Extended out-of-order detection

Extended out-of-order detection is a function in the event stream moderator that attempts to detect very late and non-correctable out-of-order events.

The extended out-of-order detection function works by remembering the largest event sequence index processed by the model logic for each unique instance ID group. If an event arrives that has an event sequence index smaller than the highest index processed, then it is too late to reorder the event and the remaining event stream for that unique instance ID is marked in error. All unprocessed events are sent to the error queue instead of being processed by the model logic.

The extended out-of-order detection mechanism maintains the list of high indexes for recently processed unique instance IDs for five minutes. If no events arrive for an instance ID for five minutes, the high index mark is discarded. Purging is needed to manage the runtime memory and persistent storage used by this function.