feat(dotnet-sdk): handle business exception and technical errors in task worker

.gitignore

@@ -46,4 +46,6 @@ dist/
 
 # dotnet
 global.json
-*DotSettings.user
+*DotSettings.user
+!sdk-dotnet/Littlehorse.sln
+*.sln

sdk-dotnet/Examples/ExceptionsHandlerExample/ExceptionsHandlerExample.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\LittleHorse.Sdk\LittleHorse.Sdk.csproj" />
+  </ItemGroup>
+
+</Project>

sdk-dotnet/Examples/ExceptionsHandlerExample/Program.cs

@@ -0,0 +1,70 @@
+using ExceptionsHandler;
+using LittleHorse.Sdk;
+using LittleHorse.Sdk.Worker;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace ExceptionsHandlerExample;
+
+public abstract class Program
+{
+    private static ServiceProvider? _serviceProvider;
+
+    private static void SetupApplication()
+    {
+        _serviceProvider = new ServiceCollection()
+            .AddLogging(config =>
+            {
+                config.AddConsole();
+                config.SetMinimumLevel(LogLevel.Debug);
+            })
+            .BuildServiceProvider();
+    }
+
+    private static LHConfig GetLHConfig(string[] args, ILoggerFactory loggerFactory)
+    {
+        var config = new LHConfig(loggerFactory);
+
+        string filePath = Path.Combine(Directory.GetCurrentDirectory(), ".config/littlehorse.config");
+        if (File.Exists(filePath))
+            config = new LHConfig(filePath, loggerFactory);
+
+        return config;
+    }
+
+    private static List<LHTaskWorker<MyWorker>> GetTaskWorkers(LHConfig config)
+    {
+        MyWorker executableExceptionHandling = new MyWorker();
+        var workers = new List<LHTaskWorker<MyWorker>>
+        {
+            new(executableExceptionHandling, "fail", config),
+            new(executableExceptionHandling, "fail-new-process", config),
+            new(executableExceptionHandling, "technical-failure", config),
+            new(executableExceptionHandling, "my-task", config)
+        };
+
+        return workers;
+    }
+
+    static void Main(string[] args)
+    {
+        SetupApplication();
+        if (_serviceProvider != null)
+        {
+            var loggerFactory = _serviceProvider.GetRequiredService<ILoggerFactory>();
+            var config = GetLHConfig(args, loggerFactory);
+            var workers = GetTaskWorkers(config);
+            foreach (var worker in workers)
+            {
+                worker.RegisterTaskDef();
+            }
+
+            Thread.Sleep(300);
+
+            foreach (var worker in workers)
+            {
+                worker.Start();
+            }
+        }
+    }
+}

sdk-dotnet/Examples/ExceptionsHandlerExample/README.md

@@ -0,0 +1,31 @@
+## Running Exceptions Handler Example
+
+This is a simple demonstration of a workflow that handles the failure of a task with
+the handleException() functionality, which spawns a child thread and then
+resumes execution when the handler thread completes.
+
+Let's run the example in `ExceptionsHandlerExample`
+
+```
+dotnet build
+dotnet run
+```
+
+In another terminal, use `lhctl` to run the workflow:
+
+```
+lhctl run example-exception-handler
+```
+
+In addition, you can check the result with:
+
+```
+# This call shows the result
+lhctl get wfRun <wf_run_id>
+
+# This will show you all nodes in tha run
+lhctl list nodeRun <wf_run_id>
+
+# This shows the task run information
+lhctl get taskRun <wf_run_id> <task_run_global_id>
+```

sdk-dotnet/Examples/ExceptionsHandlerExample/Worker.cs

@@ -0,0 +1,56 @@
+using LittleHorse.Common.Proto;
+using LittleHorse.Sdk.Worker;
+using LHTaskException = LittleHorse.Sdk.Exceptions.LHTaskException;
+
+namespace ExceptionsHandler
+{
+    public class MyWorker
+    { 
+        [LHTaskMethod("fail")]
+        public void Fail()
+        {
+            Random random = new Random();
+            int randomNumber = random.Next(6, 10);
+            var message = $"Throw New Failing Task {randomNumber}.";
+            if (randomNumber > 5)
+            {
+                throw new LHTaskException("Fail", message);
+            }
+
+            Console.WriteLine(message);
+        }
+
+        [LHTaskMethod("fail-new-process")]
+        public void FailNewProcess()
+        {
+            Random random = new Random();
+            int randomNumber = random.Next(1, 10);
+            var message = $"Throw Other Failing Task {randomNumber}";
+            if (randomNumber < 8)
+            {
+                VariableValue content = new VariableValue
+                {
+                    Str = "This is a problem"
+                };
+                throw new LHTaskException("Fail-New-Task", message, content);
+            }
+
+            Console.WriteLine(message);
+        }
+
+        [LHTaskMethod("technical-failure")]
+        public void FailForTechnicalReason()
+        {
+            String message = null!;
+            int result = message.Length;
+            Console.WriteLine(result);
+        }
+
+        [LHTaskMethod("my-task")]
+        public string PassingTask()
+        {
+            Console.WriteLine("Executing passing task.");
+            return "woohoo!";
+        }
+    }
+}

sdk-dotnet/Examples/MaskedFieldsExample/MaskedFieldsExample.csproj

@@ -4,7 +4,6 @@
         <TargetFramework>net8.0</TargetFramework>
         <Nullable>enable</Nullable>
         <ImplicitUsings>enable</ImplicitUsings>
-        <Nullable>enable</Nullable>
     </PropertyGroup>
 
     <ItemGroup>

sdk-dotnet/Examples/MaskedFieldsExample/Program.cs

@@ -1,8 +1,9 @@
-using Examples.BasicExample;
 using LittleHorse.Sdk;
 using LittleHorse.Sdk.Worker;
 
-public class Program
+namespace MaskedFieldsExample;
+
+public abstract class Program
 {
     private static ServiceProvider? _serviceProvider;
     private static void SetupApplication()
@@ -26,6 +27,19 @@ private static LHConfig GetLHConfig(string[] args, ILoggerFactory loggerFactory)
 
         return config;
     }
+
+    private static List<LHTaskWorker<MyWorker>> GetTaskWorkers(LHConfig config)
+    {
+        MyWorker executableExceptionHandling = new MyWorker();
+        var workers = new List<LHTaskWorker<MyWorker>>
+        {
+            new(executableExceptionHandling, "create-greet", config),
+            new(executableExceptionHandling, "update-greet", config),
+            new(executableExceptionHandling, "delete-greet", config)
+        };
+
+        return workers;
+    }
 
     static void Main(string[] args)
     {
@@ -34,23 +48,18 @@ static void Main(string[] args)
         {
             var loggerFactory = _serviceProvider.GetRequiredService<ILoggerFactory>();
             var config = GetLHConfig(args, loggerFactory);
+            var workers = GetTaskWorkers(config);
+            foreach (var worker in workers)
+            {
+                worker.RegisterTaskDef();
+            }
 
-            MyWorker executableCreateGreet = new MyWorker();
-            var taskWorkerCreate = new LHTaskWorker<MyWorker>(executableCreateGreet, "create-greet", config);
-            MyWorker executableUpdateGreet = new MyWorker();
-            var taskWorkerUpdate = new LHTaskWorker<MyWorker>(executableUpdateGreet, "update-greet", config);
-            MyWorker executableDeleteGreet = new MyWorker();
-            var taskWorkerDelete = new LHTaskWorker<MyWorker>(executableDeleteGreet, "delete-greet", config);
-
-            taskWorkerCreate.RegisterTaskDef();
-            taskWorkerUpdate.RegisterTaskDef();
-            taskWorkerDelete.RegisterTaskDef();
+            Thread.Sleep(300);
 
-            Thread.Sleep(1000);
-
-            taskWorkerCreate.Start();
-            taskWorkerUpdate.Start();
-            taskWorkerDelete.Start();
+            foreach (var worker in workers)
+            {
+                worker.Start();
+            }
         }
     }
-}
+}

sdk-dotnet/Examples/MaskedFieldsExample/Worker.cs

@@ -1,6 +1,6 @@
 using LittleHorse.Sdk.Worker;
 
-namespace Examples.BasicExample
+namespace MaskedFieldsExample
 {
     public class MyWorker
     {

sdk-dotnet/LittleHorse.Sdk.Tests/Helper/LHMappingHelperTest.cs

@@ -70,6 +70,16 @@ public void LHHelper_WithSystemBytesVariableType_ShouldReturnLHVariableBytesType
         Assert.True(result == VariableType.Bytes);
     }
 
+    [Fact]
+    public void LHHelper_WithSystemVoidVariableType_ShouldReturnLHVariableJsonObjType()
+    {
+        var type = typeof(void);
+
+        var result = LHMappingHelper.MapDotNetTypeToLHVariableType(type);
+
+        Assert.True(result == VariableType.JsonObj);
+    }
+
     [Fact]
     public void LHHelper_WithSystemArrayObjectVariableType_ShouldReturnLHVariableJsonArrType()
     {
@@ -145,12 +155,11 @@ public void LHHelper_WithVariableValue_ShouldReturnSameValue()
     }
 
     [Fact]
-    public void LHHelper_WithNullLHVariableValue_ShouldThrowException()
+    public void LHHelper_WithNullLHVariableValue_ShouldReturnNewLHVariableValue()
     {
-        var exception = Assert.Throws<LHInputVarSubstitutionException>
-            (() => LHMappingHelper.MapObjectToVariableValue(null));
+        var result = LHMappingHelper.MapObjectToVariableValue(null);
 
-        Assert.Equal($"There is no object to be mapped.", exception.Message);
+        Assert.NotNull(result);
     }
 
     [Fact]

sdk-dotnet/LittleHorse.Sdk/Exceptions/LHTaskException.cs

@@ -0,0 +1,22 @@
+using LittleHorse.Common.Proto;
+
+namespace LittleHorse.Sdk.Exceptions;
+
+public class LHTaskException: Exception
+{
+    public string Name { get; }
+
+    public VariableValue Content { get; }
+
+    public LHTaskException(String name, String message): base(message) 
+    {
+        Name = name;
+        Content = new VariableValue();
+    }
+
+    public LHTaskException(String name, String message, VariableValue content): base(message)
+    {
+        Name = name;
+        Content = content;
+    }
+}