Enum Error 

#[non_exhaustive]
pub enum Error {
    Transient {
        message: String,
        retry_after: Option<Duration>,
    },
    Permanent {
        message: String,
    },
    Integrity {
        message: String,
    },
    AbsentPrice {
        asset: String,
    },
    Unsupported {
        protocol: Protocol,
        capability: Capability,
        backend: Source,
    },
    Provider(Box<dyn Error + Send + Sync>),
}

Everything a fetch can fail with. The three financially-meaningful kinds are Transient (retryable), Integrity (a required source failed → fail closed), and AbsentPrice (never coerce to 0/1).

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.

Transient

A transient provider failure (HTTP 429, timeout). Safe to retry.

Fields

message: String

Human-readable cause.

retry_after: Option<Duration>

Server-advised backoff, if any.

Permanent

A permanent failure — a bad address, an unsupported chain, malformed config. Not retryable.

Fields

message: String

Human-readable cause.

Integrity

A required source failed or returned incomplete data. The engine fails closed rather than return partial financial data.

Fields

message: String

Human-readable cause.

AbsentPrice

No price is available for an asset. Never substituted with 0 or 1.

Fields

asset: String

The asset that could not be priced (symbol or address).

Unsupported

The requested capability is not offered by any registered backend of this protocol.

Fields

protocol: Protocol

The protocol asked for.

capability: Capability

The capability asked for.

backend: Source

The backend that was routed.

Provider(Box<dyn Error + Send + Sync>)

An error from an injected provider (HTTP client, RPC transport, custom adapter). Opaque on purpose so extension points aren’t forced into this enum.

Implementations

impl Error

pub fn is_retryable(&self) -> bool

Whether retrying the operation could succeed.

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

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.