public RateLimitCounter ProcessRequest(ClientRequestIdentity requestIdentity, RateLimitRule rule)
{
var counter = new RateLimitCounter
{
Timestamp = DateTime.UtcNow,
TotalRequests = 1
};
var counterId = ComputeCounterKey(requestIdentity, rule);
// serial reads and writes
lock (_processLocker)
{
var entry = _counterStore.Get(counterId);
if (entry.HasValue)
{
// entry has not expired
if (entry.Value.Timestamp + rule.PeriodTimespan.Value >= DateTime.UtcNow)
{
// increment request count
var totalRequests = entry.Value.TotalRequests + 1;
// deep copy
counter = new RateLimitCounter
{
Timestamp = entry.Value.Timestamp,
TotalRequests = totalRequests
};
}
}
// stores: id (string) - timestamp (datetime) - total_requests (long)
_counterStore.Set(counterId, counter, rule.PeriodTimespan.Value);
}
return(counter);
}
public void Set(string id, RateLimitCounter counter, TimeSpan expirationTime)
{
_memoryCache.Set(id, counter, new MemoryCacheEntryOptions().SetAbsoluteExpiration(expirationTime));
}
public void Set(string id, RateLimitCounter counter, TimeSpan expirationTime)
{
_memoryCache.SetString(id, JsonConvert.SerializeObject(counter), new DistributedCacheEntryOptions().SetAbsoluteExpiration(expirationTime));
}
public virtual void LogBlockedRequest(HttpContext httpContext, ClientRequestIdentity identity, RateLimitCounter counter, RateLimitRule rule)
{
_logger.LogInformation($"Request {identity.HttpVerb}:{identity.Path} from ClientId {identity.ClientId} has been blocked, quota {rule.Limit}/{rule.Period} exceeded by {counter.TotalRequests}. Blocked by rule {rule.UrlRegex}, TraceIdentifier {httpContext.TraceIdentifier}.");
}