Makes playable mobs GC better by reworking how GLOB.respawnable_list works (#17217)

code/modules/events/alien_infestation.dm

@@ -27,7 +27,7 @@
 		var/obj/vent = pick_n_take(vents)
 		var/mob/C = pick_n_take(candidates)
 		if(C)
-			GLOB.respawnable_list -= C.client
+			C.remove_from_respawnable_list()
 			var/mob/living/carbon/alien/larva/new_xeno = new(vent.loc)
 			new_xeno.amount_grown += (0.75 * new_xeno.max_grown)	//event spawned larva start off almost ready to evolve.
 			new_xeno.key = C.key

code/modules/events/traders.dm

@@ -47,7 +47,7 @@ GLOBAL_LIST_INIT(unused_trade_stations, list("sol"))
 		var/mob/C = pick_n_take(candidates)
 		spawn_count--
 		if(C)
-			GLOB.respawnable_list -= C.client
+			C.remove_from_respawnable_list()
 			var/mob/living/carbon/human/M = new /mob/living/carbon/human(picked_loc)
 			M.ckey = C.ckey // must be before equipOutfit, or that will runtime due to lack of mind
 			M.equipOutfit(/datum/outfit/admin/sol_trader)

code/modules/mob/dead/observer/login.dm

@@ -6,4 +6,4 @@
 
 	if(GLOB.non_respawnable_keys[ckey])
 		can_reenter_corpse = 0
-		GLOB.respawnable_list -= src
+		remove_from_respawnable_list()

code/modules/mob/dead/observer/observer.dm

@@ -164,9 +164,9 @@ Works together with spawning an observer, noted above.
 			flags &= ~GHOST_CAN_REENTER
 		var/mob/dead/observer/ghost = new(src, flags)	//Transfer safety to observer spawning proc.
 		ghost.timeofdeath = src.timeofdeath //BS12 EDIT
-		GLOB.respawnable_list -= src
+		remove_from_respawnable_list()
 		if(ghost.can_reenter_corpse)
-			GLOB.respawnable_list += ghost
+			ghost.add_to_respawnable_list()
 		else
 			GLOB.non_respawnable_keys[ckey] = 1
 		ghost.key = key

code/modules/mob/living/carbon/brain/MMI.dm

@@ -51,7 +51,7 @@
 			brainmob.forceMove(src)
 			brainmob.stat = CONSCIOUS
 			brainmob.see_invisible = initial(brainmob.see_invisible)
-			GLOB.respawnable_list -= brainmob
+			brainmob.remove_from_respawnable_list()
 			GLOB.dead_mob_list -= brainmob//Update dem lists
 			GLOB.alive_mob_list += brainmob
 
@@ -161,7 +161,7 @@
 
 	brainmob.container = null//Reset brainmob mmi var.
 	brainmob.forceMove(held_brain) //Throw mob into brain.
-	GLOB.respawnable_list += brainmob
+	brainmob.add_to_respawnable_list()
 	GLOB.alive_mob_list -= brainmob//Get outta here
 	held_brain.brainmob = brainmob//Set the brain to use the brainmob
 	held_brain.brainmob.cancel_camera()

code/modules/mob/living/death.dm

@@ -85,7 +85,7 @@
 	GLOB.dead_mob_list += src
 	if(mind)
 		mind.store_memory("Time of death: [station_time_timestamp("hh:mm:ss", timeofdeath)]", 0)
-		GLOB.respawnable_list += src
+		add_to_respawnable_list()
 
 		if(mind.name && !isbrain(src)) // !isbrain() is to stop it from being called twice
 			var/turf/T = get_turf(src)

code/modules/mob/living/stat_states.dm

@@ -54,7 +54,7 @@
 	GLOB.dead_mob_list -= src
 	GLOB.alive_mob_list += src
 	if(mind)
-		GLOB.respawnable_list -= src
+		remove_from_respawnable_list()
 	timeofdeath = null
 	if(updating)
 		update_canmove()

code/modules/mob/mob.dm

@@ -1095,6 +1095,14 @@ GLOBAL_LIST_INIT(slot_equipment_priority, list( \
 /mob/proc/activate_hand(selhand)
 	return
 
+/mob/proc/add_to_respawnable_list()
+	GLOB.respawnable_list += src
+	RegisterSignal(src, COMSIG_PARENT_QDELETING, .proc/remove_from_respawnable_list)
+
+/mob/proc/remove_from_respawnable_list()
+	GLOB.respawnable_list -= src
+	UnregisterSignal(src, COMSIG_PARENT_QDELETING)
+
 /mob/dead/observer/verb/respawn()
 	set name = "Respawn as NPC"
 	set category = "Ghost"
@@ -1115,17 +1123,13 @@ GLOBAL_LIST_INIT(slot_equipment_priority, list( \
 		var/picked = input("Please select an NPC to respawn as", "Respawn as NPC")  as null|anything in creatures
 		switch(picked)
 			if("Mouse")
-				GLOB.respawnable_list -= usr
+				remove_from_respawnable_list()
 				become_mouse()
-				spawn(5)
-					GLOB.respawnable_list += usr
 			else
 				var/mob/living/NPC = picked
 				if(istype(NPC) && !NPC.key)
-					GLOB.respawnable_list -= usr
+					remove_from_respawnable_list()
 					NPC.key = key
-					spawn(5)
-						GLOB.respawnable_list += usr
 	else
 		to_chat(usr, "You are not dead or you have given up your right to be respawned!")
 		return

code/modules/mob/new_player/new_player.dm

@@ -194,7 +194,7 @@
 			observer.name = observer.real_name
 			observer.key = key
 			QDEL_NULL(mind)
-			GLOB.respawnable_list += observer
+			observer.add_to_respawnable_list()
 			qdel(src)
 			return TRUE
 		return FALSE

code/modules/tgui/modules/ghost_hud_panel.dm

@@ -69,7 +69,7 @@ GLOBAL_DATUM_INIT(ghost_hud_panel, /datum/ui_module/ghost_hud_panel, new)
 
 				ghost.has_enabled_antagHUD = TRUE
 				ghost.can_reenter_corpse = FALSE
-				GLOB.respawnable_list -= ghost
+				ghost.remove_from_respawnable_list()
 
 			ghost.antagHUD = TRUE
 			for(var/datum/atom_hud/antag/H in GLOB.huds)