Switch lua library to NLua and implement cancellation

ChaosBot/ChaosBot.csproj

@@ -16,9 +16,9 @@
       <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.1.6" />
       <PackageReference Include="Microsoft.Extensions.Configuration" Version="3.1.6" />
       <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="3.1.6" />
-      <PackageReference Include="NeoLua" Version="1.3.11" />
       <PackageReference Include="NLog" Version="4.7.2" />
       <PackageReference Include="NLog.Extensions.Logging" Version="1.6.4" />
+      <PackageReference Include="NLua" Version="1.5.1" />
       <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="3.1.2" />
       <PackageReference Include="Pomelo.EntityFrameworkCore.MySql.Design" Version="1.1.2" />
     </ItemGroup>

ChaosBot/Discord/Services/CustomCommandHandler.cs

@@ -6,7 +6,6 @@ using ChaosBot.Services;
 using ChaosBot.Services.ProgrammingLanguageInterpreter;
 using Discord;
 using Discord.Commands;
-using Neo.IronLua;
 
 namespace ChaosBot.Discord.Services
 {

ChaosBot/Services/ProgrammingLanguageInterpreter/IProgrammingLanguageInterpreter.cs

@@ -1,10 +1,10 @@
+using System.Threading;
 using Discord.Commands;
 
 namespace ChaosBot.Services.ProgrammingLanguageInterpreter
 {
     public interface IProgrammingLanguageInterpreter
     {
-        string Interpret(SocketCommandContext context, string content, string command);
+        string Interpret(CancellationToken ct, SocketCommandContext context, string content, string command);
-        void StopExecution();
     }
 }

ChaosBot/Services/ProgrammingLanguageInterpreter/LuaProgrammingLanguageInterpreter.cs

@@ -1,48 +1,54 @@
-using System;
 using System.Linq;
+using System.Reflection;
 using System.Text;
-using System.Text.RegularExpressions;
+using System.Threading;
 using Discord.Commands;
-using Neo.IronLua;
+using NLua;
-using NLog;
 
 namespace ChaosBot.Services.ProgrammingLanguageInterpreter
 {
     internal class LuaProgrammingLanguageInterpreter : IProgrammingLanguageInterpreter
     {
-        private static readonly ILogger Logger = Program.GetLogger();
         private readonly StringBuilder _outputBuilder = new StringBuilder();
-        private Lua _lua;
+        private CancellationToken _ct;
-        
+        private Lua _state;
-        public string Interpret(SocketCommandContext context, string content, string command)
+
+        public string Interpret(CancellationToken ct, SocketCommandContext context, string content, string command)
         {
-            using (_lua = new Lua())
+            LoggingFacade.Debug($"Interpreting code for {command} using Lua");
+            LoggingFacade.Trace($"Using CancellationToken: {ct}");
+            _ct = ct;
+            LoggingFacade.Trace("Starting Lua interpreter");
+            _state = new Lua();
+            LoggingFacade.Trace("Setting Lua debug hook");
+            _state.SetDebugHook(KeraLua.LuaHookMask.Line, 0);
+            _state.DebugHook += LuaDebugHook;
+
+            MethodInfo printMethod = GetType().GetMethod("Print", BindingFlags.NonPublic | BindingFlags.Instance); 
+            LoggingFacade.Info($"Overwriting print function with {printMethod}");
+            _state["print"] = printMethod;
+            
+            LoggingFacade.Trace("Disabling Lua `import` function");
+            _state.DoString ("\nimport = function () end\n");
+
+            LoggingFacade.Trace("Running user Lua code");
+            _state.DoString(content, command);
+
+            LoggingFacade.Trace("Returning Lua output");
+            return _outputBuilder.ToString();
+        }
+
+        private void LuaDebugHook(object sender, NLua.Event.DebugHookEventArgs e)
+        {
+            if (_ct.IsCancellationRequested)
             {
-                // This needs to be dynamic if we want to call
+                Lua l = (Lua) sender;
-                // functions from within the lua environment
+                l.State.Error("Timeout kill");
-                // This is a runtime type check
-                dynamic env = _lua.CreateEnvironment();
-
-                ParamsDelegate printDel = Print;
-                env.print = printDel;
-
-                env.context = context;
-
-                string code = content;
-
-                env.dochunk(code, $"{command}.lua");
-
-                return _outputBuilder.ToString();
             }
         }
 
-        public void StopExecution()
+        // This is being used in the `Interpret` function to register the print function
-        {
+        // ReSharper disable once UnusedMember.Local
-            _lua.Dispose();
-        }
-
-        private delegate void ParamsDelegate(params object[] parameters);
-
         private void Print(params object[] parameters)
         {
             string str = string.Join(" ", from param in parameters select param == null ? string.Empty : param.ToString());

ChaosBot/Services/ProgrammingLanguageInterpreter/ProgrammingLanguageInterpreterFacade.cs

@@ -21,21 +21,19 @@ namespace ChaosBot.Services.ProgrammingLanguageInterpreter
 
             try
             {
-                Thread taskThread = null;
+                CancellationTokenSource tokenSource = new CancellationTokenSource();
                 Task<string> task = Task.Run(() =>
                 {
-                    taskThread = Thread.CurrentThread;
                     Thread.CurrentThread.Priority = ThreadPriority.Lowest;
-                    return interpreter.Interpret(context, customCommand.Content, customCommand.Command);
+                    return interpreter.Interpret(tokenSource.Token, context, customCommand.Content, customCommand.Command);
-                });
+                }, tokenSource.Token);
 
-                const int timeout = 1000;
+                const int timeout = 250;
                 bool isTaskCompleted = task.Wait(TimeSpan.FromMilliseconds(timeout));
 
                 if (!isTaskCompleted)
                 {
-                    interpreter.StopExecution();
+                    tokenSource.Cancel();
-                    taskThread.Abort();
                     throw new TimeoutException($"Command '{customCommand.Command}' took more than {timeout}ms to run. It has been killed.");
                 }
 
@@ -49,6 +47,7 @@ namespace ChaosBot.Services.ProgrammingLanguageInterpreter
             }
             catch (Exception ex)
             {
+                LoggingFacade.Exception(ex);
                 errorReason = $"There was an error with your code ({ex.GetType().Name}): {ex.Message}";
                 return false;
             }