Enum State 

pub enum State {
    Following,
    SnapshotNeeded,
    Unreachable,
    Stalled,
    Diverged,
    Maintenance,
    Recovering,
    Resyncing,
}

The twin’s state word.

Variants

Following

Polling, fetching, applying.

SnapshotNeeded

The primary no longer retains what the twin needs next.

Unreachable

The last poll could not reach the primary.

Stalled

The poll got as far as the data and then failed — the fetch died mid-range, the append would not go on the volume, an entry would not apply. The primary is not the problem; this copy stops where it stopped.

Diverged

The box at the other end is not the log this twin has been following. Its head is BELOW what this twin has already applied, and a log’s head only ever goes forward — so it is a re-imaged primary, a restore from somewhere else, or an address that now points at a different set. Stopped: an operator decides.

Maintenance

This twin is growing its own data set (T21, 2026-09-22, owner ruling: the twin grows EXACTLY like main — no restart). The grow machine has drained it: the follower applies nothing and the set may be unmounted. It still asks its primary for the head, so both ends see the word and the lag; it follows again the moment the set is mounted back.

Recovering

★ This twin is owed a growth before it may follow (cov-13, 2026-10-06): main’s data set grew while it was silent, and its volume cannot hold it — the primary refuses its fetches by name (gunnar_grpc::TWIN_TOO_SMALL) rather than let it fill part-way through main’s data. It keeps polling (so it reads heard, and monetize’s twin lane grows it) and follows the moment its report holds main’s set. Nothing is appended meanwhile.

Resyncing

★ This twin is taking a full copy (a snapshot) from its primary (twin-resync-space, 2026-10-06): it fell behind a hole main’s retention trimmed. Its old copy is kept while the volume holds both; when it does not, the twin GIVES IT UP (snapshot::DROPPED) and the why says it holds NO copy — it serves nothing then, and a crash restarts the resync.

Trait Implementations

impl Clone for State

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for State

impl Debug for State

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

Formats the value using the given formatter.

impl Display for State

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

Formats the value using the given formatter.

impl Eq for State

impl PartialEq for State

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for State