Struct SubgroupObjectMeta 

pub struct SubgroupObjectMeta {
    pub object_id: u64,
    pub extension_headers_len: u64,
    pub payload_length: u64,
    pub status: Option<u64>,
    pub wire_len: u64,
}

The framing of one draft-15 subgroup object, without its payload.

Produced by SubgroupObjectReader::read_object_meta for callers that forward an object’s bytes verbatim and never inspect the payload.

Fields

object_id: u64

Resolved absolute Object ID.

extension_headers_len: u64

Byte length of the extension-header block’s contents, excluding its length prefix.

payload_length: u64

Declared payload length. Zero when status is Some.

status: Option<u64>

Object status wire code, present only when the payload is empty.

Kept as the raw code, unlike SubgroupObject::object_status: a meta is produced by SubgroupObjectReader::read_object_meta and is never an encode input, and a relay that reads a status on one draft may hand it to a draft that numbers the same value differently. The code is still one draft-15 assigns — read_object_meta refuses the others.

wire_len: u64

Total bytes this object occupies on the wire, prefix fields included.

Implementations

impl SubgroupObjectMeta

pub fn payload_permission(&self) -> Option<PayloadPermission>

Whether this object is permitted a non-empty payload, or None when Self::status holds a code draft-15 does not assign.

Self::status is a raw wire code, so the rule of draft-15 Section 10.2.1.1 — “Any object with a status code other than zero MUST have an empty payload” — cannot be read off it without first deciding what the code means. This does that decision once: a consumer asking whether an object may carry bytes gets an answer instead of a number and a rule to apply to it.

An absent status answers PayloadPermission::Permitted rather than None. A meta has no status only when its payload length is non-zero, and Section 10.2.1.1 says of Normal that “This status is implicit for any non-zero length object” — the object has a status, the encoding just does not spell it.

None means the code is one the draft leaves unassigned, and so one it gives no payload rule for. That is not reachable through SubgroupObjectReader::read_object_meta, which refuses such a code before it can reach the field, but the fields here are public and a meta assembled by hand — by a relay carrying a status across from a draft that numbers them differently, say — can hold anything a varint can. The answer there is that draft-15 has none, not that the payload is forbidden.

pub fn extensions_permitted(&self) -> Option<bool>

Whether this object’s status is allowed to carry the extension block it declares.

The same rule SubgroupObject::extensions_permitted answers, from the declared length rather than from the bytes. A relay that forwards an object verbatim reads it through SubgroupObjectReader::read_object_meta and never copies the block, so asking this must not require having it — draft-15 Section 10.2.1.2 turns on whether the block is empty, and the length says that on its own.

A status this draft does not assign answers None rather than false, for the reason Self::payload_permission gives: the draft states no rule for a code it does not define, and a meta assembled by hand can hold one. read_object_meta refuses such a code before it reaches the field.

An absent status answers from Normal. A meta has no status only when its payload length is non-zero, and such an object is Normal by Section 10.2.1.1, so its extensions are permitted.

Trait Implementations

impl Clone for SubgroupObjectMeta

fn clone(&self) -> SubgroupObjectMeta

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SubgroupObjectMeta

impl Debug for SubgroupObjectMeta

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

Formats the value using the given formatter.

impl Eq for SubgroupObjectMeta

impl PartialEq for SubgroupObjectMeta

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for SubgroupObjectMeta