Enum Error 

#[non_exhaustive]
pub enum Error {
    Transport(String),
    TokenRefresh(TokenCacheError),
    InvalidPathPrefix {
        prefix: String,
        reason: String,
    },
    Rejected {
        code: Code,
        message: String,
    },
    RateLimited {
        message: String,
        retry_after: Option<Duration>,
    },
    ServerError {
        code: Code,
        message: String,
    },
    ProtoMismatch(String),
}

All errors returned by the Ppoppo gRPC client SDKs.

• Error::Rejected — the call reached the server and was turned down at the application layer (don’t retry as-is).
• Error::ServerError — a 5xx-class state (retry-eligible).
• Error::Transport — the call never reached the server.
• Error::RateLimited — the substrate-authoritative rate-limit denial (ResourceExhausted), carrying a retry_after hint for precise retry scheduling.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Transport(String)

Connection, TLS, or network-level failure.

TokenRefresh(TokenCacheError)

Bearer token acquisition failed before the gRPC call could be made.

InvalidPathPrefix

The configured path prefix is malformed — caught at connect time.

Fields

prefix: String

reason: String

Rejected

The server returned a non-OK gRPC status at the application layer (InvalidArgument, NotFound, PermissionDenied, Unauthenticated, FailedPrecondition, AlreadyExists, OutOfRange, Aborted, Cancelled).

Caller’s input, auth, or state is bad — do not retry as-is. ResourceExhausted is not routed here; it surfaces as Error::RateLimited which carries the retry_after hint.

Fields

code: Code

message: String

RateLimited

The rate-limit substrate denied the call (ResourceExhausted).

retry_after carries the substrate-authoritative reset duration when the server attached retry-after metadata; None means the substrate failed to surface a hint and callers should fall back to a default backoff. Consumers SHOULD wait at least retry_after before retrying — retrying earlier just trips the same bucket again (the reset instant has not passed), burning attempts without making progress.

Fields

message: String

retry_after: Option<Duration>

ServerError

The server returned a 5xx-class status (Internal, Unknown, DataLoss, Unimplemented, DeadlineExceeded). Retry-eligible.

Fields

code: Code

message: String

ProtoMismatch(String)

A required proto field was absent or could not be mapped to a domain type.

Implementations

impl Error

pub fn is_retryable(&self) -> bool

Whether retrying the same call as-is may succeed.

Mirrors the house is_retryable idiom (cf. ppoppo_error::PortErrorKind::is_retryable): transient transport loss, 5xx-class server errors, and rate-limit denials are retryable — the last only after honoring the retry_after hint (retrying earlier trips the same bucket). Application-layer rejections, a dead credential, a malformed prefix, and proto-shape mismatches are terminal: retrying reproduces the same failure.

Note ServerError carries tonic::Code::Unimplemented (see classify_status) into the retryable set: a rolling deploy can transiently return it before the method is wired on every replica. A permanently unimplemented method still fails after the retry budget; a mid-deploy one recovers — this is an intentional bias for the GKE rolling-update window, not an oversight.

The match is exhaustive (no wildcard): a future #[non_exhaustive] variant forces a compile error here rather than silently defaulting to “not retryable”, keeping the family retry taxonomy drift-proof.

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

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 From<TokenCacheError> for Error

fn from(source: TokenCacheError) -> Error

Converts to this type from the input type.