Enum RefusalCause 

#[non_exhaustive]
pub enum RefusalCause {
    SubmitNeeded,
    DrainNeeded,
    SubmitAndDrainNeeded,
    Busy,
    UnknownTarget,
    Unsupported,
    Invalid,
    Unusable(IoFault),
    Unknown(IoFault),
}

Why a backend refused a submission (DI-D-52), so the caller can take the action that clears it without probing. New causes may be added.

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.

SubmitNeeded

The submission queue is full: submitting what is queued makes room.

DrainNeeded

No more results fit in the completion queue: popping completions makes room.

SubmitAndDrainNeeded

Both: submit what is queued, and pop completions.

Busy

Another submission is under way; retry once it returns.

UnknownTarget

No target is attached under the submission’s key.

Unsupported

The backend cannot perform what is asked at all – a registered region on a backend with no registered buffers, for one. Retrying does not help.

Invalid

The submission is malformed for its target or the backend: an offset, length or buffer the target’s geometry does not admit, or a region outside its registered buffer. Retrying does not help.

Unusable(IoFault)

The backend can take no more submissions, ever; carries what it reported.

Unknown(IoFault)

The backend could not say why; carries what it reported.

Implementations

impl RefusalCause

pub fn needs_submit(&self) -> bool

Whether submitting what is queued is part of clearing it.

pub fn needs_drain(&self) -> bool

Whether popping completions is part of clearing it.

pub fn is_retryable(&self) -> bool

Whether the same submission may succeed if retried: after submitting or draining, as needs_submit and needs_drain say, or once another submission returns. An unknown cause may or may not clear; it answers false.

Trait Implementations

impl Clone for RefusalCause

fn clone(&self) -> RefusalCause

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RefusalCause

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

Formats the value using the given formatter.

impl Display for RefusalCause

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

Formats the value using the given formatter.

impl Eq for RefusalCause

impl Error for RefusalCause

The cause is the error: Unusable and Unknown name what the backend reported as their source.

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 RefusalCause

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for RefusalCause