Async environment for mods to do concurrent tasks (#11131)

builtin/async/game.lua

@@ -0,0 +1,46 @@
+core.log("info", "Initializing asynchronous environment (game)")
+
+local function pack2(...)
+	return {n=select('#', ...), ...}
+end
+
+-- Entrypoint to run async jobs, called by C++
+function core.job_processor(func, params)
+	local retval = pack2(func(unpack(params, 1, params.n)))
+
+	return retval
+end
+
+-- Import a bunch of individual files from builtin/game/
+local gamepath = core.get_builtin_path() .. "game" .. DIR_DELIM
+
+dofile(gamepath .. "constants.lua")
+dofile(gamepath .. "item_s.lua")
+dofile(gamepath .. "misc_s.lua")
+dofile(gamepath .. "features.lua")
+dofile(gamepath .. "voxelarea.lua")
+
+-- Transfer of globals
+do
+	assert(core.transferred_globals)
+	local all = core.deserialize(core.transferred_globals, true)
+	core.transferred_globals = nil
+
+	-- reassemble other tables
+	all.registered_nodes = {}
+	all.registered_craftitems = {}
+	all.registered_tools = {}
+	for k, v in pairs(all.registered_items) do
+		if v.type == "node" then
+			all.registered_nodes[k] = v
+		elseif v.type == "craftitem" then
+			all.registered_craftitems[k] = v
+		elseif v.type == "tool" then
+			all.registered_tools[k] = v
+		end
+	end
+
+	for k, v in pairs(all) do
+		core[k] = v
+	end
+end

builtin/async/mainmenu.lua

@@ -1,5 +1,4 @@
-
-core.log("info", "Initializing Asynchronous environment")
+core.log("info", "Initializing asynchronous environment")
 
 function core.job_processor(func, serialized_param)
 	local param = core.deserialize(serialized_param)
@@ -8,4 +7,3 @@ function core.job_processor(func, serialized_param)
 
 	return retval or core.serialize(nil)
 end
-

builtin/game/async.lua

@@ -0,0 +1,22 @@
+
+core.async_jobs = {}
+
+function core.async_event_handler(jobid, retval)
+	local callback = core.async_jobs[jobid]
+	assert(type(callback) == "function")
+	callback(unpack(retval, 1, retval.n))
+	core.async_jobs[jobid] = nil
+end
+
+function core.handle_async(func, callback, ...)
+	assert(type(func) == "function" and type(callback) == "function",
+		"Invalid minetest.handle_async invocation")
+	local args = {n = select("#", ...), ...}
+	local mod_origin = core.get_last_run_mod()
+
+	local jobid = core.do_async_callback(func, args, mod_origin)
+	core.async_jobs[jobid] = callback
+
+	return true
+end
+

builtin/game/init.lua

@@ -34,5 +34,6 @@ dofile(gamepath .. "voxelarea.lua")
 dofile(gamepath .. "forceloading.lua")
 dofile(gamepath .. "statbars.lua")
 dofile(gamepath .. "knockback.lua")
+dofile(gamepath .. "async.lua")
 
 profiler = nil

builtin/game/misc.lua

@@ -235,3 +235,32 @@ end
 
 -- Used for callback handling with dynamic_add_media
 core.dynamic_media_callbacks = {}
+
+
+-- Transfer of certain globals into async environment
+-- see builtin/async/game.lua for the other side
+
+local function copy_filtering(t, seen)
+	if type(t) == "userdata" or type(t) == "function" then
+		return true -- don't use nil so presence can still be detected
+	elseif type(t) ~= "table" then
+		return t
+	end
+	local n = {}
+	seen = seen or {}
+	seen[t] = n
+	for k, v in pairs(t) do
+		local k_ = seen[k] or copy_filtering(k, seen)
+		local v_ = seen[v] or copy_filtering(v, seen)
+		n[k_] = v_
+	end
+	return n
+end
+
+function core.get_globals_to_transfer()
+	local all = {
+		registered_items = copy_filtering(core.registered_items),
+		registered_aliases = core.registered_aliases,
+	}
+	return core.serialize(all)
+end

builtin/init.lua

@@ -56,8 +56,10 @@ elseif INIT == "mainmenu" then
 	if not custom_loaded then
 		dofile(core.get_mainmenu_path() .. DIR_DELIM .. "init.lua")
 	end
-elseif INIT == "async" then
-	dofile(asyncpath .. "init.lua")
+elseif INIT == "async"  then
+	dofile(asyncpath .. "mainmenu.lua")
+elseif INIT == "async_game" then
+	dofile(asyncpath .. "game.lua")
 elseif INIT == "client" then
 	dofile(clientpath .. "init.lua")
 else