mcs/class/referencesource/System.Web.Extensions/ui/AssemblyCache.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="AssemblyCache.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 //------------------------------------------------------------------------------
   6
   7 namespace System.Web.UI {
   8     using System;
   9 using System.Collections;
  10 using System.Collections.Concurrent;
  11 using System.Collections.Generic;
  12 using System.Diagnostics;
  13 using System.Diagnostics.CodeAnalysis;
  14 using System.Reflection;
  15 using System.Web.Configuration;
  16 using System.Web.Script;
  17
  18     // Caches Assembly APIs to improve performance
  19     internal static class AssemblyCache {
  20         // PERF: Cache reference to System.Web.Extensions assembly. Use ScriptManager since it's guaranteed to be in S.W.E
  21         public static readonly Assembly SystemWebExtensions = typeof(ScriptManager).Assembly;
  22         public static readonly Assembly SystemWeb = typeof(Page).Assembly;
  23
  24         private static CompilationSection _compilationSection;
  25         internal static bool _useCompilationSection = true;
  26
  27         // Maps string (assembly name) to Assembly
  28         private static readonly Hashtable _assemblyCache = Hashtable.Synchronized(new Hashtable());
  29         // Maps assembly to Version
  30         // internal so it can be manipulated by the unit test suite
  31         internal static readonly Hashtable _versionCache = Hashtable.Synchronized(new Hashtable());
  32         // Maps an assembly to its ajax framework assembly attribute. If it doesn't have one, it maps it to a null value
  33         private static readonly ConcurrentDictionary<Assembly, AjaxFrameworkAssemblyAttribute> _ajaxAssemblyAttributeCache =
  34             new ConcurrentDictionary<Assembly, AjaxFrameworkAssemblyAttribute>();
  35
  36         private static CompilationSection CompilationSection {
  37             get {
  38                 if (_compilationSection == null) {
  39                     _compilationSection = RuntimeConfig.GetAppConfig().Compilation;
  40                 }
  41                 return _compilationSection;
  42             }
  43         }
  44
  45         public static Version GetVersion(Assembly assembly) {
  46             Debug.Assert(assembly != null);
  47             Version version = (Version)_versionCache[assembly];
  48             if (version == null) {
  49                 // use new AssemblyName() instead of assembly.GetName() so it works in medium trust
  50                 version = new AssemblyName(assembly.FullName).Version;
  51                 _versionCache[assembly] = version;
  52             }
  53             return version;
  54         }
  55
  56         public static Assembly Load(string assemblyName) {
  57             Debug.Assert(!String.IsNullOrEmpty(assemblyName));
  58             Assembly assembly = (Assembly)_assemblyCache[assemblyName];
  59             if (assembly == null) {
  60                 // _useCompilationSection must be set to false in a unit test environment since there
  61                 // is no http runtime, and therefore no trust level is set.
  62                 if (_useCompilationSection) {
  63                     assembly = CompilationSection.LoadAssembly(assemblyName, true);
  64                 }
  65                 else {
  66                     assembly = Assembly.Load(assemblyName);
  67                 }
  68                 _assemblyCache[assemblyName] = assembly;
  69             }
  70             return assembly;
  71         }
  72
  73         public static bool IsAjaxFrameworkAssembly(Assembly assembly) {
  74             return (GetAjaxFrameworkAssemblyAttribute(assembly) != null);
  75         }
  76
  77         public static AjaxFrameworkAssemblyAttribute GetAjaxFrameworkAssemblyAttribute(Assembly assembly) {
  78             Debug.Assert(assembly != null);
  79             AjaxFrameworkAssemblyAttribute ajaxFrameworkAssemblyAttribute;
  80             if (!_ajaxAssemblyAttributeCache.TryGetValue(assembly, out ajaxFrameworkAssemblyAttribute)) {
  81                  ajaxFrameworkAssemblyAttribute = SafeGetAjaxFrameworkAssemblyAttribute(assembly);
  82                 _ajaxAssemblyAttributeCache.TryAdd(assembly, ajaxFrameworkAssemblyAttribute);
  83             }
  84             return ajaxFrameworkAssemblyAttribute;
  85         }
  86
  87         [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "We do not want to throw from this method.")]
  88         internal static AjaxFrameworkAssemblyAttribute SafeGetAjaxFrameworkAssemblyAttribute(ICustomAttributeProvider attributeProvider) {
  89             try {
  90                 foreach (Attribute attribute in attributeProvider.GetCustomAttributes(inherit: false)) {
  91                     AjaxFrameworkAssemblyAttribute ajaxFrameworkAttribute = attribute as AjaxFrameworkAssemblyAttribute;
  92                     if (ajaxFrameworkAttribute != null) {
  93                         return ajaxFrameworkAttribute;
  94                     }
  95                 }
  96             }
  97             catch {
  98                 //
  99             }
 100             return null;
 101         }
 102     }
 103 }