public async Task NoRaceBetweenFlushOnAddAndOnDemand()
{
const int attempts = 100 * 1000;
const int batchSize = 5;
_queue = new AsyncBatchQueue <int>(batchSize);
for (int attemptNumber = 0; attemptNumber < attempts; attemptNumber++)
{
AddAllItemsButOne(batchSize);
using (ManualResetEvent trigger = new ManualResetEvent(initialState: false))
{
Task addTask = Task.Run
(
() =>
{
trigger.WaitOne();
_queue.Add(666);
}
);
Task flushTask = Task.Run
(
() =>
{
trigger.WaitOne();
_queue.Flush();
}
);
trigger.Set();
await addTask.ConfigureAwait(true);
await flushTask.ConfigureAwait(true);
IReadOnlyList <int> batch = await _queue.TakeAsync().ConfigureAwait(true);
List <int> allItems = batch.ToList();
// This happens if Flush occurred before Add, which means there's another item from Add left unflushed.
// Gotta flush once more to extract it.
if (batch.Count < batchSize)
{
_queue.Flush();
IReadOnlyList <int> secondBatch = await _queue.TakeAsync().ConfigureAwait(true);
allItems.AddRange(secondBatch);
}
allItems.Count.Should().BeLessOrEqualTo(batchSize, $"Double flush detected at attempt #{attemptNumber}. Items: {String.Join( ", ", allItems )}");
}
}
}
public async Task MultithreadingInsertsDontCrash()
{
int insertThreads = 4;
int itemsPerThread = 100;
_queue = new AsyncBatchQueue <int>(11);
List <Task> insertTasks = Enumerable.Range(1, insertThreads)
.Select(
_ => Task.Run(
() =>
{
for (int i = 0; i < itemsPerThread; i++)
{
_queue.Add(42);
}
}))
.ToList();
await Task.WhenAll(insertTasks).ConfigureAwait(true);
_queue.Flush();
int itemsTaken = 0;
while (_queue.Count > 0)
{
itemsTaken += (await _queue.TakeAsync().ConfigureAwait(true)).Count;
}
itemsTaken.Should().Be(insertThreads * itemsPerThread);
}
public async Task ManualFlushWorks()
{
int[] array = { 0, 1, 42 };
_queue = new AsyncBatchQueue<int>( 50 );
foreach ( var item in array )
_queue.Add( item );
_queue.Flush();
var batch = await _queue.TakeAsync();
CollectionAssert.AreEqual( array, batch.ToList() );
}
public async Task ManualFlushWorks()
{
int[] array = { 0, 1, 42 };
_queue = new AsyncBatchQueue <int>(50);
foreach (var item in array)
{
_queue.Add(item);
}
_queue.Flush();
var batch = await _queue.TakeAsync().ConfigureAwait(true);
batch.Should().BeEqualTo(array);
}
public async Task MultithreadingInsertsDontCrash()
{
int insertThreads = 4;
int itemsPerThread = 100;
_queue = new AsyncBatchQueue<int>( 11 );
List<Task> insertTasks = Enumerable.Range( 1, insertThreads )
.Select(
_ => Task.Run(
() =>
{
for ( int i = 0; i < itemsPerThread; i++ )
_queue.Add( 42 );
} ) )
.ToList();
await Task.WhenAll( insertTasks );
_queue.Flush();
int itemsTaken = 0;
while ( _queue.Count > 0 )
itemsTaken += ( await _queue.TakeAsync() ).Count;
Assert.AreEqual( insertThreads * itemsPerThread, itemsTaken );
}