F# code generation Phase B: in-memory saga frames (GH-2969)

src/Testing/Wolverine.Core.FSharpContracts/Contracts.cs

@@ -1,3 +1,4 @@
+using Wolverine;
 using Wolverine.Attributes;
 using Wolverine.Runtime;
 
@@ -96,3 +97,37 @@ public void Handle(Gate command)
     {
     }
 }
+
+// -----------------------------------------------------------------------------
+// Phase B (issue GH-2969): a minimal in-memory stateful saga. Start creates the
+// saga state; Handle continues it. Exercises the Wolverine.Persistence.Sagas
+// frame set (saga-id resolution, create-new, load/assert-exists, store-or-delete)
+// against the default in-memory saga store — no external persistence.
+// -----------------------------------------------------------------------------
+
+/// <summary>Starts a <see cref="CountingSaga" />.</summary>
+public record StartCount(string Id);
+
+/// <summary>Continues a <see cref="CountingSaga" />.</summary>
+public record IncrementCount(string Id);
+
+/// <summary>A minimal stateful saga over the in-memory store.</summary>
+public class CountingSaga : Saga
+{
+    public string? Id { get; set; }
+    public int Count { get; set; }
+
+    public static CountingSaga Start(StartCount command)
+    {
+        return new CountingSaga { Id = command.Id };
+    }
+
+    public void Handle(IncrementCount command)
+    {
+        Count++;
+        if (Count >= 3)
+        {
+            MarkCompleted();
+        }
+    }
+}

src/Testing/Wolverine.Core.FSharpFixture/Generated.fs

@@ -6,6 +6,7 @@ open Microsoft.Extensions.Logging
 open System
 open System.Threading
 open System.Threading.Tasks
+open Wolverine.Persistence.Sagas
 open Wolverine.Runtime
 open Wolverine.Runtime.Handlers
 
@@ -87,3 +88,61 @@ type GateHandler1696712162() =
 
         System.Threading.Tasks.Task.CompletedTask
 
+type IncrementCountHandler540640831(inMemorySagaPersistor: Wolverine.Persistence.Sagas.InMemorySagaPersistor) =
+    inherit Wolverine.Runtime.Handlers.MessageHandler()
+    let _inMemorySagaPersistor = inMemorySagaPersistor
+
+    override _.HandleAsync(context: Wolverine.Runtime.MessageContext, cancellation: System.Threading.CancellationToken) : System.Threading.Tasks.Task =
+        // The actual message body
+        let incrementCount = context.Envelope.Message :?> Wolverine.Core.FSharpContracts.IncrementCount
+
+        // Application-specific Open Telemetry auditing
+        if not (isNull System.Diagnostics.Activity.Current) then
+            System.Diagnostics.Activity.Current.SetTag("Id", incrementCount.Id) |> ignore
+        let sagaId = if isNull incrementCount.Id then context.Envelope.SagaId else incrementCount.Id
+        if System.String.IsNullOrEmpty(sagaId) then
+            raise (Wolverine.Persistence.Sagas.IndeterminateSagaStateIdException(context.Envelope))
+        let countingSaga = _inMemorySagaPersistor.Load<Wolverine.Core.FSharpContracts.CountingSaga>(sagaId)
+        if isNull countingSaga then
+            raise (Wolverine.Persistence.Sagas.UnknownSagaException(typeof<Wolverine.Core.FSharpContracts.CountingSaga>, sagaId))
+        else
+            context.SetSagaId(sagaId)
+            if not (isNull System.Diagnostics.Activity.Current) then
+                System.Diagnostics.Activity.Current.SetTag("wolverine.saga.id", sagaId.ToString()) |> ignore
+                System.Diagnostics.Activity.Current.SetTag("wolverine.saga.type", "Wolverine.Core.FSharpContracts.CountingSaga") |> ignore
+
+            // The actual message execution
+            countingSaga.Handle(incrementCount)
+
+            // Delete the saga if completed, otherwise update it
+            if countingSaga.IsCompleted() then
+                _inMemorySagaPersistor.Delete<Wolverine.Core.FSharpContracts.CountingSaga>(sagaId)
+            else
+                _inMemorySagaPersistor.Store<Wolverine.Core.FSharpContracts.CountingSaga>(countingSaga)
+            // No unit of work
+        System.Threading.Tasks.Task.CompletedTask
+
+type StartCountHandler1561563330(inMemorySagaPersistor: Wolverine.Persistence.Sagas.InMemorySagaPersistor) =
+    inherit Wolverine.Runtime.Handlers.MessageHandler()
+    let _inMemorySagaPersistor = inMemorySagaPersistor
+
+    override _.HandleAsync(context: Wolverine.Runtime.MessageContext, cancellation: System.Threading.CancellationToken) : System.Threading.Tasks.Task =
+        // The actual message body
+        let startCount = context.Envelope.Message :?> Wolverine.Core.FSharpContracts.StartCount
+
+        // Application-specific Open Telemetry auditing
+        if not (isNull System.Diagnostics.Activity.Current) then
+            System.Diagnostics.Activity.Current.SetTag("Id", startCount.Id) |> ignore
+
+        // The actual message execution
+        let outgoing1 = Wolverine.Core.FSharpContracts.CountingSaga.Start(startCount)
+
+        context.SetSagaId(startCount.Id)
+        if not (isNull System.Diagnostics.Activity.Current) then
+            System.Diagnostics.Activity.Current.SetTag("wolverine.saga.id", startCount.Id.ToString()) |> ignore
+            System.Diagnostics.Activity.Current.SetTag("wolverine.saga.type", "Wolverine.Core.FSharpContracts.CountingSaga") |> ignore
+        if not (outgoing1.IsCompleted()) then
+            _inMemorySagaPersistor.Store<Wolverine.Core.FSharpContracts.CountingSaga>(outgoing1)
+        // No unit of work
+        System.Threading.Tasks.Task.CompletedTask
+

src/Testing/Wolverine.Core.FSharpTests/FSharpCodegenSample.cs

@@ -34,6 +34,7 @@ public static string GenerateCode()
                     opts.Discovery.IncludeType<NameHandler>();
                     opts.Discovery.IncludeType<CheckThingHandler>();
                     opts.Discovery.IncludeType<GateHandler>();
+                    opts.Discovery.IncludeType<CountingSaga>();
 
                     // Inserts ApplyExecutionDiagnosticTagsFrame at the head of every chain.
                     opts.Tracking.HandlerExecutionDiagnosticsEnabled = true;

src/Wolverine/Persistence/Sagas/AssertSagaStateExistsFrame.cs

@@ -24,4 +24,11 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
             $"throw new {typeof(UnknownSagaException)}(typeof({_sagaState.VariableType.FullNameInCode()}), {_sagaId.Usage});");
         Next?.GenerateCode(method, writer);
     }
+
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.Write(
+            $"raise ({typeof(UnknownSagaException).FSharpName()}(typeof<{_sagaState.VariableType.FSharpName()}>, {_sagaId.Usage}))");
+        Next?.GenerateFSharpCode(method, writer);
+    }
 }

src/Wolverine/Persistence/Sagas/ConditionalSagaInsertFrame.cs

@@ -30,6 +30,17 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         Next?.GenerateCode(method, writer);
     }
 
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.Write($"BLOCK:if not ({_saga.Usage}.{nameof(Saga.IsCompleted)}()) then");
+        _insert.GenerateFSharpCode(method, writer);
+        writer.FinishBlock();
+
+        _commit.GenerateFSharpCode(method, writer);
+
+        Next?.GenerateFSharpCode(method, writer);
+    }
+
     public override IEnumerable<Variable> FindVariables(IMethodVariables chain)
     {
         yield return _saga;

src/Wolverine/Persistence/Sagas/CreateNewSagaFrame.cs

@@ -28,4 +28,10 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         writer.Write($"var {Saga.Usage} = new {Saga.VariableType.FullNameInCode()}();");
         Next?.GenerateCode(method, writer);
     }
+
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.Write($"{Saga.FSharpAssignmentUsage} = {Saga.VariableType.FSharpName()}()");
+        Next?.GenerateFSharpCode(method, writer);
+    }
 }

src/Wolverine/Persistence/Sagas/PullSagaIdFromEnvelopeFrame.cs

@@ -37,6 +37,34 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         Next?.GenerateCode(method, writer);
     }
 
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        var id = SagaChain.SagaIdVariableName;
+        var ex = typeof(IndeterminateSagaStateIdException).FSharpName();
+        var envSagaId = $"{_envelope!.Usage}.{nameof(Envelope.SagaId)}";
+
+        if (SagaId.VariableType == typeof(string))
+        {
+            writer.Write($"let {id} = {envSagaId}");
+            writer.Write($"BLOCK:if System.String.IsNullOrEmpty({id}) then");
+            writer.Write($"raise ({ex}({_envelope.Usage}))");
+            writer.FinishBlock();
+        }
+        else
+        {
+            // F# auto-tuples the out-parameter TryParse; bind the id from the match, raising on failure.
+            var clrType = SagaId.VariableType.FullName; // System.Guid / System.Int64 — valid static call target
+            writer.Write($"BLOCK:let {id} =");
+            writer.Write($"BLOCK:match {clrType}.TryParse({envSagaId}) with");
+            writer.Write("| true, parsed -> parsed");
+            writer.Write($"| _ -> raise ({ex}({_envelope.Usage}))");
+            writer.FinishBlock();
+            writer.FinishBlock();
+        }
+
+        Next?.GenerateFSharpCode(method, writer);
+    }
+
     public override IEnumerable<Variable> FindVariables(IMethodVariables chain)
     {
         _envelope = chain.FindVariable(typeof(Envelope));

src/Wolverine/Persistence/Sagas/PullSagaIdFromMessageFrame.cs

@@ -73,6 +73,51 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         Next?.GenerateCode(method, writer);
     }
 
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        var id = SagaChain.SagaIdVariableName;
+        var ex = typeof(IndeterminateSagaStateIdException).FSharpName();
+        var messageMember = $"{_message!.Usage}.{_sagaIdMember.Name}";
+        var envelopeSagaId = $"{_envelope!.Usage}.{nameof(Envelope.SagaId)}";
+
+        if (_isStrongTypedId)
+        {
+            // Read straight from the message and reject the default value.
+            writer.Write($"let {id} = {messageMember}");
+            writer.Write($"BLOCK:if {id}.Equals(Unchecked.defaultof<{_sagaIdType!.FSharpName()}>) then");
+            writer.Write($"raise ({ex}({_envelope.Usage}))");
+            writer.FinishBlock();
+        }
+        else if (_sagaIdType == typeof(string))
+        {
+            // F# has no `??`; fall back to the envelope's saga id when the message member is null.
+            writer.Write($"let {id} = if isNull {messageMember} then {envelopeSagaId} else {messageMember}");
+            writer.Write($"BLOCK:if System.String.IsNullOrEmpty({id}) then");
+            writer.Write($"raise ({ex}({_envelope.Usage}))");
+            writer.FinishBlock();
+        }
+        else
+        {
+            // Guid / numeric: read from the message, else parse the envelope's saga id. F# auto-tuples
+            // the out-parameter TryParse into a (bool * value) match. Unchecked.defaultof<T> is both the
+            // numeric/Guid zero and the "indeterminate" sentinel.
+            var clrType = _sagaIdType!.FullName; // e.g. System.Guid / System.Int64 — valid for a static call
+            var fsharpType = _sagaIdType.FSharpName();
+            writer.Write($"let mutable {id} = {messageMember}");
+            writer.Write($"BLOCK:if {id} = Unchecked.defaultof<{fsharpType}> then");
+            writer.Write($"BLOCK:match {clrType}.TryParse({envelopeSagaId}) with");
+            writer.Write($"| true, parsed -> {id} <- parsed");
+            writer.Write($"| _ -> {id} <- {messageMember}");
+            writer.FinishBlock();
+            writer.FinishBlock();
+            writer.Write($"BLOCK:if {id} = Unchecked.defaultof<{fsharpType}> then");
+            writer.Write($"raise ({ex}({_envelope.Usage}))");
+            writer.FinishBlock();
+        }
+
+        Next?.GenerateFSharpCode(method, writer);
+    }
+
     private void generateStrongTypedIdCode(ISourceWriter writer)
     {
         var typeNameInCode = _sagaIdType!.FullNameInCode();

src/Wolverine/Persistence/Sagas/ResolveSagaFrame.cs

@@ -34,4 +34,11 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         _loadFrame.GenerateCode(method, writer);
         Next?.GenerateCode(method, writer);
     }
+
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        _findSagaIdFrame.GenerateFSharpCode(method, writer);
+        _loadFrame.GenerateFSharpCode(method, writer);
+        Next?.GenerateFSharpCode(method, writer);
+    }
 }

src/Wolverine/Persistence/Sagas/SagaStoreOrDeleteFrame.cs

@@ -37,4 +37,17 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
 
         Next?.GenerateCode(method, writer);
     }
+
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.WriteComment("Delete the saga if completed, otherwise update it");
+        writer.Write($"BLOCK:if {_saga.Usage}.{nameof(Saga.IsCompleted)}() then");
+        _delete.GenerateFSharpCode(method, writer);
+        writer.FinishBlock();
+        writer.Write("BLOCK:else");
+        _update.GenerateFSharpCode(method, writer);
+        writer.FinishBlock();
+
+        Next?.GenerateFSharpCode(method, writer);
+    }
 }

src/Wolverine/Persistence/Sagas/SetSagaIdFrame.cs

@@ -3,6 +3,7 @@
 using JasperFx.CodeGeneration.Frames;
 using JasperFx.CodeGeneration.Model;
 using JasperFx.Core.Reflection;
+using Wolverine.Configuration;
 using Wolverine.Runtime;
 
 namespace Wolverine.Persistence.Sagas;
@@ -41,4 +42,22 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         }
         Next?.GenerateCode(method, writer);
     }
+
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        var sagaId = FSharpEmitHelpers.FSharpUsage(_sagaId);
+        writer.Write($"{_context!.Usage}.{nameof(MessageContext.SetSagaId)}({sagaId})");
+
+        // F# has no null-conditional `?.`, and SetTag returns the Activity; guard once and pipe to ignore.
+        var current = $"{typeof(Activity).FSharpName()}.{nameof(Activity.Current)}";
+        writer.Write($"BLOCK:if not (isNull {current}) then");
+        writer.Write($"{current}.{nameof(Activity.SetTag)}(\"{WolverineTracing.SagaId}\", {sagaId}.ToString()) |> ignore");
+        if (_sagaType != null)
+        {
+            writer.Write($"{current}.{nameof(Activity.SetTag)}(\"{WolverineTracing.SagaType}\", \"{_sagaType.FullName}\") |> ignore");
+        }
+
+        writer.FinishBlock();
+        Next?.GenerateFSharpCode(method, writer);
+    }
 }

src/Wolverine/Persistence/Sagas/SetSagaIdFromSagaFrame.cs

@@ -47,4 +47,21 @@ public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
         }
         Next?.GenerateCode(method, writer);
     }
+
+    public override void GenerateFSharpCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        var member = $"{_message.Usage}.{_sagaIdMember.Name}";
+        writer.Write($"{_context!.Usage}.{nameof(MessageContext.SetSagaId)}({member})");
+
+        var current = $"{typeof(Activity).FSharpName()}.{nameof(Activity.Current)}";
+        writer.Write($"BLOCK:if not (isNull {current}) then");
+        writer.Write($"{current}.{nameof(Activity.SetTag)}(\"{WolverineTracing.SagaId}\", {member}.ToString()) |> ignore");
+        if (_sagaType != null)
+        {
+            writer.Write($"{current}.{nameof(Activity.SetTag)}(\"{WolverineTracing.SagaType}\", \"{_sagaType.FullName}\") |> ignore");
+        }
+
+        writer.FinishBlock();
+        Next?.GenerateFSharpCode(method, writer);
+    }
 }