Struct OidList 

pub struct OidList { /* private fields */ }

Many raw oids in ONE allocation.

A Vec<Vec<u8>> of oids is one heap allocation per object, and the two things a store does with a repository-sized oid set — hand it across this contract, and ask it “do you hold this” — need neither. This is the flat form: len × oid_len bytes in a single buffer, iterated as slices.

Why it is here and not in either engine

Because both engines cross this seam with one. MEASURED on oden 2026-08-15, the znippy engine serving a 69-object negotiated fetch out of the nornir mirror (12 303 objects, have closure 12 112): ReachSet::client_has alone was 12 112 Strings and 12 112 Vec<u8>s per request on the way through a hex round-trip, for a voucher whose only consumers ask its length and its membership. The gix engine pays the smaller half of the same bill — one Vec<u8> per ObjectId — and it pays it for the same reason: the contract’s type demanded one. Fixing it in one engine and not the other would be the twinning LAW 5 forbids.

What it is not

Not a set: contains is a linear scan, stated rather than hidden, because this type’s job is carrying oids cheaply. A consumer that asks membership per object builds its own index off iter — a HashSet of fixed-size keys costs one allocation for the table and none per entry, which is the whole point.

Not sorted, and not deduplicated: it preserves exactly what was pushed.

Implementations

impl OidList

pub fn new() -> Self

An empty list. Its width is decided by the first push.

pub fn with_capacity(oids: usize, oid_len: usize) -> Self

An empty list with room for oids oids of oid_len bytes, in one allocation. The width is still decided by the first push — this only reserves.

pub fn push(&mut self, oid: &[u8]) -> Result<()>

Append one raw oid.

The first push fixes the width; a later one of a different width is an error rather than a silently reinterpreted buffer, because every accessor here is len-strided and a mixed list would hand back oids that never existed.

pub fn iter(&self) -> impl ExactSizeIterator<Item = &[u8]> + '_

Every oid, in push order, borrowed out of the one buffer.

pub fn len(&self) -> usize

How many oids — not how many bytes.

pub fn is_empty(&self) -> bool

Whether it names nothing. For a voucher this is the clone case.

pub fn oid_len(&self) -> usize

The width of one oid, or 0 for an empty list.

pub fn contains(&self, oid: &[u8]) -> bool

A linear scan. Fine for a guard and for a handful of probes; wrong in a loop over a request. See the type’s header.

Trait Implementations

impl Clone for OidList

fn clone(&self) -> OidList

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for OidList

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

Formats the value using the given formatter.

impl Default for OidList

fn default() -> OidList

Returns the “default value” for a type.

impl Eq for OidList

impl<T: AsRef<[u8]>> FromIterator<T> for OidList

fn from_iter<I: IntoIterator<Item = T>>(items: I) -> Self

Collect from anything oid-shaped — Vec<u8>, &[u8], a gix ObjectId’s bytes.

A width disagreement panics here, because a FromIterator cannot fail and an engine that mixes hash kinds inside one repository has a bigger problem than this list. Use push where the input is not the store’s own index.

impl PartialEq for OidList

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for OidList