WindowLayer::ProcessDirtyRegions() no longer deadlock in case it can't send

the AS_REDRAW message.
The AS_REDRAW message is now only used as a notifier - it's arrival is not
critical anymore, IOW it's simply dropped when the queue is full.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15511 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/servers/app/ServerWindow.cpp

@@ -350,6 +350,18 @@ fDesktop->LockSingleWindow();
 }
 
 
+void
+ServerWindow::RequestRedraw()
+{
+	PostMessage(AS_REDRAW, 0);
+		// we don't care if this fails - it's only a notification, and if
+		// it fails, there are obviously enough messages in the queue
+		// already
+
+	atomic_add(&fRedrawRequested, 1);
+}
+
+
 void
 ServerWindow::SetTitle(const char* newTitle)
 {
@@ -862,9 +874,8 @@ ServerWindow::_DispatchMessage(int32 code, BPrivate::LinkReceiver &link)
 		}
 
 		case AS_REDRAW:
-			// command issued by Desktop only (via WindowLayer::ProcessDirtyRegion())
+			// Nothing to do here - the redraws are actually handled by looking
-			DTRACE(("ServerWindow %s: AS_REDRAW\n", Title()));
+			// at the fRedrawRequested member variable in _MessageLooper().
-			fWindowLayer->RedrawDirtyRegion();
 			break;
 
 		case AS_BEGIN_UPDATE:
@@ -2169,6 +2180,10 @@ ServerWindow::_MessageLooper()
 				CRITICAL("ServerWindow: a window must be hidden before it's deleted\n");
 		} else {
 			fDesktop->LockSingleWindow();
+
+			if (atomic_and(&fRedrawRequested, 0) != 0)
+				fWindowLayer->RedrawDirtyRegion();
+
 			_DispatchMessage(code, receiver);
 			fDesktop->UnlockSingleWindow();
 		}

src/servers/app/ServerWindow.h

@@ -102,6 +102,8 @@ public:
 	inline	int32				ClientToken() const { return fClientToken; }
 	inline	int32				ServerToken() const { return fServerToken; }
 
+			void				RequestRedraw();
+
 			void				GetInfo(window_info& info);
 
 private:
@@ -150,6 +152,7 @@ private:
 			::EventTarget		fEventTarget;
 
 			BMessage			fClientViewsWithInvalidCoords;
+			int32				fRedrawRequested;
 
 			int32				fServerToken;
 			int32				fClientToken;

src/servers/app/WindowLayer.cpp

@@ -624,7 +624,7 @@ WindowLayer::ProcessDirtyRegion(BRegion& region)
 		// Until the message is processed in the window
 		// thread, the desktop thread can add parts to
 		// the region as it likes.
-		ServerWindow()->PostMessage(AS_REDRAW);
+		ServerWindow()->RequestRedraw();
 	}
 
 	// this is executed from the desktop thread