[Release] LinkedLists for UT

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Wormbo

Wormbo

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Shouldn't this be in the coding section? I doubt many players will have an idea what you're going on about.

BTW: Yes, it's nice and simple, but it'll get inefficient with longer lists. I see potential room for improvement by making the list doubly-linked and possibly by reusing ListElement instances.
 
Zur

Zur

surrealistic mad cow
Jul 8, 2002
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Wormbo said:
Shouldn't this be in the coding section? I doubt many players will have an idea what you're going on about.
Click to expand...

I don't know. I tend to post questions in the coding section. Do you think an announcement would be well received ? If so, the topic can be moved over to that forum.

BTW: Yes, it's nice and simple, but it'll get inefficient with longer lists. I see potential room for improvement by making the list doubly-linked and possibly by reusing ListElement instances.
Click to expand...

Do you mean that it will get inefficient through design (you have to go through x ListElements to get the Nth object) or because unrealscript is slower ? I'll most probably add a previous method. Reusing instances is a great idea. I suppose instantiating has less of a hit than spawning but still.
 
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Wormbo

Wormbo

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Without reuse you just run into a memory problem. By default the engine only collects garbage at map change, so all the new'd ListElement objects would stay around and take up memory. There's not much you could really do about the inefficiency of linked lists in general, but e.g. Java's LinkedList class uses a doubly linked list and iterates from the closer end to access specific indices in the list. It's not that much of a performance gain, only a constant factor of two, but better than nothing. Maybe you should consider creating an access method similar to the ListIterator interface in Java, so users of your list class don't need the expensive index-based access methods and just move a "cursor" around to access and modify the list and its content.
 
Zur

Zur

surrealistic mad cow
Jul 8, 2002
11,708
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Wormbo said:
Without reuse you just run into a memory problem. By default the engine only collects garbage at map change, so all the new'd ListElement objects would stay around and take up memory.
Click to expand...

Ah, right. So reusing ListElements is definitely a good idea. I'm not sure how I'm going to go about that though. There should be some sort of pool where an instance can be fished out. Maybe an array will do the trick. Or maybe a LinkedList (lol).

There's not much you could really do about the inefficiency of linked lists in general, but e.g. Java's LinkedList class uses a doubly linked list and iterates from the closer end to access specific indices in the list.
Click to expand...

That shouldn't be hard to do. In the get(), the list size could be used to decide what end of the list is better suited for seeking.

It's not that much of a performance gain, only a constant factor of two, but better than nothing.
Click to expand...

Where did you learn about algorithm performance ?

Maybe you should consider creating an access method similar to the ListIterator interface in Java, so users of your list class don't need the expensive index-based access methods and just move a "cursor" around to access and modify the list and its content.
Click to expand...

That is going to be more complicated as I'm less familiar with ListIterator than I'd like to be. Maybe another object with a reference to a LinkedList and a ListElement will do. The calls to methods could simply be forwarded.
 
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Zur

Zur

surrealistic mad cow
Jul 8, 2002
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Azura said:
Ah, right. So reusing ListElements is definitely a good idea. I'm not sure how I'm going to go about that though. There should be some sort of pool where an instance can be fished out. Maybe an array will do the trick. Or maybe a LinkedList (lol).
Click to expand...

A better idea crossed my mind. As soon as a ListElement is removed, it can be initialized and stored in a temporary class variable. Then, when an object is added, the function can simply test if the class variable contains an ListElement and use it instead of creating a new one.

That won't be enough if clear() is used though.

Edit: Scrapped that idea and decided to create a new structure to handled this.
 
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