Crate krabka_records_legacy 

Apache Kafka legacy (v0/v1) MessageSet codec.

This crate also bridges to and from the v2 RecordBatch types in [krabka_protocol].

See the Kafka protocol docs for the wire layout that this crate implements. v0 carries no per-message timestamp. v1 adds one i64 timestamp per message (KIP-32). Both versions signal compression in the low 3 bits of the per-message attributes byte. The compressed payload is a single outer message whose value is a nested, uncompressed MessageSet.

Quick tour

• Message / Magic: per-message wire format, with a CRC and the message fields.
• ParsedRecord: cross-format view of a single offset-tagged record.
• decode_message_set / encode_flat_message_set / encode_compressed_message_set: top-level codec.
• v2_to_legacy / legacy_to_v2: bridge to and from krabka_protocol::records::RecordBatch. Use these from the Fetch handler for down-conversion, and from the Produce handler for up-conversion.

Encode and decode a v1 MessageSet

use {
    bytes::{Bytes, BytesMut},
    krabka_ids::Offset,
    krabka_records_legacy::{Magic, ParsedRecord, decode_message_set, encode_flat_message_set},
};

let records = vec![ParsedRecord {
    offset: Offset(42),
    timestamp: Some(1_713_000_000_000),
    key: Some(Bytes::from_static(b"order-42")),
    value: Some(Bytes::from_static(b"created")),
}];

let mut buf = BytesMut::new();
encode_flat_message_set(records, Magic::V1, &mut buf);
let decoded = decode_message_set(&mut &buf[..], buf.len())?;
assert2::assert!((decoded[0].offset) == (Offset(42)));

Modules

attrs

Bit layout of the legacy attributes byte.

Structs

Message

Owned legacy message, decoded after the frame parse.

ParsedRecord

A single decoded MessageSet entry.

Enums

LegacyRecordsError

Magic

Magic byte, that is, the legacy message-format version: 0 or 1.

Functions

attrs_with_compression

Panics

compression_from_attrs

Map a v0/v1 compression code to a [CompressionType].

decode_message_set

Decode a flat, uncompressed MessageSet from buf.

decode_message_set_with_policy

Decode a legacy MessageSet with explicit decompression limits.

encode_compressed_message_set

Encode a MessageSet wrapped in a single compressed outer message.

encode_flat_message_set

Encode a flat MessageSet of magic magic into buf.

legacy_to_v2

Up-convert a v0/v1 MessageSet to a v2 [RecordBatch].

legacy_to_v2_with_policy

Up-convert a legacy MessageSet using explicit decompression limits.

parsed_from_v2

Iterate the v2 batch’s records and drop control batches entirely.

v2_to_legacy

Down-convert a v2 [RecordBatch] to v0/v1 MessageSet bytes.