Make it possible to properly use operator= on BCursors by making sure the

reference counting is maintained correctly in the app_server. While reviewing
this code, I have my doubts that my previous solution for handling pending
SetViewCursor() calls is always working as it is intended.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@31131 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/app/Cursor.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006, Haiku, Inc. All Rights Reserved.
+ * Copyright 2006-2009, Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _CURSOR_H
@@ -11,31 +11,39 @@
 
 
 class BCursor : BArchivable {
-	public:
+public:
-		BCursor(const void* cursorData);
+								BCursor(const void* cursorData);
-		BCursor(BMessage* data);
+								BCursor(const BCursor& other);
-		virtual	~BCursor();
+								BCursor(BMessage* data);
+	virtual	~BCursor();
 
-		virtual	status_t	Archive(BMessage* archive, bool deep = true) const;
+	virtual	status_t			Archive(BMessage* archive,
-		static BArchivable*	Instantiate(BMessage* archive);
+									bool deep = true) const;
+	static	BArchivable*		Instantiate(BMessage* archive);
 
-	private:
+			BCursor&			operator=(const BCursor& other);
-		virtual status_t	Perform(perform_code d, void* arg);
+			bool				operator==(const BCursor& other) const;
+			bool				operator!=(const BCursor& other) const;
 
-		virtual	void		_ReservedCursor1();
+private:
-		virtual	void		_ReservedCursor2();
+	virtual	status_t			Perform(perform_code d, void* arg);
-		virtual	void		_ReservedCursor3();
-		virtual	void		_ReservedCursor4();
 
-	private:
+	virtual	void				_ReservedCursor1();
-		friend class BApplication;
+	virtual	void				_ReservedCursor2();
-		friend class BView;
+	virtual	void				_ReservedCursor3();
+	virtual	void				_ReservedCursor4();
 
-		int32				fServerToken;
+			void				_FreeCursorData();
-		bool				fNeedToFree;
-		mutable bool		fPendingViewCursor;
 
-		uint32				_reserved[6];
+private:
+	friend class BApplication;
+	friend class BView;
+
+			int32				fServerToken;
+			bool				fNeedToFree;
+	mutable	bool				fPendingViewCursor;
+
+			uint32				_reserved[6];
 };
 
 #endif	// _CURSOR_H

headers/private/app/ServerProtocol.h

@@ -68,6 +68,7 @@ enum {
 	AS_QUERY_CURSOR_HIDDEN,
 
 	AS_CREATE_CURSOR,
+	AS_REFERENCE_CURSOR,
 	AS_DELETE_CURSOR,
 
 	AS_BEGIN_RECT_TRACKING,

src/kits/app/Cursor.cpp

@@ -63,6 +63,16 @@ BCursor::BCursor(const void *cursorData)
 }
 
 
+BCursor::BCursor(const BCursor& other)
+	:
+	fServerToken(-1),
+	fNeedToFree(false),
+	fPendingViewCursor(false)
+{
+	*this = other;
+}
+
+
 BCursor::BCursor(BMessage *data)
 {
 	// undefined on BeOS
@@ -74,14 +84,7 @@ BCursor::BCursor(BMessage *data)
 
 BCursor::~BCursor()
 {
-	// Notify server to deallocate server-side objects for this cursor
+	_FreeCursorData();
-	if (fNeedToFree) {
-		BPrivate::AppServerLink link;
-		link.StartMessage(AS_DELETE_CURSOR);
-		link.Attach<int32>(fServerToken);
-		link.Attach<bool>(fPendingViewCursor);
-		link.Flush();
-	}
 }
 
 
@@ -101,6 +104,42 @@ BCursor::Instantiate(BMessage *data)
 }
 
 
+BCursor&
+BCursor::operator=(const BCursor& other)
+{
+	if (&other != this && other != *this) {
+		_FreeCursorData();
+
+		fServerToken = other.fServerToken;
+		fNeedToFree = other.fNeedToFree;
+		fPendingViewCursor = false;
+
+		if (fNeedToFree) {
+			// Tell app_server that there is another reference for this
+			// cursor data!
+			BPrivate::AppServerLink link;
+			link.StartMessage(AS_REFERENCE_CURSOR);
+			link.Attach<int32>(fServerToken);
+		}
+	}
+	return *this;
+}
+
+
+bool
+BCursor::operator==(const BCursor& other) const
+{
+	return fServerToken == other.fServerToken;
+}
+
+
+bool
+BCursor::operator!=(const BCursor& other) const
+{
+	return fServerToken != other.fServerToken;
+}
+
+
 status_t
 BCursor::Perform(perform_code d, void *arg)
 {
@@ -112,3 +151,18 @@ void BCursor::_ReservedCursor1() {}
 void BCursor::_ReservedCursor2() {}
 void BCursor::_ReservedCursor3() {}
 void BCursor::_ReservedCursor4() {}
+
+
+void
+BCursor::_FreeCursorData()
+{
+	// Notify server to deallocate server-side objects for this cursor
+	if (fNeedToFree) {
+		BPrivate::AppServerLink link;
+		link.StartMessage(AS_DELETE_CURSOR);
+		link.Attach<int32>(fServerToken);
+		link.Attach<bool>(fPendingViewCursor);
+		link.Flush();
+	}
+}
+

src/servers/app/ServerApp.cpp

@@ -939,7 +939,7 @@ ServerApp::_DispatchMessage(int32 code, BPrivate::LinkReceiver& link)
 
 			if (link.Read(cursorData, sizeof(cursorData)) >= B_OK) {
 				cursor = fDesktop->GetCursorManager().CreateCursor(fClientTeam,
-																   cursorData);
+					cursorData);
 				if (cursor == NULL)
 					status = B_NO_MEMORY;
 			}
@@ -954,6 +954,27 @@ ServerApp::_DispatchMessage(int32 code, BPrivate::LinkReceiver& link)
 			fLink.Flush();
 			break;
 		}
+		case AS_REFERENCE_CURSOR:
+		{
+			STRACE(("ServerApp %s: Reference BCursor\n", Signature()));
+			// Attached data:
+			// 1) int32 token ID of the cursor to reference
+			int32 token;
+			if (link.Read<int32>(&token) != B_OK)
+				break;
+
+			if (!fDesktop->GetCursorManager().Lock())
+				break;
+
+			ServerCursor* cursor
+				= fDesktop->GetCursorManager().FindCursor(token);
+			if (cursor != NULL)
+				cursor->Acquire();
+
+			fDesktop->GetCursorManager().Unlock();
+
+			break;
+		}
 		case AS_DELETE_CURSOR:
 		{
 			STRACE(("ServerApp %s: Delete BCursor\n", Signature()));
@@ -968,8 +989,9 @@ ServerApp::_DispatchMessage(int32 code, BPrivate::LinkReceiver& link)
 			if (!fDesktop->GetCursorManager().Lock())
 				break;
 
-			ServerCursor* cursor = fDesktop->GetCursorManager().FindCursor(token);
+			ServerCursor* cursor
-			if (cursor) {
+				= fDesktop->GetCursorManager().FindCursor(token);
+			if (cursor != NULL) {
 				if (pendingViewCursor)
 					cursor->SetPendingViewCursor(true);