Struct WalEngineConfig 

pub struct WalEngineConfig {
    pub queue_capacity: usize,
    pub max_record_bytes: usize,
    pub pipeline_window_records: usize,
    pub max_inflight_bytes: usize,
    pub max_replica_lag_bytes: usize,
    pub lane_stall_timeout: Duration,
    pub max_segment_bytes: usize,
    pub max_active_segment_bytes: usize,
    pub repair_interval: Option<Duration>,
    pub shutdown_timeout: Duration,
}

Capacity controls for the in-process transactional WAL pipeline.

Fields

queue_capacity: usize

Maximum records waiting to enter the dispatched pipeline.

This is one combined bound across the handle-to-engine channel and the engine’s internal queue, not a separate allowance for each stage. The default is 256 records, eight times the default pipeline window.

max_record_bytes: usize

Maximum application payload bytes accepted in one record.

pipeline_window_records: usize

Maximum dispatched but not yet logically committed records. Slots are replenished individually as ordered quorum completions arrive.

max_inflight_bytes: usize

Maximum encoded WAL bytes admitted but not yet resolved through the ordered quorum completion stream. Admission waits for this byte budget before taking ownership of another record.

max_replica_lag_bytes: usize

Maximum unacknowledged encoded bytes retained for one replica lane. A lane that falls farther behind is dropped so a healthy quorum can continue without retaining an unbounded retry suffix. Must be at least max_inflight_bytes.

lane_stall_timeout: Duration

Maximum interval in which a lane with retained writes may make no durable-tail progress before it is shed.

Any increase in persisted_size resets the interval, so a slow but steadily advancing lane remains live. Shedding never changes the strict-majority quorum requirement: if the remaining lanes cannot cover an admitted record, the writer poisons instead of advancing its commit watermark. The default is five seconds.

max_segment_bytes: usize

Target encoded size for automatic segment rotation.

The engine checks this threshold between records, so a segment may exceed it by one complete encoded record. This is not a hard object-size limit.

Treat this as the minimum segment-size floor for the single-pending design. With sustained encoded throughput T bytes/s and worst-case provision-plus-fold latency L seconds, choose at least T * L times an operational safety factor. If the active pending segment crosses this threshold before its refill is registered, dispatch pauses fail-closed rather than acknowledging an unregistered successor.

max_active_segment_bytes: usize

Hard encoded-byte ceiling for one active segment object.

The default is 4 GiB, deliberately far below GCS’s 5 TiB object limit. Rotation normally occurs at max_segment_bytes, but the manifest’s bounded sealed-segment directory can defer that rotation until truncation removes retained entries. Admission stops cleanly at this ceiling with Error::ActiveSegmentFull instead of letting the active object grow toward the provider limit or poisoning the healthy writer. The ceiling must fit one maximum encoded record and be at least the advisory rotation target.

repair_interval: Option<Duration>

Interval between background maintenance passes.

Each startup and periodic pass runs the dead-incarnation sweep deferred by recovery, retries deletion tombstones below the committed floor, then repairs retained sealed segments. None disables periodic passes. Startup cleanup and repair, plus targeted repair after a degraded rotation, still run without timers.

shutdown_timeout: Duration

Maximum time graceful shutdown may spend draining accepted work and joining owned background tasks before aborting them.

The default is five minutes, long enough for the default storage retry budget while still turning a wedged backend or task into a bounded error.

Trait Implementations

impl Clone for WalEngineConfig

fn clone(&self) -> WalEngineConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for WalEngineConfig

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

Formats the value using the given formatter.

impl Default for WalEngineConfig

fn default() -> Self

Returns the “default value” for a type.