First draft of some kind of Action Queue (just like the globalstep queue in to_update), but more flexible and also including delay functionality (mesecon_delayer).

The queue is also saved to a file, so that when restarting mesecons, delayers resume to the state they had when the game shut down. Needs testing.

mesecons/actionqueue.lua

@@ -0,0 +1,90 @@
+mesecon.queue.actions={} -- contains all ActionQueue actions
+
+function mesecon.queue:add_function(name, func)
+	mesecon.queue.funcs[name] = func
+end
+
+-- If add_action with twice the same overwritecheck and same position are called, the first one is overwritten
+-- use overwritecheck nil to never overwrite, but just add the event to the queue
+function mesecon.queue:add_action(pos, func, params, time, overwritecheck)
+	-- Create Action Table:
+	time = time or 0 -- time <= 0 --> execute, time > 0 --> wait time until execution
+	action = {	pos=pos,
+			func=func,
+			params=mesecon:tablecopy(params),
+			time=time,
+			owcheck=overwritecheck}
+
+	--print(dump(action))
+	-- if not using the queue, (MESECONS_GLOBALSTEP off), just execute the function an we're done
+	if not MESECONS_GLOBALSTEP then
+		mesecon.queue:execute(action)
+		return
+	end
+
+	-- Otherwise, add the action to the queue
+	if overwritecheck then -- check if old action has to be overwritten / removed:
+		for i, ac in ipairs(mesecon.queue.actions) do
+			if(mesecon:cmpPos(pos, action.pos)
+			and mesecon:cmpAny(overwritecheck, ac.owcheck)) then
+				table.remove(mesecon.queue.actions, i)
+				break
+			end
+		end
+	end
+
+	table.insert(mesecon.queue.actions, action)
+end
+
+-- execute the stored functions on a globalstep
+-- if however, the pos of a function is not loaded (get_node_or_nil == nil), do NOT execute the function
+-- this makes sure that resuming mesecons circuits when restarting minetest works fine
+-- However, even that does not work in some cases, that's why we delay the time the globalsteps
+-- start to be execute by 5 seconds
+local m_time = 0
+minetest.register_globalstep(function (dtime)
+	m_time = m_time + dtime
+	if (m_time < 5) then return end -- don't even try if server has not been running for 2 seconds
+	local actions = mesecon:tablecopy(mesecon.queue.actions)
+	mesecon.queue.actions = {}
+
+	for i, action in ipairs(actions) do
+		if action.time > 0 then
+			action.time = action.time - dtime
+			table.insert(mesecon.queue.actions, action) -- will be handled another time
+		else -- execute and remove
+			mesecon.queue:execute(action)
+		end
+	end
+end)
+
+function mesecon.queue:execute(action)
+	mesecon.queue.funcs[action.func](action.pos, unpack(action.params))
+end
+
+
+-- Store and read the ActionQueue to / from a file
+-- so that upcoming actions are remembered when the game
+-- is restarted
+
+local wpath = minetest.get_worldpath()
+local function file2table(filename)
+	local f = io.open(filename, "r")
+	if f==nil then return {} end
+	local t = f:read("*all")
+	f:close()
+	if t=="" or t==nil then return {} end
+	return minetest.deserialize(t)
+end
+
+local function table2file(filename, table)
+	local f = io.open(filename, "w")
+	f:write(minetest.serialize(table))
+	f:close()
+end
+
+mesecon.queue.actions = file2table(wpath.."/mesecon_actionqueue")
+
+minetest.register_on_shutdown(function()
+	mesecon.queue.actions = table2file(wpath.."/mesecon_actionqueue", mesecon.queue.actions)
+end)