public async Task DisposeIsHarmless()
{
Func <int, Task> taskCreator = m => Task.Run(() => XAssert.Fail());
// start queue in "paused" state with 0 parallelism
var q = new ConcurrentDrainingPriorityQueue <int, Task>(taskCreator, 0);
q.Enqueue(0, 0);
q.Dispose();
await Task.Yield();
// even after calling Dispose, all public members are still callable
// set queue to "sequential" mode with 1 degree of parallelism
q.MaxDegreeOfParallelism = 1;
q.Enqueue(0, 0);
await Task.Yield();
XAssert.AreEqual(0, q.MaxRunning);
XAssert.AreEqual(1, q.MaxDegreeOfParallelism);
XAssert.AreEqual(2, q.PriorityQueued);
XAssert.AreEqual(0, q.SemaphoreQueued);
XAssert.AreEqual(0, q.Running);
// no tasks should ever have started running, and thus all running tasks have completed
await q.WhenAllTasksCompleted();
// however, some When...tasks will never complete since we had a pending task in the queue that got never scheduled
XAssert.IsFalse(q.WhenDone().IsCompleted);
XAssert.IsFalse(q.WhenQueueDrained().IsCompleted);
}
public Task Basic()
{
return(Task.WhenAll(
new[] { 1, 2, Environment.ProcessorCount, Environment.ProcessorCount * 2, -1 }.Select(
async maxDegreeOfParallelism =>
{
const int n = 1 << 11;
int count = 0;
Func <int, Task> taskCreator =
_ => Task.Run(() => { Interlocked.Increment(ref count); });
using (var q = new ConcurrentDrainingPriorityQueue <int, Task>(taskCreator, maxDegreeOfParallelism))
{
for (int i = 0; i < n; i++)
{
q.Enqueue(i, i);
}
await q.WhenDone();
XAssert.AreEqual(0, q.PriorityQueued);
XAssert.AreEqual(0, q.SemaphoreQueued);
XAssert.AreEqual(0, q.Running);
XAssert.AreEqual(n, count);
XAssert.IsTrue(
maxDegreeOfParallelism == -1 ||
q.MaxRunning <= maxDegreeOfParallelism);
}
})));
}
public async Task FaultyTasks()
{
Func <int, Task> taskCreator = _ => Task.Run(() => { throw new Exception(); });
using (var q = new ConcurrentDrainingPriorityQueue <int, Task>(taskCreator))
{
const int Expected = 42;
int actual = 0;
q.ItemCompleted += (sender, e) =>
{
e.IsExceptionHandled = true;
if (e.Task.IsFaulted)
{
Interlocked.Increment(ref actual);
}
};
for (int i = 0; i < Expected; i++)
{
q.Enqueue(int.MaxValue, i);
}
await q.WhenDone();
XAssert.AreEqual(Expected, actual);
}
}
public async Task Priorities()
{
var dequeuedValues = new List <int>();
Func <int, Task> taskCreator = dequeuedValue => Task.Run(() => dequeuedValues.Add(dequeuedValue));
// start queue in "paused" state with 0 parallelism
using (var q = new ConcurrentDrainingPriorityQueue <int, Task>(taskCreator, 0))
{
var values = new int[1 << 11];
var r = new Random(0);
for (int i = 0; i < values.Length; i++)
{
int value = 0x7FFFFFFF & r.Next();
values[i] = value;
q.Enqueue(value, value);
}
// set queue to "sequential" mode with 1 degree of parallelism
q.MaxDegreeOfParallelism = 1;
await q.WhenDone();
Array.Sort(values);
Array.Reverse(values);
XAssert.AreEqual(values.Length, dequeuedValues.Count);
for (int i = 0; i < values.Length; i++)
{
XAssert.AreEqual(values[i], dequeuedValues[i]);
}
XAssert.AreEqual(1, q.MaxRunning);
}
}
public Task EnqueueDuringRun()
{
return(Task.WhenAll(
new[] { 1, 2, Environment.ProcessorCount, Environment.ProcessorCount * 2, -1 }.Select(
async maxDegreeOfParallelism =>
{
const int n = 11;
ConcurrentDrainingPriorityQueue <int, Task> q = null;
int count = 0;
Func <int, Task> taskCreator = m => Task.Run(
() =>
{
Interlocked.Increment(ref count);
while (--m >= 0)
{
q.Enqueue(m, m);
}
});
using (q = new ConcurrentDrainingPriorityQueue <int, Task>(taskCreator, maxDegreeOfParallelism))
{
for (int i = 0; i < n; i++)
{
q.Enqueue(i, i);
}
await q.WhenDone();
XAssert.AreEqual(0, q.PriorityQueued);
XAssert.AreEqual(0, q.SemaphoreQueued);
XAssert.AreEqual(0, q.Running);
XAssert.AreEqual((1 << n) - 1, count);
}
})));
}
public async Task MaxRunning()
{
const int N = 42;
var e = new TaskCompletionSource <int>();
Func <int, Task> taskCreator = _ => e.Task;
using (var q = new ConcurrentDrainingPriorityQueue <int, Task>(taskCreator, N))
{
for (int i = 0; i < N; i++)
{
q.Enqueue(i, i);
}
await q.WhenQueueDrained();
e.SetCanceled();
await q.WhenDone();
XAssert.AreEqual(N, q.MaxRunning);
}
}
public async Task Semaphores()
{
var semaphoreLimits = new int[] { 1, 2, 3, 4 };
SemaphoreSet <int> semaphores = new SemaphoreSet <int>();
Func <int, ItemResources> itemResourceGetter =
index =>
{
int[] semaphoreIncrements;
switch (index)
{
case 2:
case 4:
case 6:
semaphoreIncrements = new[] { 0, 1 };
break;
default:
semaphoreIncrements = null;
break;
}
return(ItemResources.Create(semaphoreIncrements));
};
var created = new TaskCompletionSource <int> [10];
var completed = new TaskCompletionSource <int> [10];
for (int i = 0; i < completed.Length; i++)
{
completed[i] = new TaskCompletionSource <int>();
created[i] = new TaskCompletionSource <int>();
}
Func <int, Task> taskCreator = index =>
{
created[index].SetResult(index);
return(completed[index].Task);
};
using (
var q = new ConcurrentDrainingPriorityQueue <int, Task>(
taskCreator,
maxDegreeOfParallelism: 0,
itemResourceGetter: itemResourceGetter,
semaphores: semaphores))
using (var item6Queued = new ManualResetEvent(false))
using (var item6Dequeued = new ManualResetEvent(false))
{
q.ItemSemaphoreQueued += (sender, e) =>
{
XAssert.AreEqual(e.Item, 6);
item6Queued.Set();
};
q.ItemSemaphoreDequeued += (sender, e) =>
{
XAssert.AreEqual(e.Item, 6);
item6Dequeued.Set();
};
for (int i = 0; i < 10; i++)
{
q.Enqueue(10 - i, i);
}
for (int i = 0; i < semaphoreLimits.Length; i++)
{
int index = semaphores.CreateSemaphore(i, semaphoreLimits[i]);
XAssert.AreEqual(index, i);
}
q.MaxDegreeOfParallelism = 3;
completed[0].SetResult(0);
completed[1].SetResult(1);
// skip 2, building up resource use...
completed[3].SetResult(3);
// skip 4, building up resource use...
completed[5].SetResult(5);
for (int i = 0; i < 5; i++)
{
await created[i].Task;
}
// item 6 cannot run, as 2 and 4 are using up the two semaphore slots
XAssert.IsFalse(created[6].Task.IsCompleted);
// Don't block, use await --- otherwise deadlock might arise as TPL may schedule a task continuation on the current thread.
await item6Queued.ToTask();
completed[2].SetResult(2);
// now that item 2 has finished, item 6 can dequeue and run...
// Don't block, use await --- otherwise deadlock might arise as TPL may schedule a task continuation on the current thread.
await item6Dequeued.ToTask();
completed[4].SetResult(4);
completed[6].SetResult(6);
for (int i = 7; i < 10; i++)
{
completed[i].SetResult(i);
}
await q.WhenDone();
for (int i = 0; i < 10; i++)
{
XAssert.IsTrue(created[i].Task.IsCompleted);
}
XAssert.AreEqual(0, q.PriorityQueued);
XAssert.AreEqual(0, q.SemaphoreQueued);
XAssert.AreEqual(0, q.Running);
}
}