GenStage integration for sketch aggregation.

This module provides consumer and producer stages that accumulate sketch data from event streams. GenStage is an optional dependency; the sub-modules are only compiled when :gen_stage is available.

Dependency

This module requires the :gen_stage package. If GenStage is not available, the sub-modules will not be compiled and calls to require_gen_stage!/0 will raise an error.

Module Overview

• ExDataSketch.GenStage.SketchConsumer -- A GenStage consumer that accumulates events into a sketch and supports periodic flushing.
• ExDataSketch.GenStage.SketchProducer -- A GenStage producer that emits merged sketches on demand.
• ExDataSketch.GenStage.SketchStage -- A combined producer-consumer that accumulates events and periodically emits merged sketches.

Quick Start

# Consumer that builds an HLL from events
{:ok, consumer} = GenStage.SketchConsumer.start_link(
  sketch_module: ExDataSketch.HLL,
  sketch_opts: [p: 14],
  subscribe_to: [{some_producer, max_demand: 100}]
)

# Read current estimate
GenStage.SketchConsumer.estimate(consumer)

# Flush and reset
flushed = GenStage.SketchConsumer.flush(consumer)

See individual module documentation for details.