/// <summary>
/// Handler1的等价代码
/// </summary>
/// <param name="vv"></param>
/// <returns></returns>
public static Task Handler1No_awiter(int vv)
{
Handler1StateMachine h1s = new Handler1StateMachine();
h1s.vv = vv;
h1s.state = -1;
h1s.builder = System.Runtime.CompilerServices.AsyncTaskMethodBuilder.Create();
h1s.builder.Start(ref h1s);
return(h1s.builder.Task);
}
/// <summary>
/// 官方的等价翻译
/// 翻译等价代码的技巧：
/// 按照原代码的顺序从上往下写，遇到await语句，就转成xxx.GetAwaiter(),并且定义一个对应的TaskAwaiter类型字段
/// 然后进入IsCompleted判断,每个await语句对应的判断块都类似，不同点：把state设为不同值，这里为方便阅读代码，按照代码顺序递增state的值
/// 关键方法：builder.AwaitUnsafeOnCompleted；这个方法不会阻塞，当前方法所在线程直接return，去执行其它任务，类库内部帮我们后续再回调到MoveNext
/// 然后定义一个标签位置，后续代码写在标签之后
/// </summary>
public void MoveNext()
{
//这里就是配合下面翻译的代码，做的配合工作
switch (this.state)
{
case 0:
goto block0;
case 1:
goto block1;
default:
break;
}
//翻译等价代码的技巧：
//按照原代码的顺序从上往下写，遇到await语句，就转成xxx.GetAwaiter(),并且定义一个对应的TaskAwaiter类型字段
//然后进入IsCompleted判断,每个await语句对应的判断块都类似，不同点：把state设为不同值，这里为方便阅读代码，按照代码顺序递增state的值
//然后定义一个标签位置，后续代码写在标签之后
Console.WriteLine("进入Handler1");
this.awaiterDelay2000 = Task.Delay(2000).GetAwaiter();
if (!this.awaiterDelay2000.IsCompleted)
{
this.state = 0;
Handler1StateMachine h1s = this;
this.builder.AwaitUnsafeOnCompleted(ref this.awaiterDelay2000, ref h1s);
return;
}
block0:
this.awaiterDelay2000.GetResult();
Console.WriteLine("执行完Task.Delay(2000)");
this.awaiterHandler2 = Program.Handler2(this.vv).GetAwaiter();
if (!this.awaiterHandler2.IsCompleted)
{
this.state = 1;
Handler1StateMachine h1s = this;
this.builder.AwaitUnsafeOnCompleted(ref this.awaiterHandler2, ref h1s);
return;
}
block1:
var rt = this.awaiterHandler2.GetResult();
this.value = rt;
Console.WriteLine("执行完Handler2");
this.state = -2;
this.builder.SetResult();
}
/// <summary>
/// 简单粗暴翻译
/// 翻译等价代码的技巧：
/// 按照原代码的顺序从上往下写，遇到await语句，就转成xxx.GetAwaiter(),并且定义一个对应的TaskAwaiter类型字段
/// 不做IsCompleted，全部利用builder.AwaitUnsafeOnCompleted方法结束当前方法，释放当前线程
/// 弊端：遇到Task.FromResult这种代码，就会有点浪费，因为没必要builder.AwaitUnsafeOnCompleted
/// </summary>
public void MoveNext2()
{
//翻译等价代码的技巧：
//按照原代码的顺序从上往下写，遇到await语句，就转成xxx.GetAwaiter(),并且定义一个对应的TaskAwaiter类型字段
//不做IsCompleted，全部利用builder.AwaitUnsafeOnCompleted方法结束当前方法，释放当前线程
//
Handler1StateMachine h1s = this;
switch (this.state)
{
case 0:
Console.WriteLine("进入Handler1");
this.awaiterDelay2000 = Task.Delay(2000).GetAwaiter();
this.state = 1;
this.builder.AwaitUnsafeOnCompleted(ref this.awaiterDelay2000, ref h1s);
return;
case 1:
this.awaiterDelay2000.GetResult();
Console.WriteLine("执行完Task.Delay(2000)");
this.awaiterHandler2 = Program.Handler2(this.vv).GetAwaiter();
this.state = 2;
this.builder.AwaitUnsafeOnCompleted(ref this.awaiterHandler2, ref h1s);
return;
case 2:
var rt = this.awaiterHandler2.GetResult();
this.value = rt;
Console.WriteLine("执行完Handler2");
this.state = 3;
this.builder.SetResult();
return;
default:
break;
}
}
