Early Assets, Lateloaded Assets, and Debugging Tools (#4696)

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## About The Pull Request
Various asset systems I want in before more TGUI work. and also
byond-tracy support... and also light update debugging...
## Changelog
🆑
tweak: Chem Master UI has been reworked slightly.

code/controllers/subsystem/asset_loading.dm

@@ -0,0 +1,30 @@
+/**
+ * Allows us to lazyload asset datums.
+ * Anything inserted here will fully load if directly gotten.
+ * So this just serves to remove the requirement to load assets fully during init.
+ */
+SUBSYSTEM_DEF(asset_loading)
+	name = "Asset Loading"
+	priority = FIRE_PRIORITY_ASSETS
+	subsystem_flags = SS_NO_INIT
+	runlevels = RUNLEVEL_LOBBY | RUNLEVELS_DEFAULT
+	var/list/datum/asset/generate_queue = list()
+
+/datum/controller/subsystem/asset_loading/fire(resumed)
+	while(length(generate_queue))
+		var/datum/asset/to_load = generate_queue[generate_queue.len]
+
+		to_load.queued_generation()
+
+		if(MC_TICK_CHECK)
+			return
+		generate_queue.len--
+
+/datum/controller/subsystem/asset_loading/proc/queue_asset(datum/asset/queue)
+#ifdef DO_NOT_DEFER_ASSETS
+	stack_trace("We queued an instance of [queue.type] for lateloading despite not allowing it")
+#endif
+	generate_queue += queue
+
+/datum/controller/subsystem/asset_loading/proc/dequeue_asset(datum/asset/queue)
+	generate_queue -= queue

code/controllers/subsystem/assets.dm

@@ -26,11 +26,11 @@ SUBSYSTEM_DEF(assets)
 	for(var/type in typesof(/datum/asset))
 		var/datum/asset/A = type
 		if (type != initial(A._abstract))
-			get_asset_datum(type)
+			load_asset_datum(type)
 
 	transport.Initialize(cache)
 
-	..()
+	return ..()
 
 /datum/controller/subsystem/assets/Recover()
 	cache = SSassets.cache

code/controllers/subsystem/early_assets.dm

@@ -0,0 +1,26 @@
+/**
+ * Initializes any assets that need to be loaded ASAP.
+ * This houses preference menu assets, since they can be loaded at any time,
+ * most dangerously before the atoms SS initializes.
+ * Thus, we want it to fail consistently in CI as if it would've if a player
+ * opened it up early.
+ */
+SUBSYSTEM_DEF(early_assets)
+	name = "Early Assets"
+	init_order = INIT_ORDER_EARLY_ASSETS
+	subsystem_flags = SS_NO_FIRE
+
+/datum/controller/subsystem/early_assets/Initialize(timeofday)
+	for (var/datum/asset/asset_type as anything in subtypesof(/datum/asset))
+		if (initial(asset_type._abstract) == asset_type)
+			continue
+
+		if (!initial(asset_type.early))
+			continue
+
+		if (!load_asset_datum(asset_type))
+			stack_trace("Could not initialize early asset [asset_type]!")
+
+		CHECK_TICK
+
+	return ..()

code/controllers/subsystem/lighting.dm

@@ -1,7 +1,12 @@
-GLOBAL_LIST_EMPTY(lighting_update_lights) // List of lighting sources  queued for update.
-GLOBAL_LIST_EMPTY(lighting_update_corners) // List of lighting corners  queued for update.
+GLOBAL_LIST_EMPTY(lighting_update_lights)  // List of lighting sources queued for update.
+GLOBAL_LIST_EMPTY(lighting_update_corners) // List of lighting corners queued for update.
 GLOBAL_LIST_EMPTY(lighting_update_objects) // List of lighting objects queued for update.
 
+#ifdef VISUALIZE_LIGHT_UPDATES
+GLOBAL_VAR_INIT(allow_duped_values,  FALSE)
+GLOBAL_VAR_INIT(allow_duped_corners, FALSE)
+#endif
+
 SUBSYSTEM_DEF(lighting)
 	name = "Lighting"
 	wait = 2

code/controllers/subsystem/processing/chemistry.dm

@@ -17,12 +17,14 @@ PROCESSING_SUBSYSTEM_DEF(chemistry)
 	initialize_chemical_reagents()
 	return ..()
 
-//Chemical Reactions - Initialises all /datum/chemical_reaction into a list
-// It is filtered into multiple lists within a list.
-// For example:
-// chemical_reaction_list["phoron"] is a list of all reactions relating to phoron
-// Note that entries in the list are NOT duplicated. So if a reaction pertains to
-// more than one chemical it will still only appear in only one of the sublists.
+/**
+ * Chemical Reactions - Initialises all /datum/chemical_reaction into a list
+ * It is filtered into multiple lists within a list.
+ * For example:
+ * - chemical_reaction_list["phoron"] is a list of all reactions relating to phoron
+ * - Note that entries in the list are NOT duplicated. So if a reaction pertains to
+ * - more than one chemical it will still only appear in only one of the sublists.
+ */
 /datum/controller/subsystem/processing/chemistry/proc/initialize_chemical_reactions()
 	var/paths = typesof(/datum/chemical_reaction) - /datum/chemical_reaction
 	chemical_reactions = list()
@@ -36,7 +38,7 @@ PROCESSING_SUBSYSTEM_DEF(chemistry)
 			LAZYINITLIST(chemical_reactions_by_reagent[reagent_id])
 			chemical_reactions_by_reagent[reagent_id] += D
 
-//Chemical Reagents - Initialises all /datum/reagent into a list indexed by reagent id
+/// Chemical Reagents - Initialises all /datum/reagent into a list indexed by reagent id
 /datum/controller/subsystem/processing/chemistry/proc/initialize_chemical_reagents()
 	var/paths = typesof(/datum/reagent) - /datum/reagent
 	chemical_reagents = list()