Module: Hecks::Bluebook::Behaviour::ProcessManager

Included in:
ProcessManager
Defined in:
lib/hecks/bluebook/behaviour/process_manager.rb

Overview

WHAT A PROCESS MANAGER DOES. Its declared half is the trigger, the states and the handlers; the compensation half — saga — is DERIVED from the handler that answers a refusal, not declared.

Instance Method Summary collapse

Instance Method Details

#correlation_head ⇒ Object 



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# File 'lib/hecks/bluebook/behaviour/process_manager.rb', line 19

def correlation_head = @correlates_by.to_s.split(".").first.to_sym

#declares_state?(state) ⇒ Boolean

WHETHER A STATE IS ONE THIS PROCEDURE DECLARES — asked of a value a real run left a saga instance holding (its live or rehydrated state), the way Lifecycle#states is asked of an aggregate's resting field. A rehydrated instance in a state no handler could have reached is corruption the durable round-trip introduced.

Returns:

  • (Boolean) 


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# File 'lib/hecks/bluebook/behaviour/process_manager.rb', line 17

def declares_state?(state) = @states.map(&:to_s).include?(state.to_s)

#handler_for(event) ⇒ Object 



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# File 'lib/hecks/bluebook/behaviour/process_manager.rb', line 10

def handler_for(event) = @handlers.find { |h| h.event_type == event.to_s }

#hecks_name ⇒ Object 



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# File 'lib/hecks/bluebook/behaviour/process_manager.rb', line 8

def hecks_name = @name

#saga ⇒ Object

The compensation half of a procedure, read off the handler that answers REFUSED.

nil for a procedure with no answer to a refusal, which is a legitimate thing to be — a hiring pipeline cannot un-interview anybody.



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# File 'lib/hecks/bluebook/behaviour/process_manager.rb', line 26

def saga
  leg = handler_for(Bluebook::ProcessManager::REFUSED)
  return nil unless leg

  # `compensations` — a STATIC PREVIEW, declaration order, not
  # one instance's own runtime history (which legs a given
  # instance actually completed is per-instance state,
  # `SagaInterpreter`'s own `completed_compensations`, not a
  # fact `Saga` — a pure declaration reading — could ever hold).
  # Every `compensates` ANY handler's own dispatch declares,
  # forward declaration order, THEN whatever this leg's own
  # hand-written body still lists — coexistence, not replacement
  # (`ProcessManagerBuilder::HandlerBuilder#dispatch_impl`'s own
  # comment): a saga can derive some of its compensation and
  # still hand-write the rest for what isn't expressible as
  # "undo command X".
  derived = handlers.flat_map { |handler| handler.dispatches.filter_map(&:compensates) }
  Bluebook::Saga.new(trigger: Bluebook::ProcessManager::REFUSED, from_state: leg.from_state,
                     to_state: leg.to_state, compensations: derived + leg.dispatches)
end

#saga? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hecks/bluebook/behaviour/process_manager.rb', line 47

def saga? = !saga.nil?