Fix possible crashes on Threading

Author: Raltyro

source/funkin/backend/scripting/MultiThreadedScript.hx

@@ -1,14 +1,9 @@
 package funkin.backend.scripting;
 
-#if ALLOW_MULTITHREADING
-import sys.thread.Thread;
-#end
-
 import hscript.IHScriptCustomBehaviour;
+import funkin.backend.utils.EngineUtil;
 
 class MultiThreadedScript implements IFlxDestroyable implements IHScriptCustomBehaviour {
-	var thread:#if ALLOW_MULTITHREADING Thread #else Dynamic #end;
-
 	/**
 	 * Script being ran.
 	 */
@@ -46,13 +41,6 @@ class MultiThreadedScript implements IFlxDestroyable implements IHScriptCustomBe
 
 		script.load();
 
-		#if ALLOW_MULTITHREADING
-		thread = Thread.createWithEventLoop(function() {
-			// Prevent the thread from being auto deleted
-			Thread.current().events.promise();
-		});
-		#end
-
 		__variables = Type.getInstanceFields(Type.getClass(this));
 	}
 
@@ -69,7 +57,7 @@ class MultiThreadedScript implements IFlxDestroyable implements IHScriptCustomBe
 
 	public function call(func:String, args:Array<Dynamic>) {
 		#if ALLOW_MULTITHREADING
-		thread.events.run(function() {
+		EngineUtil.execAsync(() -> {
 			callEnded = false;
 			returnValue = script.call(func, args);
 			callEnded = true;
@@ -85,13 +73,5 @@ class MultiThreadedScript implements IFlxDestroyable implements IHScriptCustomBe
 			script.call("destroy");
 			script.destroy();
 		}
-
-		#if ALLOW_MULTITHREADING
-		if (thread != null) {
-			thread.events.runPromised(function() {
-				// close the thing
-			});
-		}
-		#end
 	}
 }

source/funkin/backend/system/Main.hx

@@ -13,6 +13,7 @@ import funkin.backend.assets.ModsFolder;
 import funkin.backend.system.framerate.Framerate;
 import funkin.backend.system.framerate.SystemInfo;
 import funkin.backend.system.modules.*;
+import funkin.backend.utils.EngineUtil;
 import funkin.editors.SaveWarning;
 import funkin.options.PlayerSettings;
 import openfl.Assets;
@@ -22,10 +23,6 @@ import openfl.text.TextFormat;
 import openfl.utils.AssetLibrary;
 import sys.FileSystem;
 import sys.io.File;
-
-#if ALLOW_MULTITHREADING
-import sys.thread.Thread;
-#end
 #if android
 import android.content.Context;
 import android.os.Build;
@@ -61,7 +58,10 @@ class Main extends Sprite
 	// You can pretty much ignore everything from here on - your code should go in your states.
 
 	#if ALLOW_MULTITHREADING
-	public static var gameThreads:Array<Thread> = [];
+	// DEPRECATED
+	@:dox(hide) public static var gameThreads(get, set):Array<sys.thread.Thread>;
+	static function get_gameThreads() return EngineUtil.gameThreads;
+	static function set_gameThreads(v) return EngineUtil.gameThreads = v;
 	#end
 
 	public static function preInit() {
@@ -99,16 +99,8 @@ class Main extends Sprite
 		#end;
 	public static var startedFromSource:Bool = #if TEST_BUILD true #else false #end;
 
-
-	private static var __threadCycle:Int = 0;
-	public static function execAsync(func:Void->Void) {
-		#if ALLOW_MULTITHREADING
-		var thread = gameThreads[(__threadCycle++) % gameThreads.length];
-		thread.events.run(func);
-		#else
-		func();
-		#end
-	}
+	// DEPRECATED
+	@:dox(hide) public static function execAsync(func:Void->Void) EngineUtil.execAsync(func);
 
 	private static function getTimer():Int {
 		return time = Lib.getTimer();
@@ -120,10 +112,6 @@ class Main extends Sprite
 		MemoryUtil.init();
 		@:privateAccess
 		FlxG.game.getTimer = getTimer;
-		#if ALLOW_MULTITHREADING
-		for(i in 0...4)
-			gameThreads.push(Thread.createWithEventLoop(function() {Thread.current().events.promise();}));
-		#end
 		FunkinCache.init();
 		Paths.assetsTree = new AssetsLibraryList();
 

source/funkin/backend/utils/EngineUtil.hx

@@ -1,9 +1,16 @@
 package funkin.backend.utils;
 
+#if ALLOW_MULTITHREADING
+import sys.thread.Thread;
+#end
+
+#if !macro
 import funkin.backend.scripting.MultiThreadedScript;
 import funkin.backend.scripting.Script;
+#end
 
 final class EngineUtil {
+	#if !macro
 	/**
 	 * Starts a new multithreaded script.
 	 * This script will share all the variables with the current one, which means already existing callbacks will be replaced by new ones on conflict.
@@ -12,4 +19,32 @@ final class EngineUtil {
 	public static function startMultithreadedScript(path:String) {
 		return new MultiThreadedScript(path, Script.curScript);
 	}
+	#end
+
+	#if ALLOW_MULTITHREADING
+	public static var gameThreads:Array<Thread> = [];
+
+	private static var maxThreads:Int = 4;
+	private static var threadCycle:Int = 0;
+	private static var threadsInitialized:Bool = false;
+	#else
+	public static var gameThreads:Array<Dynamic> = [];
+	#end
+
+	/**
+	 * Execute a function asynchronously using existing threads when initialized with ALLOW_MULTITHREADING.
+	 * @param func Void -> Void
+	 */
+	public static function execAsync(func:Void->Void) {
+		#if ALLOW_MULTITHREADING
+		if (!threadsInitialized) {
+			threadsInitialized = true;
+			for (i in 0...maxThreads) gameThreads.push(Thread.createWithEventLoop(() -> Thread.current().events.promise()));
+		}
+		gameThreads[threadCycle].events.run(func);
+		if (++threadCycle >= maxThreads) threadCycle = 0;
+		#else
+		func();
+		#end
+	}
 }

source/lime/_internal/backend/native/NativeAudioSource.hx

@@ -122,14 +122,18 @@ class NativeAudioSource {
 	var arrayType:TypedArrayType;
 	var loopPoints:Array<Int>; // In Samples
 
-	static var threadRunning:Bool = false;
 	static var streamSources:Array<NativeAudioSource> = [];
 	static var queuedStreamSources:Array<NativeAudioSource> = [];
 
 	static var streamMutex:Mutex = new Mutex();
-	static var streamThread:Thread;
 	static var streamTimer:Timer;
 
+	#if !ALLOW_MULTITHREADING
+	static var wasEmpty:Bool = false;
+	static var threadRunning:Bool = false;
+	static var streamThread:Thread;
+	#end
+
 	var streamRemove:Bool;
 
 	var bufferLength:Int; // Size in bytes for current streamed audio buffers.
@@ -469,27 +473,31 @@ class NativeAudioSource {
 		streamMutex.release();
 	}
 
-	static function streamThreadRun() {
-		var i:Int, source:NativeAudioSource, process:Int, v:Int;
-
-		while ((i = Thread.readMessage(true)) != 0) {
-			streamMutex.acquire();
-			while (i-- > 0) {
-				if ((source = streamSources[i]).streamRemove) continue;
-				else if (source.parent.buffer == null) {
-					source.stopStream();
-					continue;
-				}
+	static function streamBuffersUpdate() {
+		streamMutex.acquire();
 
-				process = source.requestBuffers < STREAM_MIN_BUFFERS ? STREAM_MIN_BUFFERS - source.requestBuffers : 0;
-				process = STREAM_PROCESS_BUFFERS > process ? STREAM_PROCESS_BUFFERS : process;
-				if ((process = (v = STREAM_MAX_BUFFERS - source.requestBuffers) > process ? process : v) > 0) source.fillBuffers(process);
+		var i:Int = streamSources.length, source:NativeAudioSource, process:Int, v:Int;
+		while (i-- > 0) {
+			if ((source = streamSources[i]).streamRemove) continue;
+			else if (source.parent.buffer == null) {
+				source.stopStream();
+				continue;
 			}
-			streamMutex.release();
+
+			process = source.requestBuffers < STREAM_MIN_BUFFERS ? STREAM_MIN_BUFFERS - source.requestBuffers : 0;
+			process = STREAM_PROCESS_BUFFERS > process ? STREAM_PROCESS_BUFFERS : process;
+			if ((process = (v = STREAM_MAX_BUFFERS - source.requestBuffers) > process ? process : v) > 0) source.fillBuffers(process);
 		}
 
+		streamMutex.release();
+	}
+
+	#if !ALLOW_MULTITHREADING
+	static function streamThreadRun() {
+		while (Thread.readMessage(true)) streamBuffersUpdate();
 		threadRunning = false;
 	}
+	#end
 
 	static function streamUpdate() {
 		if (!streamMutex.tryAcquire()) return;
@@ -512,13 +520,28 @@ class NativeAudioSource {
 			}
 		}
 
-		streamMutex.release();
+		#if ALLOW_MULTITHREADING
+		if (streamSources.length != 0) funkin.backend.utils.EngineUtil.execAsync(streamBuffersUpdate);
+		#else
 		if (streamSources.length == 0) {
-			streamTimer.stop();
-			if (threadRunning) streamThread.sendMessage(0);
+			if (wasEmpty) {
+				wasEmpty = false;
+				streamTimer.stop();
+				if (threadRunning) streamThread.sendMessage(1);
+			}
+			else {
+				wasEmpty = true;
+				streamTimer = resetTimer(streamTimer, 1000, streamUpdate);
+			}
 		}
-		else if (threadRunning || (threadRunning = (streamThread = Thread.create(streamThreadRun)) != null))
-			streamThread.sendMessage(streamSources.length);
+		else {
+			wasEmpty = false;
+			if (threadRunning || (threadRunning = (streamThread = Thread.create(streamThreadRun)) != null)) 
+				streamThread.sendMessage(1);
+		}
+		#end
+
+		streamMutex.release();
 	}
 
 	function removeStream() {