SSoverlay improvements and tweaks (#32371)

* Overlay per-type cost logging.

Overlays will now log how long each type took to process.

Changed up how overlays was done to account for the fact its a queue and not a processor. (it was using almost none of the processing subsystem framework)

Made the overlay loop faster by making it not cut the list until the end.

Added a simple generic benchmark stat tracking system.

I don't know how much overhead this adds to overlays. i may put it behind testing or something, but i do want to test this on the serbers to get some stats.

* Removes flush() as it was creating race conditions

* Use ref

* text2file

* Atoms added as an overlay will have their pending overlays compiled before being converted to an appearance

code/controllers/subsystem/overlays.dm

@@ -1,4 +1,4 @@
-PROCESSING_SUBSYSTEM_DEF(overlays)
+SUBSYSTEM_DEF(overlays)
 	name = "Overlay"
 	flags = SS_TICKER
 	wait = 1
@@ -6,62 +6,63 @@ PROCESSING_SUBSYSTEM_DEF(overlays)
 	init_order = INIT_ORDER_OVERLAY
 	runlevels = RUNLEVELS_DEFAULT | RUNLEVEL_SETUP
 
-	stat_tag = "Ov"
-	currentrun = null
+	var/list/queue
+	var/list/stats
 	var/list/overlay_icon_state_caches
 	var/list/overlay_icon_cache
 	var/initialized = FALSE
 
-/datum/controller/subsystem/processing/overlays/PreInit()
-	LAZYINITLIST(overlay_icon_state_caches)
-	LAZYINITLIST(overlay_icon_cache)
+/datum/controller/subsystem/overlays/PreInit()
+	overlay_icon_state_caches = list()
+	overlay_icon_cache = list()
+	queue = list()
+	stats = list()
 
-/datum/controller/subsystem/processing/overlays/Initialize()
+/datum/controller/subsystem/overlays/Initialize()
 	initialized = TRUE
-	Flush()
+	fire(mc_check = FALSE)
 	..()
 
-/datum/controller/subsystem/processing/overlays/Recover()
+
+/datum/controller/subsystem/overlays/stat_entry()
+	..("Ov:[length(queue)]")
+
+
+/datum/controller/subsystem/overlays/Shutdown()
+	text2file("[GLOB.log_directory]/overlay.log", render_stats(stats))
+
+
+/datum/controller/subsystem/overlays/Recover()
 	overlay_icon_state_caches = SSoverlays.overlay_icon_state_caches
 	overlay_icon_cache = SSoverlays.overlay_icon_cache
-	processing = SSoverlays.processing
+	queue = SSoverlays.queue
 
-#define COMPILE_OVERLAYS(A)\
-	var/list/oo = A.our_overlays;\
-	var/list/po = A.priority_overlays;\
-	if(LAZYLEN(po)){\
-		if(LAZYLEN(oo)){\
-			A.overlays = oo + po;\
-		}\
-		else{\
-			A.overlays = po;\
-		}\
-	}\
-	else if(LAZYLEN(oo)){\
-		A.overlays = oo;\
-	}\
-	else{\
-		A.overlays.Cut();\
-	}\
-	A.flags_1 &= ~OVERLAY_QUEUED_1
 
-/datum/controller/subsystem/processing/overlays/fire(resumed = FALSE, mc_check = TRUE)
-	var/list/processing = src.processing
-	while(processing.len)
-		var/atom/thing = processing[processing.len]
-		processing.len--
+/datum/controller/subsystem/overlays/fire(resumed = FALSE, mc_check = TRUE)
+	var/list/queue = src.queue
+	var/static/count = 0
+	if (count)
+		var/c = count
+		count = 0 //so if we runtime on the Cut, we don't try again.
+		queue.Cut(1,c+1)
+
+	for (var/thing in queue)
+		count++
 		if(thing)
-			COMPILE_OVERLAYS(thing)
+			STAT_START_STOPWATCH
+			var/atom/A = thing
+			COMPILE_OVERLAYS(A)
+			STAT_STOP_STOPWATCH
+			STAT_LOG_ENTRY(stats, A.type)
 		if(mc_check)
 			if(MC_TICK_CHECK)
 				break
 		else
 			CHECK_TICK
 
-/datum/controller/subsystem/processing/overlays/proc/Flush()
-	if(processing.len)
-		testing("Flushing [processing.len] overlays")
-		fire(mc_check = FALSE)	//pair this thread up with the MC to get extra compile time
+	if (count)
+		queue.Cut(1,count+1)
+		count = 0
 
 /proc/iconstate2appearance(icon, iconstate)
 	var/static/image/stringbro = new()
@@ -102,6 +103,10 @@ PROCESSING_SUBSYSTEM_DEF(overlays)
 		else if(isicon(overlay))
 			new_overlays += icon2appearance(overlay)
 		else
+			if(isloc(overlay))
+				var/atom/A = overlay
+				if (A.flags_1 & OVERLAY_QUEUED_1)
+					COMPILE_OVERLAYS(A)
 			appearance_bro.appearance = overlay //this works for images and atoms too!
 			if(!ispath(overlay))
 				var/image/I = overlay
@@ -110,7 +115,7 @@ PROCESSING_SUBSYSTEM_DEF(overlays)
 	return new_overlays
 
 #define NOT_QUEUED_ALREADY (!(flags_1 & OVERLAY_QUEUED_1))
-#define QUEUE_FOR_COMPILE flags_1 |= OVERLAY_QUEUED_1; SSoverlays.processing += src;
+#define QUEUE_FOR_COMPILE flags_1 |= OVERLAY_QUEUED_1; SSoverlays.queue += src;
 /atom/proc/cut_overlays(priority = FALSE)
 	var/list/cached_overlays = our_overlays
 	var/list/cached_priority = priority_overlays

code/controllers/subsystem/ticker.dm

@@ -281,8 +281,6 @@ SUBSYSTEM_DEF(ticker)
 	collect_minds()
 	equip_characters()
 
-	SSoverlays.Flush()	//Flush the majority of the shit
-
 	GLOB.data_core.manifest()
 
 	transfer_characters()	//transfer keys to the new mobs