public void OnlyOneThreadIsInsideThePreviousPipelineStagesGetValueFunctionAtATime()
{
var container = new Container();
int EnsureOnlyOne()
{
if (container.Thread != null)
{
throw new Exception();
}
container.Thread = Thread.CurrentThread;
if (container.Thread != Thread.CurrentThread)
{
throw new Exception();
}
container.Thread = null;
return(1);
}
var input = new DataRetrievalPipelineStage <int>("", EnsureOnlyOne);
var sut = new ThreadSafePipelineStage <int>(input);
var tasks = Enumerable.Repeat(0, 1000).Select(_ => Task.Run(sut.GetValue)).ToArray();
Task.WaitAll(tasks);
Assert.Pass("No exceptions were thrown, indicating that no concurrency issues were found.");
}
public void DataRetrievalAlwaysCallsTheSpecifiedFunctionOnGetValueCall()
{
var value = new ValueRepository(2);
var sut = new DataRetrievalPipelineStage <int>("name", value.GetValue);
PipelineAssert.Value(sut, value.Value);
Assert.AreEqual(1, value.NumCalls);
sut.GetValue();
sut.GetValue();
sut.GetValue();
sut.GetValue();
Assert.AreEqual(5, value.NumCalls);
}
public void ConcurrentRetrievalsRetrievesOnlyOnceFromUpstreamStage()
{
using var completeRetrievalFlag = new EventWaitHandle(false, EventResetMode.ManualReset);
using var semaphore = new SemaphoreSlim(0);
var input = new DataRetrievalPipelineStage <object>("", () => { completeRetrievalFlag.WaitOne(); return(new object()); });
var inputTest = input.AttachTestStage();
var sut = new ThreadSafePipelineStage <object>(inputTest);
object GetObject()
{
semaphore.Release();
return(sut.GetValue());
}
var task1 = Task.Run(GetObject);
var task2 = Task.Run(GetObject);
// Attempt to get both tasks to be inside the GetValue method of the pipeline stage.
// This is, sadly, the best we can do with the current design.
// At least we at this stage know that both tasks are in a running state.
var threeSeconds = TimeSpan.FromSeconds(3);
Assert.IsTrue(semaphore.Wait(threeSeconds));
Assert.IsTrue(semaphore.Wait(threeSeconds));
Thread.Sleep(threeSeconds);
completeRetrievalFlag.Set();
Assert.IsTrue(Task.WaitAll(new[] { task1, task2 }, threeSeconds));
var result1 = task1.Result;
var result2 = task2.Result;
Assert.AreSame(result1, result2);
}
