Runs one or more events in parallel. All events will run through the following steps:

• Before callbacks
• Persist state
• Invoke action
• After callbacks

For example, if two events (for state machines A and B) are run in parallel, the order in which steps are run is:

• A - Before transition callbacks
• B - Before transition callbacks
• A - Persist new state
• B - Persist new state
• A - Invoke action
• B - Invoke action (only if different than A‘s action)
• A - After transition callbacks
• B - After transition callbacks

Note that multiple events on the same state machine / attribute cannot be run in parallel. If this is attempted, an ArgumentError will be raised.

Halting callbacks

When running multiple events in parallel, special consideration should be taken with regard to how halting within callbacks affects the flow.

For before callbacks, any :halt error that‘s thrown will immediately cancel the perform for all transitions. As a result, it‘s possible for one event‘s transition to affect the continuation of another.

On the other hand, any :halt error that‘s thrown within an after callback with only affect that event‘s transition. Other transitions will continue to run their own callbacks.

Example

  class Vehicle
    state_machine :initial => :parked do
      event :ignite do
        transition :parked => :idling
      end

      event :park do
        transition :idling => :parked
      end
    end

    state_machine :alarm_state, :namespace => 'alarm', :initial => :on do
      event :enable do
        transition all => :active
      end

      event :disable do
        transition all => :off
      end
    end
  end

  vehicle = Vehicle.new                         # => #<Vehicle:0xb7c02850 @state="parked", @alarm_state="active">
  vehicle.state                                 # => "parked"
  vehicle.alarm_state                           # => "active"

  vehicle.fire_events(:ignite, :disable_alarm)  # => true
  vehicle.state                                 # => "idling"
  vehicle.alarm_state                           # => "off"

  # If any event fails, the entire event chain fails
  vehicle.fire_events(:ignite, :enable_alarm)   # => false
  vehicle.state                                 # => "idling"
  vehicle.alarm_state                           # => "off"

  # Exception raised on invalid event
  vehicle.fire_events(:park, :invalid)          # => StateMachine::InvalidEvent: :invalid is an unknown event
  vehicle.state                                 # => "idling"
  vehicle.alarm_state                           # => "off"

Run one or more events in parallel. If any event fails to run, then a StateMachine::InvalidTransition exception will be raised.

See StateMachine::InstanceMethods#fire_events for more information.

Example

  class Vehicle
    state_machine :initial => :parked do
      event :ignite do
        transition :parked => :idling
      end

      event :park do
        transition :idling => :parked
      end
    end

    state_machine :alarm_state, :namespace => 'alarm', :initial => :active do
      event :enable do
        transition all => :active
      end

      event :disable do
        transition all => :off
      end
    end
  end

  vehicle = Vehicle.new                         # => #<Vehicle:0xb7c02850 @state="parked", @alarm_state="active">
  vehicle.fire_events(:ignite, :disable_alarm)  # => true

  vehicle.fire_events!(:ignite, :disable_alarm) # => StateMachine::InvalidTranstion: Cannot run events in parallel: ignite, disable_alarm