More ZAS performance stuff (#3186)

Should be good.

code/ZAS/Turf.dm

@@ -47,6 +47,23 @@
 
 				SSair.connect(sim, src)
 
+
+// Helper for can_safely_remove_from_zone().
+#define GET_ZONE_NEIGHBOURS(T, ret) \
+	ret = 0; \
+	if (T.zone) { \
+		for (var/_gzn_dir in gzn_check) { \
+			var/turf/simulated/other = get_step(T, _gzn_dir); \
+			if (istype(other) && other.zone == T.zone) { \
+				var/block; \
+				ATMOS_CANPASS_TURF(block, other, T); \
+				if (!(block & AIR_BLOCKED)) { \
+					ret |= _gzn_dir; \
+				} \
+			} \
+		} \
+	} \
+
 /*
 	Simple heuristic for determining if removing the turf from it's zone will not partition the zone (A very bad thing).
 	Instead of analyzing the entire zone, we only check the nearest 3x3 turfs surrounding the src turf.
@@ -54,41 +71,27 @@
 */
 
 /turf/simulated/proc/can_safely_remove_from_zone()
-	if(!zone) return 1
+	if(!zone)
+		return 1
 
-	var/check_dirs = get_zone_neighbours(src)
-	var/unconnected_dirs = check_dirs
-	var/to_check = list(NORTHEAST, NORTHWEST, SOUTHEAST, SOUTHWEST)
-	#ifdef MULTIZAS
-	to_check += list(NORTHUP, EASTUP, WESTUP, SOUTHUP, NORTHDOWN, EASTDOWN, WESTDOWN, SOUTHDOWN)
-	#endif
-	for(var/dir in to_check)
+	var/check_dirs
+	GET_ZONE_NEIGHBOURS(src, check_dirs)
+	. = check_dirs
+	for(var/dir in csrfz_check)
 
 		//for each pair of "adjacent" cardinals (e.g. NORTH and WEST, but not NORTH and SOUTH)
 		if((dir & check_dirs) == dir)
 			//check that they are connected by the corner turf
-			var/connected_dirs = get_zone_neighbours(get_step(src, dir))
+			var/turf/simulated/T = get_step(src, dir)
+			var/connected_dirs
+			GET_ZONE_NEIGHBOURS(T, connected_dirs)
 			if(connected_dirs && (dir & reverse_dir[connected_dirs]) == dir)
-				unconnected_dirs &= ~dir //they are, so unflag the cardinals in question
+				. &= ~dir //they are, so unflag the cardinals in question
 
 	//it is safe to remove src from the zone if all cardinals are connected by corner turfs
-	return !unconnected_dirs
+	. = !.
 
-//helper for can_safely_remove_from_zone()
-/turf/simulated/proc/get_zone_neighbours(turf/simulated/T)
-	. = 0
-	if(istype(T) && T.zone)
-		var/to_check = cardinal.Copy()
-		#ifdef MULTIZAS
-		to_check += list(UP, DOWN)
-		#endif
-		for(var/dir in to_check)
-			var/turf/simulated/other = get_step(T, dir)
-			if (istype(other) && other.zone == T.zone)
-				var/block
-				ATMOS_CANPASS_TURF(block, other, T)
-				if (!(block & AIR_BLOCKED) && get_dist(src, other) <= 1)
-					. |= dir
+#undef GET_ZONE_NEIGHBOURS
 
 /turf/simulated/update_air_properties()
 
@@ -202,21 +205,17 @@
 
 					SSair.connect(src, sim)
 
-
 			#ifdef ZASDBG
 				else if(verbose) log_debug("[d] has same zone.")
 
 			else if(verbose) log_debug("[d] has invalid zone.")
 			#endif
-
 		else
-
 			//Postponing connections to tiles until a zone is assured.
-			if(!postponed) postponed = list()
-			postponed.Add(unsim)
+			LAZYADD(postponed, unsim)
 
 	if(!TURF_HAS_VALID_ZONE(src)) //Still no zone, make a new one.
-		var/zone/newzone = new/zone()
+		var/zone/newzone = new
 		newzone.add(src)
 
 	#ifdef ZASDBG
@@ -227,7 +226,8 @@
 
 	//At this point, a zone should have happened. If it hasn't, don't add more checks, fix the bug.
 
-	for(var/turf/T in postponed)
+	for(var/thing in postponed)
+		var/turf/T = thing
 		SSair.connect(src, T)
 
 /turf/proc/post_update_air_properties()
@@ -304,6 +304,7 @@
 	air.volume = CELL_VOLUME
 
 /turf/simulated/proc/c_copy_air()
-	if(!air) air = new/datum/gas_mixture
-	air.copy_from(zone.air)
+	if(!air)
+		air = new /datum/gas_mixture
 	air.group_multiplier = 1
+	air.copy_from(zone.air, TRUE)

code/__defines/ZAS.dm

@@ -16,6 +16,10 @@
 #define TURF_HAS_VALID_ZONE(T) (istype(T, /turf/simulated) && T:zone && !T:zone:invalid)
 
 #ifdef MULTIZAS
+
+var/list/csrfz_check = list(NORTHEAST, NORTHWEST, SOUTHEAST, SOUTHWEST, NORTHUP, EASTUP, WESTUP, SOUTHUP, NORTHDOWN, EASTDOWN, WESTDOWN, SOUTHDOWN)
+var/list/gzn_check = list(NORTH, SOUTH, EAST, WEST, UP, DOWN)
+
 #define ATMOS_CANPASS_TURF(ret,A,B) \
 	if (A.blocks_air & AIR_BLOCKED || B.blocks_air & AIR_BLOCKED) { \
 		ret = BLOCKED; \
@@ -66,6 +70,9 @@
 	}
 #else
 
+var/list/csrfz_check = list(NORTHEAST, NORTHWEST, SOUTHEAST, SOUTHWEST)
+var/list/gzn_check = list(NORTH, SOUTH, EAST, WEST)
+
 #define ATMOS_CANPASS_TURF(ret,A,B) \
 	if (A.blocks_air & AIR_BLOCKED || B.blocks_air & AIR_BLOCKED) { \
 		ret = BLOCKED; \

code/game/turfs/simulated.dm

@@ -167,11 +167,13 @@
 		new /obj/effect/decal/cleanable/blood/oil(src)
 
 /turf/simulated/Destroy()
-	//Yeah, we're just going to rebuild the whole thing.
-	//Despite this being called a bunch during explosions,
-	//the zone will only really do heavy lifting once.
 	if (zone)
-		zone.rebuild()
+		// Try to remove it gracefully first.
+		if (can_safely_remove_from_zone())
+			c_copy_air()
+			zone.remove(src)
+		else	// Can't remove it safely, just rebuild the entire thing.
+			zone.rebuild()
 
 	// Letting this timer continue to exist can cause runtimes, so we delete it.
 	if (unwet_timer)

code/modules/xgm/xgm_gas_mixture.dm

@@ -295,15 +295,17 @@
 			. += gas[g]
 
 //Copies gas and temperature from another gas_mixture.
-/datum/gas_mixture/proc/copy_from(const/datum/gas_mixture/sample)
+// If fast is TRUE, use a less accurate method that doesn't involve list iteraton.
+/datum/gas_mixture/proc/copy_from(const/datum/gas_mixture/sample, fast = FALSE)
 	gas = sample.gas.Copy()
 	temperature = sample.temperature
-
-	update_values()
+	if (fast)
+		total_moles = sample.total_moles
+	else
+		update_values()
 
 	return 1
 
-
 //Checks if we are within acceptable range of another gas_mixture to suspend processing or merge.
 /datum/gas_mixture/proc/compare(const/datum/gas_mixture/sample, var/vacuum_exception = 0)
 	if(!sample) return 0