Merge pull request #147 from nuskey8/improve-cancel

Improved cancellation process and avoidance of infinite loops

src/Lua/Exceptions.cs

@@ -2,6 +2,7 @@ using Lua.CodeAnalysis;
 using Lua.CodeAnalysis.Syntax;
 using Lua.Internal;
 using Lua.Runtime;
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 
 namespace Lua;
@@ -67,9 +68,14 @@ public class LuaCompileException(string chunkName, SourcePosition position, int
 
 public class LuaUnDumpException(string message) : Exception(message);
 
-public class LuaRuntimeException : Exception
+internal interface ILuaTracebackBuildable
 {
-    public LuaRuntimeException(LuaThread? thread, Exception innerException) : base(innerException.Message,innerException)
+    Traceback? BuildOrGet();
+}
+
+public class LuaRuntimeException : Exception, ILuaTracebackBuildable
+{
+    public LuaRuntimeException(LuaThread? thread, Exception innerException) : base(innerException.Message, innerException)
     {
         Thread = thread;
     }
@@ -78,7 +84,7 @@ public class LuaRuntimeException : Exception
     {
         if (thread != null)
         {
-            thread.CurrentException?.Build();
+            thread.CurrentException?.BuildOrGet();
             thread.ExceptionTrace.Clear();
             thread.CurrentException = this;
         }
@@ -96,7 +102,7 @@ public class LuaRuntimeException : Exception
         {
             if (luaTraceback == null)
             {
-                Build();
+                ((ILuaTracebackBuildable)this).BuildOrGet();
             }
 
             return luaTraceback;
@@ -185,7 +191,7 @@ public class LuaRuntimeException : Exception
 
 
     [MethodImpl(MethodImplOptions.NoInlining)]
-    internal Traceback? Build()
+    Traceback? ILuaTracebackBuildable.BuildOrGet()
     {
         if (luaTraceback != null) return luaTraceback;
         if (Thread != null)
@@ -247,4 +253,50 @@ public class LuaRuntimeException : Exception
 
 public class LuaAssertionException(LuaThread? traceback, string message) : LuaRuntimeException(traceback, message);
 
-public class LuaModuleNotFoundException(string moduleName) : Exception($"module '{moduleName}' not found");
+public class LuaModuleNotFoundException(string moduleName) : Exception($"module '{moduleName}' not found");
+
+public sealed class LuaCancelledException : OperationCanceledException, ILuaTracebackBuildable
+{
+    Traceback? luaTraceback;
+
+    public Traceback? LuaTraceback
+    {
+        get
+        {
+            if (luaTraceback == null)
+            {
+                ((ILuaTracebackBuildable)this).BuildOrGet();
+            }
+
+            return luaTraceback;
+        }
+    }
+
+    internal LuaThread? Thread { get; private set; }
+
+    internal LuaCancelledException(LuaThread thread, CancellationToken cancellationToken, Exception? innerException = null) : base("The operation was cancelled during execution on Lua.", innerException, cancellationToken)
+    {
+        thread.CurrentException?.BuildOrGet();
+        thread.ExceptionTrace.Clear();
+        thread.CurrentException = this;
+        Thread = thread;
+    }
+
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    Traceback? ILuaTracebackBuildable.BuildOrGet()
+    {
+        if (luaTraceback != null) return luaTraceback;
+
+        if (Thread != null)
+        {
+            var callStack = Thread.ExceptionTrace.AsSpan();
+            if (callStack.IsEmpty) return null;
+            luaTraceback = new Traceback(Thread.State, callStack);
+            Thread.ExceptionTrace.Clear();
+            Thread = null!;
+        }
+
+        return luaTraceback;
+    }
+}

src/Lua/LuaCoroutine.cs

@@ -186,9 +186,9 @@ public sealed class LuaCoroutine : LuaThread, IValueTaskSource<LuaCoroutine.Yiel
             {
                 if (IsProtectedMode)
                 {
-                    if (ex is LuaRuntimeException luaRuntimeException)
+                    if (ex is ILuaTracebackBuildable tracebackBuildable)
                     {
-                        traceback = luaRuntimeException.Build();
+                        traceback = tracebackBuildable.BuildOrGet();
                     }
 
                     Volatile.Write(ref status, (byte)LuaThreadStatus.Dead);

src/Lua/LuaThread.cs

@@ -70,8 +70,11 @@ public abstract class LuaThread
     internal int LastVersion;
     internal int CurrentVersion;
 
-    internal LuaRuntimeException? CurrentException;
+    internal ILuaTracebackBuildable? CurrentException;
     internal readonly ReversedStack<CallStackFrame> ExceptionTrace = new();
+    
+    // internal bool CancelRequested;
+    // internal CancellationToken CancellationToken;
 
     public bool IsRunning => CallStackFrameCount != 0;
     internal LuaFunction? Hook { get; set; }
@@ -131,7 +134,7 @@ public abstract class LuaThread
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     internal LuaThreadAccess PushCallStackFrame(in CallStackFrame frame)
     {
-        CurrentException?.Build();
+        CurrentException?.BuildOrGet();
         CurrentException = null;
         ref var callStack = ref CoreData!.CallStack;
         callStack.Push(frame);

src/Lua/LuaThreadExtensions.cs

@@ -13,4 +13,19 @@ public static class LuaThreadExtensions
     {
         return new(LuaCoroutine.Create(thread, function, isProtectedMode));
     }
+
+    internal static void ThrowIfCancellationRequested(this LuaThread thread, CancellationToken cancellationToken)
+    {
+        if (cancellationToken.IsCancellationRequested)
+        {
+            Throw(thread, cancellationToken);
+        }
+
+        return;
+
+        static void Throw(LuaThread thread, CancellationToken cancellationToken)
+        {
+            throw new LuaCancelledException(thread, cancellationToken);
+        }
+    }
 }

src/Lua/Runtime/LuaStack.cs

@@ -32,7 +32,7 @@ public sealed class LuaStack(int initialSize = 256)
 
             if (1000000 < size)
             {
-                throw new LuaException("Lua Stack overflow");
+                throw new ("Lua Stack overflow");
             }
 
             Array.Resize(ref array, size);

src/Lua/Runtime/LuaThreadAccess.cs

@@ -53,6 +53,7 @@ public readonly struct LuaThreadAccess
             throw new ArgumentNullException(nameof(function));
         }
 
+        Thread.ThrowIfCancellationRequested(cancellationToken);
         var thread = Thread;
         var varArgumentCount = function.GetVariableArgumentCount(argumentCount);
         if (varArgumentCount != 0)
@@ -78,7 +79,7 @@ public readonly struct LuaThreadAccess
 
         var access = thread.PushCallStackFrame(frame);
         LuaFunctionExecutionContext context = new() { Access = access, ArgumentCount = argumentCount, ReturnFrameBase = returnBase, };
-
+        var callStackTop = thread.CallStackFrameCount;
         try
         {
             if (this.Thread.CallOrReturnHookMask.Value != 0 && !this.Thread.IsInHook)
@@ -90,7 +91,7 @@ public readonly struct LuaThreadAccess
         }
         finally
         {
-            this.Thread.PopCallStackFrame();
+            this.Thread.PopCallStackFrameUntil(callStackTop-1);
         }
     }
 

src/Lua/Runtime/LuaVirtualMachine.Debug.cs

@@ -47,7 +47,7 @@ public static partial class LuaVirtualMachine
                 countHookIsDone = true;
             }
 
-
+            context.ThrowIfCancellationRequested();
             if (context.Thread.IsLineHookEnabled)
             {
                 var sourcePositions = prototype.LineInfo;
@@ -126,6 +126,7 @@ public static partial class LuaVirtualMachine
                 context.Thread.PopCallStackFrameWithStackPop();
             }
         }
+        context.Thread.ThrowIfCancellationRequested(cancellationToken);
 
         {
             var frame = context.Thread.GetCurrentFrame();
@@ -135,7 +136,7 @@ public static partial class LuaVirtualMachine
             {
                 return r;
             }
-
+            context.Thread.ThrowIfCancellationRequested(cancellationToken);
             var top = stack.Count;
             stack.Push("return");
             stack.Push(LuaValue.Nil);

src/Lua/Runtime/LuaVirtualMachine.cs

@@ -1,6 +1,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using Lua.Internal;
+// ReSharper disable MethodHasAsyncOverload
 
 // ReSharper disable InconsistentNaming
 
@@ -255,6 +256,8 @@ public static partial class LuaVirtualMachine
                     {
                         break;
                     }
+
+                    ThrowIfCancellationRequested();
                 }
 
                 return Thread.Stack.Count - returnFrameBase;
@@ -264,6 +267,17 @@ public static partial class LuaVirtualMachine
                 pool.TryPush(this);
             }
         }
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void ThrowIfCancellationRequested()
+        {
+            if (!CancellationToken.IsCancellationRequested) return;
+            Throw();
+                
+            void Throw()
+            { 
+                GetThreadWithCurrentPc(this).ThrowIfCancellationRequested(CancellationToken);
+            }
+        }
     }
 
     enum PostOperationType
@@ -567,6 +581,7 @@ public static partial class LuaVirtualMachine
                             context.Thread.State.CloseUpValues(context.Thread, frameBase + iA - 1);
                         }
 
+                        context.ThrowIfCancellationRequested();
                         continue;
                     case OpCode.Eq:
                         Markers.Eq();
@@ -695,6 +710,7 @@ public static partial class LuaVirtualMachine
                             indexRef = index;
                             Unsafe.Add(ref indexRef, 3) = index;
                             stack.NotifyTop(iA + frameBase + 4);
+                            context.ThrowIfCancellationRequested();
                             continue;
                         }
 
@@ -799,7 +815,7 @@ public static partial class LuaVirtualMachine
         catch (Exception e)
         {
             context.State.CloseUpValues(context.Thread, context.FrameBase);
-            if (e is not LuaRuntimeException)
+            if (e is not (LuaRuntimeException or LuaCancelledException))
             {
                 var newException = new LuaRuntimeException(context.Thread, e);
                 context.PopOnTopCallStackFrames();
@@ -1003,6 +1019,7 @@ public static partial class LuaVirtualMachine
     static async ValueTask ExecuteBinaryOperationMetaMethod(int target, LuaValue vb, LuaValue vc,
         VirtualMachineExecutionContext context, OpCode opCode)
     {
+        context.ThrowIfCancellationRequested();
         var (name, description) = opCode.GetNameAndDescription();
         if (vb.TryGetMetamethod(context.State, name, out var metamethod) ||
             vc.TryGetMetamethod(context.State, name, out metamethod))
@@ -1039,12 +1056,14 @@ public static partial class LuaVirtualMachine
                     await ExecuteCallHook(functionContext, context.CancellationToken);
                     stack.PopUntil(target + 1);
                     context.PostOperation = PostOperationType.DontPop;
+                    context.ThrowIfCancellationRequested();
                     return;
                 }
 
                 await func.Func(functionContext, context.CancellationToken);
                 stack.PopUntil(target + 1);
                 context.PostOperation = PostOperationType.DontPop;
+                context.ThrowIfCancellationRequested();
                 return;
             }
             finally
@@ -1060,6 +1079,7 @@ public static partial class LuaVirtualMachine
 
     static bool Call(VirtualMachineExecutionContext context, out bool doRestart)
     {
+        context.ThrowIfCancellationRequested();
         var instruction = context.Instruction;
         var RA = instruction.A + context.FrameBase;
         var newBase = RA + 1;
@@ -1119,6 +1139,7 @@ public static partial class LuaVirtualMachine
             var awaiter = task.GetAwaiter();
 
             awaiter.GetResult();
+            context.Thread.ThrowIfCancellationRequested(context.CancellationToken);
             var instruction = context.Instruction;
             var ic = instruction.C;
 
@@ -1137,8 +1158,9 @@ public static partial class LuaVirtualMachine
         }
     }
 
-    internal static async ValueTask<int> Call(LuaThread thread, int funcIndex, int returnBase, CancellationToken ct)
+    internal static async ValueTask<int> Call(LuaThread thread, int funcIndex, int returnBase, CancellationToken cancellationToken)
     {
+        thread.ThrowIfCancellationRequested(cancellationToken);
         var stack = thread.Stack;
         var newBase = funcIndex + 1;
         var va = stack.Get(funcIndex);
@@ -1165,12 +1187,24 @@ public static partial class LuaVirtualMachine
             var functionContext = new LuaFunctionExecutionContext() { Access = access, ArgumentCount = argCount, ReturnFrameBase = returnBase };
             if (thread.CallOrReturnHookMask.Value != 0 && !thread.IsInHook)
             {
-                await ExecuteCallHook(functionContext, ct);
+                await ExecuteCallHook(functionContext, cancellationToken);
+            }
+            else
+            {
+                await func.Func(functionContext, cancellationToken);
             }
 
-            await func.Func(functionContext, ct);
+            thread.ThrowIfCancellationRequested(cancellationToken);
             return thread.Stack.Count - funcIndex;
         }
+        catch(OperationCanceledException  operationCanceledException)
+        {
+            if(operationCanceledException is not LuaCancelledException)
+            {
+                throw new LuaCancelledException(thread, cancellationToken, operationCanceledException);
+            }
+            throw;
+        }
         finally
         {
             thread.PopCallStackFrame();
@@ -1195,6 +1229,7 @@ public static partial class LuaVirtualMachine
 
     static bool TailCall(VirtualMachineExecutionContext context, out bool doRestart)
     {
+        context.ThrowIfCancellationRequested();
         var instruction = context.Instruction;
         var stack = context.Stack;
         var RA = instruction.A + context.FrameBase;
@@ -1259,6 +1294,7 @@ public static partial class LuaVirtualMachine
 
 
         task.GetAwaiter().GetResult();
+        context.ThrowIfCancellationRequested();
         if (!context.PopFromBuffer(context.CurrentReturnFrameBase, context.Stack.Count - context.CurrentReturnFrameBase))
         {
             return true;
@@ -1270,6 +1306,7 @@ public static partial class LuaVirtualMachine
 
     static bool TForCall(VirtualMachineExecutionContext context, out bool doRestart)
     {
+        context.ThrowIfCancellationRequested();
         doRestart = false;
         var instruction = context.Instruction;
         var stack = context.Stack;
@@ -1341,8 +1378,8 @@ public static partial class LuaVirtualMachine
             return false;
         }
 
-        var awaiter = task.GetAwaiter();
-        awaiter.GetResult();
+        task.GetAwaiter().GetResult();
+        context.ThrowIfCancellationRequested();
         context.Thread.PopCallStackFrame();
         TForCallPostOperation(context);
         return true;
@@ -1942,8 +1979,10 @@ public static partial class LuaVirtualMachine
     }
 
     [MethodImpl(MethodImplOptions.NoInlining)]
-    internal static async ValueTask<LuaValue> ExecuteUnaryOperationMetaMethod(LuaThread thread, LuaValue vb, OpCode opCode, CancellationToken ct)
+    internal static async ValueTask<LuaValue> ExecuteUnaryOperationMetaMethod(LuaThread thread, LuaValue vb, OpCode opCode, CancellationToken cancellationToken)
     {
+        thread.ThrowIfCancellationRequested(cancellationToken);
+
         var (name, description) = opCode.GetNameAndDescription();
 
         if (vb.TryGetMetamethod(thread.State, name, out var metamethod))
@@ -1976,11 +2015,14 @@ public static partial class LuaVirtualMachine
                 var functionContext = new LuaFunctionExecutionContext() { Access = access, ArgumentCount = argCount, ReturnFrameBase = newBase };
                 if (thread.CallOrReturnHookMask.Value != 0 && !thread.IsInHook)
                 {
-                    await ExecuteCallHook(functionContext, ct);
+                    await ExecuteCallHook(functionContext, cancellationToken);
+                }
+                else
+                {
+                    await func.Func(functionContext, cancellationToken);
                 }
 
-
-                await func.Func(functionContext, ct);
+                thread.ThrowIfCancellationRequested(cancellationToken);
                 var results = stack.GetBuffer()[newFrame.ReturnBase..];
                 var result = results.Length == 0 ? default : results[0];
                 results.Clear();
@@ -2097,8 +2139,10 @@ public static partial class LuaVirtualMachine
     }
 
     [MethodImpl(MethodImplOptions.NoInlining)]
-    internal static async ValueTask<bool> ExecuteCompareOperationMetaMethod(LuaThread thread, LuaValue vb, LuaValue vc, OpCode opCode, CancellationToken ct)
+    internal static async ValueTask<bool> ExecuteCompareOperationMetaMethod(LuaThread thread, LuaValue vb, LuaValue vc, OpCode opCode, CancellationToken cancellationToken)
     {
+        thread.ThrowIfCancellationRequested(cancellationToken);
+
         var (name, description) = opCode.GetNameAndDescription();
         bool reverseLe = false;
     ReCheck:
@@ -2133,11 +2177,14 @@ public static partial class LuaVirtualMachine
                 var functionContext = new LuaFunctionExecutionContext() { Access = access, ArgumentCount = argCount, ReturnFrameBase = newBase };
                 if (thread.CallOrReturnHookMask.Value != 0 && !thread.IsInHook)
                 {
-                    await ExecuteCallHook(functionContext, ct);
+                    await ExecuteCallHook(functionContext, cancellationToken);
+                }
+                else
+                {
+                    await func.Func(functionContext, cancellationToken);
                 }
 
-
-                await func.Func(functionContext, ct);
+                thread.ThrowIfCancellationRequested(cancellationToken);
                 var results = stack.GetBuffer()[newFrame.ReturnBase..];
                 var result = results.Length == 0 ? default : results[0];
                 results.Clear();

src/Lua/Standard/BasicLibrary.cs

@@ -1,6 +1,7 @@
 using System.Globalization;
 using Lua.Internal;
 using Lua.Runtime;
+
 // ReSharper disable MethodHasAsyncOverloadWithCancellation
 
 namespace Lua.Standard;
@@ -259,14 +260,17 @@ public sealed class BasicLibrary
         catch (Exception ex)
         {
             context.Thread.PopCallStackFrameUntil(frameCount);
-            if (ex is LuaRuntimeException luaEx)
-            {
-                luaEx.Forget();
-                return context.Return(false, luaEx.ErrorObject);
-            }
-            else
+            switch (ex)
             {
-                return context.Return(false, ex.Message);
+                case LuaCancelledException:
+                    throw;
+                case OperationCanceledException:
+                    throw new LuaCancelledException(context.Thread,cancellationToken, ex);
+                case LuaRuntimeException luaEx:
+                    luaEx.Forget();
+                    return context.Return(false, luaEx.ErrorObject);
+                default:
+                    return context.Return(false, ex.Message);
             }
         }
     }
@@ -565,6 +569,7 @@ public sealed class BasicLibrary
         {
             var thread = context.Thread;
             thread.PopCallStackFrameUntil(frameCount);
+            cancellationToken.ThrowIfCancellationRequested();
 
             var access = thread.CurrentAccess;
             if (ex is LuaRuntimeException luaEx)

tests/Lua.Tests/CancellationTest.cs

@@ -0,0 +1,180 @@
+using Lua.Standard;
+
+namespace Lua.Tests;
+
+public class CancellationTest
+{
+    LuaState state = default!;
+
+    [SetUp]
+    public void SetUp()
+    {
+        state = LuaState.Create();
+        state.OpenStandardLibraries();
+
+        state.Environment["assert"] = new LuaFunction("assert_with_wait",
+            async (context, ct) =>
+            {
+                await Task.Delay(1, ct);
+                var arg0 = context.GetArgument(0);
+
+                if (!arg0.ToBoolean())
+                {
+                    var message = "assertion failed!";
+                    if (context.HasArgument(1))
+                    {
+                        message = context.GetArgument<string>(1);
+                    }
+
+                    throw new LuaAssertionException(context.Thread, message);
+                }
+
+                return (context.Return(context.Arguments));
+            });
+        state.Environment["sleep"] = new LuaFunction("sleep",
+            (context, _) =>
+            {
+                Thread.Sleep(context.GetArgument<int>(0));
+
+                return new(context.Return());
+            });
+        state.Environment["wait"] = new LuaFunction("wait",
+            async (context, ct) =>
+            {
+                await Task.Delay(context.GetArgument<int>(0), ct);
+                return context.Return();
+            });
+    }
+
+    [Test]
+    public async Task PCall_WaitTest()
+    {
+        var source = """
+                     local function f(millisec)
+                         wait(millisec)
+                     end                     
+                     pcall(f, 500)
+                     """;
+        var cancellationTokenSource = new CancellationTokenSource();
+        cancellationTokenSource.CancelAfter(200);
+
+        try
+        {
+            await state.DoStringAsync(source, "@test.lua", cancellationTokenSource.Token);
+            Assert.Fail("Expected TaskCanceledException was not thrown.");
+        }
+        catch (Exception e)
+        {
+            Assert.That(e, Is.TypeOf<LuaCancelledException>());
+            var luaCancelledException = (LuaCancelledException)e;
+            Assert.That(luaCancelledException.InnerException, Is.TypeOf<TaskCanceledException>());
+            var luaStackTrace = luaCancelledException.LuaTraceback!.ToString();
+            Console.WriteLine(luaStackTrace);
+            Assert.That(luaStackTrace, Contains.Substring("'wait'"));
+            Assert.That(luaStackTrace, Contains.Substring("'pcall'"));
+        }
+    }
+
+    [Test]
+    public async Task PCall_SleepTest()
+    {
+        var source = """
+                     local function f(millisec)
+                         sleep(millisec)
+                     end                     
+                     pcall(f, 500)
+                     """;
+        var cancellationTokenSource = new CancellationTokenSource();
+        cancellationTokenSource.CancelAfter(250);
+
+        try
+        {
+            await state.DoStringAsync(source, "@test.lua", cancellationTokenSource.Token);
+            Assert.Fail("Expected TaskCanceledException was not thrown.");
+        }
+        catch (Exception e)
+        {
+            Assert.That(e, Is.TypeOf<LuaCancelledException>());
+            var luaCancelledException = (LuaCancelledException)e;
+            Assert.That(luaCancelledException.InnerException, Is.Null);
+            var luaStackTrace = luaCancelledException.LuaTraceback!.ToString();
+            Console.WriteLine(luaStackTrace);
+            Assert.That(luaStackTrace, Contains.Substring("'sleep'"));
+            Assert.That(luaStackTrace, Contains.Substring("'pcall'"));
+        }
+    }
+
+    [Test]
+    public async Task ForLoopTest()
+    {
+        var source = """
+                     local ret = 0
+                     for i = 1, 1000000000 do
+                         ret = ret + i
+                     end
+                     return ret
+                     """;
+        var cancellationTokenSource = new CancellationTokenSource();
+        cancellationTokenSource.CancelAfter(100);
+        cancellationTokenSource.Token.Register(() =>
+        {
+            Console.WriteLine("Cancellation requested");
+        });
+        try
+        {
+            var r = await state.DoStringAsync(source, "@test.lua", cancellationTokenSource.Token);
+            Console.WriteLine(r[0]);
+            Assert.Fail("Expected TaskCanceledException was not thrown.");
+        }
+        catch (Exception e)
+        {
+            Assert.That(e, Is.TypeOf<LuaCancelledException>());
+            Console.WriteLine(e.StackTrace);
+            var luaCancelledException = (LuaCancelledException)e;
+            Assert.That(luaCancelledException.InnerException, Is.Null);
+            var traceback = luaCancelledException.LuaTraceback;
+            if (traceback != null)
+            {
+                var luaStackTrace = traceback.ToString();
+                Console.WriteLine(luaStackTrace);
+            }
+        }
+    }
+    
+    [Test]
+    public async Task GoToLoopTest()
+    {
+        var source = """
+                     local ret = 0
+                     ::loop::
+                     ret = ret + 1
+                     goto loop
+                     return ret
+                     """;
+        var cancellationTokenSource = new CancellationTokenSource();
+        cancellationTokenSource.CancelAfter(100);
+        cancellationTokenSource.Token.Register(() =>
+        {
+            Console.WriteLine("Cancellation requested");
+        });
+        try
+        {
+            var r = await state.DoStringAsync(source, "@test.lua", cancellationTokenSource.Token);
+            Console.WriteLine(r[0]);
+            Assert.Fail("Expected TaskCanceledException was not thrown.");
+        }
+        catch (Exception e)
+        {
+            Assert.That(e, Is.TypeOf<LuaCancelledException>());
+            Console.WriteLine(e.StackTrace);
+            var luaCancelledException = (LuaCancelledException)e;
+            Assert.That(luaCancelledException.InnerException, Is.Null);
+            var traceback = luaCancelledException.LuaTraceback;
+            if (traceback != null)
+            {
+                var luaStackTrace = traceback.ToString();
+                Console.WriteLine(luaStackTrace);
+            }
+        }
+    }
+}