Struct Pending 

pub struct Pending<'a> { /* private fields */ }

A streaming append in progress. See Log::begin.

Dropped without Pending::commit or Pending::abort, it aborts (twin-streaming, 2026-10-06). The partial frame is already in the segment file, and the writer appends with O_APPEND: before this, a ? between begin and commit (a write that failed, a wire that broke under a twin’s fetch) left the half frame where it was, the next append landed AFTER it while the index recorded the offset BEFORE it, and every read of that next frame was a corrupt header — a log broken by one failed transfer. Now the half frame is cut off the segment on every path out, and a partial transfer leaves exactly nothing.

Implementations

impl Pending<'_>

pub fn seq(&self) -> u64

The sequence number this frame will commit as.

pub fn remaining(&self) -> u64

Bytes of the blob still owed.

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

Write a chunk of the blob.

pub fn commit(self) -> Result<u64>

Finish: trailer, fsync, index. Durable when this returns — and so is every frame of a group committed before it (Pending::commit_unsynced).

pub fn commit_unsynced(self) -> Result<u64>

Finish WITHOUT making it durable — one frame of a group commit (perf twin-apply-fsync, 2026-10-06). The frame is whole in the segment (staged or written, trailer and all), it holds its sequence number — the next begin takes the one after — but it is not fsynced, not indexed, not visible to readers and not the head until Log::sync (or any synced append, roll or release) makes the whole group durable with ONE fdatasync.

A crash before that loses the group’s tail, never anything acknowledged: open keeps every whole frame that reached the disk (each checks its own crc) and cuts the rest, and a twin re-fetches from its durable head.

pub fn abort(self) -> Result<()>

Give up: the partial frame is cut off the segment.

Trait Implementations

impl Drop for Pending<'_>

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.