Fixed a large client side memory leak for app_server memory.

* The areas allocated for BBitmaps were never deleted, even though the
  app_server deleted its part when the memory got freed.
* This resulted in a constant memory increase if the application in question
  would operate on many changing large bitmaps, like photos.
* Since the bitmaps are reference counted, we don't actually know when to delete
  the areas, so that the app_server now notifies the client whenever that is
  possible.
* This might fix #6824.

headers/private/app/ServerProtocol.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2010, Haiku.
+ * Copyright 2001-2012, Haiku.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -344,6 +344,12 @@ enum {
 	AS_LAST_CODE
 };
 
+// TODO: move this into a private app header, together with the rest of the
+//		private message definitions in AppDefs.h
+enum {
+	kMsgDeleteServerMemoryArea		= '_DSA',
+};
+
 // bitmap allocation flags
 enum {
 	kAllocator			= 0x1,

src/kits/app/Application.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2009, Haiku.
+ * Copyright 2001-2012, Haiku.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -601,9 +601,18 @@ BApplication::MessageReceived(BMessage *message)
 			break;
 
 		case kMsgAppServerRestarted:
-		{
 			_ReconnectToServer();
 			break;
+
+		case kMsgDeleteServerMemoryArea:
+		{
+			int32 serverArea;
+			if (message->FindInt32("server area", &serverArea) == B_OK) {
+				// The link is not used, but we currently borrow its lock
+				BPrivate::AppServerLink link;
+				fServerAllocator->RemoveArea(serverArea);
+			}
+			break;
 		}
 
 		default:

src/kits/app/ServerMemoryAllocator.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2011, Haiku, Inc. All Rights Reserved.
+ * Copyright 2006-2012, Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -131,6 +131,7 @@ status_t
 ServerMemoryAllocator::AreaAndBaseFor(area_id serverArea, area_id& _area,
 	uint8*& _base)
 {
+	// TODO: why not use a map?
 	for (int32 i = fAreas.CountItems(); i-- > 0;) {
 		area_mapping* mapping = (area_mapping*)fAreas.ItemAt(i);
 

src/kits/interface/Bitmap.cpp

@@ -1186,7 +1186,7 @@ BBitmap::_CleanUp()
 		link.Attach<int32>(fServerToken);
 		link.Flush();
 
-		// TODO: we may want to delete parts of the server memory areas here!
+		// The server areas are deleted via kMsgDeleteServerMemoryArea message
 
 		fArea = -1;
 		fServerToken = -1;

src/servers/app/ClientMemoryAllocator.cpp

@@ -179,6 +179,8 @@ ClientMemoryAllocator::Free(block* freeBlock)
 
 		fChunks.Remove(chunk);
 		delete_area(chunk->area);
+		fApplication->NotifyDeleteClientArea(chunk->area);
+
 		free(chunk);
 	}
 }

src/servers/app/ServerApp.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2010, Haiku.
+ * Copyright 2001-2012, Haiku.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -484,6 +484,21 @@ ServerApp::RemovePicture(ServerPicture* picture)
 }
 
 
+/*!	Called from the ClientMemoryAllocator whenever a server area could be
+	deleted.
+	A message is then sent to the client telling it that it can delete its
+	client area, too.
+*/
+void
+ServerApp::NotifyDeleteClientArea(area_id serverArea)
+{
+	BMessage notify(kMsgDeleteServerMemoryArea);
+	notify.AddInt32("server area", serverArea);
+
+	SendMessageToClient(&notify);
+}
+
+
 // #pragma mark - private methods
 
 

src/servers/app/ServerApp.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2010, Haiku.
+ * Copyright 2001-2012, Haiku.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -94,6 +94,8 @@ public:
 
 			BPrivate::BTokenSpace& ViewTokens() { return fViewTokens; }
 
+			void				NotifyDeleteClientArea(area_id serverArea);
+
 private:
 	virtual	void				_GetLooperName(char* name, size_t size);
 	virtual	void				_DispatchMessage(int32 code,