Implementation:Fede1024 Rust rdkafka FFI Error Helpers

Knowledge Sources	Fede1024_Rust_rdkafka
Domains	FFI, Error_Handling
Last Updated	2026-02-07 19:00 GMT

Overview

Utility function that performs exhaustive conversion from raw librdkafka C error codes to idiomatic Rust RDKafkaErrorCode enum variants.

Description

The helpers module provides the single function rd_kafka_resp_err_t_to_rdkafka_error which contains an exhaustive match statement mapping every variant of the C-generated RDKafkaRespErr enum (approximately 180 variants) to the corresponding variant of the RDKafkaErrorCode enum. This is the bridge function used by the From<RDKafkaRespErr> trait implementation on RDKafkaErrorCode, making all error conversions throughout the crate safe and complete.

Usage

This function is called internally whenever a librdkafka operation returns an error code. Users do not call this directly; instead, they interact with RDKafkaErrorCode values that have already been converted. The function ensures that every possible C error code has a corresponding Rust enum variant.

Code Reference

Source Location

• Repository: Fede1024_Rust_rdkafka
• File: rdkafka-sys/src/helpers.rs
• Lines: 1-188

Signature

pub fn rd_kafka_resp_err_t_to_rdkafka_error(err: RDKafkaRespErr) -> RDKafkaErrorCode {
    match err {
        RDKafkaRespErr::RD_KAFKA_RESP_ERR__BAD_MSG => RDKafkaErrorCode::BadMessage,
        RDKafkaRespErr::RD_KAFKA_RESP_ERR__BAD_COMPRESSION => RDKafkaErrorCode::BadCompression,
        RDKafkaRespErr::RD_KAFKA_RESP_ERR__DESTROY => RDKafkaErrorCode::Destroy,
        RDKafkaRespErr::RD_KAFKA_RESP_ERR__FAIL => RDKafkaErrorCode::Fail,
        RDKafkaRespErr::RD_KAFKA_RESP_ERR__TRANSPORT => RDKafkaErrorCode::BrokerTransportFailure,
        // ... ~180 more variants
        RDKafkaRespErr::RD_KAFKA_RESP_ERR_NO_ERROR => RDKafkaErrorCode::NoError,
        RDKafkaRespErr::RD_KAFKA_RESP_ERR_OFFSET_OUT_OF_RANGE => RDKafkaErrorCode::OffsetOutOfRange,
        // ... all broker error codes
    }
}

Import

use rdkafka_sys::helpers::rd_kafka_resp_err_t_to_rdkafka_error;
// Usually used indirectly via:
use rdkafka_sys::RDKafkaErrorCode;
let err: RDKafkaErrorCode = c_error.into(); // calls the helper internally

I/O Contract

Inputs

Name	Type	Required	Description
err	RDKafkaRespErr	Yes	Raw C error code enum variant from librdkafka

Outputs

Name	Type	Description
return	RDKafkaErrorCode	Idiomatic Rust error code enum variant

Usage Examples

Implicit Conversion via From Trait

use rdkafka_sys::{RDKafkaErrorCode, RDKafkaRespErr};

// The helper function is used implicitly through the From trait
let c_err = RDKafkaRespErr::RD_KAFKA_RESP_ERR_UNKNOWN_TOPIC_OR_PART;
let rust_err: RDKafkaErrorCode = c_err.into();
assert_eq!(rust_err, RDKafkaErrorCode::UnknownTopicOrPartition);

// Display trait gives human-readable message
println!("{}", rust_err); // "Unknown topic or partition"

Related Pages

• Environment:Fede1024_Rust_rdkafka_Rust_Librdkafka_Build_Environment