Force-load areas with mesecon usage

This is a major speedup for large mesecon machines / structures.
Force-loaded areas are stored in a file to be persistent over server
reboots. By default, areas are unloaded after 10 minutes (600s) without
usage, this can be customized with the mesecon.forceload_timeout
setting. Please turn max_forceloaded_blocks up for better performance.

3 files changed, 116 insertions, 39 deletions

diff --git a/mesecons/actionqueue.lua b/mesecons/actionqueue.lua
index a773008..e300ea7 100644
--- a/mesecons/actionqueue.lua
+++ b/mesecons/actionqueue.lua
@@ -94,25 +94,8 @@ 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")
+mesecon.queue.actions = mesecon.file2table("mesecon_actionqueue")
 
 minetest.register_on_shutdown(function()
-	mesecon.queue.actions = table2file(wpath.."/mesecon_actionqueue", mesecon.queue.actions)
+	mesecon.table2file("mesecon_actionqueue", mesecon.queue.actions)
 end)
diff --git a/mesecons/internal.lua b/mesecons/internal.lua
index 41c5c52..fc1cf8d 100644
--- a/mesecons/internal.lua
+++ b/mesecons/internal.lua
@@ -77,6 +77,8 @@ function mesecon.get_conductor(nodename)
 end
 
 function mesecon.get_any_outputrules (node)
+	if not node then return nil end
+
 	if mesecon.is_conductor(node.name) then
 		return mesecon.conductor_get_rules(node)
 	elseif mesecon.is_receptor(node.name) then
@@ -85,6 +87,8 @@ function mesecon.get_any_outputrules (node)
 end
 
 function mesecon.get_any_inputrules (node)
+	if not node then return nil end
+
 	if mesecon.is_conductor(node.name) then
 		return mesecon.conductor_get_rules(node)
 	elseif mesecon.is_effector(node.name) then
@@ -182,7 +186,9 @@ end
 
 -- Activation:
 mesecon.queue:add_function("activate", function (pos, rulename)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
+	if not node then return end
+
 	local effector = mesecon.get_effector(node.name)
 
 	if effector and effector.action_on then
@@ -203,7 +209,9 @@ end
 
 -- Deactivation
 mesecon.queue:add_function("deactivate", function (pos, rulename)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
+	if not node then return end
+
 	local effector = mesecon.get_effector(node.name)
 
 	if effector and effector.action_off then
@@ -224,7 +232,9 @@ end
 
 -- Change
 mesecon.queue:add_function("change", function (pos, rulename, changetype)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
+	if not node then return end
+
 	local effector = mesecon.get_effector(node.name)
 
 	if effector and effector.action_change then
@@ -249,6 +259,8 @@ end
 -- Conductors
 
 function mesecon.is_conductor_on(node, rulename)
+	if not node then return false end
+
 	local conductor = mesecon.get_conductor(node.name)
 	if conductor then
 		if conductor.state then
@@ -263,10 +275,13 @@ function mesecon.is_conductor_on(node, rulename)
 			return mesecon.get_bit(binstate, bit)
 		end
 	end
+
 	return false
 end
 
 function mesecon.is_conductor_off(node, rulename)
+	if not node then return false end
+
 	local conductor = mesecon.get_conductor(node.name)
 	if conductor then
 		if conductor.state then
@@ -281,6 +296,7 @@ function mesecon.is_conductor_off(node, rulename)
 			return not mesecon.get_bit(binstate, bit)
 		end
 	end
+
 	return false
 end
 
@@ -340,7 +356,7 @@ end
 -- some more general high-level stuff
 
 function mesecon.is_power_on(pos, rulename)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
 	if mesecon.is_conductor_on(node, rulename) or mesecon.is_receptor_on(node.name) then
 		return true
 	end
@@ -348,7 +364,7 @@ function mesecon.is_power_on(pos, rulename)
 end
 
 function mesecon.is_power_off(pos, rulename)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
 	if mesecon.is_conductor_off(node, rulename) or mesecon.is_receptor_off(node.name) then
 		return true
 	end
@@ -361,10 +377,11 @@ function mesecon.turnon(pos, link)
 	local depth = 1
 	while frontiers[depth] do
 		local f = frontiers[depth]
-		local node = minetest.get_node_or_nil(f.pos)
+		local node = mesecon.get_node_force(f.pos)
 
 		-- area not loaded, postpone action
 		if not node then
+			print("Mesecons: Postponing action!")
 			mesecon.queue:add_action(f.pos, "turnon", {link}, nil, true)
 		elseif mesecon.is_conductor_off(node, f.link) then
 			local rules = mesecon.conductor_get_rules(node)
@@ -377,7 +394,7 @@ function mesecon.turnon(pos, link)
 				local np = vector.add(f.pos, r)
 
 				-- area not loaded, postpone action
-				if not minetest.get_node_or_nil(np) then
+				if not mesecon.get_node_force(np) then
 					mesecon.queue:add_action(np, "turnon", {rulename},
 						nil, true)
 				else
@@ -407,7 +424,7 @@ function mesecon.turnoff(pos, link)
 	local depth = 1
 	while frontiers[depth] do
 		local f = frontiers[depth]
-		local node = minetest.get_node_or_nil(f.pos)
+		local node = mesecon.get_node_force(f.pos)
 
 		-- area not loaded, postpone action
 		if not node then
@@ -423,7 +440,7 @@ function mesecon.turnoff(pos, link)
 				local np = vector.add(f.pos, r)
 
 				-- area not loaded, postpone action
-				if not minetest.get_node_or_nil(np) then
+				if not mesecon.get_node_force(np) then
 					mesecon.queue:add_action(np, "turnoff", {rulename},
 						nil, true)
 				else
@@ -449,7 +466,8 @@ end)
 
 
 function mesecon.connected_to_receptor(pos, link)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
+	if not node then return false end
 
 	-- Check if conductors around are connected
 	local rules = mesecon.get_any_inputrules(node)
@@ -476,7 +494,7 @@ function mesecon.find_receptor_on(pos, link)
 	local depth = 1
 	while frontiers[depth] do
 		local f = frontiers[depth]
-		local node = minetest.get_node_or_nil(f.pos)
+		local node = mesecon.get_node_force(f.pos)
 
 		if not node then return false end
 		if mesecon.is_receptor_on(node.name) then return true end
@@ -503,8 +521,9 @@ function mesecon.find_receptor_on(pos, link)
 end
 
 function mesecon.rules_link(output, input, dug_outputrules) --output/input are positions (outputrules optional, used if node has been dug), second return value: the name of the affected input rule
-	local outputnode = minetest.get_node(output)
-	local inputnode = minetest.get_node(input)
+	local outputnode = mesecon.get_node_force(output)
+	local inputnode = mesecon.get_node_force(input)
+
 	local outputrules = dug_outputrules or mesecon.get_any_outputrules (outputnode)
 	local inputrules = mesecon.get_any_inputrules (inputnode)
 	if not outputrules or not inputrules then
@@ -522,12 +541,13 @@ function mesecon.rules_link(output, input, dug_outputrules) --output/input are p
 			end
 		end
 	end
+
 	return false
 end
 
 function mesecon.rules_link_rule_all(output, rule)
 	local input = vector.add(output, rule)
-	local inputnode = minetest.get_node(input)
+	local inputnode = mesecon.get_node_force(input)
 	local inputrules = mesecon.get_any_inputrules (inputnode)
 	if not inputrules then
 		return {}
@@ -540,13 +560,14 @@ function mesecon.rules_link_rule_all(output, rule)
 			table.insert(rules, inputrule)
 		end
 	end
+
 	return rules
 end
 
 function mesecon.rules_link_rule_all_inverted(input, rule)
 	--local irule = mesecon.invertRule(rule)
 	local output = vector.add(input, rule)
-	local outputnode = minetest.get_node(output)
+	local outputnode = mesecon.get_node_force(output)
 	local outputrules = mesecon.get_any_outputrules (outputnode)
 	if not outputrules then
 		return {}
@@ -566,7 +587,7 @@ function mesecon.rules_link_anydir(pos1, pos2)
 end
 
 function mesecon.is_powered(pos, rule)
-	local node = minetest.get_node(pos)
+	local node = mesecon.get_node_force(pos)
 	local rules = mesecon.get_any_inputrules(node)
 	if not rules then return false end
 
@@ -578,9 +599,10 @@ function mesecon.is_powered(pos, rule)
 			local rulenames = mesecon.rules_link_rule_all_inverted(pos, rule)
 			for _, rname in ipairs(rulenames) do
 				local np = vector.add(pos, rname)
-				local nn = minetest.get_node(np)
-				if (mesecon.is_conductor_on (nn, mesecon.invertRule(rname))
-				or mesecon.is_receptor_on (nn.name)) then
+				local nn = mesecon.get_node_force(np)
+
+				if (mesecon.is_conductor_on(nn, mesecon.invertRule(rname))
+				or mesecon.is_receptor_on(nn.name)) then
 					table.insert(sourcepos, np)
 				end
 			end
@@ -589,7 +611,7 @@ function mesecon.is_powered(pos, rule)
 		local rulenames = mesecon.rules_link_rule_all_inverted(pos, rule)
 		for _, rname in ipairs(rulenames) do
 			local np = vector.add(pos, rname)
-			local nn = minetest.get_node(np)
+			local nn = mesecon.get_node_force(np)
 			if (mesecon.is_conductor_on (nn, mesecon.invertRule(rname))
 			or mesecon.is_receptor_on (nn.name)) then
 				table.insert(sourcepos, np)
diff --git a/mesecons/util.lua b/mesecons/util.lua
index e7b6866..3827dce 100644
--- a/mesecons/util.lua
+++ b/mesecons/util.lua
@@ -201,3 +201,75 @@ function mesecon.flipstate(pos, node)
 
 	return newstate
 end
+
+-- File writing / reading utilities
+local wpath = minetest.get_worldpath()
+function mesecon.file2table(filename)
+	local f = io.open(wpath..DIR_DELIM..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
+
+function mesecon.table2file(filename, table)
+	local f = io.open(wpath..DIR_DELIM..filename, "w")
+	f:write(minetest.serialize(table))
+	f:close()
+end
+
+-- Forceloading: Force server to load area if node is nil
+local BLOCKSIZE = 16
+
+-- convert node position --> block hash
+local function hash_blockpos(pos)
+	return minetest.hash_node_position({
+		x = math.floor(pos.x/BLOCKSIZE),
+		y = math.floor(pos.y/BLOCKSIZE),
+		z = math.floor(pos.z/BLOCKSIZE)
+	})
+end
+
+-- convert block hash --> node position
+local function unhash_blockpos(hash)
+	return vector.multiply(minetest.get_position_from_hash(hash), BLOCKSIZE)
+end
+
+mesecon.forceloaded_blocks = {}
+
+-- get node and force-load area
+function mesecon.get_node_force(pos)
+	local hash = hash_blockpos(pos)
+
+	if mesecon.forceloaded_blocks[hash] == nil then
+		-- if no more forceload spaces are available, try again next time
+		if minetest.forceload_block(pos) then
+			mesecon.forceloaded_blocks[hash] = 0
+		end
+	else
+		mesecon.forceloaded_blocks[hash] = 0
+	end
+
+	return minetest.get_node_or_nil(pos)
+end
+
+minetest.register_globalstep(function (dtime)
+	for hash, time in pairs(mesecon.forceloaded_blocks) do
+		-- unload forceloaded blocks after 10 minutes without usage
+		if (time > mesecon.setting("forceload_timeout", 600)) then
+			minetest.forceload_free_block(unhash_blockpos(hash))
+			mesecon.forceloaded_blocks[hash] = nil
+		else
+			mesecon.forceloaded_blocks[hash] = time + dtime
+		end
+	end
+end)
+
+-- Store and read the forceloaded blocks to / from a file
+-- so that those blocks are remembered when the game
+-- is restarted
+mesecon.forceloaded_blocks = mesecon.file2table("mesecon_forceloaded")
+minetest.register_on_shutdown(function()
+	mesecon.table2file("mesecon_forceloaded", mesecon.forceloaded_blocks)
+end)