Struct FetchObjectReader 

pub struct FetchObjectReader {
    group_order: GroupOrder,
    prior_location: Option<(u64, u64)>,
    prior_subgroup_id: Option<u64>,
    prior_publisher_priority: Option<u8>,
    gaps: FetchGaps,
}

Resolves the delta-encoded fields of the entries on one FETCH stream.

Section 11.4.2.2 keeps two kinds of prior state apart. After an End of Range indicator, “Prior Group ID and prior Object ID: The decoded values from the End of Range indicator”, while the prior Subgroup ID and Priority come from “the last actual Object before the End of Range indicator”. After End of Group or End of Track, “The prior Object ID becomes 2^64-1”.

Fields

group_order: GroupOrder

prior_location: Option<(u64, u64)>

Group ID and Object ID the next entry resolves against.

prior_subgroup_id: Option<u64>

Subgroup ID of the last actual Object that had one.

prior_publisher_priority: Option<u8>

Publisher Priority of the last actual Object.

gaps: FetchGaps

The Prior gap conditions the stream’s Objects show.

Implementations

impl FetchObjectReader

pub fn new(group_order: GroupOrder) -> Self

A reader for a stream whose Groups arrive in group_order.

pub fn read_object_header( &mut self, buf: &mut impl Buf, ) -> Result<FetchObject, CodecError>

Decode the next entry’s header and resolve its fields.

Consumes the header only; the Object Payload stays in buf.

CodecError::MalformedObject for an entry that references a prior Object that does not exist. Section 11.4.1.1: “If the first Object in the FETCH response uses a flag that references fields in the prior Object, the Subscriber MUST close the session with MALFORMED_OBJECT.” End of Group or End of Track as the first entry names a prior Object too, and is refused the same way.

CodecError::DeltaDecodingOverflow for an ID below 0 or above 2^64-1 (Section 11.4.1.1 and Section 11.4.2.1).

Refuses, with CodecError::MalformedTrack, the Prior gap conditions an Object shows alone or after the Objects before it on the stream, as FetchGaps does, and a property block that does not parse as crate::object_properties::parse_object_properties does.

pub(crate) fn read_frame_header( &mut self, buf: &mut impl Buf, ) -> Result<FetchObject, CodecError>

Self::read_object_header without the Prior gap conditions and without reading inside the property block, for the facade’s frame and meta reads, which a forwarder uses.

fn object_location( &self, header: &FetchObjectHeader, ) -> Result<(u64, u64), CodecError>

An Object’s Location, Section 11.4.1.1.

fn range_location( &self, header: &FetchObjectHeader, ) -> Result<(u64, u64), CodecError>

An End of Range indicator’s Location, Section 11.4.2.1.

Trait Implementations

impl Clone for FetchObjectReader

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FetchObjectReader

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

Formats the value using the given formatter.