public async Task TestCancelOnOneThreadCancelsOtherTaskIfCanceled()
{
AsyncCache <int, int> cache = new AsyncCache <int, int>();
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
SemaphoreSlim resetEventSlim = new SemaphoreSlim(0, 1);
bool generatorFunc2Called = false;
Func <Task <int> > generatorFunc1 = () => Task.Run(async() =>
{
await resetEventSlim.WaitAsync(cancellationTokenSource.Token);
return(1);
}, cancellationTokenSource.Token);
Func <Task <int> > generatorFunc2 = () => Task.Run(() =>
{
generatorFunc2Called = true;
return(2);
});
// set up two threads that are concurrently updating the async cache for the same key.
// the only difference is that one thread passes in a cancellation token
// and the other does not.
Task <int> getTask1 = cache.GetAsync(key: 1, obsoleteValue: -1, singleValueInitFunc: generatorFunc1, cancellationToken: cancellationTokenSource.Token);
Task <int> getTask2 = cache.GetAsync(key: 1, obsoleteValue: -1, singleValueInitFunc: generatorFunc2, cancellationToken: cancellationTokenSource.Token);
// assert that the tasks haven't completed.
Assert.IsFalse(getTask2.IsCompleted);
Assert.IsFalse(getTask1.IsCompleted);
// cancel the first task's cancellation token.
cancellationTokenSource.Cancel();
// neither task is complete at this point.
Assert.IsFalse(getTask2.IsCompleted);
Assert.IsFalse(getTask1.IsCompleted);
try
{
await getTask1;
Assert.Fail("Should fail because of cancellation.");
}
catch (Exception e)
{
Assert.IsTrue(e as OperationCanceledException != null, e.Message);
}
try
{
await getTask2;
Assert.Fail("Should fail because of cancellation.");
}
catch (Exception e)
{
Assert.IsTrue(e as OperationCanceledException != null, e.Message);
}
Assert.IsFalse(generatorFunc2Called);
}
public async Task TestGetAsync()
{
int numberOfCacheRefreshes = 0;
Func <int, CancellationToken, Task <int> > refreshFunc = (key, cancellationToken) =>
{
Interlocked.Increment(ref numberOfCacheRefreshes);
return(Task.FromResult(key * 2));
};
AsyncCache <int, int> cache = new AsyncCache <int, int>();
List <Task> tasks = new List <Task>();
for (int i = 0; i < 10; i++)
{
for (int j = 0; j < 10; j++)
{
int key = j;
tasks.Add(cache.GetAsync(key, -1, () => refreshFunc(key, CancellationToken.None), CancellationToken.None));
}
}
await Task.WhenAll(tasks);
Assert.AreEqual(10, numberOfCacheRefreshes);
Assert.AreEqual(4, await cache.GetAsync(2, -1, () => refreshFunc(2, CancellationToken.None), CancellationToken.None));
Func <int, CancellationToken, Task <int> > refreshFunc1 = (key, cancellationToken) =>
{
Interlocked.Increment(ref numberOfCacheRefreshes);
return(Task.FromResult(key * 2 + 1));
};
List <Task> tasks1 = new List <Task>();
for (int i = 0; i < 10; i++)
{
for (int j = 0; j < 10; j++)
{
int key = j;
tasks1.Add(cache.GetAsync(key, key * 2, () => refreshFunc1(key, CancellationToken.None), CancellationToken.None));
}
for (int j = 0; j < 10; j++)
{
int key = j;
tasks1.Add(cache.GetAsync(key, key * 2, () => refreshFunc1(key, CancellationToken.None), CancellationToken.None));
}
}
await Task.WhenAll(tasks1);
Assert.AreEqual(20, numberOfCacheRefreshes);
Assert.AreEqual(5, await cache.GetAsync(2, -1, () => refreshFunc(2, CancellationToken.None), CancellationToken.None));
}
public async Task TestFailureOnOneThreadDoesNotFailAnother()
{
AsyncCache <int, int> cache = new AsyncCache <int, int>();
SemaphoreSlim resetEventSlim = new SemaphoreSlim(0, 1);
Func <Task <int> > generatorFunc1 = () => Task <int> .Run(async() =>
{
await resetEventSlim.WaitAsync();
return(this.GenerateIntFuncThatThrows());
});
Func <Task <int> > generatorFunc2 = () => Task.Run(() =>
{
return(2);
});
// set up two threads that are concurrently updating the async cache for the same key.
// the only difference is that one thread passes in a cancellation token
// and the other does not.
Task <int> getTask1 = cache.GetAsync(key: 1, obsoleteValue: -1, singleValueInitFunc: generatorFunc1, cancellationToken: CancellationToken.None);
Task <int> getTask2 = cache.GetAsync(key: 1, obsoleteValue: -1, singleValueInitFunc: generatorFunc2, cancellationToken: CancellationToken.None);
// assert that the tasks haven't completed.
Assert.IsFalse(getTask2.IsCompleted);
Assert.IsFalse(getTask1.IsCompleted);
// release a thread that causes the first to throw.
resetEventSlim.Release();
// neither task is complete at this point.
Assert.IsFalse(getTask2.IsCompleted);
Assert.IsFalse(getTask1.IsCompleted);
try
{
await getTask1;
Assert.Fail("Should fail because of exception.");
}
catch (Exception e)
{
Assert.AreEqual(typeof(InvalidOperationException), e.GetType(), e.Message);
}
// task 2 should not fail because task 1 got cancelled.
int getTaskResult2 = await getTask2;
Assert.AreEqual(2, getTaskResult2);
}
public async Task TestCancelOnOneThreadDoesNotCancelAnother()
{
AsyncCache <int, int> cache = new AsyncCache <int, int>();
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
SemaphoreSlim resetEventSlim = new SemaphoreSlim(0, 1);
Func <Task <int> > generatorFunc1 = () => Task.Run(async() =>
{
await resetEventSlim.WaitAsync(cancellationTokenSource.Token);
return(1);
}, cancellationTokenSource.Token);
Func <Task <int> > generatorFunc2 = () => Task.Run(() =>
{
return(2);
});
// set up two threads that are concurrently updating the async cache for the same key.
// the only difference is that one thread passes in a cancellation token
// and the other does not.
Task <int> getTask1 = cache.GetAsync(key: 1, obsoleteValue: -1, singleValueInitFunc: generatorFunc1, cancellationToken: cancellationTokenSource.Token);
Task <int> getTask2 = cache.GetAsync(key: 1, obsoleteValue: -1, singleValueInitFunc: generatorFunc2, cancellationToken: CancellationToken.None);
// assert that the tasks haven't completed.
Assert.IsFalse(getTask2.IsCompleted);
Assert.IsFalse(getTask1.IsCompleted);
// cancel the first task's cancellation token.
cancellationTokenSource.Cancel();
// neither task is complete at this point.
Assert.IsFalse(getTask2.IsCompleted);
Assert.IsFalse(getTask1.IsCompleted);
try
{
await getTask1;
Assert.Fail("Should fail because of cancellation.");
}
catch (TaskCanceledException)
{
}
// task 2 should not fail because task 1 got cancelled.
int getTaskResult2 = await getTask2;
Assert.AreEqual(2, getTaskResult2);
}
public async Task <IReadOnlyCollection <QueryTag> > GetQueryTagsAsync(CancellationToken cancellationToken = default)
{
if (_disposed)
{
throw new ObjectDisposedException(nameof(QueryTagService));
}
return(_enableExtendedQueryTags ? await _queryTagCache.GetAsync(cancellationToken : cancellationToken) : CoreQueryTags);
}
/// <inheritdoc />
public async ValueTask <DicomDataset> GetDicomDatasetAsync(CancellationToken cancellationToken)
{
try
{
DicomFile file = await _dicomFileCache.GetAsync(cancellationToken : cancellationToken);
return(file.Dataset);
}
catch (DicomFileException)
{
throw new InvalidInstanceException(DicomCoreResource.InvalidDicomInstance);
}
}
public async Task TestConcurrentGetAsync()
{
const string key = "a";
const string value = "b";
AsyncCache <string, string> cache = new AsyncCache <string, string>();
int hitCount = 0;
await Enumerable.Range(0, 10).ForEachAsync(
10,
_ => cache.GetAsync(
key,
null,
() =>
{
// No Interlocked, would force barriers
hitCount++;
return(Task.FromResult(value));
},
CancellationToken.None));
Assert.AreEqual(1, hitCount);
}
public Task <T> GetAsync(CancellationToken cancellationToken = default) => _cache.GetAsync(forceRefresh: false, cancellationToken: cancellationToken); // prevent users from forcing refresh
