Aura caching

AuraCache.lua

local addonName, addon = ...

local _G = _G
local CreateFrame = _G.CreateFrame
local pairs = _G.pairs
local rawget = _G.rawget
local setmetatable = _G.setmetatable
local type = _G.type
local UnitAura = _G.UnitAura
local unpack = _G.unpack
local wipe = _G.wipe

local miss, clear, direct, iterator = 0, 0, 0, 0

local heap = setmetatable({}, { __mode = 'kv' })

local function FillTable(t, ...)
	if select('#', ...) == 0 or not ... then
		if t then
			heap[t] = true
		end
		return false
	end
	if not t then
		t = next(heap) or {}
		heap[t] = nil
	end
	for i = 1, max(#t, select('#', ...)) do
		t[i] = select(i, ...)
	end
	return t
end

local function BuildFilterTable(unit, filter)
	return setmetatable({}, {
		__index = function(t, key)
			local aura
			if type(key) == "string" then
				aura = FillTable(false, UnitAura(unit, key, nil, filter))
			else
				aura = FillTable(false, UnitAura(unit, key, filter))
			end
			miss = miss + 1
			t[key] = aura
			return aura
		end
	})
end

local function BuildUnitTable(unit)
	return setmetatable({}, {
		__index = function(t, filter)
			local sub = BuildFilterTable(unit, filter)
			t[filter] = sub
			return sub
		end
	})
end

local cache = setmetatable({}, {
	__index = function(t, unit)
		local sub = BuildUnitTable(unit)
		t[unit] = sub
		return sub
	end
})

local eventFrame = CreateFrame("Frame")
eventFrame:RegisterEvent('UNIT_AURA')
eventFrame:SetScript('OnEvent', function(_, _, unit)
	local unitTable = rawget(cache, unit)
	if not unitTable then return end
	for filter, filterTable in pairs(unitTable) do
		for key, aura in pairs(filterTable) do
			heap[aura] = true
			filterTable[key] = nil
		end
	end
	clear = clear + 1
end)

function addon.UnitAura(unit, key, rank, filter)
	if not unit then return end
	if type(key) == "string" then
		filter = rank
	end
	direct = direct + 1
	local aura = cache[unit][filter or ""][key]
	if aura then
		return unpack(aura)
	end
end

local function AuraIterator(auraTable, index)
	iterator = iterator + 1
	local aura = auraTable[index+1]
	if aura then
		return index+1, unpack(aura)
	end
end

local function EmptyIterator() end

function addon.IterateAuras(unit, filter)
	if not unit then return EmptyIterator end
	return AuraIterator, cache[unit][filter or ""], 0
end

function addon.api.GetAuraCacheStats()
	local heapSize = 0
	for t in pairs(heap) do
		heapSize = heapSize + 1
	end
	return direct, iterator, miss, clear, heapSize
end