public async Task It_returns_same_value_to_concurrent_requests()
{
var seed = 0;
var barrier = new Barrier(3);
var producer = new PipelineStep <int>(() => Task.FromResult(++seed));
var firstConsumer = Task.Run(() =>
{
barrier.SignalAndWait();
return(producer.GetLatestAsync());
});
var secondConsumer = Task.Run(() =>
{
barrier.SignalAndWait();
return(producer.GetLatestAsync());
});
var thirdConsumer = Task.Run(() =>
{
barrier.SignalAndWait();
return(producer.GetLatestAsync());
});
var values = await Task.WhenAll(firstConsumer, secondConsumer, thirdConsumer);
values.Should().HaveCount(3).And.OnlyContain(i => i == 1);
}
public async Task When_invalidated_while_producing_a_value_the_consumer_waiting_will_wait_for_latest_production_to_be_finished()
{
var seed = 0;
var barrier = new Barrier(2);
PipelineStep <int> producer = null;
producer = new PipelineStep <int>(() =>
{
// will require all consumer to reach this point to move on
barrier.SignalAndWait(3.Seconds());
barrier.RemoveParticipant();
producer.Invalidate();
return(Task.FromResult(Interlocked.Increment(ref seed)));
});
var values = await Task.WhenAll(
producer.GetLatestAsync(),
producer.GetLatestAsync());
values.Should().BeEquivalentTo(2, 2);
// var values = await Task.WhenAll(firstConsumer, secondConsumer);
// values.Should().HaveCount(2).And.OnlyContain(i => i == 2);
}
public async Task It_produces_a_new_value_when_invalidated()
{
var seed = 0;
var producer = new PipelineStep <int>(() => Task.FromResult(Interlocked.Increment(ref seed)));
var value = await producer.GetLatestAsync();
value.Should().Be(1);
producer.Invalidate();
var newValue = await producer.GetLatestAsync();
newValue.Should().Be(2);
}
public async Task It_retains_the_latest_value()
{
var seed = 0;
var producer = new PipelineStep <int>(() => Task.FromResult(Interlocked.Increment(ref seed)));
var value1 = await producer.GetLatestAsync();
var value2 = await producer.GetLatestAsync();
var value3 = await producer.GetLatestAsync();
value1.Should().Be(1);
value2.Should().Be(1);
value3.Should().Be(1);
}
public async Task It_produces_a_new_value_when_there_is_none()
{
var producer = new PipelineStep <string>(() => Task.FromResult("something"));
var value = await producer.GetLatestAsync();
value.Should().Be("something");
}
public async Task When_invalidated_while_producing_a_value_the_consumer_waiting_will_wait_for_latest_production_to_be_finished()
{
var seed = 0;
var consumerBarrier = new Barrier(2);
var producerBarrier = new Barrier(2);
var producer = new PipelineStep <int>(() =>
{
// will require all consumer to reach this point to move on
producerBarrier.SignalAndWait(2.Seconds());
return(Task.FromResult(Interlocked.Increment(ref seed)));
});
var firstConsumer = Task.Run(() =>
{
var task = producer.GetLatestAsync();
// block waiting for the other consumer
consumerBarrier.SignalAndWait(2.Seconds());
return(task);
}
);
var secondConsumer = Task.Run(() =>
{
// now both consumer reached the barrier
consumerBarrier.SignalAndWait(2.Seconds());
producer.Invalidate();
// let the firs request fire
producerBarrier.RemoveParticipant();
// second request after invalidation
var task = producer.GetLatestAsync();
return(task);
}
);
var values = await Task.WhenAll(firstConsumer, secondConsumer);
values.Should().HaveCount(2).And.OnlyContain(i => i == 2);
}
public async Task It_returns_same_value_to_concurrent_requests()
{
var seed = 0;
var barrier = new Barrier(3);
var producer = new PipelineStep <int>(() =>
{
barrier.SignalAndWait(2.Seconds());
return(Task.FromResult(++seed));
});
var values = await Task.WhenAll(Enumerable.Range(0, 3)
.AsParallel()
.Select((_) => producer.GetLatestAsync()));
values.Should().HaveCount(3).And.OnlyContain(i => i == 1);
}
public async Task It_remains_invalid_if_exceptions_are_thrown()
{
var seed = 0;
var producer = new PipelineStep <int>(() =>
{
var next = Interlocked.Increment(ref seed);
if (next == 1)
{
throw new InvalidOperationException();
}
return(Task.FromResult(next));
});
producer.Awaiting(p => p.GetLatestAsync())
.Should()
.Throw <InvalidOperationException>();
var value = await producer.GetLatestAsync();
value.Should().Be(2);
}
