Enum ServerVisibility 

pub enum ServerVisibility {
    Visible,
    NotYet,
    Unknowable,
}

Issue 1686 — what a server-readiness probe answered, read the way a WAIT loop must read it.

ClientTrait::service_is_ready has three answers (issue 1008), and every wait loop in the tree — Rust’s wait_for_service / wait_for_action_server and the four C / C++ bindings — classifies the probe through Self::of, so the six loops cannot come to disagree.

The third answer is the one the loops used to drop. A backend that has no discovery (XRCE: the Agent owns the DDS participant, vtable.c keeps the slot NULL) answers Err(Unsupported) on EVERY probe, so waiting can never change it. Issue 1087 folded it into “keep waiting”, which spent the whole budget and then reported TIMEOUT — and every C / C++ client example treats TIMEOUT as “no server” and exits. So the C and C++ XRCE action and service clients could not complete a single round-trip against a server that was up and serving (measured: Action server did not appear within 10s: -2 with the server running beside it). rcl reports this case as an ERROR from rcl_service_server_is_available, not as “no”; the loops now return it at once as Unsupported, and the caller — which knows whether it may send blind — decides. The Rust service-client examples already did exactly that with the raw probe (Err ⇒ send anyway).

Variants

Visible

A matching server is visible now.

NotYet

The backend can answer, and has not seen one yet — keep waiting.

Unknowable

The backend cannot answer this question at all; waiting will not change that.

Implementations

impl ServerVisibility

pub fn of(probe: Result<bool, TransportError>) -> Self

Classify one readiness probe.

Only Unsupported is Self::Unknowable. Any other Err is a probe that failed THIS time, so the loop keeps waiting rather than giving up on a backend that does answer.

Trait Implementations

impl Clone for ServerVisibility

fn clone(&self) -> ServerVisibility

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ServerVisibility

impl Debug for ServerVisibility

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

Formats the value using the given formatter.

impl Eq for ServerVisibility

impl PartialEq for ServerVisibility

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ServerVisibility