Added ValueTask support

- This is a breaking change for custom middleware implementations
Added validation for return type handling
- This may be breaking for incorrect implementations, but highly unlikely

Examples/03-FlowRequestResponse/ReceivingMessageController.cs

@@ -9,8 +9,7 @@ namespace _03_FlowRequestResponse
     public class ReceivingMessageController
     {
         // No publisher required, responses can simply be returned
-        #pragma warning disable CA1822 // Mark members as static - not supported yet by Tapeti
+        public static async Task<QuoteResponseMessage> HandleQuoteRequest(QuoteRequestMessage message)
-        public async Task<QuoteResponseMessage> HandleQuoteRequest(QuoteRequestMessage message)
         {
             var quote = message.Amount switch
             {
@@ -29,6 +28,5 @@ namespace _03_FlowRequestResponse
                 Quote = quote
             };
         }
-        #pragma warning restore CA1822
     }
 }

Examples/05-SpeedTest/SpeedMessageController.cs

@@ -15,9 +15,11 @@ namespace _05_SpeedTest
         }
 
 
+        #pragma warning disable IDE0060 // Remove unused parameter
         public void HandleSpeedTestMessage(SpeedTestMessage message)
         {
             messageCounter.Add();
         }
+        #pragma warning restore IDE0060
     }
 }

Examples/06-StatelessRequestResponse/ReceivingMessageController.cs

@@ -8,8 +8,7 @@ namespace _06_StatelessRequestResponse
     public class ReceivingMessageController
     {
         // No publisher required, responses can simply be returned
-        #pragma warning disable CA1822 // Mark members as static - not supported yet by Tapeti
+        public static QuoteResponseMessage HandleQuoteRequest(QuoteRequestMessage message)
-        public QuoteResponseMessage HandleQuoteRequest(QuoteRequestMessage message)
         {
             var quote = message.Amount switch
             {
@@ -25,6 +24,5 @@ namespace _06_StatelessRequestResponse
                 Quote = quote
             };
         }
-        #pragma warning restore CA1822
     }
 }

Tapeti.DataAnnotations/DataAnnotationsMessageMiddleware.cs

@@ -12,12 +12,12 @@ namespace Tapeti.DataAnnotations
     internal class DataAnnotationsMessageMiddleware : IMessageMiddleware
     {
         /// <inheritdoc />
-        public async Task Handle(IMessageContext context, Func<Task> next)
+        public ValueTask Handle(IMessageContext context, Func<ValueTask> next)
         {
             var validationContext = new ValidationContext(context.Message);
             Validator.ValidateObject(context.Message, validationContext, true);
 
-            await next();
+            return next();
         }
     }
 }

Tapeti.DataAnnotations/DataAnnotationsPublishMiddleware.cs

@@ -12,12 +12,12 @@ namespace Tapeti.DataAnnotations
     internal class DataAnnotationsPublishMiddleware : IPublishMiddleware
     {
         /// <inheritdoc />
-        public async Task Handle(IPublishContext context, Func<Task> next)
+        public ValueTask Handle(IPublishContext context, Func<ValueTask> next)
         {
             var validationContext = new ValidationContext(context.Message);
             Validator.ValidateObject(context.Message, validationContext, true);
 
-            await next();
+            return next();
         }
     }
 }

Tapeti.Flow.SQL/SqlConnectionFlowRepository.cs

@@ -5,6 +5,10 @@ using System.Data.SqlClient;
 using System.Threading.Tasks;
 using Newtonsoft.Json;
 
+// Neither of these are available in language version 7 required for .NET Standard 2.0
+// ReSharper disable ConvertToUsingDeclaration
+// ReSharper disable UseAwaitUsing
+
 namespace Tapeti.Flow.SQL
 {
     /// <inheritdoc />
@@ -37,7 +41,7 @@ namespace Tapeti.Flow.SQL
 
 
         /// <inheritdoc />
-        public async Task<IEnumerable<FlowRecord<T>>> GetStates<T>()
+        public async ValueTask<IEnumerable<FlowRecord<T>>> GetStates<T>()
         {
             return await SqlRetryHelper.Execute(async () =>
             {
@@ -64,7 +68,7 @@ namespace Tapeti.Flow.SQL
         }
 
         /// <inheritdoc />
-        public async Task CreateState<T>(Guid flowID, T state, DateTime timestamp)
+        public async ValueTask CreateState<T>(Guid flowID, T state, DateTime timestamp)
         {
             await SqlRetryHelper.Execute(async () =>
             {
@@ -88,7 +92,7 @@ namespace Tapeti.Flow.SQL
         }
 
         /// <inheritdoc />
-        public async Task UpdateState<T>(Guid flowID, T state)
+        public async ValueTask UpdateState<T>(Guid flowID, T state)
         {
             await SqlRetryHelper.Execute(async () =>
             {
@@ -108,7 +112,7 @@ namespace Tapeti.Flow.SQL
         }
 
         /// <inheritdoc />
-        public async Task DeleteState(Guid flowID)
+        public async ValueTask DeleteState(Guid flowID)
         {
             await SqlRetryHelper.Execute(async () =>
             {

Tapeti.Flow.SQL/Tapeti.Flow.SQL.csproj

@@ -17,6 +17,11 @@
     <NoWarn>1701;1702</NoWarn>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(TargetFramework)'!='netstandard2.0'">
+    <!-- Suppress 'using statement can be simplified' which requires language version 8 not available in .NET Standard 2.0 -->
+    <NoWarn>IDE0063</NoWarn>
+  </PropertyGroup>
+
   <ItemGroup>
     <None Remove="scripts\Flow table.sql" />
   </ItemGroup>

Tapeti.Flow/Default/FlowBindingMiddleware.cs

@@ -31,6 +31,9 @@ namespace Tapeti.Flow.Default
             if (continuationAttribute == null)
                 return;
 
+            if (context.Method.IsStatic)
+                throw new ArgumentException($"Continuation attribute is not valid on static methods in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}");
+
             context.SetBindingTargetMode(BindingTargetMode.Direct);
             context.Use(new FlowContinuationMiddleware());
 
@@ -52,7 +55,7 @@ namespace Tapeti.Flow.Default
                 context.Result.SetHandler((messageContext, value) => HandleParallelResponse(messageContext));
             }
             else
-                throw new ArgumentException($"Result type must be IYieldPoint, Task or void in controller {context. Method.DeclaringType?.FullName}, method {context.Method.Name}");
+                throw new ArgumentException($"Result type must be IYieldPoint, Task or void in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}");
 
 
             foreach (var parameter in context.Parameters.Where(p => !p.HasBinding && p.Info.ParameterType == typeof(IFlowParallelRequest)))
@@ -62,34 +65,53 @@ namespace Tapeti.Flow.Default
 
         private static void RegisterYieldPointResult(IControllerBindingContext context)
         {
-            if (!context.Result.Info.ParameterType.IsTypeOrTaskOf(typeof(IYieldPoint), out var isTaskOf))
+            if (!context.Result.Info.ParameterType.IsTypeOrTaskOf(typeof(IYieldPoint), out var taskType))
                 return;
 
-            if (isTaskOf)
+            if (context.Method.IsStatic)
+                throw new ArgumentException($"Yield points are not valid on static methods in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}");
+
+            switch (taskType)
             {
-                context.Result.SetHandler(async (messageContext, value) =>
+                case TaskType.None:
-                {
+                    context.Result.SetHandler((messageContext, value) => HandleYieldPoint(messageContext, (IYieldPoint)value));
-                    var yieldPoint = await (Task<IYieldPoint>)value;
+                    break;
-                    if (yieldPoint != null)
+
-                        await HandleYieldPoint(messageContext, yieldPoint);
+                case TaskType.Task:
-                });
+                    context.Result.SetHandler(async (messageContext, value) =>
+                    {
+                        var yieldPoint = await (Task<IYieldPoint>)value;
+                        if (yieldPoint != null)
+                            await HandleYieldPoint(messageContext, yieldPoint);
+                    });
+                    break;
+
+                case TaskType.ValueTask:
+                    context.Result.SetHandler(async (messageContext, value) =>
+                    {
+                        var yieldPoint = await (ValueTask<IYieldPoint>)value;
+                        if (yieldPoint != null)
+                            await HandleYieldPoint(messageContext, yieldPoint);
+                    });
+                    break;
+
+                default:
+                    throw new ArgumentOutOfRangeException();
             }
-            else
-                context.Result.SetHandler((messageContext, value) => HandleYieldPoint(messageContext, (IYieldPoint)value));
         }
 
 
-        private static Task HandleYieldPoint(IMessageContext context, IYieldPoint yieldPoint)
+        private static ValueTask HandleYieldPoint(IMessageContext context, IYieldPoint yieldPoint)
         {
             var flowHandler = context.Config.DependencyResolver.Resolve<IFlowHandler>();
             return flowHandler.Execute(new FlowHandlerContext(context), yieldPoint);
         }
 
 
-        private static Task HandleParallelResponse(IMessageContext context)
+        private static ValueTask HandleParallelResponse(IMessageContext context)
         {
             if (context.TryGet<FlowMessageContextPayload>(out var flowPayload) && flowPayload.FlowIsConverging)
-                return Task.CompletedTask;
+                return default;
 
             var flowHandler = context.Config.DependencyResolver.Resolve<IFlowHandler>();
             return flowHandler.Execute(new FlowHandlerContext(context), new DelegateYieldPoint(async flowContext =>

Tapeti.Flow/Default/FlowContext.cs

@@ -17,7 +17,7 @@ namespace Tapeti.Flow.Default
         private int deleteCalled;
 
 
-        public async Task Store(bool persistent)
+        public ValueTask Store(bool persistent)
         {
             storeCalled++;
 
@@ -26,15 +26,13 @@ namespace Tapeti.Flow.Default
             if (FlowStateLock == null) throw new ArgumentNullException(nameof(FlowStateLock));
 
             FlowState.Data = Newtonsoft.Json.JsonConvert.SerializeObject(HandlerContext.Controller);
-            await FlowStateLock.StoreFlowState(FlowState, persistent);
+            return FlowStateLock.StoreFlowState(FlowState, persistent);
         }
 
-        public async Task Delete()
+        public ValueTask Delete()
         {
             deleteCalled++;
-
+            return FlowStateLock?.DeleteFlowState() ?? default;
-            if (FlowStateLock != null)
-                await FlowStateLock.DeleteFlowState();
         }
 
         public bool IsStoredOrDeleted()

Tapeti.Flow/Default/FlowContinuationMiddleware.cs

@@ -11,7 +11,7 @@ namespace Tapeti.Flow.Default
     /// </summary>
     internal class FlowContinuationMiddleware : IControllerFilterMiddleware, IControllerMessageMiddleware, IControllerCleanupMiddleware
     {
-        public async Task Filter(IMessageContext context, Func<Task> next)
+        public async ValueTask Filter(IMessageContext context, Func<ValueTask> next)
         {
             if (!context.TryGet<ControllerMessageContextPayload>(out var controllerPayload))
                 return;
@@ -27,7 +27,7 @@ namespace Tapeti.Flow.Default
         }
 
 
-        public async Task Handle(IMessageContext context, Func<Task> next)
+        public async ValueTask Handle(IMessageContext context, Func<ValueTask> next)
         {
             if (!context.TryGet<ControllerMessageContextPayload>(out var controllerPayload))
                 return;
@@ -53,7 +53,7 @@ namespace Tapeti.Flow.Default
         }
 
 
-        public async Task Cleanup(IMessageContext context, ConsumeResult consumeResult, Func<Task> next)
+        public async ValueTask Cleanup(IMessageContext context, ConsumeResult consumeResult, Func<ValueTask> next)
         {
             await next();
 
@@ -82,7 +82,7 @@ namespace Tapeti.Flow.Default
 
 
 
-        private static async Task<FlowContext> EnrichWithFlowContext(IMessageContext context)
+        private static async ValueTask<FlowContext> EnrichWithFlowContext(IMessageContext context)
         {
             if (context.TryGet<FlowMessageContextPayload>(out var flowPayload))
                 return flowPayload.FlowContext;

Tapeti.Flow/Default/FlowProvider.cs

@@ -197,7 +197,7 @@ namespace Tapeti.Flow.Default
 
         
         /// <inheritdoc />
-        public async Task Execute(IFlowHandlerContext context, IYieldPoint yieldPoint)
+        public async ValueTask Execute(IFlowHandlerContext context, IYieldPoint yieldPoint)
         {
             if (!(yieldPoint is DelegateYieldPoint executableYieldPoint))
                 throw new YieldPointException($"Yield point is required in controller {context.Controller.GetType().Name} for method {context.Method.Name}");
@@ -254,7 +254,7 @@ namespace Tapeti.Flow.Default
 
 
         /// <inheritdoc />
-        public Task Converge(IFlowHandlerContext context)
+        public ValueTask Converge(IFlowHandlerContext context)
         {
             return Execute(context, new DelegateYieldPoint(flowContext => 
                 Converge(flowContext, flowContext.ContinuationMetadata.ConvergeMethodName, flowContext.ContinuationMetadata.ConvergeMethodSync)));

Tapeti.Flow/Default/FlowStore.cs

@@ -51,7 +51,7 @@ namespace Tapeti.Flow.Default
 
 
         /// <inheritdoc />
-        public async Task Load()
+        public async ValueTask Load()
         {
             if (inUse)
                 throw new InvalidOperationException("Can only load the saved state once.");
@@ -114,17 +114,17 @@ namespace Tapeti.Flow.Default
 
 
         /// <inheritdoc />
-        public Task<Guid?> FindFlowID(Guid continuationID)
+        public ValueTask<Guid?> FindFlowID(Guid continuationID)
         {
             if (!loaded)
                 throw new InvalidOperationException("Flow store is not yet loaded.");
 
-            return Task.FromResult(continuationLookup.TryGetValue(continuationID, out var result) ? result : (Guid?)null);
+            return new ValueTask<Guid?>(continuationLookup.TryGetValue(continuationID, out var result) ? result : (Guid?)null);
         }
 
 
         /// <inheritdoc />
-        public async Task<IFlowStateLock> LockFlowState(Guid flowID)
+        public async ValueTask<IFlowStateLock> LockFlowState(Guid flowID)
         {
             if (!loaded)
                 throw new InvalidOperationException("Flow store should be loaded before storing flows.");
@@ -137,14 +137,14 @@ namespace Tapeti.Flow.Default
 
 
         /// <inheritdoc />
-        public Task<IEnumerable<ActiveFlow>> GetActiveFlows(TimeSpan minimumAge)
+        public ValueTask<IEnumerable<ActiveFlow>> GetActiveFlows(TimeSpan minimumAge)
         {
             var maximumDateTime = DateTime.UtcNow - minimumAge;
 
-            return Task.FromResult(flowStates
+            return new ValueTask<IEnumerable<ActiveFlow>>(flowStates
                 .Where(p => p.Value.CreationTime <= maximumDateTime)
                 .Select(p => new ActiveFlow(p.Key, p.Value.CreationTime))
-                .ToArray() as IEnumerable<ActiveFlow>);
+                .ToArray());
         }
 
 
@@ -173,15 +173,15 @@ namespace Tapeti.Flow.Default
                 l?.Dispose();
             }
 
-            public Task<FlowState> GetFlowState()
+            public ValueTask<FlowState> GetFlowState()
             {
                 if (flowLock == null)
                     throw new ObjectDisposedException("FlowStateLock");
 
-                return Task.FromResult(cachedFlowState?.FlowState?.Clone());
+                return new ValueTask<FlowState>(cachedFlowState?.FlowState?.Clone());
             }
 
-            public async Task StoreFlowState(FlowState newFlowState, bool persistent)
+            public async ValueTask StoreFlowState(FlowState newFlowState, bool persistent)
             {
                 if (flowLock == null)
                     throw new ObjectDisposedException("FlowStateLock");
@@ -227,7 +227,7 @@ namespace Tapeti.Flow.Default
                 }
             }
 
-            public async Task DeleteFlowState()
+            public async ValueTask DeleteFlowState()
             {
                 if (flowLock == null)
                     throw new ObjectDisposedException("FlowStateLock");

Tapeti.Flow/Default/NonPersistentFlowRepository.cs

@@ -11,27 +11,27 @@ namespace Tapeti.Flow.Default
     /// </summary>
     public class NonPersistentFlowRepository : IFlowRepository
     {
-        Task<IEnumerable<FlowRecord<T>>> IFlowRepository.GetStates<T>()
+        ValueTask<IEnumerable<FlowRecord<T>>> IFlowRepository.GetStates<T>()
         {
-            return Task.FromResult(Enumerable.Empty<FlowRecord<T>>());
+            return new ValueTask<IEnumerable<FlowRecord<T>>>(Enumerable.Empty<FlowRecord<T>>());
         }
 
         /// <inheritdoc />
-        public Task CreateState<T>(Guid flowID, T state, DateTime timestamp)
+        public ValueTask CreateState<T>(Guid flowID, T state, DateTime timestamp)
         {
-            return Task.CompletedTask;
+            return default;
         }
 
         /// <inheritdoc />
-        public Task UpdateState<T>(Guid flowID, T state)
+        public ValueTask UpdateState<T>(Guid flowID, T state)
         {
-            return Task.CompletedTask;
+            return default;
         }
 
         /// <inheritdoc />
-        public Task DeleteState(Guid flowID)
+        public ValueTask DeleteState(Guid flowID)
         {
-            return Task.CompletedTask;
+            return default;
         }
     }
 }

Tapeti.Flow/IFlowProvider.cs

@@ -108,7 +108,7 @@ namespace Tapeti.Flow
         /// </summary>
         /// <param name="context"></param>
         /// <param name="yieldPoint"></param>
-        Task Execute(IFlowHandlerContext context, IYieldPoint yieldPoint);
+        ValueTask Execute(IFlowHandlerContext context, IYieldPoint yieldPoint);
 
 
         /// <summary>
@@ -120,7 +120,7 @@ namespace Tapeti.Flow
         /// <summary>
         /// Calls the converge method for a parallel flow.
         /// </summary>
-        Task Converge(IFlowHandlerContext context);
+        ValueTask Converge(IFlowHandlerContext context);
     }
 
 

Tapeti.Flow/IFlowRepository.cs

@@ -13,7 +13,7 @@ namespace Tapeti.Flow
         /// Load the previously persisted flow states.
         /// </summary>
         /// <returns>A list of flow states, where the key is the unique Flow ID and the value is the deserialized T.</returns>
-        Task<IEnumerable<FlowRecord<T>>> GetStates<T>();
+        ValueTask<IEnumerable<FlowRecord<T>>> GetStates<T>();
 
         /// <summary>
         /// Stores a new flow state. Guaranteed to be run in a lock for the specified flow ID.
@@ -22,20 +22,20 @@ namespace Tapeti.Flow
         /// <param name="state">The flow state to be stored.</param>
         /// <param name="timestamp">The time when the flow was initially created.</param>
         /// <returns></returns>
-        Task CreateState<T>(Guid flowID, T state, DateTime timestamp);
+        ValueTask CreateState<T>(Guid flowID, T state, DateTime timestamp);
 
         /// <summary>
         /// Updates an existing flow state. Guaranteed to be run in a lock for the specified flow ID.
         /// </summary>
         /// <param name="flowID">The unique ID of the flow.</param>
         /// <param name="state">The flow state to be stored.</param>
-        Task UpdateState<T>(Guid flowID, T state);
+        ValueTask UpdateState<T>(Guid flowID, T state);
 
         /// <summary>
         /// Delete a flow state. Guaranteed to be run in a lock for the specified flow ID.
         /// </summary>
         /// <param name="flowID">The unique ID of the flow.</param>
-        Task DeleteState(Guid flowID);
+        ValueTask DeleteState(Guid flowID);
     }
 
 

Tapeti.Flow/IFlowStore.cs

@@ -17,19 +17,19 @@ namespace Tapeti.Flow
         /// If using an IFlowRepository that requires an update (such as creating tables) make
         /// sure it is called before calling Load.
         /// </summary>
-        Task Load();
+        ValueTask Load();
 
         /// <summary>
         /// Looks up the FlowID corresponding to a ContinuationID. For internal use.
         /// </summary>
         /// <param name="continuationID"></param>
-        Task<Guid?> FindFlowID(Guid continuationID);
+        ValueTask<Guid?> FindFlowID(Guid continuationID);
 
         /// <summary>
         /// Acquires a lock on the flow with the specified FlowID.
         /// </summary>
         /// <param name="flowID"></param>
-        Task<IFlowStateLock> LockFlowState(Guid flowID);
+        ValueTask<IFlowStateLock> LockFlowState(Guid flowID);
 
         /// <summary>
         /// Returns information about the currently active flows.
@@ -38,7 +38,7 @@ namespace Tapeti.Flow
         /// This is intended for monitoring purposes and should be treated as a snapshot.
         /// </remarks>
         /// <param name="minimumAge">The minimum age of the flow before it is included in the result. Set to TimeSpan.Zero to return all active flows.</param>
-        Task<IEnumerable<ActiveFlow>> GetActiveFlows(TimeSpan minimumAge);
+        ValueTask<IEnumerable<ActiveFlow>> GetActiveFlows(TimeSpan minimumAge);
     }
 
 
@@ -56,19 +56,19 @@ namespace Tapeti.Flow
         /// <summary>
         /// Acquires a copy of the flow state.
         /// </summary>
-        Task<FlowState> GetFlowState();
+        ValueTask<FlowState> GetFlowState();
 
         /// <summary>
         /// Stores the new flow state.
         /// </summary>
         /// <param name="flowState"></param>
         /// <param name="persistent"></param>
-        Task StoreFlowState(FlowState flowState, bool persistent);
+        ValueTask StoreFlowState(FlowState flowState, bool persistent);
 
         /// <summary>
         /// Disposes of the flow state corresponding to this Flow ID.
         /// </summary>
-        Task DeleteFlowState();
+        ValueTask DeleteFlowState();
     }
 
 

Tapeti.Flow/Tapeti.Flow.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1</TargetFrameworks>
@@ -18,7 +18,7 @@
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(TargetFramework)'!='netstandard2.0'">
-    <!-- Supress 'Use switch expression' which requires language version 8 not available in .NET Standard 2.0 -->
+    <!-- Suppress 'Use switch expression' which requires language version 8 not available in .NET Standard 2.0 -->
     <NoWarn>IDE0066</NoWarn>
   </PropertyGroup>
 

Tapeti.Serilog/Middleware/MessageHandlerLoggingMessageMiddleware.cs

@@ -29,7 +29,7 @@ namespace Tapeti.Serilog.Middleware
         }
         
         /// <inheritdoc />
-        public async Task Handle(IMessageContext context, Func<Task> next)
+        public async ValueTask Handle(IMessageContext context, Func<ValueTask> next)
         {
             var logger = context.Config.DependencyResolver.Resolve<global::Serilog.ILogger>();
             
@@ -41,6 +41,7 @@ namespace Tapeti.Serilog.Middleware
             
             await next();
 
+
             stopwatch.Stop();
 
             

Tapeti/Config/IControllerBindingContext.cs

@@ -19,7 +19,7 @@ namespace Tapeti.Config
     /// </summary>
     /// <param name="context"></param>
     /// <param name="value"></param>
-    public delegate Task ResultHandler(IMessageContext context, object value);
+    public delegate ValueTask ResultHandler(IMessageContext context, object value);
 
 
     /// <summary>

Tapeti/Config/IControllerCleanupMiddleware.cs

@@ -14,6 +14,6 @@ namespace Tapeti.Config
         /// <param name="context"></param>
         /// <param name="consumeResult"></param>
         /// <param name="next">Always call to allow the next in the chain to clean up</param>
-        Task Cleanup(IMessageContext context, ConsumeResult consumeResult, Func<Task> next);
+        ValueTask Cleanup(IMessageContext context, ConsumeResult consumeResult, Func<ValueTask> next);
     }
 }

Tapeti/Config/IControllerFilterMiddleware.cs

@@ -15,6 +15,6 @@ namespace Tapeti.Config
         /// <param name="context"></param>
         /// <param name="next"></param>
         /// <returns></returns>
-        Task Filter(IMessageContext context, Func<Task> next);
+        ValueTask Filter(IMessageContext context, Func<ValueTask> next);
     }
 }

Tapeti/Config/IControllerMessageMiddleware.cs

@@ -14,6 +14,6 @@ namespace Tapeti.Config
         /// </summary>
         /// <param name="context"></param>
         /// <param name="next">Call to pass the message to the next handler in the chain or call the controller method</param>
-        Task Handle(IMessageContext context, Func<Task> next);
+        ValueTask Handle(IMessageContext context, Func<ValueTask> next);
     }
 }

Tapeti/Config/IMessageMiddleware.cs

@@ -13,6 +13,6 @@ namespace Tapeti.Config
         /// </summary>
         /// <param name="context"></param>
         /// <param name="next">Call to pass the message to the next handler in the chain</param>
-        Task Handle(IMessageContext context, Func<Task> next);
+        ValueTask Handle(IMessageContext context, Func<ValueTask> next);
     }
 }

Tapeti/Config/IPublishMiddleware.cs

@@ -13,6 +13,6 @@ namespace Tapeti.Config
         /// </summary>
         /// <param name="context"></param>
         /// <param name="next">Call to pass the message to the next handler in the chain</param>
-        Task Handle(IPublishContext context, Func<Task> next);
+        ValueTask Handle(IPublishContext context, Func<ValueTask> next);
     }
 }

Tapeti/Connection/TapetiSubscriber.cs

@@ -80,14 +80,13 @@ namespace Tapeti.Connection
 
             cancellationToken = initializeCancellationTokenSource.Token;
 
-            // ReSharper disable once MethodSupportsCancellation
             Task.Run(async () =>
             {
                 await ApplyBindings(cancellationToken);
 
                 if (consuming && !cancellationToken.IsCancellationRequested)
                     await ConsumeQueues(cancellationToken);
-            });
+            }, CancellationToken.None);
         }
 
 

Tapeti/Default/ControllerMethodBinding.cs

@@ -159,7 +159,7 @@ namespace Tapeti.Default
         /// <inheritdoc />
         public async Task Invoke(IMessageContext context)
         {
-            var controller = dependencyResolver.Resolve(bindingInfo.ControllerType);
+            var controller = Method.IsStatic ? null : dependencyResolver.Resolve(bindingInfo.ControllerType);
             context.Store(new ControllerMessageContextPayload(controller, context.Binding as IControllerMethodBinding));
             
             if (!await FilterAllowed(context))
@@ -179,7 +179,7 @@ namespace Tapeti.Default
             await MiddlewareHelper.GoAsync(
                 bindingInfo.CleanupMiddleware,
                 async (handler, next) => await handler.Cleanup(context, consumeResult, next),
-                () => Task.CompletedTask);
+                () => default);
         }
 
 
@@ -192,14 +192,14 @@ namespace Tapeti.Default
                 () =>
                 {
                     allowed = true;
-                    return Task.CompletedTask;
+                    return default;
                 });
 
             return allowed;
         }
 
 
-        private delegate Task MessageHandlerFunc(IMessageContext context);
+        private delegate ValueTask MessageHandlerFunc(IMessageContext context);
 
 
         private MessageHandlerFunc WrapMethod(MethodInfo method, IEnumerable<ValueFactory> parameterFactories, ResultHandler resultHandler)
@@ -213,10 +213,11 @@ namespace Tapeti.Default
             if (method.ReturnType == typeof(Task))
                 return WrapTaskMethod(method, parameterFactories);
 
-            if (method.ReturnType.IsGenericType && method.ReturnType.GetGenericTypeDefinition() == typeof(Task<>))
+            if (method.ReturnType == typeof(ValueTask))
-                return WrapGenericTaskMethod(method, parameterFactories);
+                return WrapValueTaskMethod(method, parameterFactories);
 
-            return WrapObjectMethod(method, parameterFactories);
+            // Breaking change in Tapeti 2.9: PublishResultBinding or other middleware should have taken care of the return value. If not, don't silently discard it.
+            throw new ArgumentException($"Method {method.Name} on controller {method.DeclaringType?.FullName} returns type {method.ReturnType.FullName}, which can not be handled by Tapeti or any registered middleware");
         }
 
 
@@ -246,7 +247,7 @@ namespace Tapeti.Default
                 try
                 { 
                     method.Invoke(controllerPayload.Controller, parameterFactories.Select(p => p(context)).ToArray());
-                    return Task.CompletedTask;
+                    return default;
                 }
                 catch (Exception e)
                 {
@@ -264,7 +265,7 @@ namespace Tapeti.Default
                 var controllerPayload = context.Get<ControllerMessageContextPayload>();
                 try
                 {
-                    return (Task) method.Invoke(controllerPayload.Controller, parameterFactories.Select(p => p(context)).ToArray());
+                    return new ValueTask((Task) method.Invoke(controllerPayload.Controller, parameterFactories.Select(p => p(context)).ToArray()));
                 }
                 catch (Exception e)
                 {
@@ -275,32 +276,14 @@ namespace Tapeti.Default
         }
 
 
-        private MessageHandlerFunc WrapGenericTaskMethod(MethodBase method, IEnumerable<ValueFactory> parameterFactories)
+        private MessageHandlerFunc WrapValueTaskMethod(MethodBase method, IEnumerable<ValueFactory> parameterFactories)
         {
             return context =>
             {
                 var controllerPayload = context.Get<ControllerMessageContextPayload>();
                 try
                 {
-                    return (Task<object>)method.Invoke(controllerPayload.Controller, parameterFactories.Select(p => p(context)).ToArray());
+                    return (ValueTask)method.Invoke(controllerPayload.Controller, parameterFactories.Select(p => p(context)).ToArray());
-                }
-                catch (Exception e)
-                {
-                    AddExceptionData(e);
-                    throw;
-                }
-            };
-        }
-
-
-        private MessageHandlerFunc WrapObjectMethod(MethodBase method, IEnumerable<ValueFactory> parameterFactories)
-        {
-            return context =>
-            {
-                var controllerPayload = context.Get<ControllerMessageContextPayload>();
-                try
-                {
-                    return Task.FromResult(method.Invoke(controllerPayload.Controller, parameterFactories.Select(p => p(context)).ToArray()));
                 }
                 catch (Exception e)
                 {

Tapeti/Default/PublishResultBinding.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Diagnostics;
 using System.Reflection;
 using System.Threading.Tasks;
@@ -23,7 +23,7 @@ namespace Tapeti.Default
                 return;
 
 
-            var hasClassResult = context.Result.Info.ParameterType.IsTypeOrTaskOf(t => t.IsClass, out var isTaskOf, out var actualType);
+            var hasClassResult = context.Result.Info.ParameterType.IsTypeOrTaskOf(t => t.IsClass, out var taskType, out var actualType);
             
             var request = context.MessageClass?.GetCustomAttribute<RequestAttribute>();
             var expectedClassResult = request?.Response;
@@ -32,35 +32,55 @@ namespace Tapeti.Default
             // Tapeti 1.2: if you just want to publish another message as a result of the incoming message, explicitly call IPublisher.Publish.
             // ReSharper disable once ConvertIfStatementToSwitchStatement
             if (!hasClassResult && expectedClassResult != null || hasClassResult && expectedClassResult != actualType)
-               throw new ArgumentException($"Message handler must return type {expectedClassResult?.FullName ?? "void"} in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}, found: {actualType?.FullName ?? "void"}");
+               throw new ArgumentException($"Message handler for non-request message type {context.MessageClass?.FullName} must return type {expectedClassResult?.FullName ?? "void"} in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}, found: {actualType?.FullName ?? "void"}");
 
             if (!hasClassResult)
                 return;
 
 
 
-            if (isTaskOf)
+            switch (taskType)
             {
-                var handler = GetType().GetMethod("PublishGenericTaskResult", BindingFlags.NonPublic | BindingFlags.Static)?.MakeGenericMethod(actualType);
+                case TaskType.None:
-                Debug.Assert(handler != null, nameof(handler) + " != null");
+                    context.Result.SetHandler((messageContext, value) => Reply(value, messageContext));
+                    break;
 
-                context.Result.SetHandler(async (messageContext, value) => { await (Task) handler.Invoke(null, new[] {messageContext, value }); });
+                case TaskType.Task:
+                    var handler = GetType().GetMethod(nameof(PublishGenericTaskResult), BindingFlags.NonPublic | BindingFlags.Static)?.MakeGenericMethod(actualType);
+                    Debug.Assert(handler != null, nameof(handler) + " != null");
+
+                    context.Result.SetHandler((messageContext, value) => (ValueTask)handler.Invoke(null, new[] { messageContext, value }));
+                    break;
+
+                case TaskType.ValueTask:
+                    var valueTaskHandler = GetType().GetMethod(nameof(PublishGenericValueTaskResult), BindingFlags.NonPublic | BindingFlags.Static)?.MakeGenericMethod(actualType);
+                    Debug.Assert(valueTaskHandler != null, nameof(handler) + " != null");
+
+                    context.Result.SetHandler((messageContext, value) => (ValueTask)valueTaskHandler.Invoke(null, new[] { messageContext, value }));
+                    break;
+
+                default:
+                    throw new ArgumentOutOfRangeException();
             }
-            else
-                context.Result.SetHandler((messageContext, value) => Reply(value, messageContext));
         }
 
 
 
-        // ReSharper disable once UnusedMember.Local - used implicitly above
+        private static async ValueTask PublishGenericTaskResult<T>(IMessageContext messageContext, object value) where T : class
-        private static async Task PublishGenericTaskResult<T>(IMessageContext messageContext, object value) where T : class
         {
             var message = await (Task<T>)value;
             await Reply(message, messageContext);
         }
 
 
-        private static Task Reply(object message, IMessageContext messageContext)
+        private static async ValueTask PublishGenericValueTaskResult<T>(IMessageContext messageContext, object value) where T : class
+        {
+            var message = await (ValueTask<T>)value;
+            await Reply(message, messageContext);
+        }
+
+
+        private static async ValueTask Reply(object message, IMessageContext messageContext)
         {
             if (message == null)
                 throw new ArgumentException("Return value of a request message handler must not be null");
@@ -71,9 +91,10 @@ namespace Tapeti.Default
                 CorrelationId = messageContext.Properties.CorrelationId
             };
 
-            return !string.IsNullOrEmpty(messageContext.Properties.ReplyTo) 
+            if (!string.IsNullOrEmpty(messageContext.Properties.ReplyTo))
-                ? publisher.PublishDirect(message, messageContext.Properties.ReplyTo, properties, messageContext.Properties.Persistent.GetValueOrDefault(true)) 
+                await publisher.PublishDirect(message, messageContext.Properties.ReplyTo, properties, messageContext.Properties.Persistent.GetValueOrDefault(true));
-                : publisher.Publish(message, properties, false);
+            else
+                await publisher.Publish(message, properties, false);
         }
     }
 }

Tapeti/Helpers/MiddlewareHelper.cs

@@ -45,7 +45,7 @@ namespace Tapeti.Helpers
         /// <param name="handle">Receives the middleware which should be called and a reference to the action which will call the next. Pass this on to the middleware.</param>
         /// <param name="lastHandler">The action to execute when the innermost middleware calls next.</param>
         /// <typeparam name="T"></typeparam>
-        public static async Task GoAsync<T>(IReadOnlyList<T> middleware, Func<T, Func<Task>, Task> handle, Func<Task> lastHandler)
+        public static async ValueTask GoAsync<T>(IReadOnlyList<T> middleware, Func<T, Func<ValueTask>, ValueTask> handle, Func<ValueTask> lastHandler)
         {
             var handlerIndex = middleware?.Count - 1 ?? -1;
             if (middleware == null || handlerIndex == -1)
@@ -54,7 +54,7 @@ namespace Tapeti.Helpers
                 return;
             }
 
-            async Task HandleNext()
+            async ValueTask HandleNext()
             {
                 handlerIndex--;
                 if (handlerIndex >= 0)

Tapeti/Helpers/TaskTypeHelper.cs

@@ -3,30 +3,59 @@ using System.Threading.Tasks;
 
 namespace Tapeti.Helpers
 {
+    /// <summary>
+    /// Determines if a type is a Task, ValueTask or other type.
+    /// </summary>
+    public enum TaskType
+    {
+        /// <summary>
+        /// Type is not a Task or ValueTask.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// Type is a Task or Task&lt;T&gt;
+        /// </summary>
+        Task,
+
+        /// <summary>
+        /// Type is a ValueTask or ValueTask&lt;T&gt;
+        /// </summary>
+        ValueTask
+    }
+
+
     /// <summary>
     /// Helper methods for working with synchronous and asynchronous versions of methods.
     /// </summary>
     public static class TaskTypeHelper
     {
         /// <summary>
-        /// Determines if the given type matches the predicate, taking Task types into account.
+        /// Determines if the given type matches the predicate, taking Task and ValueTask types into account.
         /// </summary>
         /// <param name="type"></param>
         /// <param name="predicate"></param>
-        /// <param name="isTaskOf"></param>
+        /// <param name="taskType"></param>
         /// <param name="actualType"></param>
-        public static bool IsTypeOrTaskOf(this Type type, Func<Type, bool> predicate, out bool isTaskOf, out Type actualType)
+        public static bool IsTypeOrTaskOf(this Type type, Func<Type, bool> predicate, out TaskType taskType, out Type actualType)
         {
             if (type == typeof(Task))
             {
-                isTaskOf = false;
+                taskType = TaskType.Task;
+                actualType = type;
+                return false;
+            }
+
+            if (type == typeof(ValueTask))
+            {
+                taskType = TaskType.ValueTask;
                 actualType = type;
                 return false;
             }
 
             if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Task<>))
             {
-                isTaskOf = true;
+                taskType = TaskType.Task;
 
                 var genericArguments = type.GetGenericArguments();
                 if (genericArguments.Length == 1 && predicate(genericArguments[0]))
@@ -36,7 +65,19 @@ namespace Tapeti.Helpers
                 }
             }
 
-            isTaskOf = false;
+            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(ValueTask<>))
+            {
+                taskType = TaskType.ValueTask;
+
+                var genericArguments = type.GetGenericArguments();
+                if (genericArguments.Length == 1 && predicate(genericArguments[0]))
+                {
+                    actualType = genericArguments[0];
+                    return true;
+                }
+            }
+
+            taskType = TaskType.None;
             actualType = type;
             return predicate(type);
         }
@@ -47,10 +88,10 @@ namespace Tapeti.Helpers
         /// </summary>
         /// <param name="type"></param>
         /// <param name="predicate"></param>
-        /// <param name="isTaskOf"></param>
+        /// <param name="taskType"></param>
-        public static bool IsTypeOrTaskOf(this Type type, Func<Type, bool> predicate, out bool isTaskOf)
+        public static bool IsTypeOrTaskOf(this Type type, Func<Type, bool> predicate, out TaskType taskType)
         {
-            return IsTypeOrTaskOf(type, predicate, out isTaskOf, out _);
+            return IsTypeOrTaskOf(type, predicate, out taskType, out _);
         }
 
 
@@ -59,10 +100,10 @@ namespace Tapeti.Helpers
         /// </summary>
         /// <param name="type"></param>
         /// <param name="compareTo"></param>
-        /// <param name="isTaskOf"></param>
+        /// <param name="taskType"></param>
-        public static bool IsTypeOrTaskOf(this Type type, Type compareTo, out bool isTaskOf)
+        public static bool IsTypeOrTaskOf(this Type type, Type compareTo, out TaskType taskType)
         {
-            return IsTypeOrTaskOf(type, t => t == compareTo, out isTaskOf);
+            return IsTypeOrTaskOf(type, t => t == compareTo, out taskType);
         }
     }
 }

Tapeti/Tapeti.csproj

@@ -30,6 +30,7 @@
 
   <ItemGroup Condition="'$(TargetFramework)'=='netstandard2.0'">
     <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="5.0.0" />
+    <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
   </ItemGroup>
 
   <ItemGroup>

Tapeti/TapetiConfigControllers.cs

@@ -43,7 +43,7 @@ namespace Tapeti
             var controllerIsObsolete = controller.GetCustomAttribute<ObsoleteAttribute>() != null;
 
 
-            foreach (var method in controller.GetMembers(BindingFlags.Public | BindingFlags.Instance)
+            foreach (var method in controller.GetMembers(BindingFlags.Public | BindingFlags.Instance | BindingFlags.Static)
                 .Where(m => m.MemberType == MemberTypes.Method && m.DeclaringType != typeof(object) && (m as MethodInfo)?.IsSpecialName == false)
                 .Select(m => (MethodInfo)m))
             {