Ref counting for resource classes

Community Forums/Monkey2 Talk/Ref counting for resource classes

ziggy

(Posted 2015) [#1]

Wouldn't it be a very nice addition if a games oriented language could define some objects to be ref-counted? Couldn't this solve the requirement to Discard images and any other VRAM related resource, as them would be discarded automagically when thei're no longer used?
The manual discarding of images can be a source of hard to find bugs, and if a reference counting memory management of this classes can forced somehow, maybe we could make the language easier and safer to use?
Just an idea

Samah

(Posted 2015) [#2]

Something like this?

Interface IDiscardable
	Method Discard:Void()
End

Class RefCounter<T>
Private
	Global objects:Stack<T>
	Global refs:IntStack
Public
	Function Retain:Void(obj:T)
		If Not objects Then objects = New Stack<T>
		If Not refs Then refs = New IntStack
		Local idx:Int = objects.Find(obj)
		If idx >= 0 Then
			refs.Set(idx, refs.Get(idx)+1)
		End
	End

	Function Release:Void(obj:T)
		If Not objects Or Not refs Then Return
		Local idx:Int = objects.Find(obj)
		If idx >= 0 Then
			Local newVal:Int = refs.Get(idx) - 1
			refs.Set(idx, newVal)
			If newVal <= 0 Then
				Local disc:IDiscardable = IDiscardable(obj)
				If disc Then disc.Discard()
				objects.Remove(obj)
			End
		End
	End
End

Class Image Implements IDiscardable
	Method Discard:Void()
		' Image's discard stuff
	End
End

Disclaimer: I haven't compiled this.

ziggy

(Posted 2015) [#3]

mmm well, sort of but automatic. If you need to Retain and Release, then whole purpose of having ref-counting is sort of defeated.

Samah

(Posted 2015) [#4]

Right, but Mojo2 would call Retain/Release itself. It wouldn't be up to the developer. That example just makes it a generic tool so that the developer can use it for other things if they want.