public void ConsumeBlocksUntilTokensAreAvailable()
{
var time = new DateTime(2000, 01, 01);
var timeProvider = new ManualTimeProvider(time);
const int refillAmount = 1;
var refillInterval = TimeSpan.FromMinutes(1);
var refillStrategy = new FixedIntervalRefillStrategy(timeProvider, refillAmount, refillInterval);
// using spin wait strategy to ensure we update AvailableTokens as quickly as possible
var sleepStrategy = new BusyWaitSleepStrategy();
const int capacity = 10;
var bucket = new LeakyBucket(capacity, sleepStrategy, refillStrategy, timeProvider);
// first remove half the capacity
bucket.Consume(capacity / 2);
// we've consumed half of the available tokens
Assert.AreEqual(capacity / 2, bucket.AvailableTokens);
var taskStarted = new ManualResetEvent(false);
var bucketConsumeCompleted = new ManualResetEvent(false);
Task.Run(() =>
{
taskStarted.Set();
// this will block until time advances
bucket.Consume(capacity);
bucketConsumeCompleted.Set();
});
taskStarted.WaitOne();
// each loop we'll advance one refill increment and when the loop finishes
// the bucket's consume operation will succeed
var initialAmount = bucket.AvailableTokens;
for (int i = 0; i < 5; i++)
{
timeProvider.Advance(refillInterval);
Thread.Sleep(1);
// on the last loop, the bucket will consume all ten
if (i != 4)
{
// each time we advance the number of available tokens will increment by the refill amount
Assert.AreEqual(initialAmount + (1 + i) * refillAmount, bucket.AvailableTokens,
$"CurrentTime: {timeProvider.GetUtcNow():O}: Iteration: {i}"
);
}
}
// now that we've advanced, bucket consumption should have completed
// we provide for a small timeout to support non-multi-threaded machines
Assert.IsTrue(bucketConsumeCompleted.WaitOne(10));
Assert.AreEqual(0, bucket.AvailableTokens);
}
