forked from microsoft/vs-threading
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AsyncQueueTests.cs
609 lines (520 loc) · 19.7 KB
/
AsyncQueueTests.cs
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// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
using System;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.VisualStudio.Threading;
using Xunit;
public class AsyncQueueTests : TestBase
{
private AsyncQueue<GenericParameterHelper> queue;
public AsyncQueueTests(Xunit.Abstractions.ITestOutputHelper logger)
: base(logger)
{
this.queue = new AsyncQueue<GenericParameterHelper>();
}
[Fact]
public void JustInitialized()
{
Assert.Equal(0, this.queue.Count);
Assert.True(this.queue.IsEmpty);
Assert.False(this.queue.Completion.IsCompleted);
Assert.Empty(this.queue.ToArray());
}
[Fact]
public void Enqueue()
{
var value = new GenericParameterHelper(1);
this.queue.Enqueue(value);
Assert.Equal(1, this.queue.Count);
Assert.False(this.queue.IsEmpty);
Assert.Single(this.queue.ToArray());
}
[Fact]
public void TryEnqueue()
{
var value = new GenericParameterHelper(1);
Assert.True(this.queue.TryEnqueue(value));
Assert.Equal(1, this.queue.Count);
Assert.False(this.queue.IsEmpty);
Assert.Single(this.queue.ToArray());
}
[Fact]
public void OrderPreservedAcrossCancellationTokens()
{
int[] seedsToUse = new int[] { -2100387291, (int)DateTime.Now.Ticks };
foreach (int seed in seedsToUse)
{
this.Logger.WriteLine("Using random seed {0}", seed);
var r = new Random(seed);
// Prepare a bunch of unique CancellationTokens, including one CancellationToken.None.
var cts = new CancellationToken[10];
for (int i = 1; i < cts.Length; i++)
{
cts[i] = new CancellationTokenSource().Token;
}
// Arrange 100 DequeueAsync tasks that use random tokens.
var dequeueTasks = new Task<GenericParameterHelper>[100];
for (int i = 0; i < dequeueTasks.Length; i++)
{
CancellationToken ct = cts[r.Next() % cts.Length];
dequeueTasks[i] = this.queue.DequeueAsync(ct);
}
// Now enqueue that many elements
for (int i = 0; i < dequeueTasks.Length; i++)
{
this.queue.Enqueue(new GenericParameterHelper(i));
}
// And verify that the dequeue tasks got them in order.
for (int i = 0; i < dequeueTasks.Length; i++)
{
Assert.Equal(i, dequeueTasks[i].Result.Data);
}
}
}
[Fact]
public void OrderPreservedAcrossCancellationTokensAndMultipleDequeuers()
{
const int tokenCount = 3;
const int dequeueDepth = 2;
// Arrange for one unique CancellationToken per logical dequeuer.
var tokens = new CancellationToken[tokenCount];
for (int i = 0; i < tokens.Length; i++)
{
tokens[i] = new CancellationTokenSource().Token;
}
// Prepare each dequeuing CancellationToken to be used multiple times.
var dequeuers = new Task<GenericParameterHelper>[tokenCount][];
for (int i = 0; i < dequeuers.Length; i++)
{
dequeuers[i] = new Task<GenericParameterHelper>[dequeueDepth];
}
// Now in a round robin fashion, each CancellationToken gets to call DequeueAsync.
// When they've all had a turn, do it again.
for (int j = 0; j < dequeueDepth; j++)
{
for (int i = 0; i < dequeuers.Length; i++)
{
dequeuers[i][j] = this.queue.DequeueAsync(tokens[i]);
}
}
// Now enqueue enough items to let all the DequeueAsync calls complete.
for (int i = 0; i < tokenCount * dequeueDepth; i++)
{
this.queue.Enqueue(new GenericParameterHelper(i));
}
// Verify that each DequeueAsync call got the enqueued value in FIFO order.
for (int j = 0; j < dequeueDepth; j++)
{
for (int i = 0; i < dequeuers.Length; i++)
{
int actual = dequeuers[i][j].Result.Data;
Assert.Equal((j * dequeuers.Length) + i, actual);
}
}
}
[Fact]
public void PeekThrowsOnEmptyQueue()
{
Assert.Throws<InvalidOperationException>(() => this.queue.Peek());
}
[Fact]
public void TryPeek()
{
Assert.False(this.queue.TryPeek(out GenericParameterHelper? value));
Assert.Null(value);
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
Assert.True(this.queue.TryPeek(out GenericParameterHelper? peekedValue));
Assert.Same(enqueuedValue, peekedValue);
}
[Fact]
public void Peek()
{
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
GenericParameterHelper? peekedValue = this.queue.Peek();
Assert.Same(enqueuedValue, peekedValue);
// Peeking again should yield the same result.
peekedValue = this.queue.Peek();
Assert.Same(enqueuedValue, peekedValue);
// Enqueuing another element shouldn't change the peeked value.
var secondValue = new GenericParameterHelper(2);
this.queue.Enqueue(secondValue);
peekedValue = this.queue.Peek();
Assert.Same(enqueuedValue, peekedValue);
Assert.True(this.queue.TryDequeue(out GenericParameterHelper? dequeuedValue));
Assert.Same(enqueuedValue, dequeuedValue);
peekedValue = this.queue.Peek();
Assert.Same(secondValue, peekedValue);
}
[Fact]
public async Task DequeueAsyncCompletesSynchronouslyForNonEmptyQueue()
{
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(CancellationToken.None);
Assert.True(dequeueTask.GetAwaiter().IsCompleted);
GenericParameterHelper? dequeuedValue = await dequeueTask;
Assert.Same(enqueuedValue, dequeuedValue);
Assert.Equal(0, this.queue.Count);
Assert.True(this.queue.IsEmpty);
}
[Fact]
public async Task DequeueAsyncNonBlockingWait()
{
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(CancellationToken.None);
Assert.False(dequeueTask.GetAwaiter().IsCompleted);
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
GenericParameterHelper? dequeuedValue = await dequeueTask;
Assert.Same(enqueuedValue, dequeuedValue);
Assert.Equal(0, this.queue.Count);
Assert.True(this.queue.IsEmpty);
}
[Fact]
public async Task DequeueAsyncCancelledBeforeComplete()
{
var cts = new CancellationTokenSource();
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(cts.Token);
Assert.False(dequeueTask.GetAwaiter().IsCompleted);
cts.Cancel();
await Assert.ThrowsAsync<TaskCanceledException>(() => dequeueTask);
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
Assert.Equal(1, this.queue.Count);
}
[Fact]
public async Task DequeueAsyncPrecancelled()
{
var cts = new CancellationTokenSource();
cts.Cancel();
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(cts.Token);
Assert.True(dequeueTask.GetAwaiter().IsCompleted);
await Assert.ThrowsAsync<TaskCanceledException>(() => dequeueTask);
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
Assert.Equal(1, this.queue.Count);
}
[Fact]
public async Task DequeueAsyncCancelledAfterComplete()
{
var cts = new CancellationTokenSource();
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(cts.Token);
Assert.False(dequeueTask.GetAwaiter().IsCompleted);
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
cts.Cancel();
GenericParameterHelper? dequeuedValue = await dequeueTask;
Assert.True(this.queue.IsEmpty);
Assert.Same(enqueuedValue, dequeuedValue);
}
/// <summary>
/// This test attempts to exercise the race condition where the token is canceled *after*
/// the CancellationToken.Register method completes, but before the task continuation that
/// disposes that CancellationTokenRegistration is scheduled, leading to an inline execution
/// of that task continuation.
/// </summary>
/// <remarks>
/// The race is very unlikely to be hit. But with this code, and a debugger to freeze/thaw threads
/// at marked positions, it demonstrated the hang repro'd without the fix, and couldn't repro after the fix.
/// </remarks>
/// <seealso href="https://github.com/Microsoft/vs-threading/issues/458"/>
[Fact]
public async Task DequeueAsyncCancellationRace()
{
var cts = new CancellationTokenSource();
var cancelTask = Task.Run(delegate
{
cts.Cancel();
});
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(cts.Token);
await Assert.ThrowsAnyAsync<OperationCanceledException>(() => dequeueTask);
}
[Fact]
public async Task MultipleDequeuers()
{
var dequeuers = new Task<GenericParameterHelper>[5];
for (int i = 0; i < dequeuers.Length; i++)
{
dequeuers[i] = this.queue.DequeueAsync();
}
for (int i = 0; i < dequeuers.Length; i++)
{
int completedCount = 0;
while (completedCount < i)
{
await Task.WhenAny(dequeuers.Skip(completedCount)).WithTimeout(TimeSpan.FromMilliseconds(TestTimeout));
completedCount = dequeuers.Count(d => d.IsCompleted);
}
Assert.Equal(i, completedCount);
this.queue.Enqueue(new GenericParameterHelper(i));
}
for (int i = 0; i < dequeuers.Length; i++)
{
Assert.Equal(i, dequeuers[i].Result.Data);
}
}
[Fact]
public async Task MultipleDequeuersCancelled()
{
var cts = new CancellationTokenSource[2];
for (int i = 0; i < cts.Length; i++)
{
cts[i] = new CancellationTokenSource();
}
var dequeuers = new Task<GenericParameterHelper>[5];
for (int i = 0; i < dequeuers.Length; i++)
{
dequeuers[i] = this.queue.DequeueAsync(cts[i % 2].Token);
}
cts[0].Cancel(); // cancel some of them.
for (int i = 0; i < dequeuers.Length; i++)
{
if (i % 2 == 0)
{
await Assert.ThrowsAnyAsync<OperationCanceledException>(() => dequeuers[i]).WithTimeout(UnexpectedTimeout);
Assert.True(dequeuers[i].IsCanceled);
}
else
{
Assert.False(dequeuers[i].IsCanceled);
}
if (!dequeuers[i].IsCanceled)
{
this.queue.Enqueue(new GenericParameterHelper(i));
}
}
await Task.WhenAll(dequeuers).WithTimeout(UnexpectedTimeout).NoThrowAwaitable();
Assert.True(dequeuers.All(d => d.IsCompleted));
}
[Fact]
public void TryDequeue()
{
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
bool result = this.queue.TryDequeue(out GenericParameterHelper? dequeuedValue);
Assert.True(result);
Assert.Same(enqueuedValue, dequeuedValue);
Assert.Equal(0, this.queue.Count);
Assert.True(this.queue.IsEmpty);
Assert.False(this.queue.TryDequeue(out dequeuedValue));
Assert.Null(dequeuedValue);
Assert.Equal(0, this.queue.Count);
Assert.True(this.queue.IsEmpty);
}
[Fact]
public void Complete()
{
this.queue.Complete();
Assert.True(this.queue.Completion.IsCompleted);
}
[Fact]
public async Task CompleteThenDequeueAsync()
{
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
this.queue.Complete();
Assert.False(this.queue.Completion.IsCompleted);
GenericParameterHelper? dequeuedValue = await this.queue.DequeueAsync();
Assert.Same(enqueuedValue, dequeuedValue);
Assert.True(this.queue.Completion.IsCompleted);
}
[Fact]
public void CompleteThenTryDequeue()
{
var enqueuedValue = new GenericParameterHelper(1);
this.queue.Enqueue(enqueuedValue);
this.queue.Complete();
Assert.False(this.queue.Completion.IsCompleted);
Assert.True(this.queue.TryDequeue(out GenericParameterHelper? dequeuedValue));
Assert.Same(enqueuedValue, dequeuedValue);
Assert.True(this.queue.Completion.IsCompleted);
}
[Fact]
public async Task CompleteWhileDequeuersWaiting()
{
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync();
this.queue.Complete();
Assert.True(this.queue.Completion.IsCompleted);
await Assert.ThrowsAnyAsync<OperationCanceledException>(() => dequeueTask).WithTimeout(UnexpectedTimeout);
Assert.True(dequeueTask.IsCanceled);
}
[Fact]
public void CompletedQueueRejectsEnqueue()
{
this.queue.Complete();
Assert.Throws<InvalidOperationException>(() => this.queue.Enqueue(new GenericParameterHelper(1)));
Assert.True(this.queue.IsEmpty);
}
[Fact]
public void CompletedQueueRejectsTryEnqueue()
{
this.queue.Complete();
Assert.False(this.queue.TryEnqueue(new GenericParameterHelper(1)));
Assert.True(this.queue.IsEmpty);
}
[Fact]
public void DequeueCancellationAndCompletionStress()
{
var queue = new AsyncQueue<GenericParameterHelper>();
queue.Complete();
// This scenario was proven to cause a deadlock before a bug was fixed.
// This scenario should remain to protect against regressions.
int iterations = 0;
var stopwatch = Stopwatch.StartNew();
while (stopwatch.ElapsedMilliseconds < TestTimeout / 2)
{
var cts = new CancellationTokenSource();
using (var barrier = new Barrier(2))
{
var otherThread = Task.Run(delegate
{
Assert.True(barrier.SignalAndWait(TestTimeout));
queue.DequeueAsync(cts.Token);
Assert.True(barrier.SignalAndWait(TestTimeout));
});
Assert.True(barrier.SignalAndWait(TestTimeout));
cts.Cancel();
Assert.True(barrier.SignalAndWait(TestTimeout));
Assert.True(otherThread.Wait(TestTimeout));
}
iterations++;
}
this.Logger.WriteLine("Iterations: {0}", iterations);
}
[Fact]
public void NoLockHeldForCancellationContinuation()
{
var cts = new CancellationTokenSource();
Task<GenericParameterHelper>? dequeueTask = this.queue.DequeueAsync(cts.Token);
Task enqueueTask = dequeueTask.ContinueWith(
delegate
{
Task.Run(delegate
{
// Enqueue presumably requires a private lock internally.
// Since we're calling it on a different thread than the
// blocking cancellation continuation, this should deadlock
// if and only if the queue is holding a lock while invoking
// our cancellation continuation (which they shouldn't be doing).
this.queue.Enqueue(new GenericParameterHelper(1));
}).Wait();
},
TaskContinuationOptions.ExecuteSynchronously);
cts.Cancel();
enqueueTask.GetAwaiter().GetResult(); // rethrow any failures in the continuation
Assert.Equal(1, this.queue.Count);
}
[Fact]
public void OnEnqueuedNotAlreadyDispatched()
{
var queue = new DerivedQueue<int>();
bool callbackFired = false;
queue.OnEnqueuedDelegate = (value, alreadyDispatched) =>
{
Assert.Equal(5, value);
Assert.False(alreadyDispatched);
callbackFired = true;
};
queue.Enqueue(5);
Assert.True(callbackFired);
}
[Fact]
public async Task OnEnqueuedAlreadyDispatched()
{
var queue = new DerivedQueue<int>();
bool callbackFired = false;
queue.OnEnqueuedDelegate = (value, alreadyDispatched) =>
{
Assert.Equal(5, value);
Assert.True(alreadyDispatched);
callbackFired = true;
};
Task<int>? dequeuer = queue.DequeueAsync();
queue.Enqueue(5);
Assert.True(callbackFired);
Assert.Equal(5, await dequeuer.WithTimeout(UnexpectedTimeout));
}
[Fact]
public void OnDequeued()
{
var queue = new DerivedQueue<int>();
bool callbackFired = false;
queue.OnDequeuedDelegate = value =>
{
Assert.Equal(5, value);
callbackFired = true;
};
queue.Enqueue(5);
Assert.True(queue.TryDequeue(out int dequeuedValue));
Assert.True(callbackFired);
}
[Fact]
public void OnCompletedInvoked()
{
var queue = new DerivedQueue<GenericParameterHelper>();
int invoked = 0;
queue.OnCompletedDelegate = () => invoked++;
queue.Complete();
Assert.Equal(1, invoked);
// Call it again to make sure it's only invoked once.
queue.Complete();
Assert.Equal(1, invoked);
}
[SkippableFact, Trait("GC", "true")]
public void UnusedQueueGCPressure()
{
if (this.ExecuteInIsolation())
{
this.CheckGCPressure(
delegate
{
var queue = new AsyncQueue<GenericParameterHelper>();
queue.Complete();
Assert.True(queue.IsCompleted);
},
maxBytesAllocated: 81,
allowedAttempts: 30);
}
}
[Fact]
public void DequeueAsyncContinuationsNotInlinedWithinPrivateLock()
{
Task<GenericParameterHelper>? dequeuerTask = this.queue.DequeueAsync();
Task? continuationTask = dequeuerTask.ContinueWith(
_ =>
{
Assert.True(Task.Run(delegate
{
this.queue.Enqueue(new GenericParameterHelper(2));
}).Wait(UnexpectedTimeout));
},
TaskContinuationOptions.ExecuteSynchronously);
this.queue.Enqueue(new GenericParameterHelper(1));
continuationTask.Wait(UnexpectedTimeout);
}
private class DerivedQueue<T> : AsyncQueue<T>
{
internal Action<T, bool>? OnEnqueuedDelegate { get; set; }
internal Action? OnCompletedDelegate { get; set; }
internal Action<T>? OnDequeuedDelegate { get; set; }
protected override void OnEnqueued(T value, bool alreadyDispatched)
{
base.OnEnqueued(value, alreadyDispatched);
this.OnEnqueuedDelegate?.Invoke(value, alreadyDispatched);
}
protected override void OnDequeued(T value)
{
base.OnDequeued(value);
this.OnDequeuedDelegate?.Invoke(value);
}
protected override void OnCompleted()
{
base.OnCompleted();
this.OnCompletedDelegate?.Invoke();
}
}
}