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TaskCompletionSource.cs
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TaskCompletionSource.cs
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using System;
using System.Net;
using System.Threading.Tasks;
namespace Demos
{
public class TaskCompletionSource
{
[Ignore]
public void Run()
{
var webReq = WebRequest.Create("http://www.google.com");
var task = FromAsync(webReq.BeginGetResponse, webReq.EndGetResponse)
.WithTimeout(100);
var cont1 = task.ContinueWith(t => Console.WriteLine(t.Result.Headers),
TaskContinuationOptions.OnlyOnRanToCompletion);
var cont2 = task.ContinueWith(t => Console.WriteLine("Task cancelled"),
TaskContinuationOptions.OnlyOnCanceled);
Task.WaitAny(cont1, cont2);
Console.ReadKey();
}
//
// Already implemented by Task.Factory.FromAsync().
//
public static Task<T> FromAsync<T>(Func<AsyncCallback, object, IAsyncResult> begin,
Func<IAsyncResult, T> end)
{
var tcs = new TaskCompletionSource<T>();
//
// The callback of the APM begin method reflects the state of the async call
// in the proxy task associated with the task completion source.
//
begin(iar =>
{
try
{
T result = end(iar);
tcs.SetResult(result);
}
catch (Exception e)
{
tcs.SetException(e);
}
}, null);
//
// Return the proxy task.
//
return tcs.Task;
}
}
}