/// <summary>
/// Gets a <see cref="RequestCounter"/> that counted the current request according the specified rule.
/// </summary>
/// <param name="request">The client request object.</param>
/// <param name="rule">The throttle rule.</param>
/// <returns>The corresponding counter for the request.</returns>
public RequestCounter ProcessRequest(ClientRequest request, ThrottleRule rule)
{
if (rule.PeriodTimespan == null)
{
throw new InvalidOperationException("Throttle period time span is not set!");
}
var key = GetStorageKey(request, rule);
var counter = _counterStore.GetOrCreate(
key,
() => new RequestCounter
{
Timestamp = DateTime.UtcNow,
TotalRequests = 0
},
rule.PeriodTimespan.Value);
counter.Increment();
// Checks limit and enters cool down period by prolonging the counter expiration.
if (counter.TotalRequests > rule.Limit && !counter.LimitExceeded)
{
counter.LimitExceeded = true;
if (rule.CooldownTimespan.HasValue &&
DateTime.UtcNow + rule.CooldownTimespan.Value > counter.Timestamp + rule.PeriodTimespan.Value)
{
_counterStore.Set(key, counter, rule.CooldownTimespan.Value);
}
}
return(counter);
}
private string GetStorageKey(ClientRequest request, ThrottleRule rule)
{
return($"{Options.ThrottleName}_{request.ClientId}_{rule.Id}".Sha1());
}