path: root/mcs/class/System.Web/System.Web.Compilation/BuildManager.cs

//
// System.Web.Compilation.BuildManager
//
// Authors:
//	Chris Toshok (toshok@ximian.com)
//	Gonzalo Paniagua Javier (gonzalo@novell.com)
//      Marek Habersack (mhabersack@novell.com)
//
// (C) 2006-2008 Novell, Inc (http://www.novell.com)
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

#if NET_2_0

using System;
using System.CodeDom;
using System.CodeDom.Compiler;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using System.Text;
using System.Threading;
using System.Web;
using System.Web.Caching;
using System.Web.Configuration;
using System.Web.Hosting;
using System.Web.Util;

namespace System.Web.Compilation {
	public sealed class BuildManager {
		class BuildItem
		{
			public BuildProvider buildProvider;
			public AssemblyBuilder assemblyBuilder;
			public Type codeDomProviderType;
			public bool codeGenerated;
			public Assembly compiledAssembly;
			
			public CompilerParameters CompilerOptions {
				get {
					if (buildProvider == null)
						throw new HttpException ("No build provider.");
					return buildProvider.CodeCompilerType.CompilerParameters;
				}
			}

			public string VirtualPath {
				get {
					if (buildProvider == null)
						throw new HttpException ("No build provider.");
					return buildProvider.VirtualPath;
				}
			}

			public CodeCompileUnit CodeUnit {
				get {
					if (buildProvider == null)
						throw new HttpException ("No build provider.");
					return buildProvider.CodeUnit;
				}
			}
			
			public BuildItem (BuildProvider provider)
			{
				this.buildProvider = provider;
				if (provider != null)
					codeDomProviderType = GetCodeDomProviderType (provider);
			}

			public void SetCompiledAssembly (AssemblyBuilder assemblyBuilder, Assembly compiledAssembly)
			{
				if (this.compiledAssembly != null || this.assemblyBuilder == null || this.assemblyBuilder != assemblyBuilder)
					return;

				this.compiledAssembly = compiledAssembly;
			}
			
			public CodeDomProvider CreateCodeDomProvider ()
			{
				if (codeDomProviderType == null)
					throw new HttpException ("Unable to create compilation provider, no provider type given.");
				
				CodeDomProvider ret;

				try {
					ret = Activator.CreateInstance (codeDomProviderType) as CodeDomProvider;
				} catch (Exception ex) {
					throw new HttpException ("Failed to create compilation provider.", ex);
				}

				if (ret == null)
					throw new HttpException ("Unable to instantiate code DOM provider '" + codeDomProviderType + "'.");

				return ret;
			}

			public void GenerateCode ()
			{
				if (buildProvider == null)
					throw new HttpException ("Cannot generate code - missing build provider.");
				
				buildProvider.GenerateCode ();
				codeGenerated = true;
			}

			public void StoreCodeUnit ()
			{
				if (buildProvider == null)
					throw new HttpException ("Cannot generate code - missing build provider.");
				if (assemblyBuilder == null)
					throw new HttpException ("Cannot generate code - missing assembly builder.");

				buildProvider.GenerateCode (assemblyBuilder);
			}

			public override string ToString ()
			{
				string ret = "BuildItem [";
				string virtualPath = VirtualPath;
				
				if (!String.IsNullOrEmpty (virtualPath))
					ret += virtualPath;

				ret += "]";

				return ret;
			}
		}

		class BuildCacheItem
		{
			public string compiledCustomString;
			public Assembly assembly;
			public Type type;
			public string virtualPath;

			public BuildCacheItem (Assembly assembly, BuildProvider bp, CompilerResults results)
			{
				this.assembly = assembly;
				this.compiledCustomString = bp.GetCustomString (results);
				this.type = bp.GetGeneratedType (results);
				this.virtualPath = bp.VirtualPath;
			}
			
			public override string ToString ()
			{
				StringBuilder sb = new StringBuilder ("BuildCacheItem [");
				bool first = true;
				
				if (!String.IsNullOrEmpty (compiledCustomString)) {
					sb.Append ("compiledCustomString: " + compiledCustomString);
					first = false;
				}
				
				if (assembly != null) {
					sb.Append ((first ? "" : "; ") + "assembly: " + assembly.ToString ());
					first = false;
				}

				if (type != null) {
					sb.Append ((first ? "" : "; ") + "type: " + type.ToString ());
					first = false;
				}

				if (!String.IsNullOrEmpty (virtualPath)) {
					sb.Append ((first ? "" : "; ") + "virtualPath: " + virtualPath);
					first = false;
				}

				sb.Append ("]");
				
				return sb.ToString ();
			}
		}
		
		enum BuildKind {
			Unknown,
			Pages,
			NonPages,
			Application,
			Theme,
			Fake
		};

		internal const string FAKE_VIRTUAL_PATH_PREFIX = "/@@MonoFakeVirtualPath@@";
		const string BUILD_MANAGER_VIRTUAL_PATH_CACHE_PREFIX = "Build_Manager";
		static int BUILD_MANAGER_VIRTUAL_PATH_CACHE_PREFIX_LENGTH = BUILD_MANAGER_VIRTUAL_PATH_CACHE_PREFIX.Length;
		
		static object buildCacheLock = new object ();

		static Stack <BuildKind> recursiveBuilds = new Stack <BuildKind> ();
		
		//
		// Disabled - see comment at the end of BuildAssembly below
		//
		// static object buildCountLock = new object ();
		// static int buildCount = 0;
		
		static List<Assembly> AppCode_Assemblies = new List<Assembly>();
		static List<Assembly> TopLevel_Assemblies = new List<Assembly>();
		static bool haveResources;

		// The build cache which maps a virtual path to a build item with all the necessary
		// bits. 
		static Dictionary <string, BuildCacheItem> buildCache;

		// Maps the virtual path of a non-page build to the assembly that contains the
		// compiled type.
		static Dictionary <string, Assembly> nonPagesCache;
		
		static List <Assembly> referencedAssemblies = new List <Assembly> ();
		
		static Dictionary <string, object> compilationTickets;

		static Assembly globalAsaxAssembly;
		
		static Dictionary <string, BuildKind> knownFileTypes = new Dictionary <string, BuildKind> (StringComparer.OrdinalIgnoreCase) {
			{".aspx", BuildKind.Pages},
			{".asax", BuildKind.Application},
			{".ashx", BuildKind.NonPages},
			{".asmx", BuildKind.NonPages},
			{".ascx", BuildKind.NonPages},
			{".master", BuildKind.NonPages}
		};
		
		static BuildManager ()
		{
			IEqualityComparer <string> comparer;

			if (HttpRuntime.CaseInsensitive)
				comparer = StringComparer.CurrentCultureIgnoreCase;
			else
				comparer = StringComparer.CurrentCulture;

			buildCache = new Dictionary <string, BuildCacheItem> (comparer);
			nonPagesCache = new Dictionary <string, Assembly> (comparer);
			compilationTickets = new Dictionary <string, object> (comparer);
		}
		
		internal static void ThrowNoProviderException (string extension)
		{
			string msg = "No registered provider for extension '{0}'.";
			throw new HttpException (String.Format (msg, extension));
		}
		
		public static object CreateInstanceFromVirtualPath (string virtualPath, Type requiredBaseType)
		{
			// virtualPath + Exists done in GetCompiledType()
			if (requiredBaseType == null)
				throw new NullReferenceException (); // This is what MS does, but from somewhere else.

			// Get the Type.
			Type type = GetCompiledType (virtualPath);
			if (type == null)
				//throw new HttpException ("Instance creation failed for virtual
				//path '" + virtualPath + "'.");
				return null;
			
			if (!requiredBaseType.IsAssignableFrom (type)) {
				string msg = String.Format ("Type '{0}' does not inherit from '{1}'.",
								type.FullName, requiredBaseType.FullName);
				throw new HttpException (500, msg);
			}

			return Activator.CreateInstance (type, null);
		}

		public static ICollection GetReferencedAssemblies ()
		{
			List <Assembly> al = new List <Assembly> ();
			
			CompilationSection compConfig = WebConfigurationManager.GetSection ("system.web/compilation") as CompilationSection;
                        if (compConfig == null)
				return al;
			
                        bool addAssembliesInBin = false;
                        foreach (AssemblyInfo info in compConfig.Assemblies) {
                                if (info.Assembly == "*")
                                        addAssembliesInBin = true;
                                else
                                        LoadAssembly (info, al);
                        }

			foreach (Assembly topLevelAssembly in TopLevel_Assemblies)
				al.Add (topLevelAssembly);

			foreach (string assLocation in WebConfigurationManager.ExtraAssemblies)
				LoadAssembly (assLocation, al);

                        if (addAssembliesInBin)
				foreach (string s in HttpApplication.BinDirectoryAssemblies)
					LoadAssembly (s, al);

			lock (buildCacheLock) {
				foreach (Assembly asm in referencedAssemblies) {
					if (!al.Contains (asm))
						al.Add (asm);
				}

				if (globalAsaxAssembly != null)
					al.Add (globalAsaxAssembly);
			}
			
			return al;
		}

		static void LoadAssembly (string path, List <Assembly> al)
		{
			AddAssembly (Assembly.LoadFrom (path), al);
		}

		static void LoadAssembly (AssemblyInfo info, List <Assembly> al)
		{
			AddAssembly (Assembly.Load (info.Assembly), al);
		}

		static void AddAssembly (Assembly asm, List <Assembly> al)
		{
			if (al.Contains (asm))
				return;

			al.Add (asm);
		}
		
		[MonoTODO ("Not implemented, always returns null")]
		public static BuildDependencySet GetCachedBuildDependencySet (HttpContext context, string virtualPath)
		{
			return null; // null is ok here until we store the dependency set in the Cache.
		}

		internal static BuildProvider GetBuildProviderForPath (string virtualPath, bool throwOnMissing)
		{
			return GetBuildProviderForPath (virtualPath, null, throwOnMissing);
		}
		
		internal static BuildProvider GetBuildProviderForPath (string virtualPath, CompilationSection section, bool throwOnMissing)
		{
			string extension = VirtualPathUtility.GetExtension (virtualPath);
			CompilationSection c = section;

			if (c == null)
				c = WebConfigurationManager.GetSection ("system.web/compilation", virtualPath) as CompilationSection;
			
			if (c == null)
				if (throwOnMissing)
					ThrowNoProviderException (extension);
				else
					return null;
			
			BuildProviderCollection coll = c.BuildProviders;
			if (coll == null || coll.Count == 0)
				ThrowNoProviderException (extension);
			
			BuildProvider provider = coll.GetProviderForExtension (extension);
			if (provider == null)
				if (throwOnMissing)
					ThrowNoProviderException (extension);
				else
					return null;

			provider.SetVirtualPath (virtualPath);
			return provider;
		}

		static string GetAbsoluteVirtualPath (string virtualPath)
		{
			string vp;

			if (!VirtualPathUtility.IsRooted (virtualPath)) {
				HttpContext ctx = HttpContext.Current;
				HttpRequest req = ctx != null ? ctx.Request : null;

				if (req != null)
					vp = VirtualPathUtility.GetDirectory (req.FilePath) + virtualPath;
				else
					throw new HttpException ("No context, cannot map paths.");
			} else
				vp = virtualPath;
			
			if (VirtualPathUtility.IsAppRelative (vp))
				return VirtualPathUtility.ToAbsolute (vp);
			else
				return vp;
		}
		
		static BuildCacheItem GetCachedItem (string virtualPath)
		{
			BuildCacheItem ret;
			
			lock (buildCacheLock) {
				if (buildCache.TryGetValue (virtualPath, out ret))
					return ret;
			}

			return null;
		}
		
		public static Assembly GetCompiledAssembly (string virtualPath)
		{
			string vp = GetAbsoluteVirtualPath (virtualPath);
			BuildCacheItem ret = GetCachedItem (vp);
			if (ret != null)
				return ret.assembly;
			
			BuildAssembly (vp);
			ret = GetCachedItem (vp);
			if (ret != null)
				return ret.assembly;

			return null;
		}

		public static Type GetCompiledType (string virtualPath)
		{
			string vp = GetAbsoluteVirtualPath (virtualPath);
			BuildCacheItem ret = GetCachedItem (vp);

			if (ret != null)
				return ret.type;
			
			BuildAssembly (vp);
			ret = GetCachedItem (vp);
			if (ret != null)
				return ret.type;

			return null;
		}

		
		public static string GetCompiledCustomString (string virtualPath)
		{
			string vp = GetAbsoluteVirtualPath (virtualPath);
			BuildCacheItem ret = GetCachedItem (vp);
			if (ret != null)
				return ret.compiledCustomString;

			BuildAssembly (vp);
			ret = GetCachedItem (vp);
			if (ret != null)
				return ret.compiledCustomString;

			return null;
		}
		
		static List <string> GetFilesForBuild (string virtualPath, string physicalDir, out BuildKind kind)
		{
			string extension = VirtualPathUtility.GetExtension (virtualPath);
			List <string> ret = new List <string> ();
			
			if (StrUtils.StartsWith (virtualPath, FAKE_VIRTUAL_PATH_PREFIX)) {
				kind = BuildKind.Fake;
				return ret;
			}
			
			if (!knownFileTypes.TryGetValue (extension, out kind)) {
				string tmp;
				if (VirtualPathUtility.IsAbsolute (virtualPath))
					tmp = VirtualPathUtility.ToAppRelative (virtualPath);
				else
					tmp = virtualPath;
					
				if (StrUtils.StartsWith (tmp, "~/App_Themes/"))
					kind = BuildKind.Theme;
				else
					kind = BuildKind.Unknown;
			}

			if (kind == BuildKind.Theme || kind == BuildKind.Application)
				return ret;
			
			bool doBatch = BatchMode;

			lock (buildCacheLock) {
				if (recursiveBuilds.Count > 0 && recursiveBuilds.Peek () == kind)
					doBatch = false;
				recursiveBuilds.Push (kind);
			}
			
			if (doBatch) {
				string[] files = Directory.GetFiles (physicalDir, "*.*");
				BuildKind fileKind;
			
				foreach (string file in files) {
					if (!knownFileTypes.TryGetValue (Path.GetExtension (file), out fileKind))
						continue;
					
					if (kind == fileKind)
						ret.Add (file);
				}
			} else
				ret.Add (Path.Combine (physicalDir, VirtualPathUtility.GetFileName (virtualPath)));
			
			return ret;
		}

		static Type GetCodeDomProviderType (BuildProvider provider)
		{
			CompilerType codeCompilerType;
			Type codeDomProviderType = null;

			codeCompilerType = provider.CodeCompilerType;
			if (codeCompilerType != null)
				codeDomProviderType = codeCompilerType.CodeDomProviderType;
				
			if (codeDomProviderType == null)
				throw new HttpException (String.Concat ("Provider '", provider, " 'fails to specify the compiler type."));

			return codeDomProviderType;
		}
		
		static string GetVirtualPathDirectory (string virtualPath)
		{
			string vp;
			if (!VirtualPathUtility.IsRooted (virtualPath))
				vp = VirtualPathUtility.ToAbsolute ("~/" + virtualPath);
			else {
				if (VirtualPathUtility.IsAppRelative (virtualPath))
					vp = VirtualPathUtility.ToAbsolute (virtualPath);
				else
					vp = virtualPath;
			}

			return VirtualPathUtility.GetDirectory (vp);
		}

		static List <BuildItem> LoadBuildProviders (string virtualPath, string virtualDir, Dictionary <string, bool> vpCache,
							    out BuildKind kind, out string assemblyBaseName)
		{
			HttpContext ctx = HttpContext.Current;
			HttpRequest req = ctx != null ? ctx.Request : null;

			if (req == null)
				throw new HttpException ("No context available, cannot build.");

			CompilationSection section = WebConfigurationManager.GetSection ("system.web/compilation", virtualPath) as CompilationSection;
			string physicalDir = req.MapPath (virtualDir);
			
			List <string> files;
			
			try {
				files = GetFilesForBuild (virtualPath, physicalDir, out kind);
			} catch (Exception ex) {
				throw new HttpException ("Error loading build providers for path '" + virtualDir + "'.", ex);
			}

			List <BuildItem> ret = new List <BuildItem> ();
			BuildProvider provider = null;
			
			switch (kind) {
				case BuildKind.Theme:
					assemblyBaseName = "App_Theme_";
					provider = new ThemeDirectoryBuildProvider ();
					provider.SetVirtualPath (virtualPath);
					break;

				case BuildKind.Application:
					assemblyBaseName = "App_global.asax.";
					provider = new ApplicationFileBuildProvider ();
					provider.SetVirtualPath (virtualPath);
					break;

				case BuildKind.Fake:
					provider = GetBuildProviderForPath (virtualPath, section, false);
					assemblyBaseName = null;
					break;
					
				default:
					assemblyBaseName = null;
					break;
			}

			if (provider != null) {
				ret.Add (new BuildItem (provider));
				return ret;
			}
			
			string fileVirtualPath;
			string fileName;
			
			lock (buildCacheLock) {
				foreach (string f in files) {
					fileName = Path.GetFileName (f);
					fileVirtualPath = VirtualPathUtility.Combine (virtualDir, fileName);
					
					if (buildCache.ContainsKey (fileVirtualPath) || vpCache.ContainsKey (fileVirtualPath))
						continue;
					
					vpCache.Add (fileVirtualPath, true);
					provider = GetBuildProviderForPath (fileVirtualPath, section, false);
					if (provider == null)
						continue;

					ret.Add (new BuildItem (provider));
				}
			}

			return ret;
		}		

		static AssemblyBuilder CreateAssemblyBuilder (string assemblyBaseName, string virtualPath, BuildItem buildItem)
		{
			buildItem.assemblyBuilder = new AssemblyBuilder (virtualPath, buildItem.CreateCodeDomProvider (), assemblyBaseName);
			buildItem.assemblyBuilder.CompilerOptions = buildItem.CompilerOptions;
			
			return buildItem.assemblyBuilder;
		}

		static Dictionary <string, CompileUnitPartialType> GetUnitPartialTypes (CodeCompileUnit unit)
		{
			Dictionary <string, CompileUnitPartialType> ret = null;

			CompileUnitPartialType pt;
			foreach (CodeNamespace ns in unit.Namespaces) {
				foreach (CodeTypeDeclaration type in ns.Types) {
					if (type.IsPartial) {
						pt = new CompileUnitPartialType (unit, ns, type);

						if (ret == null)
							ret = new Dictionary <string, CompileUnitPartialType> ();
						
						ret.Add (pt.TypeName, pt);
					}
				}
			}

			return ret;
		}

		static bool TypeHasConflictingMember (CodeTypeDeclaration type, CodeMemberMethod member)
		{
			if (type == null || member == null)
				return false;

			CodeMemberMethod method;
			string methodName = member.Name;
			int count;
			
			foreach (CodeTypeMember m in type.Members) {
				if (m.Name != methodName)
					continue;
				
				method = m as CodeMemberMethod;
				if (method == null)
					continue;
			
				if ((count = method.Parameters.Count) != member.Parameters.Count)
					continue;

				CodeParameterDeclarationExpressionCollection methodA = method.Parameters;
				CodeParameterDeclarationExpressionCollection methodB = member.Parameters;
			
				for (int i = 0; i < count; i++)
					if (methodA [i].Type != methodB [i].Type)
						continue;

				return true;
			}
			
			return false;
		}

		static bool TypeHasConflictingMember (CodeTypeDeclaration type, CodeMemberField member)
		{
			if (type == null || member == null)
				return false;

			CodeMemberField field = FindMemberByName (type, member.Name) as CodeMemberField;
			if (field == null)
				return false;

			if (field.Type == member.Type)
				return false; // This will get "flattened" by AssemblyBuilder
			
			return true;
		}
		
		static bool TypeHasConflictingMember (CodeTypeDeclaration type, CodeTypeMember member)
		{
			if (type == null || member == null)
				return false;

			return (FindMemberByName (type, member.Name) != null);
		}

		static CodeTypeMember FindMemberByName (CodeTypeDeclaration type, string name)
		{
			foreach (CodeTypeMember m in type.Members) {
				if (m == null || m.Name != name)
					continue;
				return m;
			}

			return null;
		}
		
		static bool PartialTypesConflict (CodeTypeDeclaration typeA, CodeTypeDeclaration typeB)
		{
			bool conflict;
			Type type;
			
			foreach (CodeTypeMember member in typeB.Members) {
				conflict = false;
				type = member.GetType ();
				if (type == typeof (CodeMemberMethod))
					conflict = TypeHasConflictingMember (typeA, (CodeMemberMethod) member);
				else if (type == typeof (CodeMemberField))
					conflict = TypeHasConflictingMember (typeA, (CodeMemberField) member);
				else
					conflict = TypeHasConflictingMember (typeA, member);
				
				if (conflict)
					return true;
			}
			
			return false;
		}
		
		static bool CanAcceptCode (AssemblyBuilder assemblyBuilder, BuildItem buildItem)
		{
			CodeCompileUnit newUnit = buildItem.CodeUnit;
			if (newUnit == null)
				return true;
			
			Dictionary <string, CompileUnitPartialType> unitPartialTypes = GetUnitPartialTypes (newUnit);

			if (unitPartialTypes == null)
				return true;

			if (assemblyBuilder.Units.Count > CompilationConfig.MaxBatchSize)
				return false;
			
			CompileUnitPartialType pt;			
			foreach (List <CompileUnitPartialType> partialTypes in assemblyBuilder.PartialTypes.Values)
				foreach (CompileUnitPartialType cupt in partialTypes)
					if (unitPartialTypes.TryGetValue (cupt.TypeName, out pt) && PartialTypesConflict (cupt.PartialType, pt.PartialType))
						return false;
			
			return true;
		}
		
		static void AssignToAssemblyBuilder (string assemblyBaseName, string virtualPath, BuildItem buildItem,
						     Dictionary <Type, List <AssemblyBuilder>> assemblyBuilders)
		{
			if (!buildItem.codeGenerated)
				buildItem.GenerateCode ();
			
			List <AssemblyBuilder> builders;

			if (!assemblyBuilders.TryGetValue (buildItem.codeDomProviderType, out builders)) {
				builders = new List <AssemblyBuilder> ();
				assemblyBuilders.Add (buildItem.codeDomProviderType, builders);
			}

			// Put it in the first assembly builder that doesn't have conflicting
			// partial types
			foreach (AssemblyBuilder assemblyBuilder in builders) {
				if (CanAcceptCode (assemblyBuilder, buildItem)) {
					buildItem.assemblyBuilder = assemblyBuilder;
					buildItem.StoreCodeUnit ();
					return;
				}
			}

			// None of the existing builders can accept this unit, get it a new builder
			builders.Add (CreateAssemblyBuilder (assemblyBaseName, virtualPath, buildItem));
			buildItem.StoreCodeUnit ();
		}

		static void AssertVirtualPathExists (string virtualPath)
		{
			string realpath;
			bool fakePath;
			
			if (StrUtils.StartsWith (virtualPath, FAKE_VIRTUAL_PATH_PREFIX)) {
				realpath = virtualPath.Substring (FAKE_VIRTUAL_PATH_PREFIX.Length);
				fakePath = true;
			} else {
				HttpContext ctx = HttpContext.Current;
				HttpRequest req = ctx != null ? ctx.Request : null;

				if (req == null)
					throw new HttpException ("Missing context, cannot continue.");

				realpath = req.MapPath (virtualPath);
			}

			if (!File.Exists (realpath) && !Directory.Exists (realpath))
				throw new HttpException (404,
							 "The file '" + virtualPath + "' does not exist.",
							 fakePath ? Path.GetFileName (realpath) : virtualPath);
		}
		
		static void BuildAssembly (string virtualPath)
		{
			AssertVirtualPathExists (virtualPath);
			
			object ticket;
			bool acquired;
			string virtualDir = GetVirtualPathDirectory (virtualPath);
			BuildKind buildKind = BuildKind.Unknown;
			bool kindPushed = false;
			
			acquired = AcquireCompilationTicket (virtualDir, out ticket);
			try {
				Monitor.Enter (ticket);
				lock (buildCacheLock) {
					if (buildCache.ContainsKey (virtualPath))
						return;
				}
				
				string assemblyBaseName;
				Dictionary <string, bool> vpCache = new Dictionary <string, bool> ();
				List <BuildItem> buildItems = LoadBuildProviders (virtualPath, virtualDir, vpCache, out buildKind, out assemblyBaseName);
				kindPushed = true;

				if (buildItems.Count == 0)
					return;
				
				Dictionary <Type, List <AssemblyBuilder>> assemblyBuilders = new Dictionary <Type, List <AssemblyBuilder>> ();
				bool checkForRecursion = buildKind == BuildKind.NonPages;
				
				foreach (BuildItem buildItem in buildItems) {
					if (checkForRecursion) {
						// Expensive but, alas, necessary - the builder in
						// our list might've been put into a different
						// assembly in a recursive call.
						lock (buildCacheLock) {
							if (buildCache.ContainsKey (buildItem.VirtualPath))
								continue;
						}
					}
					
					if (buildItem.assemblyBuilder == null)
						AssignToAssemblyBuilder (assemblyBaseName, virtualPath, buildItem, assemblyBuilders);
				}
				CompilerResults results;
				Assembly compiledAssembly;
				string vp;
				BuildProvider bp;
				
				foreach (List <AssemblyBuilder> abuilders in assemblyBuilders.Values) {
					foreach (AssemblyBuilder abuilder in abuilders) {
						abuilder.AddAssemblyReference (GetReferencedAssemblies () as List <Assembly>);
						results = abuilder.BuildAssembly (virtualPath);
						
						// No results is not an error - it is possible that the assembly builder contained only .asmx and
						// .ashx files which had no body, just the directive. In such case, no code unit or code file is added
						// to the assembly builder and, in effect, no assembly is produced but there are STILL types that need
						// to be added to the cache.
						compiledAssembly = results != null ? results.CompiledAssembly : null;
						
						lock (buildCacheLock) {
							switch (buildKind) {
								case BuildKind.NonPages:
									if (compiledAssembly != null && !referencedAssemblies.Contains (compiledAssembly))
										referencedAssemblies.Add (compiledAssembly);
									break;

 								case BuildKind.Application:
 									globalAsaxAssembly = compiledAssembly;
 									break;
							}
							
							foreach (BuildItem buildItem in buildItems) {
								if (buildItem.assemblyBuilder != abuilder)
									continue;
								
								vp = buildItem.VirtualPath;
								bp = buildItem.buildProvider;
								buildItem.SetCompiledAssembly (abuilder, compiledAssembly);
								
								if (!buildCache.ContainsKey (vp)) {
									AddToCache (vp, bp);
									buildCache.Add (vp, new BuildCacheItem (compiledAssembly, bp, results));
								}

								if (compiledAssembly != null && !nonPagesCache.ContainsKey (vp))
									nonPagesCache.Add (vp, compiledAssembly);
							}
						}
					}
				}

				// WARNING: enabling this code breaks the test suite - it stays
				// disabled until I figure out what to do about it.
				// See http://support.microsoft.com/kb/319947
// 				lock (buildCountLock) {
// 					buildCount++;
// 					if (buildCount > CompilationConfig.NumRecompilesBeforeAppRestart)
// 						HttpRuntime.UnloadAppDomain ();
// 				}
			} finally {
				if (kindPushed && buildKind == BuildKind.Pages || buildKind == BuildKind.NonPages) {
					lock (buildCacheLock) {
						recursiveBuilds.Pop ();
					}
				}
				
				Monitor.Exit (ticket);
				if (acquired)
					ReleaseCompilationTicket (virtualDir);
			}
		}
		
		internal static void AddToCache (string virtualPath, BuildProvider bp)
		{
			HttpContext ctx = HttpContext.Current;
			HttpRequest req = ctx != null ? ctx.Request : null;

			if (req == null)
				throw new HttpException ("No current context.");
			
			CacheItemRemovedCallback cb = new CacheItemRemovedCallback (OnVirtualPathChanged);
			CacheDependency dep;
			ICollection col = bp.VirtualPathDependencies;
			int count;
			
			if (col != null && (count = col.Count) > 0) {
				string[] files = new string [count];
				int fileCount = 0;
				string file;
				
				foreach (object o in col) {
					file = o as string;
					if (String.IsNullOrEmpty (file))
						continue;
					files [fileCount++] = req.MapPath (file);
				}

				dep = new CacheDependency (files);
			} else
				dep = null;
			
			HttpRuntime.InternalCache.Add (BUILD_MANAGER_VIRTUAL_PATH_CACHE_PREFIX + virtualPath,
						       true,
						       dep,
						       Cache.NoAbsoluteExpiration,
						       Cache.NoSlidingExpiration,
						       CacheItemPriority.High,
						       cb);
						       
		}

		static int RemoveVirtualPathFromCaches (string virtualPath)
		{
			lock (buildCacheLock) {
				// This is expensive, but we must do it - we must not leave
				// the assembly in which the invalidated type lived. At the same
				// time, we must remove the virtual paths which were in that
				// assembly from the other caches, so that they get recompiled.
				BuildCacheItem item = GetCachedItem (virtualPath);
				if (item == null)
					return 0;

				if (buildCache.ContainsKey (virtualPath))
					buildCache.Remove (virtualPath);

				Assembly asm;
				
				if (nonPagesCache.TryGetValue (virtualPath, out asm)) {
					nonPagesCache.Remove (virtualPath);
					if (referencedAssemblies.Contains (asm))
						referencedAssemblies.Remove (asm);

					List <string> keysToRemove = new List <string> ();
					foreach (KeyValuePair <string, Assembly> kvp in nonPagesCache)
						if (kvp.Value == asm)
							keysToRemove.Add (kvp.Key);
					
					foreach (string key in keysToRemove) {
						nonPagesCache.Remove (key);

						if (buildCache.ContainsKey (key))
							buildCache.Remove (key);
					}
				}
				
				return 1;
			}
		}
		
		static void OnVirtualPathChanged (string key, object value, CacheItemRemovedReason removedReason)
		{
			string virtualPath;

			if (StrUtils.StartsWith (key, BUILD_MANAGER_VIRTUAL_PATH_CACHE_PREFIX))
				virtualPath = key.Substring (BUILD_MANAGER_VIRTUAL_PATH_CACHE_PREFIX_LENGTH);
			else
				return;

			RemoveVirtualPathFromCaches (virtualPath);
		}
		
		static bool AcquireCompilationTicket (string key, out object ticket)
                {
                        lock (((ICollection)compilationTickets).SyncRoot) {
                                if (!compilationTickets.TryGetValue (key, out ticket)) {
                                        ticket = new Mutex ();
                                        compilationTickets.Add (key, ticket);
                                        return true;
                                }
                        }
			
                        return false;
                }

                static void ReleaseCompilationTicket (string key)
                {
                        lock (((ICollection)compilationTickets).SyncRoot) {
				if (compilationTickets.ContainsKey (key))
					compilationTickets.Remove (key);
                        }
                }
		
		// The 2 GetType() overloads work on the global.asax, App_GlobalResources, App_WebReferences or App_Browsers
		public static Type GetType (string typeName, bool throwOnError)
		{
			return GetType (typeName, throwOnError, false);
		}

		public static Type GetType (string typeName, bool throwOnError, bool ignoreCase)
		{
			Type ret = null;
			try {
				foreach (Assembly asm in TopLevel_Assemblies) {
					ret = asm.GetType (typeName, throwOnError, ignoreCase);
					if (ret != null)
						break;
				}
			} catch (Exception ex) {
				throw new HttpException ("Failed to find the specified type.", ex);
			}
			return ret;
		}

		internal static ICollection GetVirtualPathDependencies (string virtualPath, BuildProvider bprovider)
		{
			BuildProvider provider = bprovider;
			if (provider == null)
				provider = GetBuildProviderForPath (virtualPath, false);
			if (provider == null)
				return null;
			return provider.VirtualPathDependencies;
		}
		
		public static ICollection GetVirtualPathDependencies (string virtualPath)
		{
			return GetVirtualPathDependencies (virtualPath, null);
		}
		
		// Assemblies built from the App_Code directory
		public static IList CodeAssemblies {
			get { return AppCode_Assemblies; }
		}

		internal static IList TopLevelAssemblies {
			get { return TopLevel_Assemblies; }
		}

		internal static bool HaveResources {
			get { return haveResources; }
			set { haveResources = value; }
		}

		internal static bool BatchMode {
			get { return CompilationConfig.Batch; }
		}

		internal static CompilationSection CompilationConfig {
			get { return WebConfigurationManager.GetSection ("system.web/compilation") as CompilationSection; }
		}
			
	}
}

#endif