Module: Celluloid::FSM

Defined in:
lib/vendor/celluloid/lib/celluloid/fsm.rb

Overview

Turn concurrent objects into finite state machines Inspired by Erlang’s gen_fsm. See www.erlang.org/doc/man/gen_fsm.html

Defined Under Namespace

Modules: ClassMethods Classes: State

Constant Summary collapse

DEFAULT_STATE =

Default state name unless one is explicitly set

:default

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(klass) ⇒ Object

Included hook to extend class methods



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# File 'lib/vendor/celluloid/lib/celluloid/fsm.rb', line 8

def self.included(klass)
  klass.send :include, Celluloid
  klass.send :extend,  ClassMethods
end

Instance Method Details

#current_state ⇒ Object Also known as: state

Obtain the current state of the FSM



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# File 'lib/vendor/celluloid/lib/celluloid/fsm.rb', line 61

def current_state
  defined?(@state) ? @state : @state = self.class.default_state
end

#transition(state_name, options = {}) ⇒ Object

Transition to another state Options:

  • delay: don’t transition immediately, wait the given number of seconds.

    This will return a Celluloid::Timer object you can use to
cancel the pending state transition.

Note: making additional state transitions will cancel delayed transitions



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# File 'lib/vendor/celluloid/lib/celluloid/fsm.rb', line 73

def transition(state_name, options = {})
  state_name = state_name.to_sym
  current_state = self.class.states[@state]

  return if current_state && current_state.name == state_name

  if current_state and not current_state.valid_transition? state_name
    valid = current_state.transitions.map(&:to_s).join(", ")
    raise ArgumentError, "#{self.class} can't change state from '#{@state}' to '#{state_name}', only to: #{valid}"
  end

  new_state = self.class.states[state_name]

  if !new_state and state_name == self.class.default_state
    # FIXME This probably isn't thread safe... or wise
    new_state = self.class.states[state_name] = State.new(state_name)
  end

  if new_state
    if options[:delay]
      @delayed_transition.cancel if @delayed_transition

      @delayed_transition = after(options[:delay]) do
        transition! new_state.name
        new_state.call(self)
      end

      return @delayed_transition
    end

    if defined?(@delayed_transition) and @delayed_transition
      @delayed_transition.cancel
      @delayed_transition = nil
    end

    transition! new_state.name
    new_state.call(self)
  else
    raise ArgumentError, "invalid state for #{self.class}: #{state_name}"
  end
end

#transition!(state_name) ⇒ Object

Immediate state transition with no sanity checks. “Dangerous!”



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# File 'lib/vendor/celluloid/lib/celluloid/fsm.rb', line 116

def transition!(state_name)
  @state = state_name
end