Struct Framed 

struct Framed {
    block: Block,
    data: Buffer,
    header: MessageHeader,
    version: MetadataVersion,
}

One encapsulated IPC message, described entirely by the checksummed bytes it starts at.

Nothing in here comes from the footer, and that is the point. The footer’s dictionaries and recordBatches vectors are the file’s table of contents, they sit outside the CRC, and a flatbuffer vector’s length is a single u32 — so clearing recordBatches is one bit flip that makes a block read back Ok with no rows in it. Not a panic and not an error: a whole table of telemetry silently gone, reported as success, which is the worst of the three outcomes and the only one no caller can react to.

The body does not need that table of contents. Every message declares its own metadata length in the 8-byte encapsulation prefix and its own body length in its flatbuffer header, both inside [0, body_len), so the messages chain: the next one starts exactly Framed::stride bytes after this one. Walking that chain costs one extra flatbuffer verify per message — a few hundred bytes each, against a CRC of the whole body — and takes the footer out of the read path.

Fields

block: Block

What arrow-rs is told about the message. Only metaDataLength is read back out of it (read_record_batch slices data by it); the offset is relative to data, which starts at the message, so it is zero.

data: Buffer

Exactly this message: metadata, padding and body, and nothing after it.

header: MessageHeader

version: MetadataVersion

Implementations

impl Framed

fn stride(&self) -> usize

Distance to the next message. metaDataLength is padded to ALIGNMENT by the writer and is at least 8, so this always advances.