automaton-simulation-de.scheduler — org.clojars.hephaistox/automaton-simulation-de 0.1.0-la

Scheduler aggregate details can be found in scheduler diagram, its global context

An event has three parameters (event-execution current-event state new-future-events):

• current-event which is the current event to execute
• state which is the state value before the event execution
• new-future-events which is the list of future events without the current event

The returned value is a event-return, which future events have no needs to be sorted, they will be by the scheduler.

This event-return contains the stop reason, that could be:

• ::no-future-events when no future events exists

• ::causality-broken when the date of the event is in the past

• ::execution-not-found when the type is unknown

• ::failed-event-execution when the execution of the event if raising an exception

• ::nil-handler when the handler is not given

• ::max-iteration-number the maximum iteartion number is reached

• See entity

• See aggregate

  Causality

  Causality is a property of the simulation model stating that a future event cannot change what has been done in the past already, so all changes in the state should not contradict any past event. For instance, anticipating an event would lead to causality violation.

handler clj/s

(handler request)

Handler is executing a request and returning a response.

An handler could be wrapped with middlewares. Params:

• request

iterate clj/s

(iterate registry sorting handler snapshot)

Iterates on the scheduler, it executes the handler based on data in the snapshot and creates the next one.

The event that is executed thanks to the code found for that event in the registry

A scheduler iteration should not access past or future events to have some information on the state of the simulation

Params:

• registry registry mapping event type to event execution
• sorting
• snapshot snapshot that will be used to iterate

Returns the response, the next snapshot, with state, future and past data updated according to event execution.

scheduler clj/s

(scheduler registry middlewares ordering initial-snapshot max-iteration)

The scheduler is creating the next scheduler-snapshot, until the stopping criteria are met. It is executing scheduler middleware with each scheduler snapshot.

For each scheduler-snapshot created, the scheduler is sorting the future events based on the event ordering defined in the event-registry. The first element in ordering is sorted first, in case of tie, the second order is used, and so on. The first event of that order is the current event, this event is executed (see event-execution). The resulting new values of state, past events, future events are used to create the new scheduler-snapshot.

Stopping criteria is checked by looking for :stop key in scheduler-iteration state being true.

Params:

• registry registry mapping event type to event execution.
• middlewares list of middlewares, executed from left to right for request and from right to left for response.
• ordering sort two events.
• initial-snapshot the snaphost to start with.
• max-iteration maximum iteration number to limit endless simulation.

Returns last snapshot