[WIP] avoid form read before reaching endpoint handler code

src/Http/HttpAbstractions.slnf

@@ -47,6 +47,7 @@
       "src\\Http\\WebUtilities\\perf\\Microbenchmarks\\Microsoft.AspNetCore.WebUtilities.Microbenchmarks.csproj",
       "src\\Http\\WebUtilities\\src\\Microsoft.AspNetCore.WebUtilities.csproj",
       "src\\Http\\WebUtilities\\test\\Microsoft.AspNetCore.WebUtilities.Tests.csproj",
+      "src\\Http\\samples\\FileManagerSample\\FileManagerSample.csproj",
       "src\\Http\\samples\\MinimalSampleOwin\\MinimalSampleOwin.csproj",
       "src\\Http\\samples\\MinimalSample\\MinimalSample.csproj",
       "src\\Http\\samples\\SampleApp\\HttpAbstractions.SampleApp.csproj",

src/Http/samples/FileManagerSample/FileController.cs

@@ -0,0 +1,117 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Mvc;
+
+namespace FileManagerSample;
+
+[ApiController]
+[Route("controller")]
+public class FileController : ControllerBase
+{
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/controller/upload
+    [HttpPost]
+    [Route("upload")]
+    public async Task<IActionResult> Upload()
+    {
+        // 1. endpoint handler
+        // 2. form feature initialization
+        // 3. calling `Request.Form.Files.First()`
+        // 4. calling `FormFeature.InnerReadFormAsync()`
+
+        if (!Request.HasFormContentType)
+        {
+            return BadRequest("The request does not contain a valid form.");
+        }
+
+        // calling ReadFormAsync allows to await for form read (not blocking file read, opposite to `Request.Form.Files.`)
+        var formFeature = Request.HttpContext.Features.GetRequiredFeature<IFormFeature>();
+        await formFeature.ReadFormAsync(HttpContext.RequestAborted);
+
+        var file = Request.Form.Files.First();
+        return Ok($"File '{file.Name}' uploaded.");
+    }
+
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/controller/upload-cts
+    [HttpPost]
+    [Route("upload-cts")]
+    public async Task<IActionResult> UploadCts(CancellationToken cancellationToken)
+    {
+        // 1. form feature initialization
+        // 2.calling `FormFeature.InnerReadFormAsync()`
+        // 3. endpoint handler
+        // 4. calling `Request.Form.Files.First()`
+
+        if (!Request.HasFormContentType)
+        {
+            return BadRequest("The request does not contain a valid form.");
+        }
+
+        var formFeature = Request.HttpContext.Features.GetRequiredFeature<IFormFeature>();
+        await formFeature.ReadFormAsync(cancellationToken);
+
+        var file = Request.Form.Files.First();
+        return Ok($"File '{file.Name}' uploaded.");
+    }
+
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/controller/upload-cts-noop
+    [HttpPost]
+    [Route("upload-cts-noop")]
+    public IActionResult UploadCtsNoop(CancellationToken cancellationToken)
+    {
+        // 1. form feature initialization
+        // 2.calling `FormFeature.InnerReadFormAsync()`
+        // 3. endpoint handler
+
+        return Ok($"Noop completed.");
+    }
+
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/controller/upload-str-noop
+    [HttpPost]
+    [Route("upload-str-noop")]
+    public IActionResult UploadStrNoop(string str)
+    {
+        // 1. form feature initialization
+        // 2.calling `FormFeature.InnerReadFormAsync()`
+        // 3. endpoint handler
+
+        return Ok($"Str completed.");
+    }
+
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/controller/upload-str-query
+    [HttpPost]
+    [Route("upload-str-query")]
+    public IActionResult UploadStrQuery([FromQuery] string str)
+    {
+        // 1. form feature initialization
+        // 2.calling `FormFeature.InnerReadFormAsync()`
+        // 3. endpoint handler
+
+        return Ok($"Query completed.");
+    }
+
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile_50mb.dat" http://localhost:5000/controller/upload-route-param/1
+    [HttpPost]
+    [Route("upload-route-param/{id}")]
+    public IActionResult UploadQueryParam(string id)
+    {
+        // 1. form feature initialization
+        // 2.calling `FormFeature.InnerReadFormAsync()`
+        // 3. endpoint handler
+
+        return Ok($"Query completed: query id = {id}");
+    }
+
+    // curl -X POST -F "file=@D:\.other\big-files\bigfile_50mb.dat" http://localhost:5000/controller/upload-file
+    [HttpPost]
+    [Route("upload-file")]
+    public IActionResult UploadForm([FromForm] IFormFile file)
+    {
+        // 1. form feature initialization
+        // 2.calling `FormFeature.InnerReadFormAsync()`
+        // 3. endpoint handler
+
+        return Ok($"File '{file.FileName}' uploaded.");
+    }
+}

src/Http/samples/FileManagerSample/FileManagerSample.csproj

@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
+    <Nullable>enable</Nullable>
+    <EnableRequestDelegateGenerator>true</EnableRequestDelegateGenerator>
+    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
+    <IsTrimmable>true</IsTrimmable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Reference Include="Microsoft.AspNetCore" />
+    <Reference Include="Microsoft.AspNetCore.Diagnostics" />
+    <Reference Include="Microsoft.AspNetCore.Hosting" />
+    <Reference Include="Microsoft.AspNetCore.Http" />
+    <Reference Include="Microsoft.AspNetCore.Http.Results" />
+    <!-- Mvc.Core is referenced only for its attributes -->
+    <Reference Include="Microsoft.AspNetCore.Mvc.Core" />
+    <Reference Include="Microsoft.AspNetCore.Mvc" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="$(RepoRoot)/src/Http/Http.Extensions/gen/Microsoft.AspNetCore.Http.RequestDelegateGenerator/Microsoft.AspNetCore.Http.RequestDelegateGenerator.csproj" OutputItemType="Analyzer" />
+  </ItemGroup>
+
+</Project>

src/Http/samples/FileManagerSample/Program.cs

@@ -0,0 +1,73 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Reflection;
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Http.Metadata;
+using Microsoft.AspNetCore.Mvc;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.WebHost.ConfigureKestrel(options =>
+{
+    // if not present, will throw similar exception:
+    //   Microsoft.AspNetCore.Server.Kestrel.Core.BadHttpRequestException: Request body too large. The max request body size is 30000000 bytes.
+    options.Limits.MaxRequestBodySize = 6L * 1024 * 1024 * 1024; // 6 GB
+
+    // optional: timeout settings
+    options.Limits.KeepAliveTimeout = TimeSpan.FromMinutes(10);
+    options.Limits.RequestHeadersTimeout = TimeSpan.FromMinutes(10);
+});
+
+builder.Services.Configure<FormOptions>(options =>
+{
+    options.MultipartBodyLengthLimit = 10L * 1024 * 1024 * 1024; // 10 GB
+});
+
+#pragma warning disable IL2026 // Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code
+builder.Services.AddControllers();
+#pragma warning restore IL2026 // Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code
+
+var app = builder.Build();
+app.Logger.LogInformation($"Current process ID: {Environment.ProcessId}");
+
+app.MapGet("/plaintext", () => "Hello, World!");
+
+// curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/upload-cts
+app.MapPost("/upload-cts", (HttpRequest request, CancellationToken cancellationToken) =>
+{
+    // 1. endpoint handler
+    // 2. form feature initialization
+    // 3. calling `Request.Form.Files.First()`
+    // 4. calling `FormFeature.InnerReadFormAsync()`
+
+    if (!request.HasFormContentType)
+    {
+        return Results.BadRequest("The request does not contain a valid form.");
+    }
+
+    var file = request.Form.Files.First();
+    return Results.Ok($"File '{file.Name}' uploaded.");
+});
+
+// curl -X POST -F "file=@D:\.other\big-files\bigfile.dat" http://localhost:5000/upload
+app.MapPost("/upload", (HttpRequest request) =>
+{
+    // 1. endpoint handler
+    // 2. form feature initialization
+    // 3. calling `Request.Form.Files.First()`
+    // 4. calling `FormFeature.InnerReadFormAsync()`
+
+    if (!request.HasFormContentType)
+    {
+        return Results.BadRequest("The request does not contain a valid form.");
+    }
+
+    var file = request.Form.Files.First();
+    return Results.Ok($"File '{file.Name}' uploaded.");
+});
+
+app.MapControllers();
+
+app.Run();

src/Http/samples/FileManagerSample/Properties/launchSettings.json

@@ -0,0 +1,13 @@
+{
+  "profiles": {
+    "HttpApiSampleApp": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "http://localhost:5000",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

src/Http/samples/FileManagerSample/appsettings.Development.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft": "Warning",
+      "Microsoft.Hosting.Lifetime": "Information"
+    }
+  }
+}

src/Http/samples/FileManagerSample/appsettings.json

@@ -0,0 +1,10 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft": "Warning",
+      "Microsoft.Hosting.Lifetime": "Information"
+    }
+  },
+  "AllowedHosts": "*"
+}

src/Mvc/Mvc.Core/src/ModelBinding/FormValueProviderFactory.cs

@@ -22,14 +22,28 @@ public Task CreateValueProviderAsync(ValueProviderFactoryContext context)
         var request = context.ActionContext.HttpContext.Request;
         if (request.HasFormContentType)
         {
+            RegisterValueProvider(context);
+
             // Allocating a Task only when the body is form data.
-            return AddValueProviderAsync(context);
+            //return AddValueProviderAsync(context);
         }
 
         return Task.CompletedTask;
     }
 
+    private static void RegisterValueProvider(ValueProviderFactoryContext context)
+    {
+        var valueProvider = new FormValueProvider(
+            BindingSource.Form,
+            new FormCollection(fields: null, files: null),
+            CultureInfo.CurrentCulture);
+
+        context.ValueProviders.Add(valueProvider);
+    }
+
+#pragma warning disable IDE0051 // Remove unused private members
     private static async Task AddValueProviderAsync(ValueProviderFactoryContext context)
+#pragma warning restore IDE0051 // Remove unused private members
     {
         var request = context.ActionContext.HttpContext.Request;
         IFormCollection form;

src/Mvc/Mvc.Core/src/ModelBinding/JQueryFormValueProviderFactory.cs

@@ -6,6 +6,7 @@
 using System.Globalization;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Core;
+using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding;
 
@@ -22,14 +23,28 @@ public Task CreateValueProviderAsync(ValueProviderFactoryContext context)
         var request = context.ActionContext.HttpContext.Request;
         if (request.HasFormContentType)
         {
+            RegisterValueProvider(context);
+
             // Allocating a Task only when the body is form data.
-            return AddValueProviderAsync(context);
+            // return AddValueProviderAsync(context);
         }
 
         return Task.CompletedTask;
     }
 
+    private static void RegisterValueProvider(ValueProviderFactoryContext context)
+    {
+        var valueProvider = new JQueryFormValueProvider(
+            BindingSource.Form,
+            values: new Dictionary<string, StringValues>(),
+            CultureInfo.CurrentCulture);
+
+        context.ValueProviders.Add(valueProvider);
+    }
+
+#pragma warning disable IDE0051 // Remove unused private members
     private static async Task AddValueProviderAsync(ValueProviderFactoryContext context)
+#pragma warning restore IDE0051 // Remove unused private members
     {
         var request = context.ActionContext.HttpContext.Request;