Trait Observer 

pub trait Observer:
    Debug
    + Send
    + Sync {
    // Provided methods
    fn on_indexes_ensured(&self, count: usize) { ... }
    fn on_backfill_started(&self, indexes: &[IndexName]) { ... }
    fn on_index_seeded(&self, index: &IndexName) { ... }
    fn on_backfill_completed(&self) { ... }
    fn on_live_started(&self) { ... }
    fn on_change_captured(&self) { ... }
    fn on_batch_committed(&self, stats: BatchStats) { ... }
    fn on_slot_lag(&self, bytes: u64) { ... }
    fn on_document_quarantined(&self, index: &str, id: &str, reason: &str) { ... }
    fn on_error(&self, error: &str) { ... }
}

A sink for the engine’s lifecycle and progress events.

See this module’s docs for the hot-path contract. All methods default to no-ops.

Provided Methods

fn on_indexes_ensured(&self, count: usize)

The target indexes have been ensured at the sink (count of them), before any documents flow.

fn on_backfill_started(&self, indexes: &[IndexName])

Backfill is starting for indexes (those the sink reported unseeded).

fn on_index_seeded(&self, index: &IndexName)

index’s backfill is complete and it has been marked seeded.

fn on_backfill_completed(&self)

The backfill phase finished (all unseeded indexes seeded), or was skipped.

fn on_live_started(&self)

Live capture has started; the pipeline is now following ongoing changes.

fn on_change_captured(&self)

One change was pulled from the source into the queue.

fn on_batch_committed(&self, stats: BatchStats)

A batch was built, flushed, and acked. See BatchStats.

fn on_slot_lag(&self, bytes: u64)

The source’s capture lag, in bytes behind the latest position — e.g. a replication slot’s distance from the server’s current WAL. Reported by whoever polls ChangeCapture::lag, not by the engine loop itself.

fn on_document_quarantined(&self, index: &str, id: &str, reason: &str)

A document was quarantined: the sink rejected it at the item level and the engine’s failure policy is to skip and continue (see FailurePolicy::Skip). The document is not applied and the batch proceeds, so it is not redelivered — this is the signal to surface it (a metric, a log, a dead-letter record). index and id are the destination’s names for it; reason is why it was rejected.

fn on_error(&self, error: &str)

The pipeline stopped on an error (rendered to a string, since the engine’s error type is not part of this neutral surface).

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Observer for FanOut

impl Observer for NoopObserver