public async Task TestReleaseThenReAcquireWithConcurrentAccess()
{
var sut = new FastAsyncLock();
using (var otherThread = new AsyncTestRunner(OtherThread))
{
await otherThread.AdvanceTo(1);
Assert.IsTrue(otherThread.HasLock());
await otherThread.AdvanceTo(2);
Assert.IsFalse(otherThread.HasLock());
using (await sut.LockAsync(CancellationToken.None))
{
await Task.Yield();
await otherThread.AdvanceAndFreezeBefore(3);
Assert.IsFalse(otherThread.HasLock());
}
await otherThread.AdvanceTo(4);
Assert.IsTrue(otherThread.HasLock());
}
async Task OtherThread(CancellationToken ct, AsyncTestRunner r)
{
using (await sut.LockAsync(CancellationToken.None))
{
await Task.Yield();
r.HasLock(true);
r.Sync(position: 1);
}
await Task.Yield();
r.HasLock(false);
r.Sync(position: 2);
using (await sut.LockAsync(CancellationToken.None))
{
await Task.Yield();
r.HasLock(true);
r.Sync(position: 3);
r.Sync(position: 4);
}
await Task.Yield();
r.HasLock(false);
}
}
public async Task TestConcurrentCancelSecondWithThird()
{
var sut = new FastAsyncLock();
var ct = new CancellationTokenSource();
var thread2LockingTask = default(Task <IDisposable>);
using (var thread1 = new AsyncTestRunner(Thread1))
using (var thread2 = new AsyncTestRunner(Thread2))
using (var thread3 = new AsyncTestRunner(Thread3))
{
// Acquire the lock on thread 1 THEN
await thread1.AdvanceTo(1);
Assert.IsTrue(thread1.HasLock());
// Try to acquire the lock from this async context
await thread2.AdvanceAndFreezeBefore(1);
//var locking = sut.LockAsync(ct.Token);
Assert.AreEqual(TaskStatus.WaitingForActivation, thread2LockingTask.Status);
Assert.IsFalse(thread2.HasLock());
// Try to acquire it on thread 3
var t3Locked = thread3.AdvanceTo(1);
await thread3.IsFrozen();
Assert.IsFalse(thread3.HasLock());
// But cancel before the other async context completes
ct.Cancel();
Assert.AreEqual(TaskStatus.Canceled, thread2LockingTask.Status);
// Release the lock from thread1, and wait for thread 3 to acquire the lock
await thread1.AdvanceAndFreezeBefore(2); // will freeze in continuation of thread 3
await t3Locked;
//Assert.IsFalse(thread1.HasLock()); // flag not set yet: the thread 1 is dead locked by the continuation of thread 3
Assert.IsTrue(thread3.HasLock());
await thread3.AdvanceToEnd();
//await thread1.AdvanceToEnd();
await Task.Delay(500);
Assert.IsFalse(thread1.HasLock());
Assert.IsFalse(thread3.HasLock());
}
async Task Thread1(CancellationToken ct2, AsyncTestRunner r)
{
using (await sut.LockAsync(ct2))
{
r.HasLock(true);
r.Sync(position: 1);
}
r.HasLock(false);
r.Sync(position: 2);
};
async Task Thread2(CancellationToken ct2, AsyncTestRunner r)
{
thread2LockingTask = sut.LockAsync(ct.Token);
using (await thread2LockingTask)
{
r.HasLock(true);
r.Sync(position: 1);
}
r.HasLock(false);
r.Sync(position: 2);
}
async Task Thread3(CancellationToken ct2, AsyncTestRunner r)
{
using (await sut.LockAsync(ct2))
{
r.HasLock(true);
r.Sync(position: 1);
}
r.HasLock(false);
r.Sync(position: 2);
};
}