From fd181833f449cd4ca691fbb3e7155a07ba7cd3fb Mon Sep 17 00:00:00 2001
From: Aaron Suen <warr1024@gmail.com>
Date: Thu, 19 Aug 2021 22:19:27 -0400
Subject: [PATCH] Limit smoke effects, e.g. from concrete cure

Standardize a "fair limiting" mechanism that
limits the items accepted into a queue, and
returns a uniform random sample when flushed.

Pass all cooking/curing smoke effects into fair
limit queue.

Apply fairl limit queue to fire sparks too.

Pliant concrete curing checks still seem to lag
the server somewhat, but at least now they
shouldn't hammer the client with particles and
kill framerate too.
---
 mods/nc_api/util_misc.lua      | 23 +++++++++++
 mods/nc_api_craft/fx_smoke.lua | 73 +++++++++++++++++++---------------
 mods/nc_fire/abm.lua           | 22 ++--------
 3 files changed, 68 insertions(+), 50 deletions(-)

diff --git a/mods/nc_api/util_misc.lua b/mods/nc_api/util_misc.lua
index f0e199f0..04cb2fb7 100644
--- a/mods/nc_api/util_misc.lua
+++ b/mods/nc_api/util_misc.lua
@@ -41,6 +41,29 @@ function nodecore.mkreg()
 	return f, t
 end
 
+function nodecore.fairlimit(max)
+	local queue = {}
+	local qty = 0
+	local function add(item)
+		qty = qty + 1
+		if qty > max then
+			local id = math_random(1, qty)
+			if id <= max then
+				queue[id] = item
+			end
+		else
+			queue[qty] = item
+		end
+	end
+	local function flush()
+		local batch = queue
+		queue = {}
+		qty = 0
+		return batch
+	end
+	return add, flush
+end
+
 function nodecore.memoize(func)
 	local cachedval
 	local cached
diff --git a/mods/nc_api_craft/fx_smoke.lua b/mods/nc_api_craft/fx_smoke.lua
index 3b052928..4fe1b1c5 100644
--- a/mods/nc_api_craft/fx_smoke.lua
+++ b/mods/nc_api_craft/fx_smoke.lua
@@ -1,41 +1,50 @@
 -- LUALOCALS < ---------------------------------------------------------
-local math, minetest, nodecore, type
-    = math, minetest, nodecore, type
+local ipairs, math, minetest, nodecore, type
+    = ipairs, math, minetest, nodecore, type
 local math_random
     = math.random
 -- LUALOCALS > ---------------------------------------------------------
 
+local smoke_add, smoke_flush = nodecore.fairlimit(50)
+
 local smoking = {}
 
+nodecore.register_globalstep("smoke queue", function()
+		for _, item in ipairs(smoke_flush()) do
+			local pos, qty, time = item.pos, item.qty, item.time
+			local now = minetest.get_us_time() / 1000000
+			local key = minetest.hash_node_position(pos)
+			local old = smoking[key]
+			if old and now < old.exp then minetest.delete_particlespawner(old.id) end
+			if (not time) or (time <= 0) then
+				smoking[key] = nil
+				return
+			end
+			if type(qty) ~= "number" then qty = 1 end
+			if qty < 1 then
+				if math_random() > qty then return end
+				qty = 1
+			end
+			smoking[key] = {
+				id = minetest.add_particlespawner({
+						texture = "nc_api_craft_smoke.png",
+						collisiondetection = true,
+						amount = (qty or 2) * time,
+						time = time,
+						minpos = {x = pos.x - 0.4, y = pos.y - 0.4, z = pos.z - 0.4},
+						maxpos = {x = pos.x + 0.4, y = pos.y + 0.4, z = pos.z + 0.4},
+						minvel = {x = -0.1, y = 0.3, z = -0.1},
+						maxvel = {x = 0.1, y = 0.7, z = 0.1},
+						minexptime = 1,
+						maxexptime = 5,
+						minsize = 1,
+						maxsize = 3
+					}),
+				exp = now + time
+			}
+		end
+	end)
+
 function nodecore.smokefx(pos, time, qty)
-	local now = minetest.get_us_time() / 1000000
-	local key = minetest.hash_node_position(pos)
-	local old = smoking[key]
-	if old and now < old.exp then minetest.delete_particlespawner(old.id) end
-	if (not time) or (time <= 0) then
-		smoking[key] = nil
-		return
-	end
-	if type(qty) ~= "number" then qty = 1 end
-	if qty < 1 then
-		if math_random() > qty then return end
-		qty = 1
-	end
-	smoking[key] = {
-		id = minetest.add_particlespawner({
-				texture = "nc_api_craft_smoke.png",
-				collisiondetection = true,
-				amount = (qty or 2) * time,
-				time = time,
-				minpos = {x = pos.x - 0.4, y = pos.y - 0.4, z = pos.z - 0.4},
-				maxpos = {x = pos.x + 0.4, y = pos.y + 0.4, z = pos.z + 0.4},
-				minvel = {x = -0.1, y = 0.3, z = -0.1},
-				maxvel = {x = 0.1, y = 0.7, z = 0.1},
-				minexptime = 1,
-				maxexptime = 5,
-				minsize = 1,
-				maxsize = 3
-			}),
-		exp = now + time
-	}
+	return smoke_add({pos = pos, time = time, qty = qty})
 end
diff --git a/mods/nc_fire/abm.lua b/mods/nc_fire/abm.lua
index f21853d5..9f53e135 100644
--- a/mods/nc_fire/abm.lua
+++ b/mods/nc_fire/abm.lua
@@ -7,13 +7,10 @@ local math_random
 
 local modname = minetest.get_current_modname()
 
-local sparks = {}
-local sparkqty = 0
-local sparkmax = 50
+local sparks_add, sparks_flush = nodecore.fairlimit(50)
+
 nodecore.register_globalstep("fire sparks", function()
-		if sparkqty < 1 then return end
-		for i = 1, #sparks do
-			local pos = sparks[i]
+		for _, pos in ipairs(sparks_flush()) do
 			minetest.after(math_random(), function()
 					minetest.add_particlespawner({
 							amount = math_random(1, 3),
@@ -35,8 +32,6 @@ nodecore.register_globalstep("fire sparks", function()
 						})
 				end)
 		end
-		sparks = {}
-		sparkqty = 0
 	end)
 
 do
@@ -55,16 +50,7 @@ do
 			chance = 1,
 			nodenames = {modname .. ":fire"},
 			action = function(pos)
-				sparkqty = sparkqty + 1
-				if sparkqty > sparkmax then
-					local sparkid = math_random(1, sparkqty)
-					if sparkid <= sparkmax then
-						sparks[sparkid] = pos
-					end
-				else
-					sparks[sparkqty] = pos
-				end
-
+				sparks_add(pos)
 				local found = {}
 				for _, dp in ipairs(flamedirs) do
 					local npos = vector.add(pos, dp)