wow i forgot some extremely important updates haha

code/__DEFINES/atmospherics.dm

@@ -152,6 +152,10 @@
 #define ATMOS_PASS_PROC -1 //ask CanAtmosPass()
 #define ATMOS_PASS_DENSITY -2 //just check density
 
+// Adjacency flags
+#define ATMOS_ADJACENT_ANY		(1<<0)
+#define ATMOS_ADJACENT_FIRELOCK	(1<<1)
+
 #define CANATMOSPASS(A, O) ( A.CanAtmosPass == ATMOS_PASS_PROC ? A.CanAtmosPass(O) : ( A.CanAtmosPass == ATMOS_PASS_DENSITY ? !A.density : A.CanAtmosPass ) )
 #define CANVERTICALATMOSPASS(A, O) ( A.CanAtmosPassVertical == ATMOS_PASS_PROC ? A.CanAtmosPass(O, TRUE) : ( A.CanAtmosPassVertical == ATMOS_PASS_DENSITY ? !A.density : A.CanAtmosPassVertical ) )
 
@@ -323,14 +327,6 @@
 #define QUANTIZE(variable)		(round(variable,0.0000001))/*I feel the need to document what happens here. Basically this is used to catch most rounding errors, however it's previous value made it so that
 															once gases got hot enough, most procedures wouldnt occur due to the fact that the mole counts would get rounded away. Thus, we lowered it a few orders of magnititude */
 
-
-#ifdef TESTING
-GLOBAL_LIST_INIT(atmos_adjacent_savings, list(0,0))
-#define CALCULATE_ADJACENT_TURFS(T) if (SSadjacent_air.queue[T]) { GLOB.atmos_adjacent_savings[1] += 1 } else { GLOB.atmos_adjacent_savings[2] += 1; SSadjacent_air.queue[T] = 1 }
-#else
-#define CALCULATE_ADJACENT_TURFS(T) SSadjacent_air.queue[T] = 1
-#endif
-
 //If you're doing spreading things related to atmos, DO NOT USE CANATMOSPASS, IT IS NOT CHEAP. use this instead, the info is cached after all. it's tweaked just a bit to allow for circular checks
 #define TURFS_CAN_SHARE(T1, T2) (LAZYACCESS(T2.atmos_adjacent_turfs, T1) || LAZYLEN(T1.atmos_adjacent_turfs & T2.atmos_adjacent_turfs))
 

code/controllers/subsystem/adjacent_air.dm

@@ -1,39 +0,0 @@
-SUBSYSTEM_DEF(adjacent_air)
-	name = "Atmos Adjacency"
-	flags = SS_BACKGROUND
-	runlevels = RUNLEVEL_GAME | RUNLEVEL_POSTGAME
-	wait = 10
-	priority = FIRE_PRIORITY_ATMOS_ADJACENCY
-	var/list/queue = list()
-
-/datum/controller/subsystem/adjacent_air/stat_entry(msg)
-#ifdef TESTING
-	msg = "P:[length(queue)], S:[GLOB.atmos_adjacent_savings[1]], T:[GLOB.atmos_adjacent_savings[2]]"
-#else
-	msg = "P:[length(queue)]"
-#endif
-	return ..()
-
-/datum/controller/subsystem/adjacent_air/Initialize()
-	while(length(queue))
-		fire(mc_check = FALSE)
-	return ..()
-
-/datum/controller/subsystem/adjacent_air/fire(resumed = FALSE, mc_check = TRUE)
-	if(SSair.thread_running())
-		pause()
-		return
-
-	var/list/queue = src.queue
-
-	while (length(queue))
-		var/turf/currT = queue[1]
-		queue.Cut(1,2)
-
-		currT.ImmediateCalculateAdjacentTurfs()
-
-		if(mc_check)
-			if(MC_TICK_CHECK)
-				break
-		else
-			CHECK_TICK

code/game/machinery/doors/firedoor.dm

@@ -34,6 +34,8 @@
 /obj/machinery/door/firedoor/Initialize(mapload)
 	. = ..()
 	CalculateAffectingAreas()
+	UpdateAdjacencyFlags()
+
 
 /obj/machinery/door/firedoor/examine(mob/user)
 	. = ..()
@@ -53,6 +55,20 @@
 		var/area/A = I
 		LAZYADD(A.firedoors, src)
 
+/obj/machinery/door/firedoor/proc/UpdateAdjacencyFlags()
+	var/turf/T = get_turf(src)
+	if(flags_1 & ON_BORDER_1)
+		for(var/t in T.atmos_adjacent_turfs)
+			if(get_dir(loc, t) == dir)
+				var/turf/open/T2 = t
+				T.atmos_adjacent_turfs[T2] |= ATMOS_ADJACENT_FIRELOCK
+				T2.atmos_adjacent_turfs[T] |= ATMOS_ADJACENT_FIRELOCK
+	else
+		for(var/t in T.atmos_adjacent_turfs)
+			var/turf/open/T2 = t
+			T.atmos_adjacent_turfs[T2] |= ATMOS_ADJACENT_FIRELOCK
+			T2.atmos_adjacent_turfs[T] |= ATMOS_ADJACENT_FIRELOCK
+
 /obj/machinery/door/firedoor/closed
 	icon_state = "door_closed"
 	opacity = TRUE

code/game/turfs/change_turf.dm

@@ -15,7 +15,7 @@ GLOBAL_LIST_INIT(blacklisted_automated_baseturfs, typecacheof(list(
 
 	if(turf_type)
 		var/turf/newT = ChangeTurf(turf_type, baseturf_type, flags)
-		CALCULATE_ADJACENT_TURFS(newT)
+		newT.ImmediateCalculateAdjacentTurfs()
 
 /turf/proc/copyTurf(turf/T)
 	if(T.type != type)
@@ -285,10 +285,7 @@ GLOBAL_LIST_INIT(blacklisted_automated_baseturfs, typecacheof(list(
 //If you modify this function, ensure it works correctly with lateloaded map templates.
 /turf/proc/AfterChange(flags) //called after a turf has been replaced in ChangeTurf()
 	levelupdate()
-	if(flags & CHANGETURF_RECALC_ADJACENT)
+	ImmediateCalculateAdjacentTurfs()
-		ImmediateCalculateAdjacentTurfs()
-	else
-		CALCULATE_ADJACENT_TURFS(src)
 
 	//update firedoor adjacency
 	var/list/turfs_to_check = get_adjacent_open_turfs(src) | src

code/game/turfs/turf.dm

@@ -75,7 +75,7 @@ GLOBAL_LIST_EMPTY(station_turfs)
 		add_overlay(/obj/effect/fullbright)
 
 	if(requires_activation)
-		CALCULATE_ADJACENT_TURFS(src)
+		ImmediateCalculateAdjacentTurfs()
 
 	if (light_power && light_range)
 		update_light()
@@ -111,7 +111,7 @@ GLOBAL_LIST_EMPTY(station_turfs)
 /turf/proc/set_temperature()
 
 /turf/proc/Initalize_Atmos(times_fired)
-	CALCULATE_ADJACENT_TURFS(src)
+	ImmediateCalculateAdjacentTurfs()
 
 /turf/Destroy(force)
 	. = QDEL_HINT_IWILLGC

code/modules/atmospherics/environmental/LINDA_system.dm

@@ -40,21 +40,19 @@
 	return FALSE
 
 /turf/proc/ImmediateCalculateAdjacentTurfs()
-	if(SSair.thread_running())
-		CALCULATE_ADJACENT_TURFS(src)
-		return
 	var/canpass = CANATMOSPASS(src, src)
 	var/canvpass = CANVERTICALATMOSPASS(src, src)
 	for(var/direction in GLOB.cardinals_multiz)
 		var/turf/T = get_step_multiz(src, direction)
 		if(!istype(T))
 			continue
-		var/opp_dir = REVERSE_DIR(direction)
 		if(isopenturf(T) && !(blocks_air || T.blocks_air) && ((direction & (UP|DOWN))? (canvpass && CANVERTICALATMOSPASS(T, src)) : (canpass && CANATMOSPASS(T, src))) )
 			LAZYINITLIST(atmos_adjacent_turfs)
 			LAZYINITLIST(T.atmos_adjacent_turfs)
-			atmos_adjacent_turfs[T] = direction
+			atmos_adjacent_turfs[T] = ATMOS_ADJACENT_ANY
-			T.atmos_adjacent_turfs[src] = opp_dir
+			T.atmos_adjacent_turfs[src] = ATMOS_ADJACENT_ANY
+			for(var/obj/machinery/door/firedoor/FD in T)
+				FD.UpdateAdjacencyFlags()
 		else
 			if (atmos_adjacent_turfs)
 				atmos_adjacent_turfs -= T
@@ -65,7 +63,8 @@
 		T.__update_auxtools_turf_adjacency_info(isspaceturf(T.get_z_base_turf()), -1)
 	UNSETEMPTY(atmos_adjacent_turfs)
 	src.atmos_adjacent_turfs = atmos_adjacent_turfs
-	set_sleeping(blocks_air)
+	for(var/obj/machinery/door/firedoor/FD in src)
+		FD.UpdateAdjacencyFlags()
 	__update_auxtools_turf_adjacency_info(isspaceturf(get_z_base_turf()))
 
 /turf/proc/set_sleeping(should_sleep)

code/modules/holodeck/area_copy.dm

@@ -138,7 +138,7 @@ GLOBAL_LIST_INIT(duplicate_forbidden_vars_by_type, typecacheof_assoc_list(list(
 
 	if(toupdate.len)
 		for(var/turf/T1 in toupdate)
-			CALCULATE_ADJACENT_TURFS(T1)
+			T1.ImmediateCalculateAdjacentTurfs()
 
 
 	return copiedobjs

code/modules/power/supermatter/supermatter.dm

@@ -952,7 +952,7 @@ GLOBAL_DATUM(main_supermatter_engine, /obj/machinery/power/supermatter_crystal)
 	playsound(T, 'sound/effects/supermatter.ogg', 50, 1)
 	T.visible_message("<span class='danger'>[T] smacks into [src] and rapidly flashes to ash.</span>",\
 	"<span class='italics'>You hear a loud crack as you are washed with a wave of heat.</span>")
-	CALCULATE_ADJACENT_TURFS(T)
+	T.ImmediateCalculateAdjacentTurfs()
 
 //Do not blow up our internal radio
 /obj/machinery/power/supermatter_crystal/contents_explosion(severity, target, origin)

tgstation.dme

@@ -353,7 +353,6 @@
 #include "code\controllers\configuration\entries\vote.dm"
 #include "code\controllers\subsystem\achievements.dm"
 #include "code\controllers\subsystem\activity.dm"
-#include "code\controllers\subsystem\adjacent_air.dm"
 #include "code\controllers\subsystem\air.dm"
 #include "code\controllers\subsystem\assets.dm"
 #include "code\controllers\subsystem\atoms.dm"