCacheEventConsumer.BLOG_TAGS_MODEL_KEY, _workContext.WorkingLanguage.Id, _storeContext.CurrentStore.Id); var cachedModel = _cacheManager.Get(cacheKey, () =>{ var model = newBlogPostTagListModel(); //get tags var tags =_blogService.GetAllBlogPostTags(_storeContext.CurrentStore.Id, _workContext.WorkingLanguage.Id) .OrderByDescending(x =>x.BlogPostCount) .Take(_blogSettings.NumberOfTags) .ToList(); //sorting tags = tags.OrderBy(x =>x.Name).ToList(); foreach (var tag intags) model.Tags.Add(newBlogPostTagModel() { Name =tag.Name, BlogPostCount =tag.BlogPostCount }); returnmodel; }); returnPartialView(cachedModel); }
上面var cachedModel = _cacheManager.Get就是从缓存中读取数据,_cacheManager的Get方法第二个参数是一个lambda表达式,可以传一个方法,这时我们就可以把数据的从数据库中的逻辑放在里面,注意:当第二次请求数据时,如果缓存中有数据,这个Lambda方法是不会执行的。为什么呢?我们可以选中_cacheManager的Get方法按F12进去看这个方法的实现就知道了:
usingSystem; namespaceNop.Core.Caching { /// <summary> ///Extensions /// </summary> public static classCacheExtensions { /// <summary> ///Get a cached item. If it's not in the cache yet, then load and cache it /// </summary> /// <typeparam name="T">Type</typeparam> /// <param name="cacheManager">Cache manager</param> /// <param name="key">Cache key</param> /// <param name="acquire">Function to load item if it's not in the cache yet</param> /// <returns>Cached item</returns> public static T Get<T>(this ICacheManager cacheManager, string key, Func<T>acquire) { return Get(cacheManager, key, 60, acquire); } /// <summary> ///Get a cached item. If it's not in the cache yet, then load and cache it /// </summary> /// <typeparam name="T">Type</typeparam> /// <param name="cacheManager">Cache manager</param> /// <param name="key">Cache key</param> /// <param name="cacheTime">Cache time in minutes (0 - do not cache)</param> /// <param name="acquire">Function to load item if it's not in the cache yet</param> /// <returns>Cached item</returns> public static T Get<T>(this ICacheManager cacheManager, string key, int cacheTime, Func<T>acquire) { if(cacheManager.IsSet(key)) { return cacheManager.Get<T>(key); } else{ var result =acquire(); if (cacheTime > 0) cacheManager.Set(key, result, cacheTime); returnresult; } } } }
可以看到其实上面_cacheManager.Get调用的是类型ICacheManager的一个扩展方法。第二个方法就可以知道,当缓存中有数据直接返回cacheManager.Get<T>(key),如果没有才进入else分支,执行参数的Lambda表达方式acquire()。
博客园的这篇文章写的不错:http://www.cnblogs.com/gusixing/archive/2012/04/12/2443799.html