Struct FileDriver 

pub struct FileDriver { /* private fields */ }

Implementations

impl FileDriver

pub fn open_or_init(dir: impl AsRef<Path>) -> Result<Arc<Self>, FileDriverError>

Open the state directory. Creates it if missing. Reads and validates the state file if present. Single-node deployments serve Leader { epoch: 0 } continuously.

Acquires an exclusive OS-level lock on the LOCK sentinel file under dir before reading state, and holds it for the lifetime of the returned driver. A second concurrent open_or_init against the same directory returns FileDriverError::AlreadyLocked immediately — FileDriver enforces its one-writer-per-directory precondition rather than trusting the operator to. The lock is released by the kernel when the driver is dropped or the process exits (including crash).

pub fn init_seeded( dir: impl AsRef<Path>, seed_physical_ms: u64, ) -> Result<(), FileDriverError>

Seed a fresh state directory with a high-water value. Used by the init CLI subcommand for migrations. Fails if state already exists.

The stored high-water is a physical_ms (the same units the allocator uses for committed_high_water), NOT a packed Timestamp. The seed argument is interpreted as the maximum physical_ms ever observed in the prior system; on first serve, the failover fence will advance above it.

Trait Implementations

impl ConsensusDriver for FileDriver

fn leadership_events(&self) -> Pin<Box<dyn Stream<Item = LeaderState> + Send>>

Stream of leadership transitions. The server holds this for its lifetime.

fn load_high_water<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<u64, ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Read the durably-persisted high-water.

fn persist_high_water<'life0, 'async_trait>( &'life0 self, at_least: u64, _epoch: Epoch, ) -> Pin<Box<dyn Future<Output = Result<u64, ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Durably advance the high-water to at least at_least. Returns the actual durably-persisted value, which is max(stored_value, at_least).

fn load_dense_seq<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 SeqKey, ) -> Pin<Box<dyn Future<Output = Result<u64, ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Read a key’s durably-committed dense counter (0 if absent). Linearized, like load_high_water. Default: unsupported.

fn advance_dense<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 SeqKey, count: u32, _expected_epoch: Epoch, ) -> Pin<Box<dyn Future<Output = Result<u64, ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Durable, linearized fetch-add for one key. Lazily creates the key at 0 on first use. Commits seq[key] += count and returns the pre-advance value as the block start. expected_epoch fences a stale proposer. Default: unsupported.

fn advance_dense_batch<'life0, 'life1, 'async_trait>( &'life0 self, entries: &'life1 [(SeqKey, u32)], _expected_epoch: Epoch, ) -> Pin<Box<dyn Future<Output = Result<Vec<u64>, ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Atomic, linearized multi-key fetch-add: advances each (key, count) and returns the per-key pre-advance block starts in request order. All-or- nothing — a cardinality or overflow rejection advances no key. Lazily creates absent keys at 0. expected_epoch fences a stale proposer. Default: unsupported.

fn load_leases<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<Vec<LeaseRecord>, ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Read the durably-committed lease set. Linearized, like load_high_water: the returned set must reflect every lease write durably committed before this call started, from any prior leader at any prior epoch. Default: unsupported.

fn persist_leases<'life0, 'life1, 'async_trait>( &'life0 self, live: &'life1 [LeaseRecord], _epoch: Epoch, ) -> Pin<Box<dyn Future<Output = Result<(), ConsensusError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Durably replace the full live lease set, atomically.

impl Debug for FileDriver

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

Formats the value using the given formatter.