private bool IsRequestForbidden(HttpContext context)
{
// lock to synchronise the multiple calls on web apis.
lock (_syncLock)
{
// read api limit rules from config or by default limit rules
var apiLimitRuleDetails = GetApiLimitRuleDetails(context);
// throttle cache is present means service threshold is reached, need to suspend the request.
if (_cache.Get(GetThrottleBaseKey(apiLimitRuleDetails.EndPointKey)) != null)
{
return(true);
}
if (!_cache.TryGetValue(apiLimitRuleDetails.EndPointKey, out CacheSetting serviceHitCounter))
{
// create service hit counter with 1
CreateOrUpdateCache(apiLimitRuleDetails.EndPointKey, _cacheSettingProvider.CreateCacheSetting(apiLimitRuleDetails.Period));
return(false);
}
// as long as threshold is not reached just increment the counter and update the service cache counter
if (serviceHitCounter.Value < apiLimitRuleDetails.Limit)
{
serviceHitCounter.Value++;
CreateOrUpdateCache(apiLimitRuleDetails.EndPointKey, serviceHitCounter);
return(false);
}
// api limit threshold is reached, need to add throttle cache in the memory to suspend subsequent calls to api for particular duration
CreateOrUpdateCache(GetThrottleBaseKey(apiLimitRuleDetails.EndPointKey), _cacheSettingProvider.CreateCacheSetting(apiLimitRuleDetails.SuspendPeriod));
return(true);
}
}
public async Task Invoke(HttpContext context)
{
if (IsRateLimitRequestRequired())
{
_logger.LogWarning(LoggingMessages.Forbidden + context.User);
// waiting for 3 seconds to serve the request.
await semaphoreSlim.WaitAsync();
try
{
await Task.Delay(3000);
}
finally
{
semaphoreSlim.Release();
}
// reset to one as we wait for 3 seconds.
CreateOrUpdateCache("RequestCount", _cacheSettingProvider.CreateCacheSetting(int.MaxValue));
}
await _next.Invoke(context);
}
public async Task <IEnumerable <ProductViewModel> > SearchFoodProducts(ProductSearchInput input)
{
string url = _httpQueryBuilder.Build(input);
var request = new HttpRequestMessage(HttpMethod.Get, url);
// create http client for downloading the food products
var client = _clientFactory.CreateClient();
// timeout 20 seconds
client.Timeout = TimeSpan.FromSeconds(20);
try
{
var response = await client.SendAsync(request);
if (!response.IsSuccessStatusCode)
{
return(Enumerable.Empty <ProductViewModel>());
}
var responseStream = await response.Content.ReadAsStringAsync();
var productDetails = JsonSerializer.Deserialize <FoodProductModel>(responseStream);
// validate if the product details is null or 0 or no products
if (!IsValid(productDetails))
{
return(Enumerable.Empty <ProductViewModel>());
}
if (!_cache.TryGetValue("PaginationCount", out CacheSetting paginationCounter))
{
// create service hit pagination counter with 1
CreateOrUpdateCache("PaginationCount", _cacheSettingProvider.CreateCacheSetting(int.MaxValue, 0));
paginationCounter = _cache.Get <CacheSetting>("PaginationCount");
}
// this condition to reset the counter as we reached the end of food products.
if (productDetails.Products.Length < paginationCounter.Value)
{
paginationCounter.Value = 0;
}
// skipping the already served foo products & taking only 5
var foodToReturn = productDetails.Products.Skip(paginationCounter.Value).Take(5);
// increment the pagination counter by 5
paginationCounter.Value += 5;
// updating the counter value
CreateOrUpdateCache("PaginationCount", paginationCounter);
return(_mapper.Map <List <ProductViewModel> >(foodToReturn));
}
catch (Exception ex)
{
//todo third party api is taking too much time.
_logger.LogError(ex.Message, request);
}
return(Enumerable.Empty <ProductViewModel>());
}