'Moderated' Tasks

[wms]

Some way in which a Task implementation may be wrapped in a 'moderated' annotation that, when applied, can control the frequency at which this Task may run using rules.

Examples of when one would need to moderate a Task include:

• Rate limiting/Throttling

  • A given Task may only be invoked n times within a given time period.
  • Could explicitly throw a 'moderation error' (similar to HTTP rate limiting.)
  • Could be silently queued (similar to _.throttle, for example.)

• Concurrency control

  • Only n processes running a given Task may run at once
  • Additional processes are silently queued
  • or subscribe to the outcome of the already-running Task (a Singleton of sorts.)

We could also match these rules based on other interesting criteria (or combinations thereof)

• Match on input predicate
• Match on Connector (for multi-Connector clusters)

[nateabele]

This is explicitly a job queue concern. If anything, the work to do here WRT mgFx would be to allow tasks to have structured metadata attached that can be passed to i.e. the scheduler.