Best way to scan unit auras

[CKlausi]

Hi,

my goal is to create an dottracker for my addon.
I am searching for an efficient way to scan my targets auras without creating too much garbage.
So I am using the OnUpdate function to call my "scanner" function, which looks like this

local auras = {}
local function GetAuras(unit, helpOrHarm)
	local auraIndex = 0
	for index = 1, 40 do
		local name, rank, icon, count, debuffType, duration, expirationTime, unitCaster, isStealable, shouldConsolidate, spellID = UnitAura(unit, index, helpOrHarm)
		if not name then break end
	
		auraIndex = auraIndex + 1
		auras[auraIndex ] = {} -- this is surely my memory problem
		auras[auraIndex ].spellID = spellID
                -- etc
	end
	
	return auras
end

I think this part auras[auraIndex ] = {} creates a lot of garbage.
Perhaps also my call in OnUpdate which looks like this

local aurasTarget = {}
local function OnUpdate(self, elapsed)
	timeelapsed = timeelapsed + elapsed
	if(timeelapsed > 0.05) then
		aurasTarget = UpdateAuras("target", "HARMFUL")
		timeelapsed = 0
	end
end

Memory will increase very fast. I am a little confused how to do this right, read a lot of code of other addons, but I don't find the right point
Perhaps someone can give me a point into the right direction how to get started with this

Best regards
Clausi

[Lombra]

Yes, that table is most likely the culprit, but you should also not be using OnUpdate to do these things, and instead use the UNIT_AURA event. You could probably use OnUpdate to update any timers you might have, though. Or maybe people use animations for these things, not sure.

[jeruku]

Your memory problem is definitely that. In your code you are creating 40 new tables every time you call GetAuras; tables are not immediately collected by the garbage collector meaning they remain in memory until the collector can do something with them.

Use the following method:

-- Looks for an existing table or creates a new one.
    auras[ auraIndex ] = auras[ auraIndex ] or {}

which is short for

if not auras[ auraIndex ] then
    auras[ auraIndex ] = {}
end

As for the other part UNIT_AURA is where you should rescan auras and update them. You can always add a Cooldown frame over the top of an aura allowing the easy display of a spiral and timer.

So it would include something like the following.

local auras -- decalre auras outside and use it for your entire addon.
 
 
local function GetAuras(unit, helpOrHarm)
-- code
    for index = 1, 40 do
        -- code to get/create aurabutton among other things
        if not aurabutton.cooldown then
            local cooldown = CreateFrame('Cooldown', nil, aurabutton, "CooldownFrameTemplate")
            cooldown:SetAllPoints(aurabutton) -- make it cover the aura
            aurabutton.cooldown = cooldown -- make it easier to access elsewhere
        end
        aurabutton.cooldown:SetCooldown((expirationTime - duration), duration)
        -- do some more stuff
    end
-- more code
end

If this is not what you are looking for please elaborate and I will be glad to assist you further.

[CKlausi]

Thank you guys, that really helped me to continue

[Banknorris]

Originally Posted by jeruku tables are not and cannot be deleted from memory until reload or exiting game.

Really? I read somewhere (don't really remember) that Lua garbage collection worked in WoW when you are out of combat but stopped when you were in combat.

Wait I found it:
http://us.battle.net/wow/en/forum/topic/4038616243#2

I know FRAMES (which are tables, but not all tables are frames) can't be deleted until reload or exiting game.

[Phanx]

Yes, tables can be garbage-collected, but userdata (the "magic" part of a frame) cannot. However, creating 40 tables in an OnUpdate function is still a massive memory leak. Garbage collection doesn't run constantly (as you've observed already, the memory used by all those tables isn't freed up immediately after the OnUpdate run) and constantly creating tables and filling up memory like that is a significant drain on system resources.

[CKlausi]

Yes that was my memory problem, now I call the aura update function on events like UNIT_AURA and PLAYER_TARGET_CHANGE etc
OnUpdate only will take care of timers which where stored into duration and expirationTime (also removed the return value, forgot that lua will reference tables, so they will become all the same)
I am also watching the SPELL_AURA_REMOVED event of COMBAT_LOG_EVENT_UNFILTERED to hide auras.

[jeruku]

Thank you for pointing that out, Phanx and Banknorris. I sometimes jumble things together when not actually writing code(well maybe occasionally).

I will edit my previous post to diffuse future confusion.

[Phanx]

Originally Posted by CKlausi I am also watching the SPELL_AURA_REMOVED event of COMBAT_LOG_EVENT_UNFILTERED to hide auras.

There is no reason to waste CPU cycles handling CLEU if you're already using UNIT_AURA.

[semlar]

Originally Posted by Phanx There is no reason to waste CPU cycles handling CLEU if you're already using UNIT_AURA.

That depends on whether the addon is tracking auras for units that don't currently have a valid unit ID.

Since it's a "dot tracker" I'm guessing they're creating timers for everything they're dotting up.

[CKlausi]

Thanks for your advice, currently I am only tracking unit ids like target and focus, so I changed it to hide no longer needed bars on UNIT_AURA event.

What would be a good throttle value for onupdate to keep the bars smooth and performance at its best?

[Lombra]

Well I would say for a bar addon you shouldn't throttle the updating of the bar value. If you don't, it might end up looking sluggish compared to the rest of the game. It's not all that CPU intensive. I think what most people have an issue with is when you do unnecessary stuff. :P