private async Task <int> SubscribeMessages(QueueName requestQueueName, CancellationToken token)
{
IQueueingService queueingService = CreateProvider();
int processedMessages = 0;
try
{
while (true)
{
// process request messages
using (Claim claim = await queueingService.ClaimMessageAsync(requestQueueName, null, TimeSpan.FromMinutes(1), TimeSpan.FromMinutes(1), token))
{
List <QueuedMessage> messagesToDelete = new List <QueuedMessage>();
foreach (QueuedMessage queuedMessage in claim.Messages)
{
CalculatorOperation operation = queuedMessage.Body.ToObject <CalculatorOperation>();
CalculatorResult result;
switch (operation._command)
{
case "+":
result = new CalculatorResult(operation, operation._operand1 + operation._operand2);
break;
case "-":
result = new CalculatorResult(operation, operation._operand1 - operation._operand2);
break;
case "*":
result = new CalculatorResult(operation, operation._operand1 * operation._operand2);
break;
case "/":
result = new CalculatorResult(operation, operation._operand1 / operation._operand2);
break;
default:
throw new InvalidOperationException();
}
messagesToDelete.Add(queuedMessage);
// Assigning result to a local suppresses a warning about calling an asynchronous operation.
// In this case, we do not need to wait for the task to finish.
Task postTask = queueingService.PostMessagesAsync(operation._replyQueueName, token, new Message <CalculatorResult>(TimeSpan.FromMinutes(5), result));
processedMessages++;
}
if (messagesToDelete.Count > 0)
{
await queueingService.DeleteMessagesAsync(requestQueueName, messagesToDelete.Select(i => i.Id), token);
}
// start the dispose process using DisposeAsync so the CancellationToken is honored
Task disposeTask = claim.DisposeAsync(token);
}
if (token.IsCancellationRequested)
{
return(processedMessages);
}
}
}
catch (AggregateException ex)
{
ex.Flatten().Handle(
e =>
{
if (e is TaskCanceledException)
{
return(true);
}
WebException webException = e as WebException;
if (webException != null)
{
if (webException.Status == WebExceptionStatus.RequestCanceled)
{
return(true);
}
}
return(false);
});
return(processedMessages);
}
catch (TaskCanceledException)
{
return(processedMessages);
}
catch (WebException ex)
{
if (ex.Status != WebExceptionStatus.RequestCanceled)
{
throw;
}
return(processedMessages);
}
}
