action不能await

class Program
{
    static int i = 0;

    static async Task Main(string[] args)
    {
        for (int i = 0; i < 3; i++)
        {
            await RunInNewScopeAsync(async () =>
            {
                var n1 = await DoWorkAsync();
                Console.WriteLine(n1);
            });
        }

        Console.WriteLine("finished...");
        Console.ReadLine();
    }

    static Task RunInNewScopeAsync(Action action)
    {
        action();
        return Task.CompletedTask;
    }

    static async Task<string> DoWorkAsync()
    {
        await Task.Delay(1000);
        return "mxd " + i++;
    }
}

　　

 今天审查一处代码（

完整实例：

using System;
using System.Threading;
using System.Threading.Tasks;

class Program
{
    static int i = 0;
    // 异步方法：模拟一个需要等待的操作
    static async Task<string> DoWorkAsync()
    {
        // 使用 Task.Delay 进行异步等待 -  推荐
        await Task.Delay(1000); // 等待3秒，期间线程可以去处理其他任务

        return "mxd " + i++;
    }

    static void RunInNewScope(Action action)
    {
        action();
    }

    static  Task RunInNewScopeAsync(Action action)
    {
        action();
        return Task.CompletedTask;
    }

    static T RunInNewScopeFunc<T>(Func<T> func)
    {
        return func();
    }

    // 主方法必须是 async 才能使用 await
    static async Task Main(string[] args)
    {
        //for (int i = 0; i < 100; i++)
        //{
        //    // 调用异步方法并等待其完成
        //    var n1 = await DoWorkAsync();
        //    Console.WriteLine(n1);
        //}

        for (int i = 0; i < 3; i++)
        {
            await RunInNewScopeAsync(async () =>
            {
                var n1 = await DoWorkAsync();
                Console.WriteLine(n1);
            });
        }

        //for (int i = 0; i < 3; i++)
        //{
        //    await RunInNewScopeFunc(async () =>
        //     {
        //         var n1 = await DoWorkAsync();
        //         Console.WriteLine(n1);
        //         return n1;
        //     });
        //}

        Console.WriteLine("finished...");

        Console.ReadLine();

    }
}

　　

遍历场次，切换数据库执行逻辑,，截图是简单示例），发现action的缺点；综合对比，后续建议都用func.

其他示例：

class Program
{
    static int i = 0;

    static async Task Main(string[] args)
    {
        for (int i = 0; i < 3; i++)
        {
            await RunInNewScopeAsync(async () =>
            {
                var n1 = await DoWorkAsync();
                Console.WriteLine(n1);
            });
        }

        Console.WriteLine("finished...");
        Console.ReadLine();
    }

    static async Task RunInNewScopeAsync(Action action)
    {
        action();
    }

    static async Task<string> DoWorkAsync()
    {
        await Task.Delay(1000);
        return "mxd " + i++;
    }
}