public void ShouldNotLeaveWaitersInQueueIfOperationIsCancelledAfterCallingRelease()
{
var @lock = new FifoSemaphore(1);
@lock.Acquire(CancellationToken.None);
try
{
var cts = new CancellationTokenSource();
cts.Cancel();
Assert.Throws <OperationCanceledException>(() => @lock.Acquire(cts.Token));
Assert.Empty(@lock._waitQueue);
cts = new CancellationTokenSource();
@lock.ForTestingPurposesOnly().JustBeforeAddingToWaitQueue += () => cts.Cancel();
Assert.Throws <OperationCanceledException>(() => @lock.Acquire(cts.Token));
Assert.Equal(1, @lock._waitQueue.Count);
Assert.True(@lock._waitQueue.First().IsCancelled);
}
finally
{
@lock.Release();
}
Assert.Empty(@lock._waitQueue);
}
public void ShouldNotLeaveWaitersInQueueIfTimeout()
{
var @lock = new FifoSemaphore(1);
@lock.Acquire(CancellationToken.None);
Assert.False(@lock.TryAcquire(TimeSpan.Zero, CancellationToken.None));
Assert.Empty(@lock._waitQueue);
}
public void RaceConditionBetweenCancellingAndReleasingWaiterFromTheQueue()
{
FifoSemaphore fs = new FifoSemaphore(2);
var cts = new CancellationTokenSource[4];
for (int i = 0; i < cts.Length; i++)
{
cts[i] = new CancellationTokenSource(TimeSpan.FromSeconds(5));
}
try
{
Parallel.For(0, 20, x =>
{
CancellationTokenSource cancellationTokenSource = cts[x % cts.Length];
while (cancellationTokenSource.IsCancellationRequested == false)
{
fs.Acquire(cancellationTokenSource.Token);
try
{
Thread.Sleep(13);
}
finally
{
fs.Release();
}
}
});
}
catch
{
// ignored
}
Assert.True(fs.TryAcquire(TimeSpan.Zero, CancellationToken.None));
try
{
Assert.True(fs.TryAcquire(TimeSpan.Zero, CancellationToken.None));
try
{
}
finally
{
fs.Release();
}
}
finally
{
fs.Release();
}
Assert.Empty(fs._waitQueue);
}
public void ShouldNotLeaveWaitersInQueueIfTimeoutAfterCallingRelease()
{
var @lock = new FifoSemaphore(1);
@lock.Acquire(CancellationToken.None);
try
{
Assert.False(@lock.TryAcquire(TimeSpan.Zero, CancellationToken.None));
Assert.Equal(1, @lock._waitQueue.Count);
Assert.True(@lock._waitQueue.First().IsTimedOut);
}
finally
{
@lock.Release();
}
Assert.Empty(@lock._waitQueue);
}
public void ShouldNotLeaveWaitersInQueueIfOperationIsCancelled()
{
var @lock = new FifoSemaphore(1);
@lock.Acquire(CancellationToken.None);
var cts = new CancellationTokenSource();
cts.Cancel();
Assert.Throws <OperationCanceledException>(() => @lock.Acquire(cts.Token));
Assert.Empty(@lock._waitQueue);
cts = new CancellationTokenSource();
@lock.ForTestingPurposesOnly().JustBeforeAddingToWaitQueue += () => cts.Cancel();
Assert.Throws <OperationCanceledException>(() => @lock.Acquire(cts.Token));
Assert.Empty(@lock._waitQueue);
}
public void ShouldRespectSemaphoreLimit()
{
var allowed = 3;
var inUse = 0;
var @lock = new FifoSemaphore(allowed);
var tasks = new List <Task>();
int numberOfTasks = 20;
int numberOfLocksPerTask = 10;
bool tasksRunning = true;
var verifyLimit = Task.Run(async() =>
{
while (tasksRunning)
{
Assert.True(inUse <= allowed);
await Task.Delay(13);
}
});
int totalNumberOfLocksTaken = 0;
for (int i = 0; i < numberOfTasks; i++)
{
var task = Task.Run(() =>
{
for (int j = 0; j < numberOfLocksPerTask; j++)
{
@lock.Acquire(CancellationToken.None);
Interlocked.Increment(ref inUse);
Interlocked.Increment(ref totalNumberOfLocksTaken);
try
{
Thread.Sleep(j);
}
finally
{
Interlocked.Decrement(ref inUse);
@lock.Release();
}
}
});
tasks.Add(task);
}
var waitResult = Task.WaitAll(tasks.ToArray(), TimeSpan.FromSeconds(30));
Assert.True(waitResult);
tasksRunning = false;
waitResult = verifyLimit.Wait(TimeSpan.FromSeconds(30));
Assert.True(waitResult);
Assert.Equal(numberOfTasks * numberOfLocksPerTask, totalNumberOfLocksTaken);
}
