http://msdn.microsoft.com/en-us/library/dd988458.aspx
UPD:
so, let's discuss this article then: http://msdn.microsoft.com/en-us/library/dd997396.aspx
I've changed that code a little:
static void Main()
{
var tokenSource2 = new CancellationTokenSource();
CancellationToken ct = tokenSource2.Token;
var task = Task.Factory.StartNew(() =>
{
// Were we already canceled?
ct.ThrowIfCancellationRequested();
bool moreToDo = true;
Thread.Sleep(5000);
while (moreToDo)
{
// Poll on this property if you have to do
// other cleanup before throwing.
if (ct.IsCancellationRequested)
{
Console.WriteLine("exit");
// Clean up here, then...
ct.ThrowIfCancellationRequested();
}
}
}, tokenSource2.Token); // this parameter useless
Console.WriteLine("sleep");
Thread.Sleep(2000);
Console.WriteLine("cancel");
tokenSource2.Cancel();
// Just continue on this thread, or Wait/WaitAll with try-catch:
try
{
task.Wait();
}
catch (AggregateException e)
{
foreach (var v in e.InnerExceptions)
{
Console.WriteLine(e.Message + " " + v.Message);
}
}
Console.ReadKey();
}
UPD: Well, this changes only task.IsCanceled
, which is imho useless, due to I still ought to implement all manually.
Due to comments, I'm posting another answer.
Consider the following code:
var tokenSource = new CancellationTokenSource();
CancellationToken ct = tokenSource.Token;
tokenSource.Cancel();
var task = Task.Factory.StartNew(() =>
{
// Were we already canceled?
ct.ThrowIfCancellationRequested();
// do some processing
});
Even if the call tokenSource.Cancel()
is issued before the task was actually started, you'll still allocate a worker thread from thread pool, so you'll waste some system resources.
But when you specify token argument in Task.Factory.StartNew
, the task will be cancelled immediately, without allocating a worker thread.