Enum PoolError 

pub enum PoolError {
    Closed,
    Empty,
    Poisoned,
}

Errors that can occur while acquiring an engine from the pool.

These map to HTTP 503 Service Unavailable at the call site — they all represent a transient inability to serve, never a client error.

Variants

Closed

The pool’s semaphore was closed (the pool is shutting down).

Empty

A permit was acquired but no idle engine was available.

This cannot happen under correct operation — permits and idle engines are kept in lock-step by construction — but is surfaced as an error rather than a panic to uphold the crate’s no-panic policy.

Poisoned

The idle mutex was poisoned by a panic in another thread.

Trait Implementations

impl Debug for PoolError

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

Formats the value using the given formatter.

impl Display for PoolError

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

Formats the value using the given formatter.

impl Error for PoolError

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.