Make access to the underlying BuildEngine.Project is thread-safe. Should fix forum-13374 and similar problems.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@2067 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/BooProject.cs

@@ -119,7 +119,7 @@ namespace Grunwald.BooBinding
 		public bool Ducky {
 			get {
 				bool val;
-				bool.TryParse(GetProperty("Ducky"), out val);
+				bool.TryParse(GetEvaluatedProperty("Ducky"), out val);
 				return val;
 			}
 		}

src/AddIns/BackendBindings/WixBinding/Project/Src/Project/WixProject.cs

@@ -111,9 +111,9 @@ namespace ICSharpCode.WixBinding
 		/// </summary>
 		public string InstallerFullPath {
 			get {
-				string outputPath = GetProperty("OutputPath") ?? String.Empty;
-				string outputType = GetProperty("OutputType") ?? String.Empty;
-				string outputName = GetProperty("OutputName") ?? String.Empty;
+				string outputPath = GetEvaluatedProperty("OutputPath") ?? String.Empty;
+				string outputType = GetEvaluatedProperty("OutputType") ?? String.Empty;
+				string outputName = GetEvaluatedProperty("OutputName") ?? String.Empty;
 				string fileName = String.Concat(outputName, GetInstallerExtension(outputType));
 				return Path.Combine(Path.Combine(Directory, outputPath), fileName);
 			}
@@ -195,7 +195,7 @@ namespace ICSharpCode.WixBinding
 		/// <returns>An empty string if the name cannot be found.</returns>
 		public string GetVariable(string name)
 		{
-			string constants = GetProperty("DefineConstants") ?? String.Empty;
+			string constants = GetEvaluatedProperty("DefineConstants") ?? String.Empty;
 			NameValuePairCollection nameValuePairs = new NameValuePairCollection(constants);
 			return WixPropertyParser.Parse(nameValuePairs.GetValue(name), this);
 		}
@@ -249,7 +249,7 @@ namespace ICSharpCode.WixBinding
 		/// AssemblyName must be implemented correctly - used when renaming projects.
 		/// </summary>
 		public override string AssemblyName {
-			get { return GetProperty("OutputName") ?? Name; }
+			get { return GetEvaluatedProperty("OutputName") ?? Name; }
 			set { SetProperty("OutputName", value); }
 		}
 		

src/Main/Base/Project/Src/Gui/WorkbenchSingleton.cs

@@ -122,10 +122,16 @@ namespace ICSharpCode.SharpDevelop.Gui
 		
 		public static bool InvokeRequired {
 			get {
-				return ((Form)workbench).InvokeRequired;
+				if (workbench == null)
+					return false; // unit test mode, don't crash
+				else
+					return ((Form)workbench).InvokeRequired;
 			}
 		}
 		
+		/// <summary>
+		/// Throws an exception if the current thread is not the main thread.
+		/// </summary>
 		internal static void AssertMainThread()
 		{
 			if (InvokeRequired) {

src/Main/Base/Project/Src/Internal/ConditionEvaluators/CompareProjectPropertyConditionEvaluator.cs

@@ -50,7 +50,7 @@ namespace ICSharpCode.SharpDevelop
 			else
 				comparisonType = (StringComparison)Enum.Parse(typeof(StringComparison), comparisonTypeText);
 			
-			return string.Equals(project.GetProperty(StringParser.Parse(condition.Properties["property"])),
+			return string.Equals(project.GetEvaluatedProperty(StringParser.Parse(condition.Properties["property"])),
 			                     StringParser.Parse(condition.Properties["equals"]),
 			                     comparisonType);
 		}

src/Main/Base/Project/Src/Project/AbstractProject.cs

@@ -52,6 +52,8 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		public virtual void Dispose()
 		{
+			WorkbenchSingleton.AssertMainThread();
+			
 			isDisposed = true;
 			if (Disposed != null) {
 				Disposed(this, EventArgs.Empty);
@@ -68,6 +70,8 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// </summary>
 		public virtual Properties CreateMemento()
 		{
+			WorkbenchSingleton.AssertMainThread();
+			
 			Properties properties = new Properties();
 			properties.Set("bookmarks", ICSharpCode.SharpDevelop.Bookmarks.BookmarkManager.GetProjectBookmarks(this).ToArray());
 			List<string> files = new List<string>();
@@ -85,6 +89,8 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		public virtual void SetMemento(Properties memento)
 		{
+			WorkbenchSingleton.AssertMainThread();
+			
 			foreach (ICSharpCode.SharpDevelop.Bookmarks.SDBookmark mark in memento.Get("bookmarks", new ICSharpCode.SharpDevelop.Bookmarks.SDBookmark[0])) {
 				ICSharpCode.SharpDevelop.Bookmarks.BookmarkManager.AddMark(mark);
 			}
@@ -95,32 +101,51 @@ namespace ICSharpCode.SharpDevelop.Project
 		#endregion
 		
 		#region Filename / Directory
-		string fileName;
+		volatile string fileName;
 		string cachedDirectoryName;
 		
+		/// <summary>
+		/// Gets the name of the project file.
+		/// (Full file name, example: @"D:\Serralongue\SharpDevelop\samples\CustomPad\CustomPad.csproj")
+		/// 
+		/// Only the getter is thread-safe.
+		/// </summary>
 		[ReadOnly(true)]
 		public string FileName {
 			get {
 				return fileName ?? "";
 			}
 			set {
+				WorkbenchSingleton.AssertMainThread();
 				Debug.Assert(Path.IsPathRooted(value));
-				fileName = value;
-				cachedDirectoryName = null;
+				
+				lock (SyncRoot) { // locking still required for Directory
+					fileName = value;
+					cachedDirectoryName = null;
+				}
 			}
 		}
 		
+		/// <summary>
+		/// Gets the directory of the project file.
+		/// This is equivalent to Path.GetDirectoryName(project.FileName);
+		/// (Example: @"D:\Serralongue\SharpDevelop\samples\CustomPad")
+		/// 
+		/// This member is thread-safe.
+		/// </summary>
 		[Browsable(false)]
 		public string Directory {
 			get {
-				if (cachedDirectoryName == null) {
-					try {
-						cachedDirectoryName = Path.GetDirectoryName(this.FileName);
-					} catch (Exception) {
-						cachedDirectoryName = "";
+				lock (SyncRoot) {
+					if (cachedDirectoryName == null) {
+						try {
+							cachedDirectoryName = Path.GetDirectoryName(this.FileName);
+						} catch (Exception) {
+							cachedDirectoryName = "";
+						}
 					}
+					return cachedDirectoryName;
 				}
-				return cachedDirectoryName;
 			}
 		}
 		#endregion
@@ -131,6 +156,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public List<ProjectSection> ProjectSections {
 			get {
+				WorkbenchSingleton.AssertMainThread();
 				return projectSections;
 			}
 		}
@@ -158,9 +184,11 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		[ReadOnly(true)]
 		[LocalizedProperty("${res:Dialog.ProjectOptions.Configuration}")]
-		public virtual string ActiveConfiguration {
+		public string ActiveConfiguration {
 			get { return activeConfiguration; }
 			set {
+				WorkbenchSingleton.AssertMainThread();
+				
 				if (activeConfiguration != value) {
 					activeConfiguration = value;
 					
@@ -180,9 +208,11 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		[ReadOnly(true)]
 		[LocalizedProperty("${res:Dialog.ProjectOptions.Platform}")]
-		public virtual string ActivePlatform {
+		public string ActivePlatform {
 			get { return activePlatform; }
 			set {
+				WorkbenchSingleton.AssertMainThread();
+				
 				if (activePlatform != value) {
 					activePlatform = value;
 					
@@ -227,7 +257,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		#endregion
 		
 		/// <summary>
-		/// Gets the list of available file item types.
+		/// Gets the list of available file item types. This member is thread-safe.
 		/// </summary>
 		public virtual ICollection<ItemType> AvailableFileItemTypes {
 			get {
@@ -235,6 +265,11 @@ namespace ICSharpCode.SharpDevelop.Project
 			}
 		}
 		
+		/// <summary>
+		/// Gets the list of items in the project. This member is thread-safe.
+		/// The returned collection is guaranteed not to change - adding new items or removing existing items
+		/// will create a new collection.
+		/// </summary>
 		[Browsable(false)]
 		public virtual ReadOnlyCollection<ProjectItem> Items {
 			get {
@@ -242,6 +277,10 @@ namespace ICSharpCode.SharpDevelop.Project
 			}
 		}
 		
+		/// <summary>
+		/// Gets all items in the project that have the specified item type.
+		/// This member is thread-safe.
+		/// </summary>
 		public virtual IEnumerable<ProjectItem> GetItemsOfType(ItemType itemType)
 		{
 			foreach (ProjectItem item in this.Items) {
@@ -312,9 +351,31 @@ namespace ICSharpCode.SharpDevelop.Project
 			throw new NotSupportedException();
 		}
 		
-		public virtual bool IsFileInProject(string fileName)
+		/// <summary>
+		/// Returns true, if a specific file (given by it's name) is inside this project.
+		/// This member is thread-safe.
+		/// </summary>
+		/// <param name="fileName">The <b>fully qualified</b> file name of the file</param>
+		public bool IsFileInProject(string fileName)
+		{
+			return FindFile(fileName) != null;
+		}
+		
+		/// <summary>
+		/// Returns the project item for a specific file; or null if the file is not found in the project.
+		/// This member is thread-safe.
+		/// </summary>
+		/// <param name="fileName">The <b>fully qualified</b> file name of the file</param>
+		public FileProjectItem FindFile(string fileName)
 		{
-			return false;
+			lock (SyncRoot) {
+				return Linq.Find(Linq.OfType<FileProjectItem>(this.Items),
+				                 delegate(FileProjectItem item) {
+				                 	return FileUtility.IsEqualFileName(item.FileName, fileName);
+				                 });
+				// return this.Items.OfType<FileProjectItem>().Find(
+				//			 item => FileUtility.IsEqualFileName(item.FileName, outputFileName));
+			}
 		}
 		
 		ParseProjectContent IProject.CreateProjectContent()

src/Main/Base/Project/Src/Project/CompilableProject.cs

@@ -97,9 +97,9 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public string IntermediateOutputFullPath {
 			get {
-				string outputPath = GetProperty("IntermediateOutputPath");
+				string outputPath = GetEvaluatedProperty("IntermediateOutputPath");
 				if (string.IsNullOrEmpty(outputPath)) {
-					outputPath = GetProperty("BaseIntermediateOutputPath");
+					outputPath = GetEvaluatedProperty("BaseIntermediateOutputPath");
 					if (string.IsNullOrEmpty(outputPath)) {
 						outputPath = "obj";
 					}
@@ -116,7 +116,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public string DocumentationFileFullPath {
 			get {
-				string file = GetProperty("DocumentationFile");
+				string file = GetEvaluatedProperty("DocumentationFile");
 				if (string.IsNullOrEmpty(file))
 					return null;
 				return Path.Combine(Directory, file);
@@ -134,18 +134,18 @@ namespace ICSharpCode.SharpDevelop.Project
 		}
 		
 		public override string AssemblyName {
-			get { return GetProperty("AssemblyName") ?? Name; }
+			get { return GetEvaluatedProperty("AssemblyName") ?? Name; }
 			set { SetProperty("AssemblyName", value); }
 		}
 		
 		public override string RootNamespace {
-			get { return GetProperty("RootNamespace") ?? ""; }
+			get { return GetEvaluatedProperty("RootNamespace") ?? ""; }
 			set { SetProperty("RootNamespace", value); }
 		}
 		
 		public override string OutputAssemblyFullPath {
 			get {
-				string outputPath = GetProperty("OutputPath") ?? "";
+				string outputPath = GetEvaluatedProperty("OutputPath") ?? "";
 				return Path.Combine(Path.Combine(Directory, outputPath), AssemblyName + GetExtension(OutputType));
 			}
 		}
@@ -154,7 +154,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		public OutputType OutputType {
 			get {
 				try {
-					return (OutputType)Enum.Parse(typeof(OutputType), GetProperty("OutputType") ?? "Exe");
+					return (OutputType)Enum.Parse(typeof(OutputType), GetEvaluatedProperty("OutputType") ?? "Exe");
 				} catch (ArgumentException) {
 					return OutputType.Exe;
 				}
@@ -233,7 +233,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public string StartProgram {
 			get {
-				return GetProperty("StartProgram") ?? "";
+				return GetEvaluatedProperty("StartProgram") ?? "";
 			}
 			set {
 				SetProperty("StartProgram", string.IsNullOrEmpty(value) ? null : value);
@@ -243,7 +243,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public string StartUrl {
 			get {
-				return GetProperty("StartURL") ?? "";
+				return GetEvaluatedProperty("StartURL") ?? "";
 			}
 			set {
 				SetProperty("StartURL", string.IsNullOrEmpty(value) ? null : value);
@@ -254,7 +254,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		public StartAction StartAction {
 			get {
 				try {
-					return (StartAction)Enum.Parse(typeof(StartAction), GetProperty("StartAction") ?? "Project");
+					return (StartAction)Enum.Parse(typeof(StartAction), GetEvaluatedProperty("StartAction") ?? "Project");
 				} catch (ArgumentException) {
 					return StartAction.Project;
 				}
@@ -267,7 +267,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public string StartArguments {
 			get {
-				return GetProperty("StartArguments") ?? "";
+				return GetEvaluatedProperty("StartArguments") ?? "";
 			}
 			set {
 				SetProperty("StartArguments", string.IsNullOrEmpty(value) ? null : value);
@@ -277,7 +277,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		[Browsable(false)]
 		public string StartWorkingDirectory {
 			get {
-				return GetProperty("StartWorkingDirectory") ?? "";
+				return GetEvaluatedProperty("StartWorkingDirectory") ?? "";
 			}
 			set {
 				SetProperty("StartWorkingDirectory", string.IsNullOrEmpty(value) ? null : value);

src/Main/Base/Project/Src/Project/CustomTool.cs

@@ -139,7 +139,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		public FileProjectItem EnsureOutputFileIsInProject(FileProjectItem baseItem, string outputFileName)
 		{
 			WorkbenchSingleton.AssertMainThread();
-			FileProjectItem outputItem = MSBuildBasedProject.FindProjectItem(project, outputFileName);
+			FileProjectItem outputItem = project.FindFile(outputFileName);
 			if (outputItem == null) {
 				outputItem = new FileProjectItem(project, ItemType.Compile);
 				outputItem.FileName = outputFileName;
@@ -331,7 +331,7 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (solution == null) return;
 			IProject project = solution.FindProjectContainingFile(e.FileName);
 			if (project == null) return;
-			FileProjectItem item = MSBuildBasedProject.FindProjectItem(project, e.FileName);
+			FileProjectItem item = project.FindFile(e.FileName);
 			if (item == null) return;
 			if (!string.IsNullOrEmpty(item.CustomTool)) {
 				RunCustomTool(item, false);

src/Main/Base/Project/Src/Project/IProject.cs

@@ -17,12 +17,15 @@ namespace ICSharpCode.SharpDevelop.Project
 {
 	/// <summary>
 	/// Base interface for projects.
+	/// Thread-safe members lock on the SyncRoot. Non-thread-safe members may only be called from the main thread.
 	/// </summary>
 	public interface IProject
 		: ISolutionFolder, IDisposable, IMementoCapable, ICanBeDirty
 	{
 		/// <summary>
-		/// Gets a list of items in the project.
+		/// Gets the list of items in the project. This member is thread-safe.
+		/// The returned collection is guaranteed not to change - adding new items or removing existing items
+		/// will create a new collection.
 		/// </summary>
 		ReadOnlyCollection<ProjectItem> Items {
 			get;
@@ -30,6 +33,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		/// <summary>
 		/// Gets all items in the project that have the specified item type.
+		/// This member is thread-safe.
 		/// </summary>
 		IEnumerable<ProjectItem> GetItemsOfType(ItemType type);
 		
@@ -40,7 +44,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		ItemType GetDefaultItemType(string fileName);
 		
 		/// <summary>
-		/// Gets the list of available file item types.
+		/// Gets the list of available file item types. This member is thread-safe.
 		/// </summary>
 		ICollection<ItemType> AvailableFileItemTypes {
 			get;
@@ -53,10 +57,16 @@ namespace ICSharpCode.SharpDevelop.Project
 			get;
 		}
 		
+		/// <summary>
+		/// Gets the language properties used for this project. This member is thread-safe.
+		/// </summary>
 		ICSharpCode.SharpDevelop.Dom.LanguageProperties LanguageProperties {
 			get;
 		}
 		
+		/// <summary>
+		/// Gets the ambience used for the project. This member is thread-safe.
+		/// </summary>
 		ICSharpCode.SharpDevelop.Dom.IAmbience Ambience {
 			get;
 		}
@@ -64,6 +74,8 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// <summary>
 		/// Gets the name of the project file.
 		/// (Full file name, example: @"D:\Serralongue\SharpDevelop\samples\CustomPad\CustomPad.csproj")
+		/// 
+		/// Only the getter is thread-safe.
 		/// </summary>
 		string FileName {
 			get;
@@ -73,6 +85,8 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// Gets the directory of the project file.
 		/// This is equivalent to Path.GetDirectoryName(project.FileName);
 		/// (Example: @"D:\Serralongue\SharpDevelop\samples\CustomPad")
+		/// 
+		/// This member is thread-safe.
 		/// </summary>
 		string Directory {
 			get;
@@ -155,11 +169,19 @@ namespace ICSharpCode.SharpDevelop.Project
 		void Save();
 		
 		/// <summary>
-		/// Returns true, if a specific file (given by it's name)
-		/// is inside this project.
+		/// Returns true, if a specific file (given by it's name) is inside this project.
+		/// This member is thread-safe.
 		/// </summary>
+		/// <param name="fileName">The <b>fully qualified</b> file name of the file</param>
 		bool IsFileInProject(string fileName);
 		
+		/// <summary>
+		/// Returns the project item for a specific file; or null if the file is not found in the project.
+		/// This member is thread-safe.
+		/// </summary>
+		/// <param name="fileName">The <b>fully qualified</b> file name of the file</param>
+		FileProjectItem FindFile(string fileName);
+		
 		/// <summary>
 		/// Gets if the project can be started.
 		/// </summary>

src/Main/Base/Project/Src/Project/Items/ProjectItem.cs

@@ -30,7 +30,7 @@ namespace ICSharpCode.SharpDevelop.Project
 	public abstract class ProjectItem : LocalizedObject, IDisposable, ICloneable
 	{
 		IProject project;
-		string fileNameCache;
+		volatile string fileNameCache;
 		
 		// either use: (bound mode)
 		BuildItem buildItem;
@@ -61,6 +61,26 @@ namespace ICSharpCode.SharpDevelop.Project
 			this.virtualMetadata = new Dictionary<string, string>();
 		}
 		
+		[Browsable(false)]
+		public IProject Project {
+			get {
+				return project;
+			}
+		}
+		
+		/// <summary>
+		/// Gets the object used for synchronization. This is project.SyncRoot for items inside a project; or
+		/// virtualMetadata for items without project.
+		/// </summary>
+		object SyncRoot {
+			get {
+				if (project != null)
+					return project.SyncRoot;
+				else
+					return virtualMetadata;
+			}
+		}
+		
 		/// <summary>
 		/// Gets if the item is added to it's owner project.
 		/// </summary>
@@ -91,53 +111,56 @@ namespace ICSharpCode.SharpDevelop.Project
 			}
 		}
 		
-		[Browsable(false)]
-		public IProject Project {
-			get {
-				return project;
-			}
-		}
-		
 		[Browsable(false)]
 		public ItemType ItemType {
 			get {
-				if (buildItem != null)
-					return new ItemType(buildItem.Name);
-				else
-					return virtualItemType;
+				lock (SyncRoot) {
+					if (buildItem != null)
+						return new ItemType(buildItem.Name);
+					else
+						return virtualItemType;
+				}
 			}
 			set {
-				if (buildItem != null)
-					buildItem.Name = value.ToString();
-				else
-					virtualItemType = value;
+				lock (SyncRoot) {
+					if (buildItem != null)
+						buildItem.Name = value.ToString();
+					else
+						virtualItemType = value;
+				}
 			}
 		}
 		
 		[Browsable(false)]
 		public string Include {
 			get {
-				if (buildItem != null)
-					return buildItem.Include;
-				else
-					return virtualInclude;
+				lock (SyncRoot) {
+					if (buildItem != null)
+						return buildItem.Include;
+					else
+						return virtualInclude;
+				}
 			}
 			set {
-				if (buildItem != null)
-					buildItem.Include = value;
-				else
-					virtualInclude = value ?? "";
-				fileNameCache = null;
+				lock (SyncRoot) {
+					if (buildItem != null)
+						buildItem.Include = value;
+					else
+						virtualInclude = value ?? "";
+					fileNameCache = null;
+				}
 			}
 		}
 		
 		#region Metadata access
 		public bool HasMetadata(string metadataName)
 		{
-			if (buildItem != null)
-				return buildItem.HasMetadata(metadataName);
-			else
-				return virtualMetadata.ContainsKey(metadataName);
+			lock (SyncRoot) {
+				if (buildItem != null)
+					return buildItem.HasMetadata(metadataName);
+				else
+					return virtualMetadata.ContainsKey(metadataName);
+			}
 		}
 		
 		/// <summary>
@@ -146,15 +169,17 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// </summary>
 		public string GetEvaluatedMetadata(string metadataName)
 		{
-			if (buildItem != null) {
-				return buildItem.GetEvaluatedMetadata(metadataName) ?? "";
-			} else {
-				string val;
-				virtualMetadata.TryGetValue(metadataName, out val);
-				if (val == null)
-					return "";
-				else
-					return MSBuildInternals.Unescape(val);
+			lock (SyncRoot) {
+				if (buildItem != null) {
+					return buildItem.GetEvaluatedMetadata(metadataName) ?? "";
+				} else {
+					string val;
+					virtualMetadata.TryGetValue(metadataName, out val);
+					if (val == null)
+						return "";
+					else
+						return MSBuildInternals.Unescape(val);
+				}
 			}
 		}
 		
@@ -173,12 +198,14 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// </summary>
 		public string GetMetadata(string metadataName)
 		{
-			if (buildItem != null) {
-				return buildItem.GetMetadata(metadataName) ?? "";
-			} else {
-				string val;
-				virtualMetadata.TryGetValue(metadataName, out val);
-				return val ?? "";
+			lock (SyncRoot) {
+				if (buildItem != null) {
+					return buildItem.GetMetadata(metadataName) ?? "";
+				} else {
+					string val;
+					virtualMetadata.TryGetValue(metadataName, out val);
+					return val ?? "";
+				}
 			}
 		}
 		
@@ -192,10 +219,12 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (string.IsNullOrEmpty(value)) {
 				RemoveMetadata(metadataName);
 			} else {
-				if (buildItem != null)
-					buildItem.SetMetadata(metadataName, value, true);
-				else
-					virtualMetadata[metadataName] = MSBuildInternals.Escape(value);
+				lock (SyncRoot) {
+					if (buildItem != null)
+						buildItem.SetMetadata(metadataName, value, true);
+					else
+						virtualMetadata[metadataName] = MSBuildInternals.Escape(value);
+				}
 			}
 		}
 		
@@ -217,10 +246,12 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (string.IsNullOrEmpty(value)) {
 				RemoveMetadata(metadataName);
 			} else {
-				if (buildItem != null)
-					buildItem.SetMetadata(metadataName, value);
-				else
-					virtualMetadata[metadataName] = value;
+				lock (SyncRoot) {
+					if (buildItem != null)
+						buildItem.SetMetadata(metadataName, value);
+					else
+						virtualMetadata[metadataName] = value;
+				}
 			}
 		}
 		
@@ -229,22 +260,27 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// </summary>
 		public void RemoveMetadata(string metadataName)
 		{
-			if (buildItem != null)
-				buildItem.RemoveMetadata(metadataName);
-			else
-				virtualMetadata.Remove(metadataName);
+			lock (SyncRoot) {
+				if (buildItem != null)
+					buildItem.RemoveMetadata(metadataName);
+				else
+					virtualMetadata.Remove(metadataName);
+			}
 		}
 		
 		/// <summary>
-		/// Gets the names of all existing meta data items on this project item.
+		/// Gets the names of all existing meta data items on this project item. The resulting collection
+		/// is a copy that will not be affected by future changes to the project item.
 		/// </summary>
 		[Browsable(false)]
 		public IEnumerable<string> MetadataNames {
 			get {
-				if (buildItem != null)
-					return MSBuildInternals.GetCustomMetadataNames(buildItem);
-				else
-					return virtualMetadata.Keys;
+				lock (SyncRoot) {
+					if (buildItem != null)
+						return MSBuildInternals.GetCustomMetadataNames(buildItem);
+					else
+						return Linq.ToArray(virtualMetadata.Keys);
+				}
 			}
 		}
 		#endregion
@@ -254,11 +290,15 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// </summary>
 		public virtual void CopyMetadataTo(ProjectItem targetItem)
 		{
-			if (this.buildItem != null && targetItem.buildItem != null) {
-				this.buildItem.CopyCustomMetadataTo(targetItem.buildItem);
-			} else {
-				foreach (string name in this.MetadataNames) {
-					targetItem.SetMetadata(name, this.GetMetadata(name));
+			lock (SyncRoot) {
+				lock (targetItem.SyncRoot) {
+					if (this.buildItem != null && targetItem.buildItem != null) {
+						this.buildItem.CopyCustomMetadataTo(targetItem.buildItem);
+					} else {
+						foreach (string name in this.MetadataNames) {
+							targetItem.SetMetadata(name, this.GetMetadata(name));
+						}
+					}
 				}
 			}
 		}
@@ -285,14 +325,16 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		BuildItem CloneBuildItem()
 		{
-			if (buildItem != null) {
-				return buildItem.Clone();
-			} else {
-				BuildItem dummyItem = new BuildItem(this.ItemType.ToString(), this.Include);
-				foreach (string name in this.MetadataNames) {
-					dummyItem.SetMetadata(name, this.GetMetadata(name));
+			lock (SyncRoot) {
+				if (buildItem != null) {
+					return buildItem.Clone();
+				} else {
+					BuildItem dummyItem = new BuildItem(this.ItemType.ToString(), this.Include);
+					foreach (string name in this.MetadataNames) {
+						dummyItem.SetMetadata(name, this.GetMetadata(name));
+					}
+					return dummyItem;
 				}
-				return dummyItem;
 			}
 		}
 		
@@ -307,9 +349,14 @@ namespace ICSharpCode.SharpDevelop.Project
 				if (project == null) {
 					throw new NotSupportedException("Not supported for items without project.");
 				}
-				if (fileNameCache == null)
-					fileNameCache = Path.Combine(project.Directory, this.Include);
-				return fileNameCache;
+				string fileName = this.fileNameCache;
+				if (fileName == null) {
+					lock (SyncRoot) {
+						fileName = Path.Combine(project.Directory, this.Include);
+						fileNameCache = fileName;
+					}
+				}
+				return fileName;
 			}
 			set {
 				if (project == null) {

src/Main/Base/Project/Src/Project/MSBuildBasedProject.cs

@@ -158,13 +158,16 @@ namespace ICSharpCode.SharpDevelop.Project
 		#region Get Property
 		/// <summary>
 		/// Retrieves the evaluated property '<paramref name="propertyName"/>' from the
-		/// active configuration/platform.
+		/// active configuration/platform. This method can retrieve any MSBuild property, including those
+		/// defined in imported .target files.
 		/// </summary>
 		/// <param name="propertyName">The name of the MSBuild property to read.</param>
 		/// <returns>The evaluated value of the property, or null if the property doesn't exist</returns>
-		public string GetProperty(string propertyName)
+		public string GetEvaluatedProperty(string propertyName)
 		{
-			return project.GetEvaluatedProperty(propertyName);
+			lock (SyncRoot) {
+				return project.GetEvaluatedProperty(propertyName);
+			}
 		}
 		
 		MSBuild.Project evaluatingTempProject;
@@ -195,13 +198,15 @@ namespace ICSharpCode.SharpDevelop.Project
 		public string GetProperty(string configuration, string platform, string propertyName,
 		                          out PropertyStorageLocations location)
 		{
-			MSBuild.BuildPropertyGroup group;
-			MSBuild.BuildProperty prop = FindPropertyObject(configuration, platform, propertyName,
-			                                                out group, out location);
-			if (prop == null)
-				return null;
-			else
-				return prop.FinalValue;
+			lock (SyncRoot) {
+				MSBuild.BuildPropertyGroup group;
+				MSBuild.BuildProperty prop = FindPropertyObject(configuration, platform, propertyName,
+				                                                out group, out location);
+				if (prop == null)
+					return null;
+				else
+					return prop.FinalValue;
+			}
 		}
 		
 		/// <summary>
@@ -243,13 +248,15 @@ namespace ICSharpCode.SharpDevelop.Project
 		                                    string propertyName,
 		                                    out PropertyStorageLocations location)
 		{
-			MSBuild.BuildPropertyGroup group;
-			MSBuild.BuildProperty prop = FindPropertyObject(configuration, platform, propertyName,
-			                                                out group, out location);
-			if (prop == null)
-				return null;
-			else
-				return prop.Value;
+			lock (SyncRoot) {
+				MSBuild.BuildPropertyGroup group;
+				MSBuild.BuildProperty prop = FindPropertyObject(configuration, platform, propertyName,
+				                                                out group, out location);
+				if (prop == null)
+					return null;
+				else
+					return prop.Value;
+			}
 		}
 		
 		/// <summary>
@@ -428,6 +435,18 @@ namespace ICSharpCode.SharpDevelop.Project
 		                        string propertyName, string newValue,
 		                        PropertyStorageLocations location,
 		                        bool treatPropertyValueAsLiteral)
+		{
+			ProjectPropertyChangedEventArgs args;
+			lock (SyncRoot) {
+				args = SetPropertyInternal(configuration, platform, propertyName, newValue, location, treatPropertyValueAsLiteral);
+			}
+			OnPropertyChanged(args);
+		}
+		
+		ProjectPropertyChangedEventArgs SetPropertyInternal(string configuration, string platform,
+		                                                    string propertyName, string newValue,
+		                                                    PropertyStorageLocations location,
+		                                                    bool treatPropertyValueAsLiteral)
 		{
 			PropertyStorageLocations oldLocation;
 			MSBuild.BuildPropertyGroup existingPropertyGroup;
@@ -562,7 +581,7 @@ namespace ICSharpCode.SharpDevelop.Project
 				                    propertyInsertionPosition,
 				                    treatPropertyValueAsLiteral);
 			}
-			OnPropertyChanged(args);
+			return args;
 		}
 		
 		/// <summary>
@@ -611,17 +630,29 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		#region IProjectItemListProvider interface
 		List<ProjectItem> items = new List<ProjectItem>();
-		ReadOnlyCollection<ProjectItem> itemsReadOnly;
-		ICollection<ItemType> availableFileItemTypes = ItemType.DefaultFileItems;
+		volatile ReadOnlyCollection<ProjectItem> itemsReadOnly;
+		volatile ICollection<ItemType> availableFileItemTypes = ItemType.DefaultFileItems;
 		
+		/// <summary>
+		/// Gets the list of items in the project. This member is thread-safe.
+		/// The returned collection is guaranteed not to change - adding new items or removing existing items
+		/// will create a new collection.
+		/// </summary>
 		public override ReadOnlyCollection<ProjectItem> Items {
 			get {
-				return itemsReadOnly ?? (itemsReadOnly = items.AsReadOnly());
+				ReadOnlyCollection<ProjectItem> c = itemsReadOnly;
+				if (c == null) {
+					lock (SyncRoot) {
+						c = Array.AsReadOnly(items.ToArray());
+					}
+					itemsReadOnly = c;
+				}
+				return c;
 			}
 		}
 		
 		/// <summary>
-		/// Gets the list of available file item types.
+		/// Gets the list of available file item types. This member is thread-safe.
 		/// </summary>
 		public override ICollection<ItemType> AvailableFileItemTypes {
 			get {
@@ -634,22 +665,27 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// </summary>
 		internal void CreateItemsListFromMSBuild()
 		{
-			foreach (ProjectItem item in items) {
-				item.Dispose();
-			}
-			items.Clear();
+			WorkbenchSingleton.AssertMainThread();
 			
-			Set<ItemType> availableFileItemTypes = new Set<ItemType>();
-			availableFileItemTypes.AddRange(ItemType.DefaultFileItems);
-			foreach (MSBuild.BuildItem item in project.GetEvaluatedItemsByName("AvailableItemName")) {
-				availableFileItemTypes.Add(new ItemType(item.Include));
-			}
-			this.availableFileItemTypes = availableFileItemTypes.AsReadOnly();
-			
-			foreach (MSBuild.BuildItem item in project.EvaluatedItems) {
-				if (item.IsImported) continue;
+			lock (SyncRoot) {
+				foreach (ProjectItem item in items) {
+					item.Dispose();
+				}
+				items.Clear();
+				itemsReadOnly = null; // remove readonly variant of item list - will regenerate on next Items call
+				
+				Set<ItemType> availableFileItemTypes = new Set<ItemType>();
+				availableFileItemTypes.AddRange(ItemType.DefaultFileItems);
+				foreach (MSBuild.BuildItem item in project.GetEvaluatedItemsByName("AvailableItemName")) {
+					availableFileItemTypes.Add(new ItemType(item.Include));
+				}
+				this.availableFileItemTypes = availableFileItemTypes.AsReadOnly();
 				
-				items.Add(CreateProjectItem(item));
+				foreach (MSBuild.BuildItem item in project.EvaluatedItems) {
+					if (item.IsImported) continue;
+					
+					items.Add(CreateProjectItem(item));
+				}
 			}
 		}
 		
@@ -662,30 +698,35 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (item.IsAddedToProject)
 				throw new ArgumentException("item is already added to project", "item");
 			
-			items.Add(item);
-			foreach (MSBuild.BuildItemGroup g in project.ItemGroups) {
-				if (g.IsImported || !string.IsNullOrEmpty(g.Condition) || g.Count == 0)
-					continue;
-				if (g[0].Name == item.ItemType.ItemName) {
-					MSBuildInternals.AddItemToGroup(g, item);
-					return;
-				}
-				if (g[0].Name == "Reference")
-					continue;
-				if (ItemType.DefaultFileItems.Contains(new ItemType(g[0].Name))) {
-					if (ItemType.DefaultFileItems.Contains(item.ItemType)) {
+			WorkbenchSingleton.AssertMainThread();
+			
+			lock (SyncRoot) {
+				items.Add(item);
+				itemsReadOnly = null; // remove readonly variant of item list - will regenerate on next Items call
+				foreach (MSBuild.BuildItemGroup g in project.ItemGroups) {
+					if (g.IsImported || !string.IsNullOrEmpty(g.Condition) || g.Count == 0)
+						continue;
+					if (g[0].Name == item.ItemType.ItemName) {
 						MSBuildInternals.AddItemToGroup(g, item);
 						return;
-					} else {
+					}
+					if (g[0].Name == "Reference")
 						continue;
+					if (ItemType.DefaultFileItems.Contains(new ItemType(g[0].Name))) {
+						if (ItemType.DefaultFileItems.Contains(item.ItemType)) {
+							MSBuildInternals.AddItemToGroup(g, item);
+							return;
+						} else {
+							continue;
+						}
 					}
+					
+					MSBuildInternals.AddItemToGroup(g, item);
+					return;
 				}
-				
-				MSBuildInternals.AddItemToGroup(g, item);
-				return;
+				MSBuild.BuildItemGroup newGroup = project.AddNewItemGroup();
+				MSBuildInternals.AddItemToGroup(newGroup, item);
 			}
-			MSBuild.BuildItemGroup newGroup = project.AddNewItemGroup();
-			MSBuildInternals.AddItemToGroup(newGroup, item);
 		}
 		
 		bool IProjectItemListProvider.RemoveProjectItem(ProjectItem item)
@@ -697,39 +738,24 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (!item.IsAddedToProject)
 				return false;
 			
-			if (items.Remove(item)) {
-				project.RemoveItem(item.BuildItem);
-				item.BuildItem = null; // make the item free again
-				return true;
-			} else {
-				throw new InvalidOperationException("Expected that the item is added to this project!");
+			WorkbenchSingleton.AssertMainThread();
+			
+			lock (SyncRoot) {
+				if (items.Remove(item)) {
+					itemsReadOnly = null; // remove readonly variant of item list - will regenerate on next Items call
+					project.RemoveItem(item.BuildItem);
+					item.BuildItem = null; // make the item free again
+					return true;
+				} else {
+					throw new InvalidOperationException("Expected that the item is added to this project!");
+				}
 			}
 		}
-		
-		public override bool IsFileInProject(string fileName)
-		{
-			return FindProjectItem(this, fileName) != null;
-		}
-		
-		public FileProjectItem FindFile(string fileName)
-		{
-			return FindProjectItem(this, fileName);
-		}
-		
-		internal static FileProjectItem FindProjectItem(IProject project, string fileName)
-		{
-			return Linq.Find(Linq.OfType<FileProjectItem>(project.Items),
-			                 delegate(FileProjectItem item) {
-			                 	return FileUtility.IsEqualFileName(item.FileName, fileName);
-			                 });
-			// return project.Items.OfType<FileProjectItem>().Find(
-			//			 item => FileUtility.IsEqualFileName(item.FileName, outputFileName));
-		}
 		#endregion
 		
 		#region Wrapped MSBuild Properties
 		public override string AppDesignerFolder {
-			get { return GetProperty("AppDesignerFolder"); }
+			get { return GetEvaluatedProperty("AppDesignerFolder"); }
 			set { SetProperty("AppDesignerFolder", value); }
 		}
 		#endregion
@@ -773,12 +799,12 @@ namespace ICSharpCode.SharpDevelop.Project
 				InitializeMSBuildProject();
 				
 				project.Load(fileName);
-				this.ActiveConfiguration = GetProperty("Configuration") ?? this.ActiveConfiguration;
-				this.ActivePlatform = GetProperty("Platform") ?? this.ActivePlatform;
+				this.ActiveConfiguration = GetEvaluatedProperty("Configuration") ?? this.ActiveConfiguration;
+				this.ActivePlatform = GetEvaluatedProperty("Platform") ?? this.ActivePlatform;
 				
 				CreateItemsListFromMSBuild();
 				LoadConfigurationPlatformNamesFromMSBuild();
-				IdGuid = GetProperty("ProjectGuid");
+				IdGuid = GetEvaluatedProperty("ProjectGuid");
 			} finally {
 				isLoading = false;
 			}
@@ -788,7 +814,9 @@ namespace ICSharpCode.SharpDevelop.Project
 		#region Saving
 		public override void Save(string fileName)
 		{
-			project.Save(fileName);
+			lock (SyncRoot) {
+				project.Save(fileName);
+			}
 		}
 		#endregion
 		
@@ -796,8 +824,10 @@ namespace ICSharpCode.SharpDevelop.Project
 		protected override void OnActiveConfigurationChanged(EventArgs e)
 		{
 			if (!isLoading) {
-				project.GlobalProperties.SetProperty("Configuration", this.ActiveConfiguration, true);
-				CreateItemsListFromMSBuild();
+				lock (SyncRoot) {
+					project.GlobalProperties.SetProperty("Configuration", this.ActiveConfiguration, true);
+					CreateItemsListFromMSBuild();
+				}
 			}
 			base.OnActiveConfigurationChanged(e);
 		}
@@ -805,8 +835,10 @@ namespace ICSharpCode.SharpDevelop.Project
 		protected override void OnActivePlatformChanged(EventArgs e)
 		{
 			if (!isLoading) {
-				project.GlobalProperties.SetProperty("Platform", this.ActivePlatform, true);
-				CreateItemsListFromMSBuild();
+				lock (SyncRoot) {
+					project.GlobalProperties.SetProperty("Platform", this.ActivePlatform, true);
+					CreateItemsListFromMSBuild();
+				}
 			}
 			base.OnActivePlatformChanged(e);
 		}

src/Main/Base/Project/Src/Project/MSBuildInternals.cs

@@ -246,17 +246,22 @@ namespace ICSharpCode.SharpDevelop.Project
 			if (newRawPath == null)
 				throw new ArgumentNullException("newRawPath");
 			
-			XmlAttribute a = (XmlAttribute)typeof(MSBuild.Import).InvokeMember(
-				"ProjectPathAttribute",
-				BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
-				null, import, null
-			);
-			a.Value = newRawPath;
-			EndXmlManipulation(project.MSBuildProject);
+			lock (project.SyncRoot) {
+				XmlAttribute a = (XmlAttribute)typeof(MSBuild.Import).InvokeMember(
+					"ProjectPathAttribute",
+					BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
+					null, import, null
+				);
+				a.Value = newRawPath;
+				EndXmlManipulation(project.MSBuildProject);
+			}
 			project.CreateItemsListFromMSBuild();
 		}
 		
-		public static IEnumerable<string> GetCustomMetadataNames(MSBuild.BuildItem item)
+		/// <summary>
+		/// Gets an array containing all custom metadata names.
+		/// </summary>
+		public static string[] GetCustomMetadataNames(MSBuild.BuildItem item)
 		{
 			ArrayList a = (ArrayList)typeof(MSBuild.BuildItem).InvokeMember(
 				"GetAllCustomMetadataNames",

src/Main/Base/Project/Src/Project/Solution/AbstractSolutionFolder.cs

@@ -12,23 +12,40 @@ using ICSharpCode.SharpDevelop.Gui;
 namespace ICSharpCode.SharpDevelop.Project
 {
 	/// <summary>
-	/// Description of ISolutionFolderContainer.
+	/// Default implementation for ISolutionFolderContainer. Thread-safe.
 	/// </summary>
 	public abstract class AbstractSolutionFolder : LocalizedObject, ISolutionFolder
 	{
+		readonly object syncRoot = new object();
+		
 		ISolutionFolderContainer parent   = null;
 		string                   typeGuid = null;
 		string                   idGuid   = null;
 		string                   location = null;
 		string                   name     = null;
 		
+		/// <summary>
+		/// Gets the object used for thread-safe synchronization.
+		/// All members lock on this object, but if you manipulate underlying structures
+		/// (such as the MSBuild project for MSBuildBasedProjects) directly, you will have to lock on this object.
+		/// </summary>
+		public object SyncRoot {
+			get { return syncRoot; }
+		}
+		
+		/// <summary>
+		/// Gets the solution this project belongs to. Returns null for projects that are not (yet) added to
+		/// any solution; or are added to a solution folder that is not added to any solution.
+		/// </summary>
 		[Browsable(false)]
 		public virtual Solution ParentSolution {
 			get {
-				if (parent != null)
-					return parent.ParentSolution;
-				else
-					return null;
+				lock (syncRoot) {
+					if (parent != null)
+						return parent.ParentSolution;
+					else
+						return null;
+				}
 			}
 		}
 		
@@ -68,7 +85,9 @@ namespace ICSharpCode.SharpDevelop.Project
 				return parent;
 			}
 			set {
-				parent = value;
+				lock (syncRoot) {
+					parent = value;
+				}
 			}
 		}
 		

src/Main/Base/Project/Src/Project/Solution/ISolutionFolder.cs

@@ -10,15 +10,32 @@ using System;
 namespace ICSharpCode.SharpDevelop.Project
 {
 	/// <summary>
-	/// Description of ISolutionFolderContainer.
+	/// An project-like entry in a solution, for example a solution folder or a project.
+	/// Implementing classes are required to implement this interface in a thread-safe manner.
+	/// Thread-safe members lock on the SyncRoot. Non-thread-safe members may only be called from the main thread.
 	/// </summary>
 	public interface ISolutionFolder
 	{
+		/// <summary>
+		/// Gets the object used for thread-safe synchronization.
+		/// Thread-safe members lock on this object, but if you manipulate underlying structures
+		/// (such as the MSBuild project for MSBuildBasedProjects) directly, you will have to lock on this object.
+		/// </summary>
+		object SyncRoot {
+			get;
+		}
+		
+		/// <summary>
+		/// Gets/Sets the container that contains this folder. This member is thread-safe.
+		/// </summary>
 		ISolutionFolderContainer Parent {
 			get;
 			set;
 		}
 		
+		/// <summary>
+		/// Gets the solution the solution folder/project belongs to. This member is thread-safe.
+		/// </summary>
 		Solution ParentSolution {
 			get;
 		}