Making an object pool: suggestions?

[Major Cooke]

I thought I'd give an object pool a try for recycling actors (in particularly special effects) a try, simply starting off with just special effects and maybe missile actors.

However, something tells me this may not have as much of a beneficial impact due to the VM versus just spawning and destroying, but I'd like to hear thoughts about that.

Would it be more beneficial just to have all the actors in a single dynamic array and search through them all? Or would it be better to have two arrays and two dedicated functions meant to 'mark' (like memory) the objects as free or used and move them over?

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The former means calling fewer functions for the VM to execute, but it has to search through every actor in there (there's multiple types too so I can't just push/pop it).

The latter means shorter searches and can immediately grab the first proper entry that matches the class type as it's guaranteed to be free. This moves over to the used array and is set as such, but there's more VM calls... they're just not as intensive as spawn/destroy.

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How it works so far:

Code: Select all

Class D4DHandler : EventHandler
{
	Array<D4DActor> Pool, Free;

	override void WorldUnloaded(WorldEvent e)
	{
		Pool.Clear();
		Free.Clear();
	}

	D4DActor FindFree(Class<D4DActor> mo)
	{
		if (!mo || Free.Size() < 1)
			return null;
			
		for (int i = 0; i < Free.Size(); i++)
		{
			let mo = D4DActor(Free[i]);
			if (mo && mo.GetClass() == mo)
				return mo;
		}
		
		return null;
	}
	
	// Indicate this object is free to re-use.
	void MarkFree(D4DActor mo)
	{
		if (!mo)	return;
		
		int i = Pool.Find(mo);
		if (i < Pool.Size())
		{
			Pool.Delete(i);
			if (Free.Find(mo) >= Free.Size())
				Free.Push(mo);
		}
		mo.freed = true;
	}
	
	// Indicate this object is being used
	void MarkUsed(D4DActor mo)
	{
		if (!mo)	return;
		
		int i = Free.Find(mo);
		if (i < Free.Size())
		{
			Free.Delete(i);
			if (Pool.Find(mo) >= Pool.Size())
				Pool.Push(mo);
		}
		mo.freed = false;
	}
}

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Furthermore, when an actor is marked as free, they gain NOINTERACTION, NOSECTOR, don't move, turn completely invisible and their tick functions do nothing until no longer free. When used again, they go through an A_SpawnItemEx-esque chain of code (for now, until I can get the rest of the spawn functions up and going) for 'reinitialization'... which is the reason why it's currently limited to just SFX so I don't have to take care of so many variables that aren't even touched.