Reworked Batching Interface

src/HotChocolate/AspNetCore/src/AspNetCore/MiddlewareBase.cs

@@ -14,6 +14,7 @@ public class MiddlewareBase : IDisposable
 {
     private readonly RequestDelegate _next;
     private readonly IHttpResultSerializer _resultSerializer;
+    private bool? _batching = null;
     private bool _disposed;
 
     protected MiddlewareBase(
@@ -141,13 +142,17 @@ protected async ValueTask<ISchema> GetSchemaAsync(CancellationToken cancellation
             requestBuilder.SetOperation(operationNames[i]);
 
             await requestInterceptor.OnCreateAsync(
-                context, requestExecutor, requestBuilder, context.RequestAborted);
+                context,
+                requestExecutor,
+                requestBuilder,
+                context.RequestAborted);
 
             requestBatch[i] = requestBuilder.Create();
         }
 
         return await requestExecutor.ExecuteBatchAsync(
-            requestBatch, cancellationToken: context.RequestAborted);
+            requestBatch,
+            cancellationToken: context.RequestAborted);
     }
 
     protected static async Task<IResponseStream> ExecuteBatchAsync(
@@ -172,7 +177,8 @@ protected async ValueTask<ISchema> GetSchemaAsync(CancellationToken cancellation
         }
 
         return await requestExecutor.ExecuteBatchAsync(
-            requestBatch, cancellationToken: context.RequestAborted);
+            requestBatch,
+            cancellationToken: context.RequestAborted);
     }
 
     protected static AllowedContentType ParseContentType(HttpContext context)

src/HotChocolate/AspNetCore/test/AspNetCore.Tests/__snapshots__/HttpPostMiddlewareTests.BatchRequest_GetHero_And_GetHuman_MultiPart.snap

@@ -2,9 +2,4 @@
 Content-Type: application/json; charset=utf-8
 
 {"data":{"hero":{"id":"1000"}}}
----
-Content-Type: application/json; charset=utf-8
-
-{"data":{"human":{"name":"Luke Skywalker"}}}
----
 -----

src/HotChocolate/Core/src/Execution/AutoUpdateRequestExecutorProxy.cs

@@ -24,7 +24,7 @@ public class AutoUpdateRequestExecutorProxy : IRequestExecutor
         _executorProxy = requestExecutorProxy;
         _executor = initialExecutor;
 
-        _executorProxy.ExecutorEvicted += (sender, args) => BeginUpdateExecutor();
+        _executorProxy.ExecutorEvicted += (_, _) => BeginUpdateExecutor();
 
         BeginUpdateExecutor();
     }
@@ -146,10 +146,9 @@ public class AutoUpdateRequestExecutorProxy : IRequestExecutor
     /// Returns a stream of query results.
     /// </returns>
     public Task<IResponseStream> ExecuteBatchAsync(
-        IEnumerable<IQueryRequest> requestBatch,
-        bool allowParallelExecution = false,
+        IReadOnlyList<IQueryRequest> requestBatch,
         CancellationToken cancellationToken = default) =>
-        _executor.ExecuteBatchAsync(requestBatch, allowParallelExecution, cancellationToken);
+        _executor.ExecuteBatchAsync(requestBatch, cancellationToken);
 
     private void BeginUpdateExecutor() =>
         Task.Run(UpdateExecutorAsync);

src/HotChocolate/Core/src/Execution/Batching/BatchExecutor.Enumerable.cs

@@ -17,7 +17,7 @@ internal partial class BatchExecutor
 {
     private sealed class BatchExecutorEnumerable : IAsyncEnumerable<IQueryResult>
     {
-        private readonly IEnumerable<IQueryRequest> _requestBatch;
+        private readonly IReadOnlyList<IQueryRequest> _requestBatch;
         private readonly IRequestExecutor _requestExecutor;
         private readonly IErrorHandler _errorHandler;
         private readonly ITypeConverter _typeConverter;
@@ -29,7 +29,7 @@ private sealed class BatchExecutorEnumerable : IAsyncEnumerable<IQueryResult>
         private Dictionary<string, FragmentDefinitionNode>? _fragments;
 
         public BatchExecutorEnumerable(
-            IEnumerable<IQueryRequest> requestBatch,
+            IReadOnlyList<IQueryRequest> requestBatch,
             IRequestExecutor requestExecutor,
             IErrorHandler errorHandler,
             ITypeConverter typeConverter,
@@ -51,11 +51,12 @@ private sealed class BatchExecutorEnumerable : IAsyncEnumerable<IQueryResult>
         public async IAsyncEnumerator<IQueryResult> GetAsyncEnumerator(
             CancellationToken cancellationToken = default)
         {
-            foreach (IQueryRequest queryRequest in _requestBatch)
+            for (var i = 0; i < _requestBatch.Count; i++)
             {
+                IQueryRequest queryRequest = _requestBatch[i];
                 var request = (IReadOnlyQueryRequest)queryRequest;
-                IQueryResult result =
-                    await ExecuteNextAsync(request, cancellationToken).ConfigureAwait(false);
+                IQueryResult result = await ExecuteNextAsync(
+                    request, cancellationToken).ConfigureAwait(false);
                 yield return result;
 
                 if (result.Data is null)
@@ -155,8 +156,7 @@ private sealed class BatchExecutorEnumerable : IAsyncEnumerable<IQueryResult>
 
                 if (!exported[variableName].Any())
                 {
-                    if (variables != null
-                        && variables.TryGetValue(variableName, out var value))
+                    if (variables != null && variables.TryGetValue(variableName, out var value))
                     {
                         merged[variableName] = value;
                     }
@@ -165,8 +165,7 @@ private sealed class BatchExecutorEnumerable : IAsyncEnumerable<IQueryResult>
                 {
                     var list = new List<object?>();
 
-                    if (variables != null
-                        && variables.TryGetValue(variableName, out var value))
+                    if (variables != null && variables.TryGetValue(variableName, out var value))
                     {
                         if (value is IReadOnlyCollection<object?> l)
                         {
@@ -178,21 +177,16 @@ private sealed class BatchExecutorEnumerable : IAsyncEnumerable<IQueryResult>
                         }
                     }
 
-                    foreach (ExportedVariable variable in
-                        exported[variableName])
+                    foreach (ExportedVariable variable in exported[variableName])
                     {
-                        SerializeListValue(
-                            variable,
-                            variableDefinition.Type,
-                            list);
+                        SerializeListValue(variable, variableDefinition.Type, list);
                     }
 
                     merged[variableName] = list;
                 }
                 else
                 {
-                    if (variables != null
-                        && variables.TryGetValue(variableName, out var value))
+                    if (variables != null && variables.TryGetValue(variableName, out var value))
                     {
                         merged[variableName] = value;
                     }

src/HotChocolate/Core/src/Execution/Batching/BatchExecutor.cs

@@ -27,13 +27,11 @@ internal partial class BatchExecutor
 
     public IAsyncEnumerable<IQueryResult> ExecuteAsync(
         IRequestExecutor requestExecutor,
-        IEnumerable<IQueryRequest> requestBatch)
-    {
-        return new BatchExecutorEnumerable(
+        IReadOnlyList<IQueryRequest> requestBatch)
+        => new BatchExecutorEnumerable(
             requestBatch,
             requestExecutor,
             _errorHandler,
             _typeConverter,
             _inputFormatter);
-    }
 }

src/HotChocolate/Core/src/Execution/Batching/ExportDirectiveType.cs

@@ -2,11 +2,9 @@
 
 namespace HotChocolate.Execution.Batching;
 
-public sealed class ExportDirectiveType
-    : DirectiveType<ExportDirective>
+public sealed class ExportDirectiveType : DirectiveType<ExportDirective>
 {
-    protected override void Configure(
-        IDirectiveTypeDescriptor<ExportDirective> descriptor)
+    protected override void Configure(IDirectiveTypeDescriptor<ExportDirective> descriptor)
     {
         descriptor.Name(ExportDirectiveHelper.Name);
         descriptor.Location(DirectiveLocation.Field);

src/HotChocolate/Core/src/Execution/DependencyInjection/RequestExecutorServiceProviderExtensions.cs

@@ -269,20 +269,23 @@ await GetRequestExecutorAsync(services, schemaName, cancellationToken)
     /// The cancellation token.
     /// </param>
     /// <returns>
-    /// Returns the execution result of the given GraphQL <paramref name="query" />.
-    ///
+    /// <para>Returns the execution result of the given GraphQL <paramref name="query" />.</para>
+    /// <para>
     /// If the request operation is a simple query or mutation the result is a
     /// <see cref="IQueryResult" />.
-    ///
+    /// </para>
+    /// <para>
     /// If the request operation is a query or mutation where data is deferred, streamed or
     /// includes live data the result is a <see cref="IResponseStream" /> where each result
     /// that the <see cref="IResponseStream" /> yields is a
     /// <see cref="IQueryResult" />.
-    ///
+    /// </para>
+    /// <para>
     /// If the request operation is a subscription the result is a
     /// <see cref="IResponseStream" /> where each result that the
     /// <see cref="IResponseStream" /> yields is a
     /// <see cref="IQueryResult" />.
+    /// </para>
     /// </returns>
     public static async Task<IExecutionResult> ExecuteRequestAsync(
         this IRequestExecutorBuilder builder,
@@ -322,8 +325,7 @@ await BuildRequestExecutorAsync(builder, schemaName, cancellationToken)
     /// </returns>
     public static async Task<IResponseStream> ExecuteBatchRequestAsync(
         this IServiceProvider services,
-        IEnumerable<IQueryRequest> requestBatch,
-        bool allowParallelExecution = false,
+        IReadOnlyList<IQueryRequest> requestBatch,
         NameString schemaName = default,
         CancellationToken cancellationToken = default)
     {
@@ -332,7 +334,7 @@ await GetRequestExecutorAsync(services, schemaName, cancellationToken)
                 .ConfigureAwait(false);
 
         return await executor
-            .ExecuteBatchAsync(requestBatch, allowParallelExecution, cancellationToken)
+            .ExecuteBatchAsync(requestBatch, cancellationToken)
             .ConfigureAwait(false);
     }
 }

src/HotChocolate/Core/src/Execution/IRequestExecutor.cs

@@ -70,7 +70,6 @@ public interface IRequestExecutor
     /// Returns a stream of query results.
     /// </returns>
     Task<IResponseStream> ExecuteBatchAsync(
-        IEnumerable<IQueryRequest> requestBatch,
-        bool allowParallelExecution = false,
+        IReadOnlyList<IQueryRequest> requestBatch,
         CancellationToken cancellationToken = default);
 }

src/HotChocolate/Core/src/Execution/RequestExecutor.cs

@@ -15,6 +15,7 @@ internal sealed class RequestExecutor : IRequestExecutor
     private readonly RequestDelegate _requestDelegate;
     private readonly BatchExecutor _batchExecutor;
     private readonly ObjectPool<RequestContext> _contextPool;
+    private readonly bool _parallelBatching;
 
     public RequestExecutor(
         ISchema schema,
@@ -103,8 +104,7 @@ internal sealed class RequestExecutor : IRequestExecutor
     }
 
     public Task<IResponseStream> ExecuteBatchAsync(
-        IEnumerable<IQueryRequest> requestBatch,
-        bool allowParallelExecution = false,
+        IReadOnlyList<IQueryRequest> requestBatch,
         CancellationToken cancellationToken = default)
     {
         if (requestBatch is null)

src/HotChocolate/Core/src/Execution/RequestExecutorProxy.cs

@@ -9,9 +9,9 @@ namespace HotChocolate.Execution;
 /// The <see cref="RequestExecutorProxy"/> is a helper class that represents a executor for
 /// one specific schema and handles the resolving and hot-swapping the specific executor.
 /// </summary>
-public class RequestExecutorProxy : IDisposable
+public sealed class RequestExecutorProxy : IDisposable
 {
-    private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
+    private readonly SemaphoreSlim _semaphore = new(1, 1);
     private readonly IRequestExecutorResolver _executorResolver;
     private readonly NameString _schemaName;
     private IRequestExecutor? _executor;
@@ -82,18 +82,14 @@ await executor
     /// <param name="requestBatch">
     /// The GraphQL request batch.
     /// </param>
-    /// <param name="allowParallelExecution">
-    /// Defines if the executor is allowed to execute the batch in parallel.
-    /// </param>
     /// <param name="cancellationToken">
     /// The cancellation token.
     /// </param>
     /// <returns>
     /// Returns a stream of query results.
     /// </returns>
     public async Task<IResponseStream> ExecuteBatchAsync(
-        IEnumerable<IQueryRequest> requestBatch,
-        bool allowParallelExecution = false,
+        IReadOnlyList<IQueryRequest> requestBatch,
         CancellationToken cancellationToken = default)
     {
         if (requestBatch == null)
@@ -107,7 +103,7 @@ await GetRequestExecutorAsync(cancellationToken)
 
         IResponseStream result =
             await executor
-                .ExecuteBatchAsync(requestBatch, allowParallelExecution, cancellationToken)
+                .ExecuteBatchAsync(requestBatch, cancellationToken)
                 .ConfigureAwait(false);
 
         return result;
@@ -196,13 +192,7 @@ private void EvictRequestExecutor(object? sender, RequestExecutorEvictedEventArg
 
     public void Dispose()
     {
-        Dispose(true);
-        GC.SuppressFinalize(this);
-    }
-
-    protected virtual void Dispose(bool disposing)
-    {
-        if (!_disposed && disposing)
+        if (!_disposed)
         {
             _executor = null;
             _semaphore.Dispose();

src/HotChocolate/Core/src/Execution/Serialization/MultiPartResponseStreamFormatter.cs

@@ -81,7 +81,7 @@ public sealed partial class MultiPartResponseStreamFormatter : IResponseStreamFo
             {
                 await WriteResultAsync(result, outputStream, ct).ConfigureAwait(false);
 
-                if (result.HasNext ?? true)
+                if (result.HasNext ?? false)
                 {
                     await WriteNextAsync(outputStream, ct).ConfigureAwait(false);
                     await outputStream.FlushAsync(ct).ConfigureAwait(false);
@@ -119,7 +119,7 @@ public sealed partial class MultiPartResponseStreamFormatter : IResponseStreamFo
         await outputStream.WriteAsync(CrLf, 0, CrLf.Length, ct).ConfigureAwait(false);
     }
 
-    private async Task WriteResultHeaderAsync(
+    private static async Task WriteResultHeaderAsync(
         Stream outputStream,
         CancellationToken ct)
     {
@@ -134,7 +134,7 @@ public sealed partial class MultiPartResponseStreamFormatter : IResponseStreamFo
         await outputStream.WriteAsync(CrLf, 0, CrLf.Length, ct).ConfigureAwait(false);
     }
 
-    private async Task WriteNextAsync(
+    private static async Task WriteNextAsync(
         Stream outputStream,
         CancellationToken ct)
     {
@@ -143,7 +143,7 @@ public sealed partial class MultiPartResponseStreamFormatter : IResponseStreamFo
         await outputStream.WriteAsync(CrLf, 0, CrLf.Length, ct).ConfigureAwait(false);
     }
 
-    private async Task WriteEndAsync(
+    private static async Task WriteEndAsync(
         Stream outputStream,
         CancellationToken ct)
     {