public Task SetAsync(string id, RateLimitCounter counter, TimeSpan?expirationTime)
{
var options = new MemoryCacheEntryOptions
{
Priority = CacheItemPriority.NeverRemove
};
if (expirationTime.HasValue)
{
options.SetAbsoluteExpiration(expirationTime.Value);
}
_cache.Set(id, counter, options);
return(Task.CompletedTask);
}
public async Task <RateLimitCounter> ProcessRequest(ClientRequestIdentity requestIdentity, RateLimitOptions option)
{
RateLimitCounter counter = new RateLimitCounter(DateTime.UtcNow, 1);
var rule = option.RateLimitRule;
var counterId = ComputeCounterKey(requestIdentity, option);
// serial reads and writes
lock (_processLocker)
{
var entry = _rateLimitStore.Get(counterId);
if (entry.HasValue)
{
// entry has not expired
if (entry.Value.Timestamp + TimeSpan.FromSeconds(rule.PeriodTimespan) >= DateTime.UtcNow)
{
// increment request count
var totalRequests = entry.Value.TotalRequests + 1;
// deep copy
counter = new RateLimitCounter(entry.Value.Timestamp, totalRequests);
}
}
}
if (counter.TotalRequests > rule.Limit)
{
var retryAfter = RetryAfterFrom(counter.Timestamp, rule);
if (retryAfter > 0)
{
var expirationTime = rule.PeriodTimespan;
await _rateLimitStore.SetAsync(counterId, counter, TimeSpan.FromSeconds(expirationTime));
}
else
{
await _rateLimitStore.RemoveAsync(counterId);
}
}
else
{
var expirationTime = ConvertToTimeSpan(rule.Period);
await _rateLimitStore.SetAsync(counterId, counter, expirationTime);
}
return(counter);
}
public Task SaveRateLimitCounter(ClientRequestIdentity requestIdentity, RateLimitOptions option, RateLimitCounter counter, TimeSpan expirationTime)
{
var counterId = ComputeCounterKey(requestIdentity, option);
// stores: id (string) - timestamp (datetime) - total_requests (long)
_rateLimitStore.SetAsync(counterId, counter, expirationTime);
return(Task.CompletedTask);
}
public 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}. TraceIdentifier {httpContext.TraceIdentifier}.");
}