do not use minetest.find_node_near, I guess it's a bit laggy

moremesecons_jammer/init.lua

@@ -1,49 +1,85 @@
 local JAMMER_MAX_DISTANCE = 10
 
-minetest.after(0, function() -- After load all mods
+-- see wireless jammer
-function mesecon.turnon(pos, link) -- Overwrite mesecons function.
+local get = vector.get_data_from_pos
-	local frontiers = {{pos = pos, link = link}}
+local set = vector.set_data_to_pos
+local remove = vector.remove_data_from_pos
 
-	local depth = 1
+local jammers = {}
-	while frontiers[depth] do
+local function add_jammer(pos)
-		local f = frontiers[depth]
+	if get(jammers, pos.z,pos.y,pos.x) then
-		local node = minetest.get_node_or_nil(f.pos)
+		return
+	end
+	set(jammers, pos.z,pos.y,pos.x, true)
+end
 
-		-- area not loaded, postpone action
+local function remove_jammer(pos)
-		if not node then
+	remove(jammers, pos.z,pos.y,pos.x)
-			mesecon.queue:add_action(f.pos, "turnon", {link}, nil, true)
+end
-		elseif minetest.find_node_near(f.pos, JAMMER_MAX_DISTANCE, {"moremesecons_jammer:jammer_on"}) then -- JAMMER
-			break
-		elseif mesecon.is_conductor_off(node, f.link) then
-			local rules = mesecon.conductor_get_rules(node)
 
-			minetest.swap_node(f.pos, {name = mesecon.get_conductor_on(node, f.link),
+local function is_jammed(pos)
-				param2 = node.param2})
+	local pz,py,px = vector.unpack(pos)
-
+	for z,yxs in pairs(jammers) do
-			-- call turnon on neighbors: normal rules
+		if math.abs(pz-z) <= JAMMER_MAX_DISTANCE then
-			for _, r in ipairs(mesecon.rule2meta(f.link, rules)) do
+			for y,xs in pairs(yxs) do
-				local np = mesecon.addPosRule(f.pos, r)
+				if math.abs(py-y) <= JAMMER_MAX_DISTANCE then
-
+					for x in pairs(xs) do
-				-- area not loaded, postpone action
+						if math.abs(px-x) <= JAMMER_MAX_DISTANCE
-				if not minetest.get_node_or_nil(np) then
+						and (px-x)^2+(py-y)^2+(pz-z)^2 <= JAMMER_MAX_DISTANCE^2 then
-					mesecon.queue:add_action(np, "turnon", {rulename},
+							return true
-						nil, true)
+						end
-				else
-					local links = mesecon.rules_link_rule_all(f.pos, r)
-					for _, l in ipairs(links) do
-						table.insert(frontiers, {pos = np, link = l})
 					end
 				end
 			end
-		elseif mesecon.is_effector(node.name) then
-			mesecon.changesignal(f.pos, node, f.link, mesecon.state.on, depth)
-			if mesecon.is_effector_off(node.name) then
-				mesecon.activate(f.pos, node, f.link, depth)
-			end
 		end
-		depth = depth + 1
 	end
+	return false
 end
+
+minetest.after(0, function() -- After load all mods
+	function mesecon.turnon(pos, link) -- Overwrite mesecons function.
+		local frontiers = {{pos = pos, link = link}}
+
+		local depth = 1
+		while frontiers[depth] do
+			local f = frontiers[depth]
+			local node = minetest.get_node_or_nil(f.pos)
+
+			-- area not loaded, postpone action
+			if not node then
+				mesecon.queue:add_action(f.pos, "turnon", {link}, nil, true)
+			elseif is_jammed(f.pos) then -- JAMMER
+				return
+			elseif mesecon.is_conductor_off(node, f.link) then
+				local rules = mesecon.conductor_get_rules(node)
+
+				minetest.swap_node(f.pos, {name = mesecon.get_conductor_on(node, f.link),
+					param2 = node.param2})
+
+				-- call turnon on neighbors: normal rules
+				for _, r in ipairs(mesecon.rule2meta(f.link, rules)) do
+					local np = mesecon.addPosRule(f.pos, r)
+
+					-- area not loaded, postpone action
+					if not minetest.get_node_or_nil(np) then
+						mesecon.queue:add_action(np, "turnon", {rulename},
+							nil, true)
+					else
+						local links = mesecon.rules_link_rule_all(f.pos, r)
+						for _, l in ipairs(links) do
+							table.insert(frontiers, {pos = np, link = l})
+						end
+					end
+				end
+			elseif mesecon.is_effector(node.name) then
+				mesecon.changesignal(f.pos, node, f.link, mesecon.state.on, depth)
+				if mesecon.is_effector_off(node.name) then
+					mesecon.activate(f.pos, node, f.link, depth)
+				end
+			end
+			depth = depth + 1
+		end
+	end
 end)
 
 mesecon.register_node("moremesecons_jammer:jammer", {
@@ -54,15 +90,21 @@ mesecon.register_node("moremesecons_jammer:jammer", {
 	groups = {dig_immediate=2},
 	mesecons = {effector = {
 		action_on = function(pos)
+			add_jammer(pos)
 			minetest.swap_node(pos, {name="moremesecons_jammer:jammer_on"})
-		end }}
+		end
+	}},
 },{
 	tiles = {"moremesecons_jammer_on.png"},
 	groups = {dig_immediate=2, not_in_creative_inventory=1},
 	mesecons = {effector = {
 		action_off = function(pos)
+			remove_jammer(pos)
 			minetest.swap_node(pos, {name="moremesecons_jammer:jammer_off"})
-		end }}
+		end
+	}},
+	on_destruct = remove_jammer,
+	on_construct = add_jammer,
 })
 
 minetest.register_craft({
@@ -70,3 +112,10 @@ minetest.register_craft({
 	recipe = {{"group:mesecon_conductor_craftable", "default:mese", "group:mesecon_conductor_craftable"},
 		{"", "moremesecons_wireless:jammer_off", ""}}
 })
+
+minetest.register_abm({
+	nodenames = {"moremesecons_jammer:jammer_on"},
+	interval = 5,
+	chance = 1,
+	action = add_jammer
+})