public async Task TestBasicUsage()
{
using var queue = new ResultNagleQueue <int, int>(
maxDegreeOfParallelism: 1,
interval: TimeSpan.FromMilliseconds(1),
batchSize: 10);
queue.Start(async values =>
{
await Task.Yield();
return(values.Select(i => i + 1).ToList());
});
var values = new[] { 1, 20, 50, 121 };
var resultTasks = new List <Task <int> >();
foreach (var value in values)
{
resultTasks.Add(queue.EnqueueAsync(value));
}
var results = await Task.WhenAll(resultTasks);
for (int i = 0; i < values.Length; i++)
{
results[i].Should().Be(values[i] + 1);
}
}
public async Task AvoidUnobservedExceptions()
{
// This test makes sure that when an error is happening in the callback provided to ResultNagleQueue
// the errors won't became unhandled and the operation won't stuck.
Exception unobservedException = null;
EventHandler <UnobservedTaskExceptionEventArgs> handler = (sender, args) =>
{
unobservedException = args.Exception;
};
try
{
TaskScheduler.UnobservedTaskException += handler;
var task = createAndUseResultNagleQueue();
_outputHelper.WriteLine($"Got t. Scheduling ContinueWith. Status={task.Status}");
var continuationTask = task.ContinueWith(
t =>
{
_outputHelper.WriteLine("Continue with");
var e = t.Exception?.InnerExceptions.FirstOrDefault();
_outputHelper.WriteLine($"Continuation: {t.Status}, E: {e?.GetHashCode()}");
});
_outputHelper.WriteLine("Before delay");
await Task.Delay(1000);
_outputHelper.WriteLine("Forcing full GC");
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
unobservedException.Should().BeNull();
_outputHelper.WriteLine($"Awaiting continuation. task.Status={task.Status}, continuationTask.Status={continuationTask.Status}");
await continuationTask;
}
finally
{
_outputHelper.WriteLine("In finally");
TaskScheduler.UnobservedTaskException -= handler;
}
async Task createAndUseResultNagleQueue()
{
using var queue = new ResultNagleQueue <int, int>(
maxDegreeOfParallelism: 1,
interval: TimeSpan.FromMilliseconds(1),
batchSize: 2);
queue.Start(
async list =>
{
await Task.Yield();
_outputHelper.WriteLine("Inside Start's callback.");
var e = new Exception(string.Join(", ", list.Select(n => n.ToString())));
throw e;
});
// Enqueue more item then the batch size.
// It is very important to enqueue more item then the batch size
// to make sure the callback is called more than once.
// If the callback will never be called the second time
// the third EnqueueAsync will never be finished causing two issues:
// this method will never be finished and TaskUnobservedException will be raised
// when queue instance will go out of scope.
_outputHelper.WriteLine("Before EnqueueAsync");
var t1 = queue.EnqueueAsync(1);
var t2 = queue.EnqueueAsync(2);
var t3 = queue.EnqueueAsync(3);
_outputHelper.WriteLine("Before Task.WhenAll");
await Task.WhenAll(t1, t2, t3);
_outputHelper.WriteLine("After EnqueueAsync");
}
}