implement ReaderWritelLockSlim to resolve threading issues

Author: jpbruyere

src/GraphicObjects/Docker.cs

@@ -146,14 +146,16 @@ protected override void onDraw (Cairo.Context gr)
 				gr.Clip ();
 			}
 
-			lock (Children) {
-				foreach (GraphicObject g in Children) {
-					if (CurrentInterface.DragAndDropOperation?.DragSource == g)
-						continue;
-					g.Paint (ref gr);
-				}
+			childrenRWLock.EnterReadLock ();
+
+			foreach (GraphicObject g in Children) {
+				if (CurrentInterface.DragAndDropOperation?.DragSource == g)
+					continue;
+				g.Paint (ref gr);
 			}
 
+			childrenRWLock.ExitReadLock ();
+
 			if (showDockingTarget) {
 				Rectangle r;
 				if (mainStack == null)

src/GraphicObjects/GraphicObject.cs

@@ -34,6 +34,7 @@
 using Cairo;
 using System.Diagnostics;
 using Crow.IML;
+using System.Threading;
 
 namespace Crow
 {
@@ -42,6 +43,8 @@ namespace Crow
 	/// </summary>
 	public class GraphicObject : ILayoutable, IValueChange, IDisposable
 	{
+		internal ReaderWriterLockSlim parentRWLock = new ReaderWriterLockSlim();
+
 		#region IDisposable implementation
 		protected bool disposed = false;
 
@@ -66,6 +69,7 @@ protected virtual void Dispose(bool disposing){
 				if (IsQueueForRedraw)
 				throw new Exception("Trying to dispose an object queued for Redraw: " + this.ToString());
 				#endif
+
 				if (CurrentInterface.HoverWidget != null) {
 					if (CurrentInterface.HoverWidget.IsOrIsInside(this))
 						CurrentInterface.HoverWidget = null;
@@ -80,13 +84,15 @@ protected virtual void Dispose(bool disposing){
 				}
 				if (!localDataSourceIsNull)
 					DataSource = null;
+
+				parentRWLock.EnterWriteLock();
 				parent = null;
+				parentRWLock.ExitWriteLock();
 			} else
 				Debug.WriteLine ("!!! Finalized by GC: {0}", this.ToString ());
 			Clipping?.Dispose ();
 			bmp?.Dispose ();
 			disposed = true;
-
 		}  
 		#endregion
 
@@ -217,7 +223,7 @@ public virtual void Initialize(){
 		//TODO: we should ensure the whole parsed widget tree is the last painted
 		public Rectangle LastPaintedSlot;
 		/// <summary>Prevent requeuing multiple times the same widget</summary>
-		public bool IsQueueForRedraw = false;
+		public bool IsQueueForClipping = false;
 		/// <summary>drawing Cache, if null, a redraw is done, cached or not</summary>
 		public Surface bmp;
 		public bool IsDirty = true;
@@ -243,11 +249,12 @@ [XmlIgnore]public virtual ILayoutable Parent {
 				if (parent == value)
 					return;
 				DataSourceChangeEventArgs e = new DataSourceChangeEventArgs (parent, value);
-				lock (CurrentInterface.LayoutMutex) {
-					parent = value;
-				}
-					onParentChanged (this, e);
-				
+
+				parentRWLock.EnterWriteLock();
+				parent = value;
+				parentRWLock.ExitWriteLock();
+									
+				onParentChanged (this, e);
 			}
 		}
 		[XmlIgnore]public ILayoutable LogicalParent {
@@ -774,7 +781,7 @@ public virtual Size MaximumSize {
 		/// Seek first logical tree upward if logicalParent is set, or seek graphic tree for
 		/// a not null dataSource that will be active for all descendants having dataSource=null
 		/// </summary>
-		[XmlAttributeAttribute]//[DefaultValue(null)]
+		[XmlAttributeAttribute]
 		public virtual object DataSource {
 			set {
 				if (DataSource == value)
@@ -784,12 +791,11 @@ public virtual object DataSource {
 				dataSource = value;
 				dse.NewDataSource = DataSource;
 
-				//prevent setting null causing stack overflow in specific case
 				if (dse.NewDataSource == dse.OldDataSource)
 					return;
-				lock (CurrentInterface.LayoutMutex) {
-					OnDataSourceChanged (this, dse);
-				}
+			
+				OnDataSourceChanged (this, dse);
+
 
 				NotifyValueChanged ("DataSource", DataSource);
 			}
@@ -854,9 +860,9 @@ public IList<Command> ContextCommands {
 		/// <summary> Loads the default values from XML attributes default </summary>
 		public void loadDefaultValues()
 		{
-			#if DEBUG_LOAD
-			Debug.WriteLine ("LoadDefValues for " + this.ToString ());
-			#endif
+//			#if DEBUG_LOAD
+//			Debug.WriteLine ("LoadDefValues for " + this.ToString ());
+//			#endif
 
 			Type thisType = this.GetType ();
 
@@ -1138,13 +1144,12 @@ public virtual void ClippingRegistration(){
 			#if DEBUG_UPDATE
 			Debug.WriteLine (string.Format("ClippingRegistration -> {0}", this.ToString ()));
 			#endif
-			lock(CurrentInterface.LayoutMutex){
-				IsQueueForRedraw = false;
-				if (Parent == null)
-					return;
+			parentRWLock.EnterReadLock ();
+			if (parent != null) {					
 				Parent.RegisterClip (LastPaintedSlot);
 				Parent.RegisterClip (Slot);
 			}
+			parentRWLock.ExitReadLock ();
 		}
 		/// <summary>
 		/// Add clip rectangle to this.clipping and propagate up to root

src/GraphicObjects/Group.cs

@@ -31,12 +31,15 @@
 using Cairo;
 using System.Diagnostics;
 using System.Reflection;
+using System.Threading;
 
 
 namespace Crow
 {
 	public class Group : GraphicObject
     {
+		protected ReaderWriterLockSlim childrenRWLock = new ReaderWriterLockSlim();
+
 		#region CTOR
 		public Group () : base() {}
 		public Group(Interface iface) : base(iface){}
@@ -62,10 +65,13 @@ public bool MultiSelect
             set { _multiSelect = value; }
         }
 		public virtual void AddChild(GraphicObject g){
-			lock (Children) {
-				g.Parent = this;
-				Children.Add (g);
-			}
+			childrenRWLock.EnterWriteLock();
+
+			g.Parent = this;
+			Children.Add (g);
+
+			childrenRWLock.ExitWriteLock();
+
 			g.RegisteredLayoutings = LayoutingType.None;
 			g.LayoutChanged += OnChildLayoutChanges;
 			g.RegisterForLayouting (LayoutingType.Sizing | LayoutingType.ArrangeChildren);
@@ -79,8 +85,11 @@ public virtual void RemoveChild(GraphicObject child)
 					CurrentInterface.HoverWidget = null;
 			}
 
-			lock (Children)
-				Children.Remove(child);
+			childrenRWLock.EnterWriteLock ();
+
+			Children.Remove(child);
+
+			childrenRWLock.ExitWriteLock ();
 
 			if (child == largestChild && Width == Measure.Fit)
 				searchLargestChild ();
@@ -96,10 +105,13 @@ public virtual void DeleteChild(GraphicObject child)
 			child.Dispose ();
         }
 		public virtual void InsertChild (int idx, GraphicObject g) {
-			lock (Children) {
-				g.Parent = this;
-				Children.Insert (idx, g);
-			}
+			childrenRWLock.EnterWriteLock ();
+				
+			g.Parent = this;
+			Children.Insert (idx, g);
+
+			childrenRWLock.ExitWriteLock ();
+
 			g.RegisteredLayoutings = LayoutingType.None;
 			g.LayoutChanged += OnChildLayoutChanges;
 			g.RegisterForLayouting (LayoutingType.Sizing | LayoutingType.ArrangeChildren);
@@ -109,15 +121,17 @@ public virtual void DeleteChild (int idx) {
 		}
 		public virtual void ClearChildren()
 		{
-			lock (Children) {
-				while (Children.Count > 0) {
-					GraphicObject g = Children [Children.Count - 1];
-					g.LayoutChanged -= OnChildLayoutChanges;
-					Children.RemoveAt (Children.Count - 1);
-					g.Dispose ();
-				}
+			childrenRWLock.EnterWriteLock ();
+
+			while (Children.Count > 0) {
+				GraphicObject g = Children [Children.Count - 1];
+				g.LayoutChanged -= OnChildLayoutChanges;
+				Children.RemoveAt (Children.Count - 1);
+				g.Dispose ();
 			}
 
+			childrenRWLock.ExitWriteLock ();
+
 			resetChildrenMaxSize ();
 
 			this.RegisterForLayouting (LayoutingType.Sizing);
@@ -128,45 +142,56 @@ public void putWidgetOnTop(GraphicObject w)
 		{
 			if (Children.Contains(w))
 			{
-				lock (Children) {
-					Children.Remove (w);
-					Children.Add (w);
-				}
+				childrenRWLock.EnterWriteLock ();
+
+				Children.Remove (w);
+				Children.Add (w);
+
+				childrenRWLock.ExitWriteLock ();
 			}
 		}
 		public void putWidgetOnBottom(GraphicObject w)
 		{
 			if (Children.Contains(w))
 			{
-				lock (Children) {
-					Children.Remove (w);
-					Children.Insert (0, w);
-				}
+				childrenRWLock.EnterWriteLock ();
+
+				Children.Remove (w);
+				Children.Insert (0, w);
+
+				childrenRWLock.ExitWriteLock ();
 			}
 		}
 
 		#region GraphicObject overrides
 		public override void OnDataSourceChanged (object sender, DataSourceChangeEventArgs e)
 		{
 			base.OnDataSourceChanged (this, e);
-			lock (Children) {
-				foreach (GraphicObject g in children)
-					if (g.localDataSourceIsNull & g.localLogicalParentIsNull)
-						g.OnDataSourceChanged (g, e);
-			}
+
+			childrenRWLock.EnterReadLock ();
+
+			foreach (GraphicObject g in children)
+				if (g.localDataSourceIsNull & g.localLogicalParentIsNull)
+					g.OnDataSourceChanged (g, e);
+			
+			childrenRWLock.ExitReadLock ();
 		}
 		public override GraphicObject FindByName (string nameToFind)
 		{
 			if (Name == nameToFind)
 				return this;
 			GraphicObject tmp = null;
-			lock (Children) {
-				foreach (GraphicObject w in Children) {
-					tmp = w.FindByName (nameToFind);
-					if (tmp != null)
-						break;
-				}
+
+			childrenRWLock.EnterReadLock ();
+
+			foreach (GraphicObject w in Children) {
+				tmp = w.FindByName (nameToFind);
+				if (tmp != null)
+					break;
 			}
+
+			childrenRWLock.ExitReadLock ();
+
 			return tmp;
 		}
 		public override bool Contains (GraphicObject goToFind)
@@ -207,10 +232,11 @@ public override void OnLayoutChanges (LayoutingType layoutType)
 		{
 			base.OnLayoutChanges (layoutType);
 
+			childrenRWLock.EnterReadLock ();
 			//position smaller objects in group when group size is fit
 			switch (layoutType) {
 			case LayoutingType.Width:
-				foreach (GraphicObject c in Children){
+				foreach (GraphicObject c in Children) {
 					if (c.Width.Units == Unit.Percent)
 						c.RegisterForLayouting (LayoutingType.Width);
 					else
@@ -226,6 +252,7 @@ public override void OnLayoutChanges (LayoutingType layoutType)
 				}
 				break;
 			}
+			childrenRWLock.ExitReadLock ();
 		}
 		protected override void onDraw (Context gr)
 		{
@@ -239,11 +266,13 @@ protected override void onDraw (Context gr)
 				gr.Clip ();
 			}
 
-			lock (Children) {
+			childrenRWLock.EnterReadLock ();
+
 				foreach (GraphicObject g in Children) {
 					g.Paint (ref gr);
 				}
-			}
+
+			childrenRWLock.ExitReadLock ();
 			gr.Restore ();
 		}
 		protected override void UpdateCache (Context ctx)
@@ -268,16 +297,18 @@ protected override void UpdateCache (Context ctx)
 					gr.Clip ();
 				}
 
-				lock (Children) {
-					foreach (GraphicObject c in Children) {
-						if (!c.Visible)
-							continue;
-						if (Clipping.Contains (c.Slot + ClientRectangle.Position) == RegionOverlap.Out)
-							continue;
-						c.Paint (ref gr);
-					}
+				childrenRWLock.EnterReadLock ();
+
+				foreach (GraphicObject c in Children) {
+					if (!c.Visible)
+						continue;
+					if (Clipping.Contains (c.Slot + ClientRectangle.Position) == RegionOverlap.Out)
+						continue;
+					c.Paint (ref gr);
 				}
 
+				childrenRWLock.ExitReadLock ();
+
 				#if DEBUG_CLIP_RECTANGLE
 				Clipping.stroke (gr, Color.Amaranth.AdjustAlpha (0.8));
 				#endif