C#中間件如何優雅地處理超時請求

在C#中，我們可以使用中間件來處理超時請求。以下是一個簡單的示例，展示了如何優雅地處理超時請求：

1. 首先，創建一個名為TimeoutMiddleware的類，該類將包含我們的超時處理邏輯。

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;

public class TimeoutMiddleware
{
    private readonly RequestDelegate _next;
    private readonly TimeSpan _timeout;

    public TimeoutMiddleware(RequestDelegate next, TimeSpan timeout)
    {
        _next = next;
        _timeout = timeout;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        using var cts = new CancellationTokenSource();
        var task = _next(context);

        if (await Task.WhenAny(task, Task.Delay(_timeout, cts.Token)) == task)
        {
            // The request completed within the timeout period.
            cts.Cancel();
            await task;
        }
        else
        {
            // The request timed out.
            context.Response.StatusCode = 408; // Request Timeout
            await context.Response.WriteAsync("Request timed out.");
        }
    }
}

2. 接下來，創建一個擴展方法，以便于在Startup類中配置中間件。

using Microsoft.AspNetCore.Builder;
using System;

public static class TimeoutMiddlewareExtensions
{
    public static IApplicationBuilder UseTimeoutMiddleware(this IApplicationBuilder builder, TimeSpan timeout)
    {
        return builder.UseMiddleware<TimeoutMiddleware>(timeout);
    }
}

3. 最后，在Startup類的Configure方法中配置中間件。

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        // Add your services here...
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        // Configure the timeout middleware with a 5-second timeout.
        app.UseTimeoutMiddleware(TimeSpan.FromSeconds(5));

        // Add your other middleware and endpoints here...
    }
}

現在，當請求超過5秒未完成時，中間件將返回一個408 Request Timeout狀態碼。你可以根據需要調整超時時間。