C# 异步转同步 TaskCompletionSource

勤奋不止 2020-12-24

展开全文

本文通过TaskCompletionSource，实现异步转同步

首先有一个异步方法，如下异步任务延时2秒后，返回一个结果

1     private static async Task<string> TestWithResultAsync()
2     {
3         Debug.WriteLine("1. 异步任务start……");
4         await Task.Delay(2000);
5         Debug.WriteLine("2. 异步任务end……");
6         return "2秒以后";
7     }

如何使用TaskCompletionSource将此异步方法转成同步呢？

1     private void TaskCompleteSourceButton_OnClick(object sender, RoutedEventArgs e)
2     {
3         var result = AwaitByTaskCompleteSource(TestWithResultAsync);
4         Debug.WriteLine($"4. TaskCompleteSource_OnClick end:{result}");
5     }

TaskCompletionSource使用步骤：

获取var sourceTask =TaskCompletionSource.Task，
等待此sourceTask结果-sourceTask.Result
设置设置sourceTask.Result的结果值

 1     private string AwaitByTaskCompleteSource(Func<Task<string>> func)
 2     {
 3         var taskCompletionSource = new TaskCompletionSource<string>();
 4         var task1 = taskCompletionSource.Task;
 5         Task.Run(async () =>
 6         {
 7             var result = await func.Invoke();
 8             taskCompletionSource.SetResult(result);
 9         });
10         var task1Result = task1.Result;
11         Debug.WriteLine($"3. AwaitByTaskCompleteSource end:{task1Result}");
12         return task1Result;
13     }