Struct IdAllocator 

pub struct IdAllocator { /* private fields */ }

Allocates globally unique VIDs and EIDs using auto-increment counters.

This allocator uses batch reservation to minimize object store writes:

• Reserves a batch of IDs (e.g., 1000) from the object store
• Allocates from the local batch until exhausted
• Reserves a new batch when needed

Implementations

impl IdAllocator

pub async fn new( store: Arc<dyn ObjectStore>, path: Path, batch_size: u64, ) -> Result<Self>

Creates a new ID allocator, loading existing state from object store.

pub async fn allocate_vid(&self) -> Result<Vid>

Allocates a new VID.

Returns a globally unique, auto-incrementing vertex ID.

pub async fn allocate_vids(&self, count: usize) -> Result<Vec<Vid>>

Allocates multiple VIDs at once.

pub async fn allocate_eid(&self) -> Result<Eid>

Allocates a new EID.

Returns a globally unique, auto-incrementing edge ID.

pub async fn allocate_eids(&self, count: usize) -> Result<Vec<Eid>>

Allocates multiple EIDs at once.

pub async fn current_vid(&self) -> u64

Returns the current VID counter value (next VID that would be allocated).

pub async fn current_eid(&self) -> u64

Returns the current EID counter value (next EID that would be allocated).

pub async fn current_hwm(&self) -> (u64, u64)

Snapshot the current high-water-marks for VID and EID.

Returns (next_vid, next_eid) — the values the next allocations would produce if not constrained by batch reservation. Used by Phase 2 fork-creation to bootstrap a fork’s allocator above primary’s range without going through disk (the primary and fork allocators may live on different ObjectStore instances, making file-copy bootstrap fragile).

pub async fn checkpoint(&self) -> Result<()>

Force a checkpoint of the in-memory state to the underlying object store.

Used by Phase 2 fork creation to bootstrap a fork’s allocator from primary’s current HWM. Without this, primary’s allocator has an in-memory state that the on-disk manifest doesn’t yet reflect (the disk file is only updated on batch-boundary crossings), and the fork would start at VID 0 — colliding with primary rows visible through the base_paths chain.

Idempotent and safe to call frequently; the persisted manifest reflects the same state if nothing has changed.

Errors

Returns the underlying anyhow::Error from persist_manifest (object-store put failure).