Enum LifecycleTransition 

#[repr(u8)]
pub enum LifecycleTransition {
    Configure = 1,
    Cleanup = 2,
    Activate = 3,
    Deactivate = 4,
    ShutdownUnconfigured = 5,
    ShutdownInactive = 6,
    ShutdownActive = 7,
    ErrorRecovery = 60,
}

Lifecycle transition (REP-2002)

Each transition has a specific source state. Shutdown has three variants because it can originate from Unconfigured, Inactive, or Active.

The discriminants ARE lifecycle_msgs/msg/Transition (issue 1099)

These numbers are not ours to choose. They cross the C ABI as NROS_LIFECYCLE_TRANSITION_*, they are what nros::LifecycleNode::trigger_transition(uint8_t) accepts, and they are what a ChangeState request carries on the wire — so a caller reaching any one of those surfaces with a literal must get the transition ROS 2 would give them.

They did not, until issue 1099: Activate/Deactivate/Cleanup were 2/3/4 where upstream is 3/4/2, so a ported trigger_transition(2) on an Inactive node ACTIVATED it and returned OK where ROS 2 cleans it up. Four of eight ids disagreed, and only the wire path translated — the C and C++ paths passed the raw byte through.

The one id with no upstream counterpart is Self::ErrorRecovery: upstream 8 is TRANSITION_DESTROY, which we do not implement (nothing is deallocated in a fixed arena), and upstream models error recovery as the IMPLICIT TRANSITION_ON_ERROR_SUCCESS = 60. So ErrorRecovery is 60 — the id transition_wire() in nros-node already put on the wire for it — and 8 is now rejected rather than silently meaning error recovery.

Do not renumber these. nros_c::lifecycle re-asserts every one against its NROS_LIFECYCLE_TRANSITION_* literal (issue 0792), and nros-node’s transition_wire / from_msg_transition_id are now identity functions that a test pins.

Variants

Configure = 1

Unconfigured -> (configuring) -> Inactive (lifecycle_msgs TRANSITION_CONFIGURE)

Cleanup = 2

Inactive -> (cleaning up) -> Unconfigured (lifecycle_msgs TRANSITION_CLEANUP)

Activate = 3

Inactive -> (activating) -> Active (lifecycle_msgs TRANSITION_ACTIVATE)

Deactivate = 4

Active -> (deactivating) -> Inactive (lifecycle_msgs TRANSITION_DEACTIVATE)

ShutdownUnconfigured = 5

Unconfigured -> (shutting down) -> Finalized (lifecycle_msgs TRANSITION_UNCONFIGURED_SHUTDOWN)

ShutdownInactive = 6

Inactive -> (shutting down) -> Finalized (lifecycle_msgs TRANSITION_INACTIVE_SHUTDOWN)

ShutdownActive = 7

Active -> (shutting down) -> Finalized (lifecycle_msgs TRANSITION_ACTIVE_SHUTDOWN)

ErrorRecovery = 60

ErrorProcessing -> (error recovery) -> Unconfigured (lifecycle_msgs TRANSITION_ON_ERROR_SUCCESS; see the type doc for why this is 60 and not 8 — 8 is upstream’s TRANSITION_DESTROY.)

Implementations

impl LifecycleTransition

pub const ALL: [LifecycleTransition; 8]

Every transition in the REP-2002 graph, in lifecycle_msgs id order.

phase-417 W4.f. The three shutdown variants are listed separately because their source_state differs, which is also rclcpp’s graph shape. nros_node::lifecycle_services served this table over ~/get_transition_graph while holding it privately, so a node’s own code could not read its transition table in ANY of our three languages; this is the one table all of them now read.

pub fn from_shorthand( state: LifecycleState, name: &str, ) -> Option<LifecycleTransition>

Resolve a shorthand transition name from the current state.

“shutdown” maps to the correct variant based on the current state. Returns None if the shorthand is not valid from the given state.

pub const fn from_u8(value: u8) -> Option<LifecycleTransition>

Try to convert from a lifecycle_msgs/msg/Transition id.

0 (TRANSITION_CREATE) and 8 (TRANSITION_DESTROY) are upstream ids we deliberately do not implement — construction and deallocation are not transitions in a fixed arena — so both are None rather than aliases for something else (issue 1099).

pub const fn source_state(&self) -> LifecycleState

Get the source state required for this transition.

pub const fn label_cstr(&self) -> &'static CStr

The lifecycle_msgs/msg/Transition.label for this transition, NUL-terminated. See LifecycleState::label_cstr for why the C spelling is the source.

The three shutdown variants share the label "shutdown" — that is upstream’s wire spelling, and from_shorthand is what resolves it back against the current state.

pub fn label(&self) -> &'static str

The lifecycle_msgs/msg/Transition.label for this transition.

pub const fn goal_state(&self) -> LifecycleState

The state this transition ADVERTISES as its destination — rclcpp’s Transition::goal_state().

It is the state a SUCCEEDING callback reaches, which is what the transition graph advertises. A failing callback routes to ErrorProcessing or rolls back at runtime; that is apply_transition’s business and orthogonal to the advertised graph.

Trait Implementations

impl Clone for LifecycleTransition

fn clone(&self) -> LifecycleTransition

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for LifecycleTransition

impl Debug for LifecycleTransition

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Eq for LifecycleTransition

impl Hash for LifecycleTransition

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for LifecycleTransition

fn eq(&self, other: &LifecycleTransition) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for LifecycleTransition