Merge pull request #8911 from Ghommie/Ghommie-cit145

Porting a couple atmos performance code improvements.

code/modules/atmospherics/gasmixtures/gas_mixture.dm

@@ -38,8 +38,11 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 	for(var/id in cached_gases)
 		. += cached_gases[id] * cached_gasheats[id]
 
-/datum/gas_mixture/turf/heat_capacity()
-	. = ..()
+/datum/gas_mixture/turf/heat_capacity() // Same as above except vacuums return HEAT_CAPACITY_VACUUM
+	var/list/cached_gases = gases
+	var/list/cached_gasheats = GLOB.meta_gas_specific_heats
+	for(var/id in cached_gases)
+		. += cached_gases[id] * cached_gasheats[id]
 	if(!.)
 		. += HEAT_CAPACITY_VACUUM //we want vacuums in turfs to have the same heat capacity as space
 
@@ -331,22 +334,19 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 /datum/gas_mixture/react(datum/holder)
 	. = NO_REACTION
 	var/list/cached_gases = gases
-	if(!cached_gases.len)
+	if(!length(cached_gases))
 		return
-	var/possible
+	var/list/reactions = list()
 	for(var/I in cached_gases)
-		if(GLOB.nonreactive_gases[I])
-			continue
-		possible = TRUE
-		break
-	if(!possible)
+		reactions += SSair.gas_reactions[I]
+	if(!length(reactions))
 		return
 	reaction_results = new
 	var/temp = temperature
 	var/ener = THERMAL_ENERGY(src)
 
 	reaction_loop:
-		for(var/r in SSair.gas_reactions)
+		for(var/r in reactions)
 			var/datum/gas_reaction/reaction = r
 
 			var/list/min_reqs = reaction.min_requirements
@@ -376,14 +376,11 @@ GLOBAL_LIST_INIT(meta_gas_fusions, meta_gas_fusion_list())
 					continue reaction_loop
 			//at this point, all requirements for the reaction are satisfied. we can now react()
 			*/
-
 			. |= reaction.react(src, holder)
 			if (. & STOP_REACTIONS)
 				break
 	if(.)
 		GAS_GARBAGE_COLLECT(gases)
-		if(temperature < TCMB) //just for safety
-			temperature = TCMB
 
 //Takes the amount of the gas you want to PP as an argument
 //So I don't have to do some hacky switches/defines/magic strings

code/modules/atmospherics/gasmixtures/gas_types.dm

@@ -78,22 +78,26 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	var/moles_visible = null
 	var/dangerous = FALSE //currently used by canisters
 	var/fusion_power = 0 //How much the gas accelerates a fusion reaction
+	var/rarity = 0 // relative rarity compared to other gases, used when setting up the reactions list.
 
 /datum/gas/oxygen
 	id = "o2"
 	specific_heat = 20
 	name = "Oxygen"
+	rarity = 900
 
 /datum/gas/nitrogen
 	id = "n2"
 	specific_heat = 20
 	name = "Nitrogen"
+	rarity = 1000
 
 /datum/gas/carbon_dioxide //what the fuck is this?
 	id = "co2"
 	specific_heat = 30
 	name = "Carbon Dioxide"
 	fusion_power = 3
+	rarity = 700
 
 /datum/gas/plasma
 	id = "plasma"
@@ -102,6 +106,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	gas_overlay = "plasma"
 	moles_visible = MOLES_GAS_VISIBLE
 	dangerous = TRUE
+	rarity = 800
 
 /datum/gas/water_vapor
 	id = "water_vapor"
@@ -110,6 +115,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	gas_overlay = "water_vapor"
 	moles_visible = MOLES_GAS_VISIBLE
 	fusion_power = 8
+	rarity = 500
 
 /datum/gas/hypernoblium
 	id = "nob"
@@ -118,6 +124,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	gas_overlay = "freon"
 	moles_visible = MOLES_GAS_VISIBLE
 	dangerous = TRUE
+	rarity = 50
 
 /datum/gas/nitrous_oxide
 	id = "n2o"
@@ -126,6 +133,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	gas_overlay = "nitrous_oxide"
 	moles_visible = MOLES_GAS_VISIBLE * 2
 	dangerous = TRUE
+	rarity = 600
 
 /datum/gas/nitryl
 	id = "no2"
@@ -135,6 +143,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	moles_visible = MOLES_GAS_VISIBLE
 	dangerous = TRUE
 	fusion_power = 15
+	rarity = 100
 
 /datum/gas/tritium
 	id = "tritium"
@@ -144,6 +153,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	moles_visible = MOLES_GAS_VISIBLE
 	dangerous = TRUE
 	fusion_power = 1
+	rarity = 300
 
 /datum/gas/bz
 	id = "bz"
@@ -151,18 +161,21 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	name = "BZ"
 	dangerous = TRUE
 	fusion_power = 8
+	rarity = 400
 
 /datum/gas/stimulum
 	id = "stim"
 	specific_heat = 5
 	name = "Stimulum"
 	fusion_power = 7
+	rarity = 1
 
 /datum/gas/pluoxium
 	id = "pluox"
 	specific_heat = 80
 	name = "Pluoxium"
 	fusion_power = 10
+	rarity = 200
 
 /datum/gas/miasma
 	id = "miasma"
@@ -171,6 +184,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	name = "Miasma"
 	gas_overlay = "miasma"
 	moles_visible = MOLES_GAS_VISIBLE * 60
+	rarity = 250
 
 /obj/effect/overlay/gas
 	icon = 'icons/effects/atmospherics.dmi'

code/modules/atmospherics/gasmixtures/reactions.dm

@@ -1,19 +1,36 @@
 //All defines used in reactions are located in ..\__DEFINES\reactions.dm
 
 /proc/init_gas_reactions()
-	var/list/reaction_types = list()
+	. = list()
+	for(var/type in subtypesof(/datum/gas))
+		.[type] = list()
+
 	for(var/r in subtypesof(/datum/gas_reaction))
 		var/datum/gas_reaction/reaction = r
-		if(!initial(reaction.exclude))
-			reaction_types += reaction
-	reaction_types = sortList(reaction_types, /proc/cmp_gas_reactions)
+		if(initial(reaction.exclude))
+			continue
+		reaction = new r
+		var/datum/gas/reaction_key
+		for (var/req in reaction.min_requirements)
+			if (ispath(req))
+				var/datum/gas/req_gas = req
+				if (!reaction_key || initial(reaction_key.rarity) > initial(req_gas.rarity))
+					reaction_key = req_gas
+		.[reaction_key] += list(reaction)
+		sortTim(., /proc/cmp_gas_reactions, TRUE)
 
-	. = list()
-	for(var/path in reaction_types)
-		. += new path
-
-/proc/cmp_gas_reactions(datum/gas_reaction/a, datum/gas_reaction/b) //sorts in descending order of priority
-	return initial(b.priority) - initial(a.priority)
+/proc/cmp_gas_reactions(list/datum/gas_reaction/a, list/datum/gas_reaction/b) // compares lists of reactions by the maximum priority contained within the list
+	if (!length(a) || !length(b))
+		return length(b) - length(a)
+	var/maxa
+	var/maxb
+	for (var/datum/gas_reaction/R in a)
+		if (R.priority > maxa)
+			maxa = R.priority
+	for (var/datum/gas_reaction/R in b)
+		if (R.priority > maxb)
+			maxb = R.priority
+	return maxb - maxa
 
 /datum/gas_reaction
 	//regarding the requirements lists: the minimum or maximum requirements must be non-zero.
@@ -364,7 +381,7 @@
 	cached_gases[/datum/gas/nitrous_oxide] -= reaction_efficency
 	cached_gases[/datum/gas/plasma]  -= 2*reaction_efficency
 
-	SSresearch.science_tech.add_point_type(TECHWEB_POINT_TYPE_DEFAULT, (reaction_efficency**0.5)*BZ_RESEARCH_AMOUNT)	
+	SSresearch.science_tech.add_point_type(TECHWEB_POINT_TYPE_DEFAULT, (reaction_efficency**0.5)*BZ_RESEARCH_AMOUNT)
 
 	if(energy_released > 0)
 		var/new_heat_capacity = air.heat_capacity()