From 1ecbd23a5b653679abf272ebf84ee553a0ddd7c9 Mon Sep 17 00:00:00 2001
From: Fluffy <65877598+FluffyGhoster@users.noreply.github.com>
Date: Fri, 1 Dec 2023 13:14:21 +0100
Subject: [PATCH] Optimize air alarms processing and light overlays (#17715)

* hfhdg

* asf

* sdf

* fsfa
---
 code/game/machinery/alarm.dm                  | 28 ++++++++++++
 code/modules/lighting/lighting_overlay.dm     | 25 ++++++-----
 code/modules/xgm/xgm_gas_mixture.dm           | 14 +++---
 html/changelogs/fluffyghost-optimizations.yml | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 18 deletions(-)
 create mode 100644 html/changelogs/fluffyghost-optimizations.yml

diff --git a/code/game/machinery/alarm.dm b/code/game/machinery/alarm.dm
index cc46695ba53..573c5e7535c 100644
--- a/code/game/machinery/alarm.dm
+++ b/code/game/machinery/alarm.dm
@@ -153,6 +153,13 @@ pixel_x = 10;
 
 	var/global/image/alarm_overlay
 
+	//Used to cache the previous gas mixture result, and evaluate if we can skip processing or not
+	var/previous_environment_group_multiplier = null
+	var/previous_environment_temperature = null
+	var/previous_environment_total_moles = null
+	var/previous_environment_volume = null
+	var/list/previous_environment_gas = list()
+
 /obj/machinery/alarm/north
 	PRESET_NORTH
 
@@ -361,6 +368,27 @@ pixel_x = 10;
 
 	var/datum/gas_mixture/environment = location.return_air()
 
+	var/is_same_environment = TRUE
+	for(var/k in environment.gas)
+		if(environment.gas[k] != previous_environment_gas[k])
+			is_same_environment = FALSE
+			previous_environment_gas = environment.gas.Copy()
+			break
+	if(is_same_environment)
+		if(	(environment.temperature != previous_environment_temperature) ||\
+			(environment.group_multiplier != previous_environment_group_multiplier) ||\
+			(environment.total_moles != previous_environment_total_moles) ||\
+			(environment.volume != previous_environment_volume)
+		)
+			is_same_environment = FALSE
+			previous_environment_group_multiplier = environment.group_multiplier
+			previous_environment_temperature = environment.temperature
+			previous_environment_total_moles = environment.total_moles
+			previous_environment_volume = environment.volume
+
+	if(is_same_environment)
+		return
+
 	//Handle temperature adjustment here.
 	handle_heating_cooling(environment)
 
diff --git a/code/modules/lighting/lighting_overlay.dm b/code/modules/lighting/lighting_overlay.dm
index 5f6e7b6f0a9..785ad255118 100644
--- a/code/modules/lighting/lighting_overlay.dm
+++ b/code/modules/lighting/lighting_overlay.dm
@@ -59,18 +59,21 @@
 
 	// See LIGHTING_CORNER_DIAGONAL in lighting_corner.dm for why these values are what they are.
 	var/list/corners = T.corners
-	var/datum/lighting_corner/cr = dummy_lighting_corner
-	var/datum/lighting_corner/cg = dummy_lighting_corner
-	var/datum/lighting_corner/cb = dummy_lighting_corner
-	var/datum/lighting_corner/ca = dummy_lighting_corner
-	if (corners)
-		cr = corners[3] || dummy_lighting_corner
-		cg = corners[2] || dummy_lighting_corner
-		cb = corners[4] || dummy_lighting_corner
-		ca = corners[1] || dummy_lighting_corner
 
-	var/max = max(cr.cache_mx, cg.cache_mx, cb.cache_mx, ca.cache_mx)
-	luminosity = max > LIGHTING_SOFT_THRESHOLD
+	//Local cache, because otherwise it accesses the global variable repeatedly, which is slower
+	var/dummy_lighting_corner_cache = dummy_lighting_corner
+
+	var/datum/lighting_corner/cr = dummy_lighting_corner_cache
+	var/datum/lighting_corner/cg = dummy_lighting_corner_cache
+	var/datum/lighting_corner/cb = dummy_lighting_corner_cache
+	var/datum/lighting_corner/ca = dummy_lighting_corner_cache
+	if (corners)
+		cr = corners[3] || dummy_lighting_corner_cache
+		cg = corners[2] || dummy_lighting_corner_cache
+		cb = corners[4] || dummy_lighting_corner_cache
+		ca = corners[1] || dummy_lighting_corner_cache
+
+	luminosity = max(cr.cache_mx, cg.cache_mx, cb.cache_mx, ca.cache_mx) > LIGHTING_SOFT_THRESHOLD
 
 	var/rr = cr.cache_r
 	var/rg = cr.cache_g
diff --git a/code/modules/xgm/xgm_gas_mixture.dm b/code/modules/xgm/xgm_gas_mixture.dm
index 022d315bd91..b278289e930 100644
--- a/code/modules/xgm/xgm_gas_mixture.dm
+++ b/code/modules/xgm/xgm_gas_mixture.dm
@@ -1,18 +1,18 @@
 /datum/gas_mixture
-	//Associative list of gas moles.
-	//Gases with 0 moles are not tracked and are pruned by update_values()
+	///Associative list of gas moles.
+	///Gases with 0 moles are not tracked and are pruned by update_values()
 	var/list/gas
-	//Temperature in Kelvin of this gas mix.
+	///Temperature in Kelvin of this gas mix.
 	var/temperature = 0
 
-	//Sum of all the gas moles in this mix.  Updated by update_values()
+	///Sum of all the gas moles in this mix.  Updated by update_values()
 	var/total_moles = 0
-	//Volume of this mix.
+	///Volume of this mix.
 	var/volume = CELL_VOLUME
-	//Size of the group this gas_mixture is representing.  1 for singletons.
+	///Size of the group this gas_mixture is representing.  1 for singletons.
 	var/group_multiplier = 1
 
-	//List of active tile overlays for this gas_mixture.  Updated by check_tile_graphic()
+	///List of active tile overlays for this gas_mixture.  Updated by check_tile_graphic()
 	var/list/graphic
 
 /datum/gas_mixture/New(_volume = CELL_VOLUME, _temperature = 0, _group_multiplier = 1)
diff --git a/html/changelogs/fluffyghost-optimizations.yml b/html/changelogs/fluffyghost-optimizations.yml
new file mode 100644
index 00000000000..40629f3a942
--- /dev/null
+++ b/html/changelogs/fluffyghost-optimizations.yml
@@ -0,0 +1,43 @@
+################################
+# Example Changelog File
+#
+# Note: This file, and files beginning with ".", and files that don't end in ".yml" will not be read. If you change this file, you will look really dumb.
+#
+# Your changelog will be merged with a master changelog. (New stuff added only, and only on the date entry for the day it was merged.)
+# When it is, any changes listed below will disappear.
+#
+# Valid Prefixes:
+#   bugfix
+#   wip (For works in progress)
+#   tweak
+#   soundadd
+#   sounddel
+#   rscadd (general adding of nice things)
+#   rscdel (general deleting of nice things)
+#   imageadd
+#   imagedel
+#   maptweak
+#   spellcheck (typo fixes)
+#   experiment
+#   balance
+#   admin
+#   backend
+#   security
+#   refactor
+#################################
+
+# Your name.
+author: FluffyGhost
+
+# Optional: Remove this file after generating master changelog.  Useful for PR changelogs that won't get used again.
+delete-after: True
+
+# Any changes you've made.  See valid prefix list above.
+# INDENT WITH TWO SPACES.  NOT TABS.  SPACES.
+# SCREW THIS UP AND IT WON'T WORK.
+# Also, all entries are changed into a single [] after a master changelog generation. Just remove the brackets when you add new entries.
+# Please surround your changes in  double quotes ("), as certain characters otherwise screws up compiling. The quotes will not show up in the changelog.
+changes:
+  - refactor: "DMdoced some ZAS variables from comments."
+  - backend: "Optimized air alarms not to reprocess gasses if the atmosphere has not changed, saving more than half of the median execution time."
+  - backend: "Optimized lights overlay updating, which is now around 10 percent more performant in median execution time."