public async Task ExponentialBackoffTestShouldThrowTooManyRetriesAsync()
{
var subject = new ExponentialBackoff(1, 1, 2);
await subject.DelayAsync().ConfigureAwait(false);
await Assert.ThrowsExceptionAsync <TooManyRetryAttemptsException>(async() => await subject.DelayAsync().ConfigureAwait(false)).ConfigureAwait(false);
}
public void ExponentialBackoffTestShouldProgressExponentially()
{
const int maxDelay = 500000;
var maxLog = (int)Math.Ceiling(Math.Log(maxDelay, 2));
var subject = new ExponentialBackoff(20, 1, maxDelay);
for (var i = 0; i < maxLog; i++)
{
Assert.AreEqual(TimeSpan.FromMilliseconds(Math.Pow(2, i)), subject.GetDelay(i));
}
for (var i = maxLog; i < 5000; i++)
{
Assert.AreEqual(TimeSpan.FromMilliseconds(maxDelay), subject.GetDelay(i));
}
}
/// <summary>
/// RunAsync will attempt to execute the a task with a exponential retry
/// </summary>
/// <param name="func">task to execute</param>
/// <returns>exponentially backed off task</returns>
public async Task RunAsync(Func <Task> func)
{
var backoff = new ExponentialBackoff(_maxRetries, _delayMilliseconds, _maxDelayMilliseconds);
retry:
try
{
await func().ConfigureAwait(false);
}
catch (Exception ex) when(ex is TimeoutException || ex is HttpRequestException || ex is TaskCanceledException || ex is OperationCanceledException || ex is TransientManagedIdentityException)
{
Debug.WriteLine(ex.ToString());
await backoff.DelayAsync().ConfigureAwait(false);
goto retry;
}
}