Avoiding Infinite Loops in Event-Driven Execution Semantics

[aly-farahat]

One way to avoid infinite loops in event-driven execution semantics is to adopt a hybrid execution approach. In this approach, there is a fundamental time-based cycle execution. All generated events in a particular cycle are to be handled in the next timed-cycle. One way to implement that is to queue all the events generated in cycle n into their corresponding input queues. At the beginning of cycle n + 1, the number of events in both internal and external queues are measured, then this number of events is handled similar to an event-driven semantics. After the event quota is reached, the execution sleeps until the next timed cycle (n+2) and reiterates the process.

This way, we get the benefit of both worlds,
1- Avoid potential infinite execution without sleeping, as we have a finite number of events to be handled every cycle,
2- Avoid the burden on the designer where he has to think about the order in which events are handled; i.e., the notion of downstream execution.

The proposal is to add a @hybrid_based keyword to support this semantics in addition to the existing ones.