carrot_cake/consumers/
error.rs

1use std::fmt;
2
3/// The error type returned by message handlers.
4#[derive(Debug)]
5pub struct HandlerError<E> {
6    /// The underlying error type returned by the message handler.
7    pub inner_error: E,
8    /// `error_type` distinguishes two classes of errors:
9    /// - transient errors; message processing might succeed if retried after a short delay
10    /// - fatal errors; no matter how many times you retry, processing will never succeed
11    ///
12    /// Check out [`ErrorType`]'s documentation for more details.
13    pub error_type: ErrorType,
14}
15
16impl<E: std::error::Error + 'static> std::error::Error for HandlerError<E> {
17    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
18        Some(&self.inner_error)
19    }
20}
21
22impl<E: fmt::Display> fmt::Display for HandlerError<E> {
23    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
24        write!(
25            f,
26            "Handling of a message failed due to a {} issue - ",
27            self.error_type
28        )?;
29        write!(f, ".\n{}", self.inner_error)
30    }
31}
32
33/// Types of failure when handling a message.
34/// Used by the pub sub framework to handle retries/nacks/dead letter queues/etc.
35#[derive(Debug, Clone, Eq, PartialEq)]
36pub enum ErrorType {
37    /// Message processing might succeed if retried after a short delay.
38    ///
39    /// E.g. the message handler encountered a time out when trying to call an API to fulfil
40    /// the message processing requirements.
41    ///
42    /// The pubsub framework will execute the [transient error hook](crate::consumers::ConsumerTransientErrorHook)
43    /// before nacking the message.
44    Transient,
45    /// Message processing will never succeed, no matter how many times you retry or how long
46    /// you wait.
47    ///
48    /// E.g. the message payload is malformed and cannot be deserialized.
49    ///
50    /// The message will be nacked.
51    Fatal,
52}
53
54impl fmt::Display for ErrorType {
55    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
56        match self {
57            Self::Transient => write!(f, "transient"),
58            Self::Fatal => write!(f, "fatal"),
59        }
60    }
61}
carrot_cake/consumers/error.rs

carrot_cake/consumers/
error.rs
