/// <summary>
/// Executes the <see cref="Func{T}"/> provided n times, awaiting for the task to be completed, limiting the
/// concurrency.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="action"></param>
/// <param name="times"></param>
/// <param name="limit"></param>
/// <returns>A Task that can be awaited.</returns>
public static Task TimesLimit <T>(Func <Task <T> > action, int times, int limit)
{
var tcs = new TaskCompletionSource <bool>();
var counter = new SendReceiveCounter();
for (var i = 0; i < limit; i++)
{
SendNew(action, tcs, counter, times);
}
return(tcs.Task);
}
private static void SendNew <T>(Func <Task <T> > action, TaskCompletionSource <bool> tcs, SendReceiveCounter counter, int maxLength)
{
var sendCount = counter.IncrementSent();
if (sendCount > maxLength)
{
return;
}
var t1 = action();
t1.ContinueWith(t =>
{
if (t.Exception != null)
{
// ReSharper disable once AssignNullToNotNullAttribute
tcs.TrySetException(t.Exception.InnerException);
return;
}
var received = counter.IncrementReceived();
if (received == maxLength)
{
tcs.TrySetResult(true);
return;
}
SendNew(action, tcs, counter, maxLength);
}, TaskContinuationOptions.ExecuteSynchronously);
}
private static void SendNew <T>(Func <Task <T> > action, TaskCompletionSource <bool> tcs, SendReceiveCounter counter, int maxLength)
{
var sendCount = counter.IncrementSent();
if (sendCount > maxLength)
{
return;
}
Task.Run(async() =>
{
try
{
await action().ConfigureAwait(false);
}
catch (Exception ex)
{
tcs.TrySetException(ex);
return;
}
var received = counter.IncrementReceived();
if (received == maxLength)
{
tcs.TrySetResult(true);
return;
}
SendNew(action, tcs, counter, maxLength);
}).Forget();
}
