public bool IsOutOfOrderMessage()

in src/DurableTask.AzureStorage/Messaging/OrchestrationSession.cs [140:202]
41 lines of code
18 McCabe index (conditional complexity)

        public bool IsOutOfOrderMessage(MessageData message)
        {
            if (message.TaskMessage.Event.EventType != EventType.TaskCompleted &&
                message.TaskMessage.Event.EventType != EventType.TaskFailed &&
                message.TaskMessage.Event.EventType != EventType.SubOrchestrationInstanceCompleted &&
                message.TaskMessage.Event.EventType != EventType.SubOrchestrationInstanceFailed &&
                message.TaskMessage.Event.EventType != EventType.TimerFired &&
                !(message.TaskMessage.Event.EventType == EventType.EventRaised && Core.Common.Entities.IsEntityInstance(message.Sender.InstanceId) && !Core.Common.Entities.IsEntityInstance(this.Instance.InstanceId)))
            {
                // The above message types are the only ones that can potentially be considered out-of-order.
                return false;
            }

            if (this.IsNonexistantInstance() && message.OriginalQueueMessage.DequeueCount > 5)
            {
                // The first five times a message for a nonexistant instance is dequeued, give the message the benefit
                // of the doubt and assume that the instance hasn't had its history table populated yet. After the 
                // fifth execution, ~30 seconds have passed and the most likely scenario is that this is a zombie event. 
                // This means the history table for the message's orchestration no longer exists, either due to an explicit 
                // PurgeHistory request or due to a ContinueAsNew call cleaning the old execution's history.
                return false;
            }

            if (this.LastCheckpointTime > message.TaskMessage.Event.Timestamp)
            {
                // LastCheckpointTime represents the time at which the most recent history checkpoint completed.
                // The checkpoint is written to the history table only *after* all queue messages are sent.
                // A message is out of order when its timestamp *preceeds* the most recent checkpoint timestamp.
                // In this case, we see that the checkpoint came *after* the message, so there is no out-of-order
                // concern. Note that this logic only applies for messages sent by orchestrations to themselves.
                // The next check considers the other cases (activities, sub-orchestrations, etc.).
                // Orchestration checkpoint time information was added only after v1.6.4.
                return false;
            }

            if (Utils.TryGetTaskScheduledId(message.TaskMessage.Event, out int taskScheduledId))
            {
                // This message is a response to a task. Search the history to make sure that we've recorded the fact that
                // this task was scheduled.
                HistoryEvent mostRecentTaskEvent = this.RuntimeState.Events.LastOrDefault(e => e.EventId == taskScheduledId);
                if (mostRecentTaskEvent != null)
                {
                    return false;
                }
            }

            if (message.TaskMessage.Event.EventType == EventType.EventRaised)
            {
                // This EventRaised message is a response to an EventSent message.
                var requestId = ((EventRaisedEvent)message.TaskMessage.Event).Name;
                if (requestId != null)
                {
                    HistoryEvent mostRecentTaskEvent = this.RuntimeState.Events.FirstOrDefault(e => e.EventType == EventType.EventSent && FindRequestId(((EventSentEvent)e).Input)?.ToString() == requestId);
                    if (mostRecentTaskEvent != null)
                    {
                        return false;
                    }
                }
            }

            // The message is out of order and cannot be handled by the current session.
            return true;
        }