nopCommerce 数据缓存

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。

  1. namespace Nop.Core.Caching
    {
    /// <summary>
    /// Cache manager interface
    /// </summary>
    public interface ICacheManager
    {
    /// <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>(string 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>
    void Set(string key, object data, int cacheTime);
    /// <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(string key);
    /// <summary>
    /// Removes the value with the specified key from the cache
    /// </summary>
    /// <param name="key">/key</param>
    void Remove(string key);
    /// <summary>
    /// Removes items by pattern
    /// </summary>
    /// <param name="pattern">pattern</param>
    void RemoveByPattern(string pattern);
    /// <summary>
    /// Clear all cache data
    /// </summary>
    void Clear();
    }
    }
    二、Nop.Core.Caching.MemoryCacheManager 接口ICacheManager具体实现是在类Nop.Core.Caching.MemoryCacheManager: using System;
    using System.Collections.Generic;
    using System.Runtime.Caching;
    using System.Text.RegularExpressions;
    namespace Nop.Core.Caching
    {
    /// <summary>
    /// Represents a manager for caching between HTTP requests (long term caching)
    /// </summary>
    public partial class MemoryCacheManager : ICacheManager
    {
    protected ObjectCache Cache
    {
    get
    {
    return MemoryCache.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>(string key)
    {
    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, int cacheTime)
    {
    if (data == null)
    return;
    var policy = new CacheItemPolicy();
    policy.AbsoluteExpiration = DateTime.Now + TimeSpan.FromMinutes(cacheTime);
    Cache.Add(new CacheItem(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(string key)
    {
    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(string key)
    {
    Cache.Remove(key);
    }
    /// <summary>
    /// Removes items by pattern
    /// </summary>
    /// <param name="pattern">pattern</param>
    public virtual void RemoveByPattern(string pattern)
    {
    var regex = new Regex(pattern, RegexOptions.Singleline | RegexOptions.Compiled | RegexOptions.IgnoreCase);
    var keysToRemove = new List<String>();
    foreach (var item in Cache)
    if (regex.IsMatch(item.Key))
    keysToRemove.Add(item.Key);
    foreach (string key in keysToRemove)
    {
    Remove(key);
    }
    }
    /// <summary>
    /// Clear all cache data
    /// </summary>
    public virtual void Clear()
    {
    foreach (var item in Cache)
    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:

  1. using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Text.RegularExpressions;
    using System.Web;
    namespace Nop.Core.Caching
    {
    /// <summary>
    /// Represents a manager for caching during an HTTP request (short term caching)
    /// </summary>
    public partial class PerRequestCacheManager : ICacheManager
    {
    private readonly HttpContextBase _context;
    /// <summary>
    /// Ctor
    /// </summary>
    /// <param name="context">Context</param>
    public PerRequestCacheManager(HttpContextBase context)
    {
    this._context = context;
    }
    /// <summary>
    /// Creates a new instance of the NopRequestCache class
    /// </summary>
    protected virtual IDictionary 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:

  1. //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:

  1. [ChildActionOnly]
    public ActionResult 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 = new BlogPostTagListModel();
    //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 in tags)
    model.Tags.Add(new BlogPostTagModel()
    {
    Name = tag.Name,
    BlogPostCount = tag.BlogPostCount
    });
    return model;
    });
    return PartialView(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:

  1. using System;
    namespace Nop.Core.Caching
    {
    /// <summary>
    /// Extensions
    /// </summary>
    public static class CacheExtensions
    {
    /// <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, , 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 > )
    cacheManager.Set(key, result, cacheTime);
    return result;
    }
    }
    }
    }

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

上一篇:centos7下安装docker(18.3docker日志---logging driver---fluentd)


下一篇:Javascript 原型注意事项