Enum TimerUnavailableError 

#[non_exhaustive]
pub enum TimerUnavailableError {
    WorkerThreadSpawnFailed {
        source: Error,
    },
    SchedulerWorkerTerminated,
    TimeDriverDisabled,
    RuntimeShuttingDown,
    BackendUnavailable {
        backend: &'static str,
        source: Box<dyn StdError + Send + Sync + 'static>,
    },
}

Describes a backend failure that prevented timer registration or completion.

Each variant preserves the most specific stable source exposed by its backend. Custom Timer implementations should use BackendUnavailable to retain their own error rather than reducing it to display text. The enum is non-exhaustive; callers must retain a fallback arm when matching it.

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.

WorkerThreadSpawnFailed

The standard timer could not spawn its shared scheduler worker.

Fields

source: Error

I/O error returned by the native thread builder.

SchedulerWorkerTerminated

The standard timer scheduler worker exited before the deadline.

TimeDriverDisabled

Available on crate feature tokio only.

The target asynchronous runtime has no enabled time driver.

Tokio currently exposes this condition by panicking while creating a future sleep. TokioTimer catches that unwind and returns this variant, but the process panic hook runs before unwinding. Consequently the hook may still log or otherwise observe the panic, and a panic = "abort" build cannot convert it into this error.

RuntimeShuttingDown

Available on crate feature tokio only.

The target asynchronous runtime shut down before a pending timer future completed.

BackendUnavailable

A custom timer backend is unavailable.

Fields

backend: &'static str

Stable name identifying the custom backend.

source: Box<dyn StdError + Send + Sync + 'static>

Backend-specific error that prevented timer registration or completion.

Trait Implementations

impl Debug for TimerUnavailableError

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

Formats the value using the given formatter.

impl Display for TimerUnavailableError

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

Formats the value using the given formatter.

impl Error for TimerUnavailableError

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<TimerUnavailableError> for TimeError

fn from(source: TimerUnavailableError) -> Self

Wraps a timer-backend failure as a monotonic time error.

Parameters

• source - Timer-backend failure to wrap.

Returns

A monotonic time error retaining source.