Chained Deadlines based on capacity

[Ichthyostega]

As a Lumiera Developer,
I need a service to determine deadlines for best effort computations,
to be able to integrate non-timebound computation methods with time based scheduling.

a design challenge

Since the Render Engine is based on time-bound scheduling and asynchronous messaging, the interface for instructing render operations requires a mandatory deadline specification, which poses the challenge of conflicting goals:

• setting the deadlines too tight may cause some frames to drop-out, in contradiction of the »implicit contract« of best effort computation: setting a binding timeline is waived here in exchange for guaranteed 100% quality; drop-outs must be detected and amended (or better avoided altogether)
• setting the deadlines excessively loose will clog the Scheduler and associated memory management with mostly obsolete data; doing so does not necessarily pose a threat for system integrity, but may lead to sub-optimal resource usage and self-regulation. The proposed solution is to provide a dedicated service to be used by Job-Planning, based on the same functionality used for time-bound rendering, but augmented additionally with some kind of trap and guard mechanism to detect and amend timing glitches. Moreover, building such a self-regulation scheme requires some degree of experimentation and observation of real-world usage.