public void TokensBecomeAvailableAtLimitPerSecondRate()
{
// arrange
var clock = new FakeSystemClock();
var limiter = new Limiter(new Limit(10), 50, clock);
// act
var initiallyAllowed = limiter.AllowN(clock.UtcNow, 50);
var thenNotAllowed1 = limiter.Allow();
clock.Advance(TimeSpan.FromMilliseconds(100));
var oneTokenAvailable = limiter.Allow();
var thenNotAllowed2 = limiter.Allow();
clock.Advance(TimeSpan.FromMilliseconds(200));
var twoTokensAvailable1 = limiter.Allow();
var twoTokensAvailable2 = limiter.Allow();
var thenNotAllowed3 = limiter.Allow();
// assert
initiallyAllowed.ShouldBeTrue();
thenNotAllowed1.ShouldBeFalse();
oneTokenAvailable.ShouldBeTrue();
thenNotAllowed2.ShouldBeFalse();
twoTokensAvailable1.ShouldBeTrue();
twoTokensAvailable2.ShouldBeTrue();
thenNotAllowed3.ShouldBeFalse();
}
public async Task ManyWaitsStackUp()
{
await Policy
.Handle <ShouldAssertException>()
.RetryAsync(3)
.ExecuteAsync(async() =>
{
// arrange
var limiter = new Limiter(new Limit(10), 5);
using var cancellation = new CancellationTokenSource(TimeSpan.FromSeconds(5));
// act
while (cancellation.IsCancellationRequested == false)
{
var task = limiter.WaitAsync(cancellation.Token);
if (!task.IsCompleted)
{
await task.ConfigureAwait(false);
break;
}
}
var delayOne = new Stopwatch();
delayOne.Start();
var delayTwo = new Stopwatch();
delayTwo.Start();
var delayThree = new Stopwatch();
delayThree.Start();
var waits = new List <Task>
{
limiter.WaitAsync(cancellation.Token),
limiter.WaitAsync(cancellation.Token),
limiter.WaitAsync(cancellation.Token),
};
var taskOne = await Task.WhenAny(waits.ToArray()).ConfigureAwait(false);
await taskOne.ConfigureAwait(false);
delayOne.Stop();
waits.Remove(taskOne);
var taskTwo = await Task.WhenAny(waits.ToArray()).ConfigureAwait(false);
await taskTwo.ConfigureAwait(false);
delayTwo.Stop();
waits.Remove(taskTwo);
var taskThree = await Task.WhenAny(waits.ToArray()).ConfigureAwait(false);
await taskThree.ConfigureAwait(false);
delayThree.Stop();
waits.Remove(taskThree);
// assert
delayOne.Elapsed.ShouldBe(TimeSpan.FromMilliseconds(100), tolerance: TimeSpan.FromMilliseconds(25));
delayTwo.Elapsed.ShouldBe(TimeSpan.FromMilliseconds(200), tolerance: TimeSpan.FromMilliseconds(25));
delayThree.Elapsed.ShouldBe(TimeSpan.FromMilliseconds(300), tolerance: TimeSpan.FromMilliseconds(25));
}).ConfigureAwait(false);
}
public async Task WaitAsyncCausesPauseLikeReserve()
{
// arrange
var limiter = new Limiter(new Limit(10), 5);
using var cancellation = new CancellationTokenSource(TimeSpan.FromSeconds(5));
// act
while (cancellation.IsCancellationRequested == false)
{
var task = limiter.WaitAsync(cancellation.Token);
if (!task.IsCompleted)
{
await task.ConfigureAwait(false);
break;
}
}
var delayOne = new Stopwatch();
delayOne.Start();
await limiter.WaitAsync(cancellation.Token).ConfigureAwait(false);
delayOne.Stop();
var delayTwoMore = new Stopwatch();
delayTwoMore.Start();
await limiter.WaitAsync(2, cancellation.Token).ConfigureAwait(false);
delayTwoMore.Stop();
await Task.Delay(TimeSpan.FromMilliseconds(150)).ConfigureAwait(false);
var delayAlreadyAvailable = new Stopwatch();
delayAlreadyAvailable.Start();
await limiter.WaitAsync(cancellation.Token).ConfigureAwait(false);
delayAlreadyAvailable.Stop();
var delayHalfAvailable = new Stopwatch();
delayHalfAvailable.Start();
await limiter.WaitAsync(cancellation.Token).ConfigureAwait(false);
delayHalfAvailable.Stop();
// assert
delayOne.Elapsed.ShouldBe(TimeSpan.FromMilliseconds(100), tolerance: TimeSpan.FromMilliseconds(25));
delayTwoMore.Elapsed.ShouldBe(TimeSpan.FromMilliseconds(200), tolerance: TimeSpan.FromMilliseconds(25));
delayAlreadyAvailable.Elapsed.ShouldBe(TimeSpan.Zero, tolerance: TimeSpan.FromMilliseconds(5));
delayHalfAvailable.Elapsed.ShouldBe(TimeSpan.FromMilliseconds(50), tolerance: TimeSpan.FromMilliseconds(25));
}
public void FirstTokenIsAvailable()
{
// arrange
var clock = new FakeSystemClock();
var limiter = new Limiter(new Limit(10), 1, clock);
// act
var allowed = limiter.Allow();
// assert
allowed.ShouldBe(true);
}
/// <summary>
/// Initializes a new instance of the <see cref="Reservation"/> class.
/// </summary>
/// <param name="limiter">The limiter.</param>
/// <param name="ok">if set to <c>true</c> [ok].</param>
/// <param name="tokens">The tokens.</param>
/// <param name="timeToAct">The time to act.</param>
/// <param name="limit">The limit.</param>
public Reservation(
ISystemClock clock,
Limiter limiter,
bool ok,
double tokens = default,
DateTimeOffset timeToAct = default,
Limit limit = default)
{
_clock = clock;
_limiter = limiter;
Ok = ok;
_tokens = tokens;
TimeToAct = timeToAct;
_limit = limit;
}
public void AsManyAsBurstTokensAreAvailableRightAway(int burst)
{
// arrange
var clock = new FakeSystemClock();
var limiter = new Limiter(new Limit(10), burst, clock);
// act
var allowed = new List <bool>();
foreach (var index in Enumerable.Range(1, burst))
{
allowed.Add(limiter.Allow());
}
var notAllowed = limiter.Allow();
// assert
allowed.ShouldAllBe(item => item == true);
notAllowed.ShouldBeFalse();
}
public void ReserveTellsYouHowLongToWait()
{
// arrange
var clock = new FakeSystemClock();
var limiter = new Limiter(new Limit(10), 50, clock);
// act
var initiallyAllowed = limiter.AllowN(clock.UtcNow, 50);
var thenNotAllowed1 = limiter.Allow();
var reserveOne = limiter.Reserve();
var delayOne = reserveOne.Delay();
var reserveTwoMore = limiter.Reserve(clock.UtcNow, 2);
var delayTwoMore = reserveTwoMore.Delay();
clock.Advance(TimeSpan.FromMilliseconds(450));
var reserveAlreadyAvailable = limiter.Reserve();
var delayAlreadyAvailable = reserveAlreadyAvailable.Delay();
var reserveHalfAvailable = limiter.Reserve();
var delayHalfAvailable = reserveHalfAvailable.Delay();
// assert
initiallyAllowed.ShouldBeTrue();
thenNotAllowed1.ShouldBeFalse();
reserveOne.Ok.ShouldBeTrue();
delayOne.ShouldBe(TimeSpan.FromMilliseconds(100));
reserveTwoMore.Ok.ShouldBeTrue();
delayTwoMore.ShouldBe(TimeSpan.FromMilliseconds(300));
reserveAlreadyAvailable.Ok.ShouldBeTrue();
delayAlreadyAvailable.ShouldBe(TimeSpan.Zero);
reserveHalfAvailable.Ok.ShouldBeTrue();
delayHalfAvailable.ShouldBe(TimeSpan.FromMilliseconds(50));
}