Struct WatermarkGenerator 

pub struct WatermarkGenerator { /* private fields */ }

Generates watermarks by tracking the maximum observed event timestamp.

A watermark is emitted at max_event_ts - max_out_of_order_ms after every advance_threshold events. This provides a balance between latency and tolerance for out-of-order events.

Implementations

impl WatermarkGenerator

pub fn new(max_out_of_order_ms: i64) -> Self

Create a generator that tolerates up to max_out_of_order_ms of lateness.

Watermarks are emitted every 100 events by default.

pub fn with_advance_threshold(self, threshold: usize) -> Self

Set the event count after which a watermark is emitted.

pub fn with_source_id(self, source_id: impl Into<String>) -> Self

Set the source identifier embedded in emitted watermarks.

pub fn observe(&mut self, event_timestamp_ms: i64) -> Option<StreamWatermark>

Observe an event with event_timestamp_ms.

Returns Some(watermark) when the threshold is reached, otherwise None.

pub fn current_watermark(&self) -> i64

Current watermark timestamp: max_event_ts - max_out_of_order_ms.

Returns i64::MIN before any event has been observed.

pub fn is_late(&self, event_timestamp_ms: i64) -> bool

Return true if event_timestamp_ms is before the current watermark.