Fixes for network calculation issues

This fixes several issues:
* More than one switching station could become active on large networks
 - Switching stations now semi-permanently become disabled if another is present
 - Power monitors have been added to replace the function of "slave" switching stations, to discourage overuse of switching stations
* Networks did not reliably "split" when cutting a cable
 - I "may" have caused this issue, but I believe it is solved by this
* Machines did not run without a player near the switching station
 - Active switching stations now forceload themselves, and free the forceloaded block if disabled, dug, or disconnected
 - Machines are only loaded to run them (as before), so only one mapblock (or two if the bottom edge of the switching station is a mapblock boundary) is loaded
 - Cables are still only loaded during a full network recalculation

technic/machines/init.lua

@@ -8,6 +8,7 @@ dofile(path.."/MV/init.lua")
 dofile(path.."/HV/init.lua")
 
 dofile(path.."/switching_station.lua")
+dofile(path.."/power_monitor.lua")
 dofile(path.."/supply_converter.lua")
 
 dofile(path.."/other/init.lua")

technic/machines/power_monitor.lua

@@ -0,0 +1,61 @@
+-- POWER MONITOR
+-- The power monitor can be used to monitor how much power is available on a network,
+-- similarly to the old "slave" switching stations.
+
+local S = technic.getter
+
+minetest.register_craft({
+	output = "technic:power_monitor",
+	recipe = {
+		{"",                 "",                       ""},
+		{"",                 "technic:machine_casing", "default:copper_ingot"},
+		{"technic:lv_cable", "technic:lv_cable",       "technic:lv_cable"}
+	}
+})
+
+minetest.register_node("technic:power_monitor",{
+	description = S("Power Monitor"),
+	tiles  = {"technic_water_mill_top_active.png", "technic_water_mill_top_active.png",
+                  "technic_water_mill_top_active.png", "technic_water_mill_top_active.png",
+	          "technic_water_mill_top_active.png", "technic_water_mill_top_active.png"},
+	groups = {snappy=2, choppy=2, oddly_breakable_by_hand=2, technic_all_tiers=1, technic_machine=1},
+	connect_sides = {"bottom"},
+	sounds = default.node_sound_wood_defaults(),
+	on_construct = function(pos)
+		local meta = minetest.get_meta(pos)
+		meta:set_string("infotext", S("Power Monitor"))
+	end,
+})
+
+minetest.register_abm({
+	nodenames = {"technic:power_monitor"},
+	label = "Power Monitor",
+	interval   = 1,
+	chance     = 1,
+	action = function(pos, node, active_object_count, active_object_count_wider)
+		local meta = minetest.get_meta(pos)
+		local network_hash = technic.cables[minetest.hash_node_position(pos)]
+		local network = network_hash and minetest.get_position_from_hash(network_hash)
+		local sw_pos = network and {x=network.x,y=network.y+1,z=network.z}
+		local timeout = 0
+		for tier in pairs(technic.machines) do
+			timeout = math.max(meta:get_int(tier.."_EU_timeout"),timeout)
+		end
+		if timeout > 0 and sw_pos and minetest.get_node(sw_pos).name == "technic:switching_station" then
+			local sw_meta = minetest.get_meta(sw_pos)
+			local supply = sw_meta:get_int("supply")
+			local demand = sw_meta:get_int("demand")
+			meta:set_string("infotext",
+					S("Power Monitor. Supply: @1 Demand: @2",
+					technic.pretty_num(supply), technic.pretty_num(demand)))
+		else
+			meta:set_string("infotext",S("Power Monitor Has No Network"))
+		end
+	end,
+})
+
+for tier in pairs(technic.machines) do
+	-- RE in order to use the "timeout" functions, although it consumes 0 power
+	technic.register_machine(tier, "technic:power_monitor", "RE")
+end
+

technic/machines/register/cables.lua

@@ -20,8 +20,13 @@ local function clear_networks(pos)
 		{x=pos.x,   y=pos.y,   z=pos.z+1},
 		{x=pos.x,   y=pos.y,   z=pos.z-1}}
 	for _,connected_pos in pairs(positions) do
-		if technic.cables[minetest.hash_node_position(connected_pos)] then
-			technic.networks[technic.cables[minetest.hash_node_position(connected_pos)]] = nil
+		local net = technic.cables[minetest.hash_node_position(connected_pos)]
+		if net and technic.networks[net] then
+			for _,v in pairs(technic.networks[net].all_nodes) do
+				local pos1 = minetest.hash_node_position(v)
+				technic.cables[pos1] = nil
+			end
+			technic.networks[net] = nil
 		end
 	end
 end

technic/machines/switching_station.lua

@@ -58,6 +58,11 @@ minetest.register_node("technic:switching_station",{
 		meta:set_string("infotext", S("Switching Station"))
 		meta:set_string("active", 1)
 	end,
+	after_dig_node = function(pos)
+		minetest.forceload_free_block(pos)
+		pos.y = pos.y - 1
+		minetest.forceload_free_block(pos)
+	end,
 })
 
 --------------------------------------------------
@@ -89,6 +94,7 @@ local check_node_subp = function(PR_nodes, RE_nodes, BA_nodes, SP_nodes, all_nod
 		add_new_cable_node(all_nodes, pos,network_id)
 	elseif machines[name] then
 		--dprint(name.." is a "..machines[name])
+		meta:set_string(tier.."_network",minetest.pos_to_string(sw_pos))
 		if     machines[name] == technic.producer then
 			add_new_cable_node(PR_nodes, pos, network_id)
 		elseif machines[name] == technic.receiver then
@@ -102,7 +108,6 @@ local check_node_subp = function(PR_nodes, RE_nodes, BA_nodes, SP_nodes, all_nod
 			-- Another switching station -> disable it
 			add_new_cable_node(SP_nodes, pos, network_id)
 			meta:set_int("active", 0)
-			meta:set_string("active_pos", minetest.serialize(sw_pos))
 		elseif machines[name] == technic.battery then
 			add_new_cable_node(BA_nodes, pos, network_id)
 		end
@@ -159,7 +164,7 @@ local get_network = function(sw_pos, pos1, tier)
 		i = i + 1
 	until all_nodes[i] == nil
 	technic.networks[minetest.hash_node_position(pos1)] = {tier = tier, PR_nodes = PR_nodes,
-			RE_nodes = RE_nodes, BA_nodes = BA_nodes, SP_nodes = SP_nodes}
+			RE_nodes = RE_nodes, BA_nodes = BA_nodes, SP_nodes = SP_nodes, all_nodes = all_nodes}
 	return PR_nodes, BA_nodes, RE_nodes
 end
 
@@ -185,27 +190,30 @@ minetest.register_abm({
 		local BA_nodes
 		local RE_nodes
 		local machine_name = S("Switching Station")
-
-		if meta:get_int("active") ~= 1 then
-			meta:set_int("active", 1)
-			local active_pos = minetest.deserialize(meta:get_string("active_pos"))
-			if active_pos then
-				local meta1 = minetest.get_meta(active_pos)
-				meta:set_string("infotext", S("%s (Slave)"):format(meta1:get_string("infotext")))
-			end
-			return
-		end
 		
 		-- Which kind of network are we on:
 		pos1 = {x=pos.x, y=pos.y-1, z=pos.z}
 
+		--Disable if necessary
+		if meta:get_int("active") ~= 1 then
+			minetest.forceload_free_block(pos)
+			minetest.forceload_free_block(pos1)
+			meta:set_string("infotext",S("%s Already Present"):format(machine_name))
+			return
+		end
+
 		local name = minetest.get_node(pos1).name
 		local tier = technic.get_cable_tier(name)
 		if tier then
+			-- Forceload switching station
+			minetest.forceload_block(pos)
+			minetest.forceload_block(pos1)
 			PR_nodes, BA_nodes, RE_nodes = get_network(pos, pos1, tier)
 		else
 			--dprint("Not connected to a network")
 			meta:set_string("infotext", S("%s Has No Network"):format(machine_name))
+			minetest.forceload_free_block(pos)
+			minetest.forceload_free_block(pos1)
 			return
 		end
 		
@@ -293,6 +301,10 @@ minetest.register_abm({
 				S("@1. Supply: @2 Demand: @3",
 				machine_name, technic.pretty_num(PR_eu_supply), technic.pretty_num(RE_eu_demand)))
 
+		-- Data that will be used by the power monitor
+		meta:set_int("supply",PR_eu_supply)
+		meta:set_int("demand",RE_eu_demand)
+
 		-- If the PR supply is enough for the RE demand supply them all
 		if PR_eu_supply >= RE_eu_demand then
 		--dprint("PR_eu_supply"..PR_eu_supply.." >= RE_eu_demand"..RE_eu_demand)
@@ -354,6 +366,7 @@ minetest.register_abm({
 			meta1 = minetest.get_meta(pos1)
 			meta1:set_int(eu_input_str, 0)
 		end
+		
 	end,
 })
 
@@ -376,6 +389,7 @@ minetest.register_abm({
 	interval   = 1,
 	chance     = 1,
 	action = function(pos, node, active_object_count, active_object_count_wider)
+		local meta = minetest.get_meta(pos)
 		for tier, machines in pairs(technic.machines) do
 			if machines[node.name] and switching_station_timeout_count(pos, tier) then
 				local nodedef = minetest.registered_nodes[node.name]
@@ -394,6 +408,23 @@ minetest.register_abm({
 	end,
 })
 
+--Re-enable disabled switching station if necessary, similar to the timeout above
+minetest.register_abm({
+	nodenames = {"technic:switching_station"},
+	interval   = 1,
+	chance     = 1,
+	action = function(pos, node, active_object_count, active_object_count_wider)
+		local meta = minetest.get_meta(pos)
+		local pos1 = {x=pos.x,y=pos.y-1,z=pos.z}
+		local tier = technic.get_cable_tier(minetest.get_node(pos1).name)
+		if not tier then return end
+		if switching_station_timeout_count(pos, tier) then
+			local meta = minetest.get_meta(pos)
+			meta:set_int("active",1)
+		end
+	end,
+})
+
 for tier, machines in pairs(technic.machines) do
 	-- SPECIAL will not be traversed
 	technic.register_machine(tier, "technic:switching_station", "SPECIAL")