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LibTSM/Util/ObjectPool.lua

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+-- ------------------------------------------------------------------------------ --
+--                                TradeSkillMaster                                --
+--                          https://tradeskillmaster.com                          --
+--    All Rights Reserved - Detailed license information included with addon.     --
+-- ------------------------------------------------------------------------------ --
+
+--- ObjectPool Functions.
+-- @module ObjectPool
+
+local _, TSM = ...
+local ObjectPool = TSM.Init("Util.ObjectPool")
+local Debug = TSM.Include("Util.Debug")
+local private = {
+	debugLeaks = TSM.__IS_TEST_ENV or false,
+	instances = {},
+	context = {},
+}
+local DEBUG_STATS_MIN_COUNT = 1
+
+
+
+-- ============================================================================
+-- Metatable
+-- ============================================================================
+
+local OBJECT_POOL_MT = {
+	__index = {
+		Get = function(self)
+			local context = private.context[self]
+			local obj = tremove(context.freeList)
+			if not obj then
+				context.numCreated = context.numCreated + 1
+				obj = context.createFunc()
+				assert(obj)
+			end
+			if private.debugLeaks then
+				context.state[obj] = (Debug.GetStackLevelLocation(2 + context.extraStackOffset) or "?").." -> "..(Debug.GetStackLevelLocation(3 + context.extraStackOffset) or "?")
+			else
+				context.state[obj] = "???"
+			end
+			return obj
+		end,
+		Recycle = function(self, obj)
+			local context = private.context[self]
+			assert(context.state[obj])
+			context.state[obj] = nil
+			tinsert(context.freeList, obj)
+		end,
+	},
+	__newindex = function(self, key, value) error("Object pool cannot be modified") end,
+	__metatable = false,
+}
+
+
+
+-- ============================================================================
+-- Module Functions
+-- ============================================================================
+
+--- Create a new object pool.
+-- @tparam string name The name of the object pool for debug purposes
+-- @tparam function createFunc The function which is called to create a new object
+-- @tparam[opt=0] number extraStackOffset The extra stack offset for tracking where objects are being used from or nil to disable stack info
+-- @treturn ObjectPool The object pool object
+function ObjectPool.New(name, createFunc, extraStackOffset)
+	assert(createFunc)
+	assert(not private.instances[name])
+	local pool = setmetatable({}, OBJECT_POOL_MT)
+	private.context[pool] = {
+		createFunc = createFunc,
+		extraStackOffset = extraStackOffset or 0,
+		freeList = {},
+		state = {},
+		numCreated = 0,
+	}
+	private.instances[name] = private.context[pool]
+	return pool
+end
+
+function ObjectPool.EnableLeakDebug()
+	private.debugLeaks = true
+end
+
+function ObjectPool.GetDebugInfo()
+	local debugInfo = {}
+	for name, context in pairs(private.instances) do
+		local numCreated, numInUse, info = private.GetDebugStats(context)
+		debugInfo[name] = {
+			numCreated = numCreated,
+			numInUse = numInUse,
+			info = info,
+		}
+	end
+	return debugInfo
+end
+
+
+
+-- ============================================================================
+-- Private Helper Functions
+-- ============================================================================
+
+function private.GetDebugStats(context)
+	local counts = {}
+	local totalCount = 0
+	for _, caller in pairs(context.state) do
+		counts[caller] = (counts[caller] or 0) + 1
+		totalCount = totalCount + 1
+	end
+	local debugInfo = {}
+	for info, count in pairs(counts) do
+		if count > DEBUG_STATS_MIN_COUNT then
+			tinsert(debugInfo, format("[%d] %s", count, info))
+		end
+	end
+	if #debugInfo == 0 then
+		tinsert(debugInfo, "<none>")
+	end
+	return context.numCreated, totalCount, debugInfo
+end