Content ID caching in Lua (#12444)

* Cache content IDs in Lua

Co-authored-by: sfan5 <sfan5@live.de>

builtin/async/game.lua

@@ -13,9 +13,12 @@ end
 
 -- Import a bunch of individual files from builtin/game/
 local gamepath = core.get_builtin_path() .. "game" .. DIR_DELIM
+local commonpath = core.get_builtin_path() .. "common" .. DIR_DELIM
+
+local builtin_shared = {}
 
 dofile(gamepath .. "constants.lua")
-dofile(gamepath .. "item_s.lua")
+assert(loadfile(commonpath .. "item_s.lua"))(builtin_shared)
 dofile(gamepath .. "misc_s.lua")
 dofile(gamepath .. "features.lua")
 dofile(gamepath .. "voxelarea.lua")
@@ -57,3 +60,5 @@ setmetatable(core.registered_items, alias_metatable)
 setmetatable(core.registered_nodes, alias_metatable)
 setmetatable(core.registered_craftitems, alias_metatable)
 setmetatable(core.registered_tools, alias_metatable)
+
+builtin_shared.cache_content_ids()

builtin/common/item_s.lua

@@ -4,6 +4,8 @@
 -- Server or writable access to IGameDef on the engine side.
 -- (The '_s' stands for standalone.)
 
+local builtin_shared = ...
+
 --
 -- Item definition helpers
 --
@@ -177,3 +179,47 @@ function core.strip_param2_color(param2, paramtype2)
 	-- paramtype2 == "color" requires no modification.
 	return param2
 end
+
+-- Content ID caching
+
+local old_get_content_id = core.get_content_id
+local old_get_name_from_content_id = core.get_name_from_content_id
+
+local name2content = setmetatable({}, {
+	__index = function(self, name)
+		return old_get_content_id(name)
+	end,
+})
+
+local content2name = setmetatable({}, {
+	__index = function(self, id)
+		return old_get_name_from_content_id(id)
+	end,
+})
+
+function core.get_content_id(name)
+	return name2content[name]
+end
+
+function core.get_name_from_content_id(id)
+	return content2name[id]
+end
+
+-- Cache content IDs after they have stopped changing.
+function builtin_shared.cache_content_ids()
+	for name in pairs(core.registered_nodes) do
+		local id = old_get_content_id(name)
+		name2content[name] = id
+		content2name[id] = name
+	end
+	-- unknown is not in the registered node list.
+	local unknown_name = old_get_name_from_content_id(core.CONTENT_UNKNOWN)
+	name2content[unknown_name] = core.CONTENT_UNKNOWN
+	content2name[core.CONTENT_UNKNOWN] = unknown_name
+
+	for name in pairs(core.registered_aliases) do
+		if core.registered_nodes[name] then
+			name2content[name] = old_get_content_id(name)
+		end
+	end
+end

builtin/game/init.lua

@@ -8,7 +8,7 @@ local gamepath   = scriptpath .. "game".. DIR_DELIM
 local builtin_shared = {}
 
 dofile(gamepath .. "constants.lua")
-dofile(gamepath .. "item_s.lua")
+assert(loadfile(commonpath .. "item_s.lua"))(builtin_shared)
 assert(loadfile(gamepath .. "item.lua"))(builtin_shared)
 dofile(gamepath .. "register.lua")
 
@@ -37,4 +37,6 @@ dofile(gamepath .. "statbars.lua")
 dofile(gamepath .. "knockback.lua")
 dofile(gamepath .. "async.lua")
 
+core.after(0, builtin_shared.cache_content_ids)
+
 profiler = nil

games/devtest/mods/experimental/commands.lua

@@ -43,6 +43,79 @@ minetest.register_chatcommand("test_bulk_set_node", {
 	end,
 })
 
+-- Safeguard against too much optimization. This way the results cannot be optimized
+-- away, but they can be garbage collected (due to __mode = "k").
+_G._bench_content_ids_data = setmetatable({}, {__mode = "k"})
+
+local function bench_name2content()
+	local t = {}
+	_G._bench_content_ids_data[t] = true
+
+	local get_content_id = minetest.get_content_id
+
+	local start = minetest.get_us_time()
+
+	for i = 1, 200 do
+		for name in pairs(minetest.registered_nodes) do
+			t[#t + 1] = get_content_id(name)
+		end
+	end
+
+	local finish = minetest.get_us_time()
+
+	return (finish - start) / 1000
+end
+
+local function bench_content2name()
+	local t = {}
+	_G._bench_content_ids_data[t] = true
+
+	-- Try to estimate the highest content ID that's used
+	-- (not accurate but good enough for this test)
+	local n = 0
+	for _ in pairs(minetest.registered_nodes) do
+		n = n + 1
+	end
+
+	local get_name_from_content_id = minetest.get_name_from_content_id
+
+	local start = minetest.get_us_time()
+
+	for i = 1, 200 do
+		for j = 0, n do
+			t[#t + 1] = get_name_from_content_id(j)
+		end
+	end
+
+	local finish = minetest.get_us_time()
+
+	return (finish - start) / 1000
+end
+
+minetest.register_chatcommand("bench_name2content", {
+	params = "",
+	description = "Benchmark: Conversion from node names to content IDs",
+	func = function(name, param)
+		minetest.chat_send_player(name, "Benchmarking minetest.get_content_id. Warming up ...")
+		bench_name2content()
+		minetest.chat_send_player(name, "Warming up finished, now benchmarking ...")
+		local time = bench_name2content()
+		return true, ("Time: %.2f ms"):format(time)
+	end,
+})
+
+minetest.register_chatcommand("bench_content2name", {
+	params = "",
+	description = "Benchmark: Conversion from content IDs to node names",
+	func = function(name, param)
+		minetest.chat_send_player(name, "Benchmarking minetest.get_name_from_content_id. Warming up ...")
+		bench_content2name()
+		minetest.chat_send_player(name, "Warming up finished, now benchmarking ...")
+		local time = bench_content2name()
+		return true, ("Time: %.2f ms"):format(time)
+	end,
+})
+
 minetest.register_chatcommand("bench_bulk_set_node", {
 	params = "",
 	description = "Benchmark: Bulk-set 99×99×99 stone nodes",

games/devtest/mods/unittests/content_ids.lua

@@ -0,0 +1,37 @@
+core.register_alias("unittests:test_content_ids_alias1", "air")
+core.register_alias("unittests:test_content_ids_alias2", "~")
+
+local function test_content_ids()
+	assert(core.get_content_id("air") == core.CONTENT_AIR)
+	assert(core.get_content_id("unittests:test_content_ids_alias1") == core.CONTENT_AIR)
+	assert(core.get_content_id("unknown") == core.CONTENT_UNKNOWN)
+	assert(core.get_content_id("ignore") == core.CONTENT_IGNORE)
+
+	assert(core.get_name_from_content_id(core.CONTENT_AIR) == "air")
+	assert(core.get_name_from_content_id(core.CONTENT_UNKNOWN) == "unknown")
+	assert(core.get_name_from_content_id(core.CONTENT_IGNORE) == "ignore")
+
+	assert(pcall(core.get_content_id, "~") == false)
+	assert(pcall(core.get_content_id, "unittests:test_content_ids_alias2") == false)
+	assert(pcall(core.get_content_id) == false)
+	assert(core.get_name_from_content_id(0xFFFF) == "unknown")
+	assert(pcall(core.get_name_from_content_id) == false)
+end
+
+-- Run while mod is loading.
+test_content_ids()
+
+-- Run after mods have loaded.
+unittests.register("test_content_ids", test_content_ids)
+
+-- Run in async environment.
+local function test_content_ids_async(cb)
+	local function func(test_func)
+		local ok, err = pcall(test_func)
+		if not ok then
+			return err
+		end
+	end
+	core.handle_async(func, cb, test_content_ids)
+end
+unittests.register("test_content_ids_async", test_content_ids_async, {async=true})

games/devtest/mods/unittests/init.lua

@@ -178,6 +178,7 @@ dofile(modpath .. "/crafting.lua")
 dofile(modpath .. "/itemdescription.lua")
 dofile(modpath .. "/async_env.lua")
 dofile(modpath .. "/entity.lua")
+dofile(modpath .. "/content_ids.lua")
 
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