Struct FetchObject 

pub struct FetchObject {
    pub group_id: VarInt,
    pub subgroup_id: VarInt,
    pub object_id: VarInt,
    pub publisher_priority: u8,
    pub extension_headers: Vec<u8>,
    pub status: Option<ObjectStatus>,
    pub payload: Vec<u8>,
}

One object carried on a fetch stream.

Every object on a fetch stream is self-describing — unlike subgroup streams, there is no delta encoding and extension headers are always length-prefixed (the length is zero when absent).

Fields

group_id: VarInt

Group ID.

subgroup_id: VarInt

Subgroup ID. For objects whose Forwarding Preference is Datagram, this is set to the Object ID.

object_id: VarInt

Object ID.

publisher_priority: u8

Publisher priority.

extension_headers: Vec<u8>

Raw extension-header bytes (opaque sequence of Key-Value-Pairs).

status: Option<ObjectStatus>

Object status when payload.is_empty(), otherwise None.

payload: Vec<u8>

Object payload.

Implementations

impl FetchObject

pub fn status(&self) -> ObjectStatus

The status this object resolves to.

The wire carries a status field only on an empty object, so an object holding bytes is ObjectStatus::Normal whatever status says.

pub fn permits_payload(&self) -> bool

Whether this object’s status permits it a non-empty payload.

Answered from the status alone, for the reason SubgroupObject::permits_payload gives. Note that Self::encode_checked refuses the pairing this reports on, so a false here is a value that will not be written rather than one already on the wire.

pub fn encode_checked(&self, buf: &mut impl BufMut) -> Result<(), CodecError>

Encode one fetch object, refusing a value the wire shape cannot carry.

A fetch object holds a status and a payload in the same value, and the wire form has room for only one: the Object Status field is written only when Object Payload Length is zero. Self::encode settles that by following the status and dropping the payload, which loses the payload without saying so. This refuses instead, before any byte is written, so a rejected object leaves buf untouched.

Section 10.2.1.1: “Any object with a status code other than zero MUST have an empty payload.” Normal beside a payload is therefore not a disagreement — it is the status a payload-bearing object already has — and it is written as an ordinary payload-bearing object.

Extension headers on an Object Does Not Exist status are refused for the separate reason given in Section 10.2.1.2.

Unlike a subgroup stream, a fetch object always carries its Extension Headers Length field, so a length of zero is an ordinary object with no extensions and is written as such.

pub fn encode(&self, buf: &mut impl BufMut)

Encode one fetch object.

Infallible because the status is taken as the authority on framing, and lossy for the same reason: a payload set beside a status is discarded here without a word. Prefer Self::encode_checked, which refuses that combination rather than resolving it.

pub fn decode(buf: &mut impl Buf) -> Result<Self, CodecError>

Decode one fetch object.

pub fn decode_meta(buf: &mut impl Buf) -> Result<FetchObjectMeta, CodecError>

Decode one fetch object’s framing without copying its payload.

Consumes exactly the bytes Self::decode consumes.

Trait Implementations

impl Clone for FetchObject

fn clone(&self) -> FetchObject

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FetchObject

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

Formats the value using the given formatter.

impl Eq for FetchObject

impl PartialEq for FetchObject

fn eq(&self, other: &FetchObject) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for FetchObject