Struct HandlerError 

pub struct HandlerError { /* private fields */ }

A handler processing failure, reported to the manager as a genErr Response.

Returned as the Err side of HandlerResult from MibHandler::get and MibHandler::get_next when the handler failed to process the request — the backing store was unreachable, a lock was poisoned, a hardware read timed out. It is distinct from the RFC 3416 exception values, which are successful answers about the MIB:

Situation	Return
Object/instance doesn’t exist	Ok(GetResult::NoSuchObject / NoSuchInstance)
No more OIDs in the subtree	Ok(GetNextResult::EndOfMibView)
Couldn’t find out (backend failure)	Err(HandlerError)

When a handler returns an error, the agent answers the whole request with error-status genErr and error-index set to the failing variable binding (RFC 3416 Section 4.2.1), for all protocol versions. The message and source are logged by the agent; they are never sent on the wire — genErr carries no detail.

Construction

Any std::error::Error converts via ?, or build one from a message:

use async_snmp::handler::{HandlerError, HandlerResult, GetResult};

fn read_backend() -> std::io::Result<i32> {
    Err(std::io::Error::other("device bus timeout"))
}

fn get_value() -> HandlerResult<GetResult> {
    let raw = read_backend()?; // io::Error -> HandlerError
    Ok(GetResult::Value(async_snmp::Value::Integer(raw)))
}

let err: HandlerError = HandlerError::new("cache poisoned");
assert_eq!(err.message(), "cache poisoned");
assert!(get_value().is_err());

HandlerError intentionally does not implement std::error::Error: that keeps the blanket From<E: std::error::Error> conversion (and with it ? on arbitrary error types) possible, the same trade-off anyhow::Error makes. It is a terminal type — the agent consumes it; nothing converts out of it.

Implementations

impl HandlerError

pub fn new(message: impl Into<Cow<'static, str>>) -> Self

Create an error from a message describing what failed.

pub fn message(&self) -> &str

The failure message (used for agent-side logging only; never sent on the wire).

pub fn source(&self) -> Option<&(dyn Error + 'static)>

The underlying error this was converted from, if any.

Trait Implementations

impl Debug for HandlerError

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

Formats the value using the given formatter.

impl Display for HandlerError

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

Formats the value using the given formatter.

impl<E: Error + Send + Sync + 'static> From<E> for HandlerError

fn from(err: E) -> Self

Converts to this type from the input type.