使用计时器等待进程完成

Question

假设有两个按钮调用异步函数

  int packProcesses=0;  //the number of processes we are dealing with
    bool busy = false;  //are we busy?
   int v=10;
  private async void button5_Click(object sender, EventArgs e)
  {
    packProcesses++;
    busy = true;
    Trace.WriteLine("PROCESSES " + packProcesses + " busy? " + busy);
    //Do something
    var result = await DelayAndReturnAsync(v);
    //finished?
    packProcesses--;
    if (packProcesses <= 0) busy = false;
    Trace.WriteLine("Processes " + packProcesses + " busy? " + busy);
    }

    private async void button6_Click(object sender, EventArgs e)
     {
       packProcesses++;
       busy = true;
       Trace.WriteLine("PROCESSES " + packProcesses + " busy? " + busy);

        //Do something
        var result = await DelayAndReturnAsync(v);
        //finished?
        packProcesses--;
        if (packProcesses <= 0) busy = false;
        Trace.WriteLine("Processes " + packProcesses + " busy? " + busy);
        }

异步函数在哪里

 async Task<int>DelayAndReturnAsync(int val)
  {
   await Task.Delay(TimeSpan.FromSeconds(val)).ConfigureAwait(false);
   Trace.WriteLine("Time" + DateTime.Now);
    return val;
   }

我想要另一个按钮来调用这两个按钮。 如果我只是将两个单击功能一个接一个地放置，我将同时启动两个进程。

因为我希望一个进程在另一个进程之后启动

 private async void button8_Click(object sender, EventArgs e)
  {
  button5_Click(sender, e);
   do
    {
     await Task.Delay(1000);
     } while (busy);
    button6_Click(sender, e);
    }

我的想法来自this answer

这是个好主意吗？我不想为了做到这一点而阻塞 CPU。 有没有更好的方法来等待一个进程完成来启动另一个进程？

Answer 1

您可以将您的逻辑从处理程序内部移动到另一个方法：

private async void button1_Click(object sender, EventArgs e)
{
    await Process1();
}

private async Task Process1()
{
    packProcesses++;
    busy = true;
    Trace.WriteLine("PROCESSES " + packProcesses + " busy? " + busy);
    //Do something
    var result = await DelayAndReturnAsync(v);
    //finished?
    packProcesses--;
    if (packProcesses <= 0) busy = false;
    Trace.WriteLine("Processes " + packProcesses + " busy? " + busy);
}

private async void button2_Click(object sender, EventArgs e)
{
    await Process2();
}

private async Task Process2()
{
    packProcesses++;
    busy = true;
    Trace.WriteLine("PROCESSES " + packProcesses + " busy? " + busy);

    //Do something
    var result = await DelayAndReturnAsync(v);
    //finished?
    packProcesses--;
    if (packProcesses <= 0) busy = false;
    Trace.WriteLine("Processes " + packProcesses + " busy? " + busy);
}

然后你可以等待他们两个：

private async void button3_Click(object sender, EventArgs e)
{
    await Process1();
    await Process2();
}

Answer 2

如果可以的话，我会尽量避免让您的 button6_Click 和 button5_Click 方法返回 void。相反，如果您让他们返回Task，您可以await 他们。

private async Task button5_Click(object sender, EventArgs e) 
{ ... }

private async Task button8_Click(object sender, EventArgs e) 
{
     await button5_Click(sender, e);
     await button6_Click(sender, e);
}

编辑：

private async Task HandleButton5_Click() 
{
     ...
}    

private async void button5_Click(object sender, EventArgs e) 
{  
    await HandleButton5_Click();
}

private async void button8_Click(object sender, EventArgs e) 
{
     button5_Click(sender, e);
     button6_Click(sender, e);
}