public static async Task Run([QueueTrigger(QueueName, Connection = "AzureWebJobsStorage")] string item,
TraceWriter log)
{
if (!MessageHelper.TryDeserializeMessage(item, out Message message))
{
// Could not deserialize message - no amount of retries will help with this, so treat as fatal error.
log.Error("Message could not be derserialized.");
}
else
{
var maxRetries = int.Parse(EnvironmentVariables.GetValue("MaxRetries"));
var visibilityTimeouts = EnvironmentVariables.GetValue("VisibilityTimeoutsInSeconds")
.Split(',')
.Select(int.Parse)
.ToArray();
var dequeueCount = await StorageHelper.GetMessageDequeueCount(MessageStatusTableName, message.Id);
log.Info($"Processing message with Id: {message.Id}. Dequeue count: {dequeueCount}.");
var result = MessageHelper.PerformOperation(message);
var delay = visibilityTimeouts.Take(dequeueCount - 1).Sum();
await StorageHelper.LogMessageResult(LogTableName, message.Id, dequeueCount, delay, result);
switch (result)
{
case OperationResult.Success:
log.Info("Message sucessfully processed.");
break;
case OperationResult.FailFatal:
log.Error("Message failed with fatal error.");
break;
case OperationResult.FailCanRetry:
// Allow message to process BUT if not exceeded maximum retries, put back on the queue with an increasing delay.
if (dequeueCount >= maxRetries)
{
log.Error("Message with failed with tranisent error but maximum number of retries has been met.");
}
else
{
log.Warning("Message with failed with tranisent error. Putting message back on queue for retrying");
await StorageHelper.SaveMessageDequeueCount(MessageStatusTableName, message.Id, dequeueCount + 1);
await StorageHelper.AddToQueue(QueueName, item, TimeSpan.FromSeconds(visibilityTimeouts[dequeueCount - 1]));
}
break;
}
}
}
