Enum TaskGroupError 

#[non_exhaustive]
pub enum TaskGroupError<E> {
    ZeroConcurrency,
    ExcessiveConcurrency {
        max_concurrency: usize,
        upper_bound: usize,
    },
    TaskFailed {
        index: usize,
        error: E,
    },
    TaskJoinFailed {
        index: Option<usize>,
        source: JoinError,
    },
}

Error returned by bounded task helpers.

Operation errors preserve the caller-provided error as std::error::Error source when E implements Error. Tokio join failures expose the original JoinError as the source so callers can distinguish panics from external task cancellation.

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.

ZeroConcurrency

max_concurrency must be greater than zero.

ExcessiveConcurrency

max_concurrency exceeded MAX_CONCURRENCY.

Fields

max_concurrency: usize

Rejected concurrency bound.

upper_bound: usize

Largest accepted concurrency bound.

TaskFailed

An operation failed while running in first-error mode.

Fields

index: usize

Zero-based input index.

error: E

Caller-provided failure cause.

TaskJoinFailed

A spawned Tokio task failed to join.

Fields

index: Option<usize>

Zero-based input index when the failed task reported it.

Current helper implementations return None for Tokio join failures because JoinSet reports panics and runtime cancellation without the task’s input index. Future helper variants may use Some if they can preserve that association.

source: JoinError

Tokio join error.

Trait Implementations

impl<E: Debug> Debug for TaskGroupError<E>

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

Formats the value using the given formatter.

impl<E> Display for TaskGroupError<E>

where E: Display,

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

Formats the value using the given formatter.

impl<E> Error for TaskGroupError<E>

where E: Error + 'static,

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.