public virtual async Task <RateLimitCounter> ProcessRequestAsync(ClientRequestIdentity requestIdentity, RateLimitRule rule)
{
var counter = new RateLimitCounter
{
Timestamp = DateTime.UtcNow,
Count = 1
};
var counterId = BuildCounterKey(requestIdentity, rule);
// serial reads and writes on same key
using (await AsyncLock.WriterLockAsync(counterId).ConfigureAwait(false))
{
var entry = await _counterStore.GetAsync(counterId);
if (entry.IsNotNull())
{
// entry has not expired
if (entry.Timestamp + rule.PeriodTimespan.Value >= DateTime.UtcNow)
{
// increment request count
var totalCount = entry.Count + _config.RateIncrementer?.Invoke() ?? 1;
// deep copy
counter = new RateLimitCounter
{
Timestamp = entry.Timestamp,
Count = totalCount
};
}
}
// stores: id (string) - timestamp (datetime) - total_requests (long)
await _counterStore.SetAsync(counterId, counter, rule.PeriodTimespan.Value);
}
return(counter);
}
public virtual RateLimitHeaders GetRateLimitHeaders(RateLimitCounter counter, RateLimitRule rule)
{
var headers = new RateLimitHeaders();
double remaining;
DateTime reset;
if (counter.IsNotNull())
{
reset = counter.Timestamp + (rule.PeriodTimespan ?? rule.Period.ToTimeSpan());
remaining = rule.Limit - counter.Count;
}
else
{
reset = DateTime.UtcNow + (rule.PeriodTimespan ?? rule.Period.ToTimeSpan());
remaining = rule.Limit;
}
headers.Reset = reset.ToUniversalTime().ToString("o", DateTimeFormatInfo.InvariantInfo);
headers.Limit = rule.Period;
headers.Remaining = remaining.ToString();
return(headers);
}
protected override void LogBlockedRequest(HttpContext httpContext, ClientRequestIdentity identity, RateLimitCounter counter, RateLimitRule rule)
{
_logger.LogInformation($"Request {identity.HttpVerb}:{identity.Path} from IP {identity.ClientIp} has been blocked, quota {rule.Limit}/{rule.Period} exceeded by {counter.Count}. Blocked by rule {rule.Endpoint}, TraceIdentifier {httpContext.TraceIdentifier}.");
}
protected abstract void LogBlockedRequest(HttpContext httpContext, ClientRequestIdentity identity, RateLimitCounter counter, RateLimitRule rule);