CS中缓存对性能的优化起了非常大的作用,今天做一次深入的研究。经过大致的代码浏览发现CS中的缓存分为2种:一种采用System.Web.Caching,另一种采用HttpContext.Items(由于CS大量的采用服务器端控件没有使用页面级的缓存)。
首先研究一下System.web.Caching.Cache的使用
在CommunityServerComponents项目中发现了CommunityServer.Components.CSCache,查看一下代码
private CSCache(){}
//>> Based on Factor = 5 default value
publicstaticreadonlyint DayFactor = 17280;
publicstaticreadonlyint HourFactor = 720;
publicstaticreadonlyint MinuteFactor = 12;
privatestaticreadonly Cache _cache;
privatestaticint Factor = 5;
publicstaticvoid ReSetFactor(int cacheFactor)
{
Factor = cacheFactor;
}
///
/// Static initializer should ensure we only have to look up the current cache
/// instance once.
///
static CSCache()
{
HttpContext context = HttpContext.Current;
if(context != null)
{
_cache = context.Cache;
}
else
{
_cache = HttpRuntime.Cache;
}
}
发现其实是对System.Web.Caching.Cache作了一个封装(在CS中这样的例子比比皆是如:CSContext),主要实现了一下功能:
1、插入:Insert、MicroInsert(插入生存周期短的缓存项目)、Max(插入生存周期很长的缓存项目,在系统运行期间永久缓存)
2、获取:Get
3、移除:Remove、RemoveByPattern
4、全部清除:Clear
另外大家看一下“privatestaticint Factor = 5;”,如果希望不用缓存则直接设置为Factor=0即可,如果希望延长缓存生存周期则适当调大Factor值,也可以在CommunityServer.config中修改“cacheFactor”的数值。
2、获取:Get
3、移除:Remove、RemoveByPattern
4、全部清除:Clear
另外大家看一下“privatestaticint Factor = 5;”,如果希望不用缓存则直接设置为Factor=0即可,如果希望延长缓存生存周期则适当调大Factor值,也可以在CommunityServer.config中修改“cacheFactor”的数值。
在解决方案中搜索一下“CSCache”,会发现有63个文件,分析一下缓存内容主要有2种类型:配置文件及从数据库读取的实体。
一个是配置文件信息(例如:CommunityServer.Configuration.CSConfiguration、CommunityServer.Galleries.Components.GalleryConfiguration、CommunityServer.Blogs.Components.WeblogConfiguration等)
例如CommunityServer.Configuration.CSConfiguration
例如CommunityServer.Configuration.CSConfiguration
publicstatic CSConfiguration GetConfig()
{
CSConfiguration config = CSCache.Get(CacheKey) as CSConfiguration;
if(config == null)
{
string path;
if(HttpContext.Current != null)
path = HttpContext.Current.Server.MapPath("~/communityserver.config");
else
path = Directory.GetCurrentDirectory() + Path.DirectorySeparatorChar + "communityserver.config";
XmlDocument doc = new XmlDocument();
doc.Load(path);
config = new CSConfiguration(doc);
CSCache.Max(CacheKey,config,new CacheDependency(path));
CSCache.ReSetFactor(config.CacheFactor);
}
return config;
}
publicstatic CSConfiguration GetConfig()
{
CSConfiguration config = CSCache.Get(CacheKey) as CSConfiguration;
if(config == null)
{
string path;
if(HttpContext.Current != null)
path = HttpContext.Current.Server.MapPath("~/communityserver.config");
else
path = Directory.GetCurrentDirectory() + Path.DirectorySeparatorChar + "communityserver.config";
XmlDocument doc = new XmlDocument();
doc.Load(path);
config = new CSConfiguration(doc);
CSCache.Max(CacheKey,config,new CacheDependency(path));
CSCache.ReSetFactor(config.CacheFactor);
}
return config;
}
可以看到对communityserver.config的配置信息在第一次使用时从配置文件中读取出来并加入采用CSCache.Max()永久缓存,其失效策略为communityserver.config文件的更改。回顾一下,System.Web.Caching.Cache的失效策略一般有三种情况:文件的更改、缓存中其他缓存内容的更改、定义失效时间。GalleryConfiguration及WeblogConfiguration内的缓存失效策略是第2种情况的一个示例
publicstatic WeblogConfiguration Instance()
{
string cacheKey = "WeblogConfiguration";
WeblogConfiguration config = CSCache.Get(cacheKey) as WeblogConfiguration;
if(config == null)
{
XmlNode node = CSConfiguration.GetConfig().GetConfigSection("CommunityServer/Weblog");
config = new WeblogConfiguration();
...
CacheDependency dep = new CacheDependency(null, newstring[]);
CSCache.Insert(cacheKey, config, dep);
}
return config;
}
另一种是数据库实体的缓存,以CommunityServer.Discussions.Components.Posts为例
publicstatic PostSet GetPosts(int postID, int pageIndex, int pageSize, int sortBy, int sortOrder)
{
PostSet postSet;
CSContext csContext = CSContext.Current;
string key = "Forum-Posts::P:-PI:-PS:-SB:-SO:";
string postCollectionKey = string.Format(key,postID,pageIndex,pageSize, sortBy, sortOrder);
// Attempt to retrieve from Cache
postSet = CSCache.Get(postCollectionKey) as PostSet; // forumContext.Context.Cache[postCollectionKey];
if (postSet == null) {
// Create Instance of the CommonDataProvider
ForumDataProvider dp = ForumDataProvider.Instance();
postSet = dp.GetPosts(postID, pageIndex, pageSize, sortBy, sortOrder, CSContext.Current.User.UserID, true);
CSCache.Insert(postCollectionKey,postSet,6);
}
return postSet;
}
GetPosts()首先从缓存中读取postSet = CSCache.Get(postCollectionKey) as PostSet;
如果缓存中不存在则从数据库中读取并放入缓存(缓存失效策略为定义的时间段),这是CS减少数据库连接次数最有效的方式。另外其缓存key值的设置规则也是非常值得学习的。
如果缓存中不存在则从数据库中读取并放入缓存(缓存失效策略为定义的时间段),这是CS减少数据库连接次数最有效的方式。另外其缓存key值的设置规则也是非常值得学习的。
然后研究一下HttpContext.Items的使用
publicstatic WeblogConfiguration Instance()
{
string cacheKey = "WeblogConfiguration";
WeblogConfiguration config = CSCache.Get(cacheKey) as WeblogConfiguration;
if(config == null)
{
XmlNode node = CSConfiguration.GetConfig().GetConfigSection("CommunityServer/Weblog");
config = new WeblogConfiguration();
...
CacheDependency dep = new CacheDependency(null, newstring[]);
CSCache.Insert(cacheKey, config, dep);
}
return config;
}
另一种是数据库实体的缓存,以CommunityServer.Discussions.Components.Posts为例
publicstatic PostSet GetPosts(int postID, int pageIndex, int pageSize, int sortBy, int sortOrder)
{
PostSet postSet;
CSContext csContext = CSContext.Current;
string key = "Forum-Posts::P:-PI:-PS:-SB:-SO:";
string postCollectionKey = string.Format(key,postID,pageIndex,pageSize, sortBy, sortOrder);
// Attempt to retrieve from Cache
postSet = CSCache.Get(postCollectionKey) as PostSet; // forumContext.Context.Cache[postCollectionKey];
if (postSet == null) {
// Create Instance of the CommonDataProvider
ForumDataProvider dp = ForumDataProvider.Instance();
postSet = dp.GetPosts(postID, pageIndex, pageSize, sortBy, sortOrder, CSContext.Current.User.UserID, true);
CSCache.Insert(postCollectionKey,postSet,6);
}