Enum GatedError 

pub enum GatedError {
    FeatureUnavailable {
        feature: Feature,
        negotiated: ProtocolVersion,
    },
    NoProgressToken,
    NoStateKey,
    MalformedAnswer {
        reason: String,
    },
}

Why a feature-specific call was refused.

Every variant here is a refusal the peer never sees. The distinction from a JSON-RPC error matters: an error the peer sees is a protocol interaction, and this crate is careful about when it sends one. A handler that asks for a capability the session does not have is not a protocol error — the request was well formed and the server simply cannot serve it the way the handler imagined. Sending a JSON-RPC error there teaches the peer something false about the protocol, so the failure stays on this side of the wire and the handler is told directly.

That is the whole reason this type exists rather than reusing the lower-time LowerError: one happens during a translation the peer asked for, the other happens before anything is written at all.

Variants

FeatureUnavailable

The negotiated revision and the peer’s declared capabilities do not include the feature the call needs.

The negotiated version is carried rather than left to the caller to remember, because “elicitation is unavailable” is an answer nobody can act on without knowing what was negotiated.

Fields

feature: Feature

The feature the call needed.

negotiated: ProtocolVersion

The revision this session actually settled on.

NoProgressToken

A progress report was attempted on a request that was never given a progress token.

Separate from FeatureUnavailable because the fix is different: progress is available on every revision, and the client is the one that declined to open a channel.

NoStateKey

A requestState was to be sealed and the server holds no key.

A server built in-process with no key, serving through no transport that would have supplied one. Sealing under a placeholder would hand out a state any client could forge, which is worse than refusing.

MalformedAnswer

The peer’s answer to a server-initiated request did not arrive as JSON, or the exchange did not complete.

The gate is not implicated — the call was permitted, and the failure is the peer’s or the transport’s. Kept here so a handler has one error type to match rather than a gate error and a transport error.

Fields

reason: String

What the transport reported.

A String because the transport names its own failures and the application layer has no business enumerating them. The rule is that application code never names a third-party error type; a transport’s own description is data the adapter chose to hand over.

Implementations

impl GatedError

pub const fn feature(&self) -> Option<Feature>

The feature this refusal is about, when there is one.

A progress-token refusal is about no feature, which is why this returns an Option rather than inventing one — a caller logging the answer wants to omit the field, not print a placeholder that reads as a claim.

pub const fn wrote_nothing(&self) -> bool

Whether nothing was written to the transport before this refusal.

Always true, and that is the point: the gate runs before the exchange, so a refused call cannot have left a partial frame behind. The MalformedAnswer case is the exception in spirit — the request was written, because the gate had passed and the failure came afterwards — so it reports false.

Trait Implementations

impl Clone for GatedError

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GatedError

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

Formats the value using the given formatter.

impl Display for GatedError

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

Formats the value using the given formatter.

impl Eq for GatedError

impl Error for GatedError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for GatedError

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for GatedError