Stamina container optimizations (#5869)

## About The Pull Request

frees up some processing time processing stamina on things that do not
care about stamina.

## Changelog
:cl:
refactor: The Stamina subsystem no longer wastes time trying to process
stamina on dead mobs, or mobs that don't even care about stamina in the
first place.
/:cl:

Author: Absolucy

code/modules/mob/living/living.dm

@@ -1,6 +1,6 @@
 /mob/living/Initialize(mapload)
 	. = ..()
-	stamina = new(src)
+	stamina = new(src) // monkestation edit: stamina rework
 	if(current_size != RESIZE_DEFAULT_SIZE)
 		update_transform(current_size)
 	AddElement(/datum/element/movetype_handler)

monkestation/code/controllers/subsystem/stamina.dm

@@ -18,9 +18,10 @@ SUBSYSTEM_DEF(stamina)
 	//cache for sanic speed (lists are references anyways)
 	var/list/current_run = currentrun
 
+	var/seconds_per_tick = world.tick_lag * wait * 0.1
 	while(length(current_run))
 		var/datum/stamina_container/thing = current_run[length(current_run)]
 		current_run.len--
-		thing.update(world.tick_lag * wait * 0.1)
+		thing.update(seconds_per_tick)
 		if (MC_TICK_CHECK)
 			return

monkestation/code/datums/stamina_container.dm

@@ -17,13 +17,22 @@
 	var/is_regenerating = TRUE
 	//unga bunga
 	var/process_stamina = TRUE
+	/// Used to determine when the stamina changes, to properly run on_stamina_update on the parent.
+	VAR_PRIVATE/should_notify_parent = FALSE
 
 	///cooldowns
 	///how long until we can lose stamina again
 	COOLDOWN_DECLARE(stamina_grace_period)
 	///how long stamina is paused for
 	COOLDOWN_DECLARE(paused_stamina)
 
+	/// Signals which we react in order to re-check if we should be processing or not.
+	var/static/list/update_on_signals = list(
+		COMSIG_MOB_STATCHANGE,
+		SIGNAL_ADDTRAIT(TRAIT_NO_TRANSFORM),
+		SIGNAL_REMOVETRAIT(TRAIT_NO_TRANSFORM),
+	)
+
 /datum/stamina_container/New(parent, maximum = STAMINA_MAX, regen_rate = STAMINA_REGEN)
 	if(maximum <= 0)
 		stack_trace("Attempted to initialize stamina container with an invalid maximum limit of [maximum], defaulting to [STAMINA_MAX]")
@@ -32,15 +41,21 @@
 	src.maximum = maximum
 	src.regen_rate = regen_rate
 	src.current = maximum
-	START_PROCESSING(SSstamina, src)
+	RegisterSignals(parent, update_on_signals, PROC_REF(update_process))
+	RegisterSignal(parent, COMSIG_MOVABLE_MOVED, PROC_REF(nullspace_move_check))
+	update_process()
 
 /datum/stamina_container/Destroy()
-	parent?.stamina = null
+	if(!isnull(parent))
+		parent.stamina = null
+		UnregisterSignal(parent, update_on_signals)
+		UnregisterSignal(parent, COMSIG_MOVABLE_MOVED)
 	parent = null
 	STOP_PROCESSING(SSstamina, src)
 	return ..()
 
 /datum/stamina_container/proc/update(seconds_per_tick = 1)
+	var/last_current = current
 	if(process_stamina == TRUE)
 		if(!is_regenerating)
 			if(!COOLDOWN_FINISHED(src, paused_stamina))
@@ -49,8 +64,10 @@
 
 		if(seconds_per_tick)
 			current = min(current + (regen_rate*seconds_per_tick), maximum)
-		if(seconds_per_tick && decrement)
-			current = max(current + (-decrement*seconds_per_tick), 0)
+			if(decrement)
+				current = max(current + (-decrement*seconds_per_tick), 0)
+		if(current != last_current)
+			should_notify_parent = TRUE
 		loss = maximum - current
 		loss_as_percent = loss ? (loss == maximum ? 0 : loss / maximum * 100) : 0
 
@@ -59,7 +76,9 @@
 	else if(!(current == maximum))
 		process_stamina = TRUE
 
-	parent.on_stamina_update()
+	if(should_notify_parent)
+		parent.on_stamina_update()
+		should_notify_parent = FALSE
 
 ///Pause stamina regeneration for some period of time. Does not support doing this from multiple sources at once because I do not do that and I will add it later if I want to.
 /datum/stamina_container/proc/pause(time)
@@ -86,7 +105,10 @@
 	var/modify = parent.pre_stamina_change(amt, forced)
 	if(base_modify)
 		modify = amt
+	var/old_current = current
 	current = round(clamp(current + modify, 0, maximum), DAMAGE_PRECISION)
+	if(current != old_current)
+		should_notify_parent = TRUE
 	update()
 	if((amt < 0) && is_regenerating)
 		pause(STAMINA_REGEN_TIME)
@@ -104,12 +126,42 @@
 	if(stamina_after_loss < lowest_stamina_value)
 		amount = current - lowest_stamina_value
 
+	var/old_current = current
 	current = round(clamp(current + amount, 0, maximum), DAMAGE_PRECISION)
+	if(current != old_current)
+		should_notify_parent = TRUE
 	update()
 	if((amount < 0) && is_regenerating)
 		pause(STAMINA_REGEN_TIME)
 	return amount
 
+/// Signal handler for COMSIG_MOVABLE_MOVED to ensure that update_process() gets called whenever moving to/from nullspace.
+/datum/stamina_container/proc/nullspace_move_check(atom/movable/mover, atom/old_loc, dir, force)
+	SIGNAL_HANDLER
+	if(isnull(old_loc) || isnull(mover.loc))
+		update_process()
+
+/// Returns if the container should currently be processing or not.
+/datum/stamina_container/proc/should_process()
+	SHOULD_BE_PURE(TRUE)
+	if(QDELETED(parent) || isnull(parent.loc))
+		return FALSE
+	if(!parent.uses_stamina)
+		return FALSE
+	if(parent.stat == DEAD)
+		return FALSE
+	if(HAS_TRAIT(parent, TRAIT_NO_TRANSFORM))
+		return FALSE
+	return TRUE
+
+/// Checks to see if the container should be processing, and starts/stops it.
+/datum/stamina_container/proc/update_process()
+	SIGNAL_HANDLER
+	if(should_process())
+		START_PROCESSING(SSstamina, src)
+	else
+		STOP_PROCESSING(SSstamina, src)
+
 /// Sets the maximum amount of stamina.
 /// Always use this instead of directly setting the stamina var, as this has sanity checks, and immediately updates afterwards.
 /datum/stamina_container/proc/set_maximum(value = STAMINA_MAX)
@@ -122,3 +174,15 @@
 	maximum = value
 	update()
 	return TRUE
+
+/mob/living/carbon
+	uses_stamina = TRUE
+
+/mob/living/carbon/alien
+	uses_stamina = FALSE
+
+/mob/living/basic
+	uses_stamina = TRUE
+
+/mob/living/simple_animal
+	uses_stamina = TRUE

monkestation/code/modules/mob/living/living_defines.dm

@@ -7,3 +7,5 @@
 	///The talk chime set to use when speaking.
 	var/voice_type
 
+	/// If TRUE, then this mob has a stamina container initialized, and will use stamina.
+	var/uses_stamina = FALSE