Module sink 

Sink adapter trait and built-in implementations.

The SinkAdapter trait is the primary integration point for embedders that want to connect the CDC runtime output to a downstream system (Kafka, database, HTTP endpoint, etc.). Implement SinkAdapter on your own type and pass it to the runtime’s event processing loop.

Built-in adapters

Adapter	Notes
MemorySinkAdapter	In-memory; for tests and rapid prototyping
StdoutSink	Writes NDJSON to stdout; for local debugging and Docker deployments
FileJsonlSink	Appends NDJSON to a file with async I/O, batching, and rotation
FanOutSinkAdapter	Delivers each event to every child sink concurrently
BoxedSink	Type-erased heap-allocated adapter for dynamic dispatch

Delivery contract

Every SinkAdapter implementation advertises its delivery guarantee via SinkAdapter::delivery_guarantee. Adapters that support transactional checkpoint barriers should also override transactional_checkpoint_barrier_capable and the three barrier methods.

Dynamic dispatch

SinkAdapter is not object-safe (it uses RPITIT). Use BoxedSink for Box<dyn …> style dispatch and FanOutSinkAdapter to fan out to a heterogeneous set of sinks.

Conformance testing

AdapterConformanceSuite verifies that a custom SinkAdapter implementation honours the contract (ordering, flush semantics, post-close error behaviour).

Re-exports

pub use fan_out::FanOutSinkAdapter;

pub use file_jsonl::FileJsonlSink;

pub use file_jsonl::FileJsonlSinkConfig;

pub use stdout::StdoutSink;

Modules

fan_out

FanOutSinkAdapter — delivers each event to every child sink concurrently.

file_jsonl

FileJsonlSink — append-only NDJSON file sink with async I/O, in-memory batching, size-based rotation, and configurable fsync cadence.

stdout

StdoutSink — writes newline-delimited JSON to stdout.

Structs

AdapterConformanceSuite

Convenience harness that runs all base adapter conformance scenarios against a single SinkAdapter + AdapterGoldenFixture pair.

AdapterGoldenFixture

A set of events used as input for a single conformance scenario.

BasicAdapterConformance

Default conformance validator for SinkAdapter implementations.

BoxedSink

A heap-allocated, type-erased SinkAdapter for dynamic dispatch.

MemorySinkAdapter

In-memory sink adapter for testing and rapid prototyping.

SinkDeliveryMetrics

A snapshot of delivery counters exposed by a SinkAdapter for observability.

TestResult

Result of a single conformance scenario.

Enums

SinkDeliveryGuarantee

The delivery guarantee an adapter can offer to the pipeline.

Traits

SinkAdapter

Trait for sending CDC events to a downstream system.