Struct WriteOutcome 

pub struct WriteOutcome {
    pub num_objects: u32,
    pub pack_id: ObjectId,
    pub bytes_written: u64,
    pub objects_copied_from_pack: usize,
    pub objects_recompressed: usize,
    pub objects_deltified: usize,
    pub thin_bases_offered: usize,
    pub thin_bases_vetoed: usize,
    pub closure_bases_declined: usize,
}

What one packfile emission produced.

Filled in from the engine’s own PackStats on the way out of GitServe::emit_pack, so every number is read back off what the engine reported rather than restated from what was asked for.

No Default, and that is a property rather than an omission: ObjectId has none, and an outcome with a zeroed pack id is one that claims a pack was written and cannot name it. gunnar-pack’s own WriteOutcome refused the same shape for the same reason.

Fields

num_objects: u32

How many objects the pack contains. Zero is legal.

pack_id: ObjectId

The pack’s identity: the checksum over every byte preceding it, which is also the pack’s trailing bytes and the pack-<id>.pack name git gives it.

bytes_written: u64

Total bytes written, header and trailer included.

objects_copied_from_pack: usize

Objects whose already-deflated pack entry was copied verbatim: no inflate, no deflate, delta chains preserved.

This and the next field are pack-copy’s applied output. A byte count and a wall clock cannot tell a pack-copy from a re-deflate; these two can, and the day an engine starts re-deflating, objects_recompressed climbs instead of a test staying green.

objects_recompressed: usize

Objects the engine deflated from their decompressed content.

objects_deltified: usize

Objects emitted as a newly computed delta against another object in the same pack.

Zero on the serve path, which reuses the pushing client’s deltas and has no encoder. It exists because bytes_written alone cannot tell a deltified pack from a whole-object one: on 2026-08-03 the client shipped 407.08 MiB of pack at 0.0% deltified while every byte count, wall clock and correctness test in the tree was green.

thin_bases_offered: usize

Thin-delta bases the engine offered — entries copied as an OBJ_REF_DELTA naming a base outside this pack.

Why the offer is counted and not only the refusal

objects_recompressed says how many objects lost their delta, and cannot say how many could have kept it. A voucher that refuses everything and a transfer that had no thin deltas to begin with produce the same recompressed count and are opposite situations. The refusal rate — thin_bases_vetoed over this — is the number that tells them apart, and no other field here can be made to yield it.

thin_bases_vetoed: usize

Of those, the ones the client_has voucher would not vouch for, whose objects were therefore written whole.

closure_bases_declined: usize

Deltas a base closure declined because the base it would have named is an object this pack already carries, at a location in another pack of a multi-pack store.

Zero on a single-pack store, on a negotiated fetch and whenever the closure is off.

Trait Implementations

impl Clone for WriteOutcome

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 WriteOutcome

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

Formats the value using the given formatter.

impl Eq for WriteOutcome

impl PartialEq for WriteOutcome

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for WriteOutcome