Module: Tasker::Concerns::IdempotentStateTransitions

Extended by:
ActiveSupport::Concern
Included in:
Events::Publisher, Orchestration::Coordinator, Orchestration::StepExecutor, Orchestration::TaskFinalizer, Orchestration::TaskInitializer, Orchestration::TaskReenqueuer
Defined in:
lib/tasker/concerns/idempotent_state_transitions.rb

Overview

IdempotentStateTransitions provides helper methods for safely transitioning state machine objects without throwing errors on same-state transitions.

This concern extracts the common pattern of checking current state before attempting transitions to handle Statesman’s restriction on same-state transitions.

Instance Method Summary collapse

Instance Method Details

#conditional_transition_to(state_machine_object, target_state, allowed_from_states, metadata = {}) ⇒ Symbol

Safely transition to target state only if current state matches one of the allowed from states

Parameters:

  • state_machine_object (Object) —

    Object with a state_machine method

  • target_state (String) —

    The desired target state

  • allowed_from_states (Array<String>) —

    States from which transition is allowed

  • metadata (Hash) (defaults to: {}) —

    Optional metadata for the transition

Returns:

  • (Symbol) —

    :transitioned, :already_target, :invalid_from_state



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# File 'lib/tasker/concerns/idempotent_state_transitions.rb', line 67

def conditional_transition_to(state_machine_object, target_state, allowed_from_states, metadata = {})
  current_state = state_machine_object.state_machine.current_state

  # Already in target state - idempotent
  return :already_target if current_state == target_state

  # Check if current state allows this transition
  unless allowed_from_states.include?(current_state)
    allowed_states_list = allowed_from_states.join(', ')
    Rails.logger.debug do
      "#{self.class.name}: Cannot transition #{state_machine_object.class.name} #{state_machine_object.id} " \
        "from #{current_state} to #{target_state}. Allowed from states: #{allowed_states_list}"
    end
    return :invalid_from_state
  end

  # Perform the transition
  state_machine_object.state_machine.transition_to!(target_state, metadata)
  Rails.logger.debug do
    "#{self.class.name}: Successfully transitioned" \
      "#{state_machine_object.class.name} #{state_machine_object.id} " \
      "from #{current_state} to #{target_state}"
  end
  :transitioned
rescue StandardError => e
  Rails.logger.error do
    "#{self.class.name}: Failed to transition #{state_machine_object.class.name} #{state_machine_object.id} " \
      "to #{target_state}: #{e.message}"
  end
  raise
end

#in_any_state?(state_machine_object, states) ⇒ Boolean

Check if an object is in any of the specified states

Parameters:

  • state_machine_object (Object) —

    Object with a state_machine method

  • states (Array<String>) —

    States to check against

Returns:

  • (Boolean) —

    True if current state is in the provided states



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# File 'lib/tasker/concerns/idempotent_state_transitions.rb', line 120

def in_any_state?(state_machine_object, states)
  current_state = safe_current_state(state_machine_object)
  return false if current_state.nil?

  states.include?(current_state)
end

#safe_current_state(state_machine_object) ⇒ String?

Get current state safely, handling cases where state machine might not exist

Parameters:

  • state_machine_object (Object) —

    Object with a state_machine method

Returns:

  • (String, nil) —

    Current state or nil if no state machine



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# File 'lib/tasker/concerns/idempotent_state_transitions.rb', line 103

def safe_current_state(state_machine_object)
  return nil unless state_machine_object.respond_to?(:state_machine)

  state_machine_object.state_machine.current_state
rescue StandardError => e
  Rails.logger.warn do
    "#{self.class.name}: Could not get current state for #{state_machine_object.class.name} " \
      "#{state_machine_object.id}: #{e.message}"
  end
  nil
end

#safe_transition_to(state_machine_object, target_state, metadata = {}) ⇒ Boolean

Safely transition a state machine object to a target state

Checks the current state first and only attempts transition if different. This prevents Statesman’s “Cannot transition from X to X” errors.

Parameters:

  • state_machine_object (Object) —

    Object with a state_machine method

  • target_state (String) —

    The desired target state

  • metadata (Hash) (defaults to: {}) —

    Optional metadata for the transition

Returns:

  • (Boolean) —

    True if transition occurred, false if already in target state



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# File 'lib/tasker/concerns/idempotent_state_transitions.rb', line 22

def safe_transition_to(state_machine_object, target_state, metadata = {})
  current_state = state_machine_object.state_machine.current_state

  if current_state == target_state
    Rails.logger.debug do
      "#{self.class.name}: #{state_machine_object.class.name} #{state_machine_object.id} " \
        "already in #{target_state}, skipping transition"
    end
    return false
  end

  Rails.logger.debug do
    "#{self.class.name}: Transitioning #{state_machine_object.class.name} #{state_machine_object.id} " \
      "from #{current_state} to #{target_state}"
  end

  state_machine_object.state_machine.transition_to!(target_state, metadata)
  true
rescue Statesman::GuardFailedError => e
  Rails.logger.debug do
    "#{self.class.name}: Guard clause prevented transition of #{state_machine_object.class.name} " \
      "#{state_machine_object.id} from '#{current_state}' to '#{target_state}': #{e.message}"
  end
  false
rescue Statesman::TransitionFailedError => e
  Rails.logger.warn do
    "#{self.class.name}: Invalid transition for #{state_machine_object.class.name} " \
      "#{state_machine_object.id} from '#{current_state}' to '#{target_state}': #{e.message}"
  end
  false
rescue StandardError => e
  Rails.logger.error do
    "#{self.class.name}: Failed to transition #{state_machine_object.class.name} #{state_machine_object.id} " \
      "to #{target_state}: #{e.message}"
  end
  raise
end