Orchard详解--第八篇 拓展模块及引用的预处理

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  从上一篇可以看出Orchard在处理拓展模块时主要有两个组件,一个是Folder另一个是Loader,前者用于搜索后者用于加载。
  其中Folder一共有三个:Module Folder、Core Folder、ThemeFolder。Loader有引用加载器(Referenced Module Loader)、核心模块加载器(Core Module Loader)、预编译模块加载器(Precompiled Module Loader)、动态模块加载器(Dynamic Module Loader)。它们在代码里可以看到,在创建容器时对与Folder和Loader的注册:

 1               builder.RegisterType<ExtensionLoaderCoordinator>().As<IExtensionLoaderCoordinator>().SingleInstance();
 2                         builder.RegisterType<ExtensionMonitoringCoordinator>().As<IExtensionMonitoringCoordinator>().SingleInstance();
 3                         builder.RegisterType<ExtensionManager>().As<IExtensionManager>().SingleInstance();
 4                         {
 5                             builder.RegisterType<ExtensionHarvester>().As<IExtensionHarvester>().SingleInstance();
 6                             builder.RegisterType<ModuleFolders>().As<IExtensionFolders>().SingleInstance()
 7                                 .WithParameter(new NamedParameter("paths", extensionLocations.ModuleLocations));
 8                             builder.RegisterType<CoreModuleFolders>().As<IExtensionFolders>().SingleInstance()
 9                                 .WithParameter(new NamedParameter("paths", extensionLocations.CoreLocations));
10                             builder.RegisterType<ThemeFolders>().As<IExtensionFolders>().SingleInstance()
11                                 .WithParameter(new NamedParameter("paths", extensionLocations.ThemeLocations));
12 
13                             builder.RegisterType<CoreExtensionLoader>().As<IExtensionLoader>().SingleInstance();
14                             builder.RegisterType<ReferencedExtensionLoader>().As<IExtensionLoader>().SingleInstance();
15                             builder.RegisterType<PrecompiledExtensionLoader>().As<IExtensionLoader>().SingleInstance();
16                             builder.RegisterType<DynamicExtensionLoader>().As<IExtensionLoader>().SingleInstance();
17                             builder.RegisterType<RawThemeExtensionLoader>().As<IExtensionLoader>().SingleInstance();
18                         }

  这里需要注意的是,除了以上的Loader外,这里还有一个Raw Theme Extension Loader。
  接下来看Folder是如何工作的:
  三个Folder的实现可以说是一致的,都是通过ExtensionHarvester去获取一个ExtensionDescriptior列表:

  

1      public IEnumerable<ExtensionDescriptor> AvailableExtensions() {
2             return _extensionHarvester.HarvestExtensions(_paths, DefaultExtensionTypes.Module, "Module.txt", false/*isManifestOptional*/);
3         }

  仅仅是路径和文件名称(Module.txt和Theme.txt)不同。所以可以这样说,模块和主题的搜索工作是通过ExtensionHarvester完成的。

 1     public IEnumerable<ExtensionDescriptor> HarvestExtensions(IEnumerable<string> paths, string extensionType, string manifestName, bool manifestIsOptional) {
 2             return paths
 3                 .SelectMany(path => HarvestExtensions(path, extensionType, manifestName, manifestIsOptional))
 4                 .ToList();
 5         }
 6         private IEnumerable<ExtensionDescriptor> HarvestExtensions(string path, string extensionType, string manifestName, bool manifestIsOptional) {
 7             string key = string.Format("{0}-{1}-{2}", path, manifestName, extensionType);
 8            return _cacheManager.Get(key, true, ctx => {
 9                 if (!DisableMonitoring) {
10                     Logger.Debug("Monitoring virtual path \\"{0}\\"", path);
11                     ctx.Monitor(_webSiteFolder.WhenPathChanges(path));
12                 }
13                 return AvailableExtensionsInFolder(path, extensionType, manifestName, manifestIsOptional).ToReadOnlyCollection();
14             });
15         }

  从上面代码可以看出Harvester内部还使用了缓存机制,以路径、文件名称和类型(模块还是主题)来作为关键字。它缓存的内容是当前目录下的一个拓展描述列表。
  描述信息包括:

 1     public string Location { get; set; }
 2         public string Id { get; set; }
 3         public string VirtualPath { get { return Location + "/" + Id; } }
 4         public string ExtensionType { get; set; }
 5         public string Name { get; set; }
 6         public string Path { get; set; }
 7         public string Description { get; set; }
 8         public string Version { get; set; }
 9         public string OrchardVersion { get; set; }
10         public string Author { get; set; }
11         public string WebSite { get; set; }
12         public string Tags { get; set; }
13         public string AntiForgery { get; set; }
14         public string Zones { get; set; }
15         public string BaseTheme { get; set; }
16         public string SessionState { get; set; }
17         public LifecycleStatus LifecycleStatus { get; set; }
18 
19         public IEnumerable<FeatureDescriptor> Features { get; set; }    
View Code

  功能描述信息包括:

1         public ExtensionDescriptor Extension { get; set; }
2         public string Id { get; set; }
3         public string Name { get; set; }
4         public string Description { get; set; }
5         public string Category { get; set; }
6         public int Priority { get; set; }
7         public IEnumerable<string> Dependencies { get; set; }    
View Code

  Harvester中的GetDescriptorForExtension和GetFeaturesForExtension两个方法分别用于通过Module.txt或Theme.txt文件来获取拓展描述和功能描述信息(此处暂未对功能描述信息的依赖列表赋值)。其中拓展会作为一个默认的功能。

  Loader
  当Folder完成描述信息的构建后,Loader将通过这些描述信息来探测和加载模块。以下是Loader的接口定义:

 1     public interface IExtensionLoader {
 2         int Order { get; }
 3         string Name { get; }
 4 
 5         IEnumerable<ExtensionReferenceProbeEntry> ProbeReferences(ExtensionDescriptor extensionDescriptor);
 6         Assembly LoadReference(DependencyReferenceDescriptor reference);
 7         void ReferenceActivated(ExtensionLoadingContext context, ExtensionReferenceProbeEntry referenceEntry);
 8         void ReferenceDeactivated(ExtensionLoadingContext context, ExtensionReferenceProbeEntry referenceEntry);
 9         bool IsCompatibleWithModuleReferences(ExtensionDescriptor extension, IEnumerable<ExtensionProbeEntry> references);
10 
11         ExtensionProbeEntry Probe(ExtensionDescriptor descriptor);
12         ExtensionEntry Load(ExtensionDescriptor descriptor);
13 
14         void ExtensionActivated(ExtensionLoadingContext ctx, ExtensionDescriptor extension);
15         void ExtensionDeactivated(ExtensionLoadingContext ctx, ExtensionDescriptor extension);
16         void ExtensionRemoved(ExtensionLoadingContext ctx, DependencyDescriptor dependency);
17 
18         void Monitor(ExtensionDescriptor extension, Action<IVolatileToken> monitor);
19 
20         /// <summary>
21         /// Return a list of references required to compile a component (e.g. a Razor or WebForm view)
22         /// depending on the given module. 
23         /// Each reference can either be an assembly name or a file to pass to the 
24         /// IBuildManager.GetCompiledAssembly() method (e.g. a module .csproj project file).
25         /// </summary>
26         IEnumerable<ExtensionCompilationReference> GetCompilationReferences(DependencyDescriptor dependency);
27         /// <summary>
28         /// Return the list of dependencies (as virtual path) of the given module.
29         /// If any of the dependency returned in the list is updated, a component depending 
30         /// on the assembly produced for the module must be re-compiled.
31         /// For example, Razor or WebForms views needs to be recompiled when a dependency of a module changes.
32         /// </summary>
33         IEnumerable<string> GetVirtualPathDependencies(DependencyDescriptor dependency);
34     }

  从上面接口可以看到Loader有很多方法,它们具有什么功能?
  根据接口,可以将其方法分为以下几类:
  ● 拓展模块:
    ○ 探测:ExtensionProbeEntry Probe(ExtensionDescriptor descriptor);
    ○ 加载:ExtensionEntry Load(ExtensionDescriptor descriptor);
  ● 模块引用:
    ○ 探测:IEnumerable<ExtensionReferenceProbeEntry> ProbeReferences(ExtensionDescriptor extensionDescriptor);
    ○ 加载:Assembly LoadReference(DependencyReferenceDescriptor reference);
  ● 激活与停用:
    ○ 模块激活:void ExtensionActivated(ExtensionLoadingContext ctx, ExtensionDescriptor extension);
    ○ 模块停用:void ExtensionDeactivated(ExtensionLoadingContext ctx, ExtensionDescriptor extension);
    ○ 模块删除:void ExtensionRemoved(ExtensionLoadingContext ctx, DependencyDescriptor dependency);
    ○ 引用激活:void ReferenceActivated(ExtensionLoadingContext context, ExtensionReferenceProbeEntry referenceEntry);
    ○ 引用停用:void ReferenceDeactivated(ExtensionLoadingContext context, ExtensionReferenceProbeEntry referenceEntry);
  ● 监控:void Monitor(ExtensionDescriptor extension, Action<IVolatileToken> monitor);
  ● 编译需要的引用:IEnumerable<ExtensionCompilationReference> GetCompilationReferences(DependencyDescriptor dependency);
  ● 依赖路径支持:IEnumerable<string> GetVirtualPathDependencies(DependencyDescriptor dependency);  

  按照上面的分类,可以大致猜测Loader的使用过程:探测(模块和引用)---->加载(模块和引用)----->激活引用----->激活模块。然后其它接口用于管理拓展的启用和停用,以及编译时的一些辅助。

  从前一篇文章告诉我们的是Orchard的模块激活是以"Module.txt"文件作为输入然后输出一个System.Type的列表。之前通过Folder已经搜索了所有相关目录,解析每一个目录下的Module.txt或Theme.txt文件,生成了一个Extension Descriptor对象列表。
  现在Orchard将通过这些对象使用Loader来探测实际模块以及实际引用的相关信息:
  先放上代码(位于ExtensionLoaderCoordinator类型的CreateLoadingContext方法):

 1        Logger.Information("Probing extensions");
 2             var availableExtensionsProbes1 = _parallelCacheContext
 3                 .RunInParallel(availableExtensions, extension => 
 4                     _loaders.Select(loader => loader.Probe(extension)).Where(entry => entry != null).ToArray())
 5                 .SelectMany(entries => entries)
 6                 .GroupBy(entry => entry.Descriptor.Id);
 7 
 8             var availableExtensionsProbes = _parallelCacheContext
 9                 .RunInParallel(availableExtensionsProbes1, g =>
10                     new { Id = g.Key, Entries = SortExtensionProbeEntries(g, virtualPathModficationDates)})
11                 .ToDictionary(g => g.Id, g => g.Entries, StringComparer.OrdinalIgnoreCase);
12             Logger.Information("Done probing extensions");
13 
14             var deletedDependencies = previousDependencies
15                 .Where(e => !availableExtensions.Any(e2 => StringComparer.OrdinalIgnoreCase.Equals(e2.Id, e.Name)))
16                 .ToList();
17 
18             // Collect references for all modules
19             Logger.Information("Probing extension references");
20             var references = _parallelCacheContext
21                 .RunInParallel(availableExtensions, extension => _loaders.SelectMany(loader => loader.ProbeReferences(extension)).ToList())
22                 .SelectMany(entries => entries)
23                 .ToList();
24             Logger.Information("Done probing extension references");

  从上面代码可以看到它做了三件事:1、探测所有的拓展信息。2、根据路径修改时间对探测信息进行排序。3、探测所有引用信息。

探测拓展信息:

1 .RunInParallel(availableExtensions, extension => 
2                     _loaders.Select(loader => loader.Probe(extension)).Where(entry => entry != null).ToArray())

  根据代码可以看出,对于每一个可用拓展,需要通过所有loader的探测:

  1. CoreExtensionLoader:很直接的判断是否来至于Core目录下,然后直接组建ExtensionProbeEntry。

 1     public override ExtensionProbeEntry Probe(ExtensionDescriptor descriptor) {
 2             if (Disabled)
 3                 return null;
 4 
 5             if (descriptor.Location == "~/Core") {
 6                 return new ExtensionProbeEntry {
 7                     Descriptor = descriptor,
 8                     Loader = this,
 9                     Priority = 100, // Higher priority because assemblies in ~/bin always take precedence
10                     VirtualPath = "~/Core/" + descriptor.Id,
11                     VirtualPathDependencies = Enumerable.Empty<string>(),
12                 };
13             }
14             return null;
15         }

    2. PrecompiledExtensionLoader:根据Id(模块名称)获取程序集文件路径,并组建ExtensionProbeEntry。它的依赖列表也是当前程序集。

 1 ...
 2        Logger.Information("Probing for module \'{0}\'", descriptor.Id);
 3 
 4             var assemblyPath = GetAssemblyPath(descriptor);
 5             if (assemblyPath == null)
 6                 return null;
 7 
 8             var result = new ExtensionProbeEntry {
 9                 Descriptor = descriptor,
10                 Loader = this,
11                 VirtualPath = assemblyPath,
12                 VirtualPathDependencies = new[] { assemblyPath },
13             };
14 
15             Logger.Information("Done probing for module \'{0}\'", descriptor.Id);
16 ...

    3. DynamicExtensionLoader:与PrecompiledExtensionLoader相似,只不过这里获取的是模块的csproj文件。但是这里要注意的是它的依赖信息通过GetDependencies方法获取了相关的文件信息。

 1         Logger.Information("Probing for module \'{0}\'", descriptor.Id);
 2 
 3             string projectPath = GetProjectPath(descriptor);
 4             if (projectPath == null)
 5                 return null;
 6 
 7             var result = new ExtensionProbeEntry {
 8                 Descriptor = descriptor,
 9                 Loader = this,
10                 VirtualPath = projectPath,
11                 VirtualPathDependencies = GetDependencies(projectPath).ToList(),
12             };
13 
14             Logger.Information("Done probing for module \'{0}\'", descriptor.Id);    
15 ---
16  public ProjectFileDescriptor Parse(TextReader reader) {
17             var document = XDocument.Load(XmlReader.Create(reader));
18             return new ProjectFileDescriptor {
19                 AssemblyName = GetAssemblyName(document),
20                 SourceFilenames = GetSourceFilenames(document).ToArray(),
21                 References = GetReferences(document).ToArray()
22             };
23         }
24 private static string GetAssemblyName(XDocument document) {
25             return document
26                 .Elements(ns("Project"))
27                 .Elements(ns("PropertyGroup"))
28                 .Elements(ns("AssemblyName"))
29                 .Single()
30                 .Value;
31         }
32 
33         private static IEnumerable<string> GetSourceFilenames(XDocument document) {
34             return document
35                 .Elements(ns("Project"))
36                 .Elements(ns("ItemGroup"))
37                 .Elements(ns("Compile"))
38                 .Attributes("Include")
39                 .Select(c => c.Value);
40         }
41 
42         private static IEnumerable<ReferenceDescriptor> GetReferences(XDocument document) {
43             var assemblyReferences = document
44                 .Elements(ns("Project"))
45                 .Elements(ns("ItemGroup"))
46                 .Elements(ns("Reference"))
47                 .Where(c => c.Attribute("Include") != null)
48                 .Select(c => {
49                             string path = null;
50                             XElement attribute = c.Elements(ns("HintPath")).FirstOrDefault();
51                             if (attribute != null) {
52                                 path = attribute.Value;
53                             }
54 
55                             return new ReferenceDescriptor {
56                                 SimpleName = ExtractAssemblyName(c.Attribute("Include").Value),
57                                 FullName = c.Attribute("Include").Value,
58                                 Path = path,
59                                 ReferenceType = ReferenceType.Library
60                             };
61                         });
62 
63             var projectReferences = document
64                 .Elements(ns("Project"))
65                 .Elements(ns("ItemGroup"))
66                 .Elements(ns("ProjectReference"))
67                 .Attributes("Include")
68                 .Select(c => new ReferenceDescriptor {
69                     SimpleName = Path.GetFileNameWithoutExtension(c.Value),
70                     FullName = Path.GetFileNameWithoutExtension(c.Value),
71                     Path = c.Value,
72                     ReferenceType = ReferenceType.Project
73                 });
74 
75             return assemblyReferences.Union(projectReferences);
76         }
View Code

  获取依赖信息,实际上就是解析csproj这个xml文件。

    4. RawThemeExtensionLoader:这个Loader比较特殊,它用于加载~/themes目录下没有代码的主题。如果存在csproj和bin目录下的程序集都会被忽略。

 1        // Temporary - theme without own project should be under ~/themes
 2             if (descriptor.Location.StartsWith("~/Themes",StringComparison.InvariantCultureIgnoreCase)) {
 3                 string projectPath = _virtualPathProvider.Combine(descriptor.Location, descriptor.Id,
 4                                            descriptor.Id + ".csproj");
 5 
 6                 // ignore themes including a .csproj in this loader
 7                 if ( _virtualPathProvider.FileExists(projectPath) ) {
 8                     return null;
 9                 }
10 
11                 var assemblyPath = _virtualPathProvider.Combine(descriptor.Location, descriptor.Id, "bin",
12                                                 descriptor.Id + ".dll");
13 
14                 // ignore themes with /bin in this loader
15                 if ( _virtualPathProvider.FileExists(assemblyPath) )
16                     return null;
17 
18                 return new ExtensionProbeEntry {
19                     Descriptor = descriptor,
20                     Loader = this,
21                     VirtualPath = descriptor.VirtualPath,
22                     VirtualPathDependencies = Enumerable.Empty<string>(),
23                 };
24             }

    5. ReferencedExtensionLoader:引用拓展比较特殊,因为引用拓展是直接被根项目引用的模块项目,这些模块当根项目编译时,它们也会被编译并放置到根项目的bin目录下。

 1           var assembly = _buildManager.GetReferencedAssembly(descriptor.Id);
 2             if (assembly == null)
 3                 return null;
 4 
 5             var assemblyPath = _virtualPathProvider.Combine("~/bin", descriptor.Id + ".dll");
 6 
 7             return new ExtensionProbeEntry {
 8                 Descriptor = descriptor,
 9                 Loader = this,
10                 Priority = 100, // Higher priority because assemblies in ~/bin always take precedence
11                 VirtualPath = assemblyPath,
12                 VirtualPathDependencies = new[] { assemblyPath },
13             };

注:这里BulidManager中是通过一个DefaultAssemblyLoader来加载程序集的,DefaultAssemblyLoader类型自身维护了一个ConcurrentDictionary<string, Assembly> _loadedAssemblies字典,用于通过程序集的Short Name来存取程序集,如果程序集不存在时就通过程序集的Full Name、Short Name甚至通过程序集解析器来解析出程序集的名称,最后通过这些名称依次通过.net的Assembly调用Load(name)的方法加载返回并对结果进行缓存。
Orchard中有三种名称解析器:AppDomainAssemblyNameResolver、OrchardFrameworkAssemblyNameResolver以及GacAssemblyNameResolver。 它们分别从AppDomain、OrchardFramework依赖的DefaultAssemblyLoader中以及.Net全局程序集中查找程序集。

  从上面的分析可知,它主要的操作是通过ExtensionDescriptor来获取对应模块的程序集路径和优先级,并以当前的加载器打包,以便后续用于加载对应程序集。最终ExtensionProbeEntry是以描述Id进行分组的,意味这同一个拓展存在多个探测实体(来自于不同Loader,主要是有不同的优先级以及路径修改时间)。

探测信息排序:

  这里主要是将上面获取的ExtensionProbeEntry,针对每一个Key(即ExtensionDescriptor.Id)通过优先级来分组,然后取出优先级最高的组,如果改组中存在多个项(如预编译加载器和动态加载器都探测到相应模块,且它们优先级一致)时,根据它们依赖路径的最新修改时间再次进行排序(上面创建ExtensionProbeEntry时VirtualPathDependencies一般为程序集路径,但是动态加载器是所有依赖文件路径,句话说只要任意文件的修改日期大于编译库的信息,那么动态加载器对应的探测实体就会排在前面优先使用)。