public async Task <IHttpActionResult> Post(TaskRequest request)
{
Logger.InfoFormat("Received task {taskJson}", request.TaskJson);
TaskBase taskObject = request.TaskJson.FromJson <TaskBase>();
// check error rate
string cacheKey = $"error-rate:{taskObject.GetType().Name}";
if (CurrentHttpContext.Instance().Cache.Get(cacheKey) is not RateLimit cacheItem)
{
// allow 1 error per hour
cacheItem = RateLimit.Create(cacheKey, 1, 1, 3600);
CurrentHttpContext.Instance().Cache.Insert(
cacheKey,
cacheItem,
null,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.Default,
(key, item, reason) =>
Logger.InfoFormat(
"cache item '{key}' removed due to '{reason}'",
key,
reason));
}
_ = cacheItem.UpdateAllowance(DateTime.Now);
if (cacheItem.Allowance < 1)
{
Logger.InfoFormat(
"throttling {cacheKey} due to allowance = {allowance}",
cacheKey,
cacheItem.Allowance.ToString("N2"));
return(Ok(
$"throttled due to unhandled exception (allowance = {cacheItem.Allowance:N2})"));
}
IDisposable scope = NLog.NestedDiagnosticsLogicalContext.Push(taskObject.BusinessKey);
try
{
Logger.Info("begin");
IHttpActionResult result = await Transact <IHttpActionResult>(async databases =>
{
// check for published task
PublishedTask?publishedTask =
await databases.Snittlistan.PublishedTasks.SingleOrDefaultAsync(
x => x.MessageId == request.MessageId);
if (publishedTask is null)
{
return(BadRequest($"no published task found with message id {request.MessageId}"));
}
if (publishedTask.HandledDate.HasValue)
{
return(Ok($"task with message id {publishedTask.MessageId} already handled"));
}
bool handled = await HandleMessage(
taskObject,
request.CorrelationId ?? default,
request.MessageId ?? default,
databases);
if (handled)
{
publishedTask.MarkHandled(DateTime.Now);
}
return(Ok());
});
return(result);
}
catch (Exception ex)
{
Logger.WarnFormat(
ex,
"decreasing allowance for {cacheKey}",
cacheKey);
_ = cacheItem.DecreaseAllowance();
throw;
}
finally
{
Logger.Info("end");
scope.Dispose();
}
}
public async Task Handle(HandlerContext <TCommand> context)
{
(string key, int rate, int perSeconds) = GetRate(context);
// check cache
if (CurrentHttpContext.Instance().Cache.Get(key) is not RateLimit cacheItem)
{
cacheItem = RateLimit.Create(key, 1, rate, perSeconds);
Logger.InfoFormat(
"add {key} to cache: {@cacheItem}",
key,
cacheItem);
CurrentHttpContext.Instance().Cache.Insert(
key,
cacheItem,
null,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.Default,
(key, item, reason) =>
Logger.InfoFormat(
"cache item '{key}' removed due to '{reason}'",
key,
reason));
}
// check database
KeyValueProperty?rateLimitProperty =
await CompositionRoot.Databases.Snittlistan.KeyValueProperties
.SingleOrDefaultAsync(x => x.Key == key);
if (rateLimitProperty == null)
{
KeyValueProperty keyValueProperty = new(
context.Tenant.TenantId,
key,
RateLimit.Create(key, 1, rate, perSeconds));
rateLimitProperty =
CompositionRoot.Databases.Snittlistan.KeyValueProperties.Add(keyValueProperty);
}
else
{
rateLimitProperty.ModifyValue <RateLimit>(
r => r.SetRate(rate).SetPerSeconds(perSeconds),
x => Logger.InfoFormat("before: {@x}", x),
x => Logger.InfoFormat("after: {@x}", x));
}
DateTime now = DateTime.Now;
rateLimitProperty.ModifyValue <RateLimit>(
x => x.UpdateAllowance(now),
x => Logger.InfoFormat("before: {@x}", x),
x => Logger.InfoFormat("after: {@x}", x));
_ = cacheItem.UpdateAllowance(now);
double allowance = rateLimitProperty.GetValue <RateLimit, double>(x => x.Allowance);
if (allowance < 1 || cacheItem.Allowance < 1)
{
string message =
$"(db) allowance = {allowance:N2}, (cache) allowance = {cacheItem.Allowance:N2}, wait to reach 1";
throw new HandledException(message);
}
TEmail email = await CreateEmail(context);
EmailState state = email.State;
_ = CompositionRoot.Databases.Snittlistan.SentEmails.Add(new(
email.From,
email.To,
email.Bcc,
email.Subject,
state));
Logger.InfoFormat("sending email {@email}", email);
await CompositionRoot.EmailService.SendAsync(email);
rateLimitProperty.ModifyValue <RateLimit>(
x => x.DecreaseAllowance(),
x => Logger.InfoFormat("before: {@x}", x),
x => Logger.InfoFormat("after: {@x}", x));
_ = cacheItem.DecreaseAllowance();
}