add support for preloading the icon_exists cache

.gitignore

@@ -1,3 +1,6 @@
+# monkestation addition: icon_exists cache
+icon_exists_cache.json
+
 ###Files and folders specified here will never be tracked.
 
 # Local overrides--you can use this to change the config for your dev environment (like setting up SQL) without worrying about committing it

code/__HELPERS/icons.dm

@@ -1470,10 +1470,25 @@ GLOBAL_LIST_EMPTY(transformation_animation_objects)
 /// If you want a stack trace to be output when the given state/file doesn't exist, use
 /// `/proc/icon_exists_or_scream()`.
 /proc/icon_exists(file, state)
-	var/static/list/icon_states_cache = list()
+	// monkestation start: icon_exists cache
+	var/static/list/icon_states_cache
+	if(isnull(icon_states_cache))
+#ifdef PRELOAD_ICON_EXISTS_CACHE
+		icon_states_cache = load_icon_exists_cache() || list()
+#else
+		icon_states_cache = list()
+#endif
+	// monkestation end
 	if(isnull(file) || isnull(state))
 		return FALSE //This is common enough that it shouldn't panic, imo.
 
+	// monkestation start: icon_exists cache
+#ifdef PRELOAD_ICON_EXISTS_CACHE
+	if(isfile(file) && !isnull(icon_states_cache["[file]"]?[state]))
+		return TRUE
+#endif
+	// monkestation end
+
 	if(isnull(icon_states_cache[file]))
 		icon_states_cache[file] = list()
 		for(var/istate in icon_states(file))

code/__HELPERS/~monkestation-helpers/icons.dm

@@ -63,3 +63,33 @@
 	var/job_type = job.type
 	if(icon_cache[job_type] && (include_unknown || !unknown_huds[job_type]))
 		return icon(icon_cache[job_type])
+
+#ifdef PRELOAD_ICON_EXISTS_CACHE
+/proc/load_icon_exists_cache()
+	. = null
+	if(!fexists("icon_exists_cache.json"))
+		log_world("icon_exists_cache.json doesn't exist, not loading cache")
+		return
+	var/cache_file = rustg_file_read("icon_exists_cache.json")
+	if(!rustg_json_is_valid(cache_file))
+		log_world("did not load icon_exists cache: file exists but wasn't valid json")
+		CRASH("did not load icon_exists cache: file exists but wasn't valid json")
+	var/list/cache_data = json_decode(cache_file)
+	if(!islist(cache_data))
+		log_world("did not load icon_exists cache: file exists but wasn't valid json")
+		CRASH("did not load icon_exists cache: file exists and is valid json, but did not decode into an object")
+	var/list/icons = cache_data["icons"]
+	if(!islist(icons))
+		log_world("did not load icon_exists cache: 'icons' key was not a list")
+		CRASH("did not load icon_exists cache: 'icons' key was not a list")
+	var/cache_revision = cache_data["revision"]
+	if(!isnull(cache_revision))
+		var/revision = rustg_git_revparse("HEAD")
+		if(cache_revision != revision)
+			log_world("did not load icon_exists cache: revision ([cache_revision]) mismatched current server revision ([revision])")
+			return
+		log_world("loaded icon_exists cache for [revision]")
+	else
+		log_world("loaded icon_exists cache without verifying revision")
+	return icons
+#endif

code/_compile_options.dm

@@ -84,9 +84,12 @@
 /// If this is uncommented, will profile mapload atom initializations
 // #define PROFILE_MAPLOAD_INIT_ATOM
 
-/// If uncommented, Dreamluau will be fully disabled.
+/// If this is uncommented, Dreamluau will be fully disabled.
 // #define DISABLE_DREAMLUAU
 
+/// If this is uncommented, /proc/icon_exists will attempt to load an initial cache from icon_exists_cache.json
+// #define PRELOAD_ICON_EXISTS_CACHE
+
 // OpenDream currently doesn't support byondapi, so automatically disable it on OD,
 // unless CIBUILDING is defined - we still want to lint dreamluau-related code.
 // Get rid of this whenever it does have support.