Struct SubgroupObjectMeta

Source

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

Expand description

The framing of one draft-19 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 properties 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.

§wire_len: u64

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

Implementations§

Source §

impl SubgroupObjectMeta

Source

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

What the Object Status registry says about this object’s payload, or None if the registry has no row for its status.

Draft-19 Section 15.9, Table 16 gives the registry a “Payload” column, and Section 11.2.1.1 makes it the rule: an Object has an empty payload unless its status is registered as permitting one. Table 16 fills the column in for the three statuses draft-19 assigns — 0x0 Normal is “Yes”, 0x3 End of Group and 0x4 End of Track are “No” — and requires every future registration to fill it in too.

status is None for an object whose payload length is non-zero, because the encoding puts a status field only where the payload does not go. Such an object’s status is Normal, the one row permitting the payload it is carrying, so this answers PayloadPermission::Permitted rather than None.

The None this does return means something else entirely: a status code with no row in the registry, for which the draft supplies no answer and this must not invent one. SubgroupObjectReader never produces such a meta — it refuses an unassigned code while decoding — but every field here is public, so a caller that assembled a meta by hand, or carried a status across from a draft numbering the set differently, can hold one.

Answered from the status alone. payload_length is not consulted: on a status that permits a payload it says only whether this particular object took the offer, and on one that forbids a payload a non-zero length is the malformation a caller uses this to detect, not evidence about the rule.