Greatly improve performance by making use of VoxelManips in turnoff

Instead of seperately looking for onstate receptors along equipotential
sections of the circuit before turning off, do that while already
modifying the VoxelManip. In case an onstate receptor is found, discard
the VoxelManip cache, otherwise commit it after turnoff is completed.

mesecons/init.lua

@@ -101,8 +101,6 @@ function mesecon.receptor_on(pos, rules)
 end
 
 mesecon.queue:add_function("receptor_off", function (pos, rules)
-	mesecon.vm_begin()
-
 	rules = rules or mesecon.rules.default
 
 	-- if area (any of the rule targets) is not loaded, keep trying and call this again later
@@ -118,15 +116,19 @@ mesecon.queue:add_function("receptor_off", function (pos, rules)
 		local np = vector.add(pos, rule)
 		local rulenames = mesecon.rules_link_rule_all(pos, rule)
 		for _, rulename in ipairs(rulenames) do
-			if not mesecon.connected_to_receptor(np, mesecon.invertRule(rule)) then
+			mesecon.vm_begin()
-				mesecon.turnoff(np, rulename)
-			else
 			mesecon.changesignal(np, minetest.get_node(np), rulename, mesecon.state.off, 2)
-			end
-		end
-	end
 
+			-- Turnoff returns true if turnoff process was successful, no onstate receptor
+			-- was found along the way. Commit changes that were made in voxelmanip. If turnoff
+			-- returns true, an onstate receptor was found, abort voxelmanip transaction.
+			if (mesecon.turnoff(np, rulename)) then
 				mesecon.vm_commit()
+			else
+				mesecon.vm_abort()
+			end
+		end
+	end
 end)
 
 function mesecon.receptor_off(pos, rules)

mesecons/internal.lua

@@ -41,7 +41,6 @@
 -- mesecon.turnoff(pos, link)				--> link is the input rule that caused calling turnoff, turns off every connected node, iterative
 -- mesecon.connected_to_receptor(pos, link)		--> Returns true if pos is connected to a receptor directly or via conductors, iterative
 -- mesecon.rules_link(output, input, dug_outputrules)	--> Returns true if outputposition + outputrules = inputposition and inputposition + inputrules = outputposition (if the two positions connect)
--- mesecon.rules_link_anydir(outp., inp., d_outpr.)	--> Same as rules mesecon.rules_link but also returns true if output and input are swapped
 -- mesecon.is_powered(pos)				--> Returns true if pos is powered by a receptor or a conductor
 
 -- RULES ROTATION helpers
@@ -371,6 +370,10 @@ function mesecon.is_power_off(pos, rulename)
 	return false
 end
 
+-- Turn off an equipotential section starting at `pos`, which outputs in the direction of `link`.
+-- Breadth-first search. Map is abstracted away in a voxelmanip.
+-- Follow all all conductor paths replacing conductors that were already
+-- looked at, activating / changing all effectors along the way.
 function mesecon.turnon(pos, link)
 	local frontiers = {{pos = pos, link = link}}
 
@@ -384,7 +387,7 @@ function mesecon.turnon(pos, link)
 		elseif mesecon.is_conductor_off(node, f.link) then
 			local rules = mesecon.conductor_get_rules(node)
 
-			-- call turnon on neighbors
+			-- Call turnon on neighbors
 			for _, r in ipairs(mesecon.rule2meta(f.link, rules)) do
 				local np = vector.add(f.pos, r)
 				for _, l in ipairs(mesecon.rules_link_rule_all(f.pos, r)) do
@@ -403,8 +406,25 @@ function mesecon.turnon(pos, link)
 	end
 end
 
+-- Turn on an equipotential section starting at `pos`, which outputs in the direction of `link`.
+-- Breadth-first search. Map is abstracted away in a voxelmanip.
+-- Follow all all conductor paths replacing conductors that were already
+-- looked at, deactivating / changing all effectors along the way.
+-- In case an onstate receptor is discovered, abort the process by returning false, which will
+-- cause `receptor_off` to discard all changes made in the voxelmanip.
+-- Contrary to turnon, turnoff has to cache all change and deactivate signals so that they will only
+-- be called in the very end when we can be sure that no conductor was found along the path.
+--
+-- Signal table entry structure:
+-- {
+--	pos = position of effector,
+--	node = node descriptor (name, param1 and param2),
+--	link = link the effector is connected to,
+--	depth = indicates order in which signals wire fired, higher is later
+-- }
 function mesecon.turnoff(pos, link)
 	local frontiers = {{pos = pos, link = link}}
+	local signals = {}
 
 	local depth = 1
 	while frontiers[1] do
@@ -415,10 +435,19 @@ function mesecon.turnoff(pos, link)
 			-- Area does not exist; do nothing
 		elseif mesecon.is_conductor_on(node, f.link) then
 			local rules = mesecon.conductor_get_rules(node)
-
-			-- call turnoff on neighbors
 			for _, r in ipairs(mesecon.rule2meta(f.link, rules)) do
 				local np = vector.add(f.pos, r)
+
+				-- Check if an onstate receptor is connected. If that is the case,
+				-- abort this turnoff process by returning false. `receptor_off` will
+				-- discard all the changes that we made in the voxelmanip:
+				for _, l in ipairs(mesecon.rules_link_rule_all_inverted(f.pos, r)) do
+					if mesecon.is_receptor_on(mesecon.get_node_force(np).name) then
+						return false
+					end
+				end
+
+				-- Call turnoff on neighbors
 				for _, l in ipairs(mesecon.rules_link_rule_all(f.pos, r)) do
 					table.insert(frontiers, {pos = np, link = l})
 				end
@@ -426,94 +455,25 @@ function mesecon.turnoff(pos, link)
 
 			mesecon.swap_node_force(f.pos, mesecon.get_conductor_off(node, f.link))
 		elseif mesecon.is_effector(node.name) then
-			mesecon.changesignal(f.pos, node, f.link, mesecon.state.off, depth)
+			table.insert(signals, {
-			if mesecon.is_effector_on(node.name) and not mesecon.is_powered(f.pos) then
+				pos = f.pos,
-				mesecon.deactivate(f.pos, node, f.link, depth)
+				node = node,
-			end
+				link = f.link,
+				depth = depth
+			})
 		end
 		depth = depth + 1
 	end
+
+	for _, sig in ipairs(signals) do
+		mesecon.changesignal(sig.pos, sig.node, sig.link, mesecon.state.off, sig.depth)
+		if mesecon.is_effector_on(sig.node.name) and not mesecon.is_powered(sig.pos) then
+			mesecon.deactivate(sig.pos, sig.node, sig.link, sig.depth)
+		end
 	end
 
-function mesecon.connected_to_receptor(pos, link)
-	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)
-	if not rules then return false end
-
-	for _, rule in ipairs(mesecon.rule2meta(link, rules)) do
-		local links = mesecon.rules_link_rule_all_inverted(pos, rule)
-		for _, l in ipairs(links) do
-			local np = vector.add(pos, l)
-			if mesecon.find_receptor_on(np, mesecon.invertRule(l)) then
 	return true
 end
-		end
-	end
-
-	return false
-end
-
-function mesecon.find_receptor_on(pos, link)
-	local frontiers = {{pos = pos, link = link}}
-	local checked = {}
-
-	-- List of positions that have been searched for onstate receptors
-	local depth = 1
-	while frontiers[depth] do
-		local f = frontiers[depth]
-		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
-		if mesecon.is_conductor_on(node, f.link) then
-			local rules = mesecon.conductor_get_rules(node)
-
-			-- call turnoff on neighbors: normal rules
-			for _, r in ipairs(mesecon.rule2meta(f.link, rules)) do
-				local np = vector.add(f.pos, r)
-
-				local links = mesecon.rules_link_rule_all_inverted(f.pos, r)
-				for _, l in ipairs(links) do
-					local checkedstring = np.x..np.y..np.z..l.x..l.y..l.z
-					if not checked[checkedstring] then
-						table.insert(frontiers, {pos = np, link = l})
-						checked[checkedstring] = true
-					end
-				end
-			end
-
-		end
-		depth = depth + 1
-	end
-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 = 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
-		return
-	end
-
-	for _, outputrule in ipairs(mesecon.flattenrules(outputrules)) do
-		-- Check if output sends to input
-		if vector.equals(vector.add(output, outputrule), input) then
-			for _, inputrule in ipairs(mesecon.flattenrules(inputrules)) do
-				-- Check if input accepts from output
-				if  vector.equals(vector.add(input, inputrule), output) then
-					return true, inputrule
-				end
-			end
-		end
-	end
-
-	return false
-end
 
 function mesecon.rules_link_rule_all(output, rule)
 	local input = vector.add(output, rule)
@@ -552,10 +512,6 @@ function mesecon.rules_link_rule_all_inverted(input, rule)
 	return rules
 end
 
-function mesecon.rules_link_anydir(pos1, pos2)
-	return mesecon.rules_link(pos1, pos2) or mesecon.rules_link(pos2, pos1)
-end
-
 function mesecon.is_powered(pos, rule)
 	local node = mesecon.get_node_force(pos)
 	local rules = mesecon.get_any_inputrules(node)