/// <summary>
/// 2.5 WhenAny; note that when first task completes, others continue work
/// </summary>
/// <param name="span"></param>
/// <returns></returns>
public static async Task CalcUntilTimeout(TimeSpan span)
{
Console.WriteLine($"Starting with timeout span in seconds = {span.TotalSeconds}");
using var cts = new CancellationTokenSource(span);
CancellationTokenSource cancelTokenSource = new CancellationTokenSource();
Task <long> work = CustomAwaiter.TryAwaitCustomType(cancelTokenSource.Token);
Task timeout = Task.Delay(Timeout.InfiniteTimeSpan, cts.Token);
try
{
//both Tasks will work to completion until something cancels work!
Task completedTask = await Task.WhenAny(timeout, work);
if (completedTask == timeout)
{
cancelTokenSource.Cancel();
Console.WriteLine("Timeout task completed before calculations");
}
else
{
Console.WriteLine($"Got {work.Result} from WhenAll Task");
}
}
catch (TaskCanceledException)
{
Console.WriteLine("TaskCanceledException");
}
}
//also there is AsyncEx lib with OrderByCompletion method
//it returns array of tasks which will complete in order
public static async Task <long> Calc()
{
List <Task <long> > tasks = new List <Task <long> >();
foreach (var unused in Enumerable.Range(0, 5))
{
tasks.Add(CustomAwaiter.TryAwaitCustomType(CancellationToken.None));
}
long acc = 0L;
foreach (var t in tasks)
{
//wait for tasks in parallel, but we dont care which finishes first
//because we process results sequentially
var ret = await t;
acc += ret;
}
// var test = tasks.Select(async tq =>
// {
// var ret = await tq;
// acc += ret;
// }).ToArray();
// await Task.WhenAll(test);
async Task <int> DelayAndReturn(int val)
{
await Task.Delay(val);
return(val);
}
var tasks1 = new[] { DelayAndReturn(200), DelayAndReturn(400), DelayAndReturn(100) };
var proc = tasks1.Select(async t =>
{
var r = await t;
Console.WriteLine(r);
}).ToArray(); //start all tasks
await Task.WhenAll(proc); //and wait for them to finish
//100-200-400 because all tasks work in parallel
//wait one task after another
var tasks2 = new[] { DelayAndReturn(200), DelayAndReturn(400), DelayAndReturn(100) };
foreach (var task in tasks2)
{
var r = await task;
Console.WriteLine(r);
}
//200-400-100 because tasks are started one after another
return(acc);
}
public static async Task CalcWithDelays()
{
for (int i = 0; i < 3; i++)
{
var current = DateTime.Now;
await CustomAwaiter.TryAwaitCustomType(CancellationToken.None);
await Task.Delay(i *1500);
Console.WriteLine($"Total time was {(DateTime.Now -current).TotalMilliseconds} + with current delay {i*1500}");
}
}