Status
Current state: "Under Discussion"
Discussion thread: TBD
JIRA: TBD
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
Rich functions are one of the essential parts of stream processing. There are several use-cases where users cannot express their business logic with current un-rich methods especially when init(Some params)
, close()
methods are needed.
Public Interfaces
KStream.java
KStream<K, V> filter(RichPredicate<? super K, ? super V> predicate); KStream<K, V> filterNot(RichPredicate<? super K, ? super V> predicate); <KR> KStream<KR, V> selectKey(RichKeyValueMapper<? super K, ? super V, ? extends KR> mapper); <KR, VR> KStream<KR, VR> map(RichKeyValueMapper<? super K, ? super V, ? extends KeyValue<? extends KR, ? extends VR>> mapper); <VR> KStream<K, VR> mapValues(RichValueMapper<? super V, ? extends VR> mapper); <KR, VR> KStream<KR, VR> flatMap(final RichKeyValueMapper<? super K, ? super V, ? extends Iterable<? extends KeyValue<? extends KR, ? extends VR>>> mapper); <VR> KStream<K, VR> flatMapValues(final RichValueMapper<? super V, ? extends Iterable<? extends VR>> processor); void foreach(final RichForeachAction<? super K, ? super V> action); KStream<K, V> peek(final RichForeachAction<? super K, ? super V> action); KStream<K, V>[] branch(final RichPredicate<? super K, ? super V>... predicates); <KR> KGroupedStream<KR, V> groupBy(final RichKeyValueMapper<? super K, ? super V, KR> selector); <KR> KGroupedStream<KR, V> groupBy(final RichKeyValueMapper<? super K, ? super V, KR> selector, final Serde<KR> keySerde, final Serde<V> valSerde); <VO, VR> KStream<K, VR> join(final KStream<K, VO> otherStream, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final JoinWindows windows); <VO, VR> KStream<K, VR> join(final KStream<K, VO> otherStream, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final JoinWindows windows, final Serde<K> keySerde, final Serde<V> thisValueSerde, final Serde<VO> otherValueSerde); <VO, VR> KStream<K, VR> leftJoin(final KStream<K, VO> otherStream, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final JoinWindows windows); <VO, VR> KStream<K, VR> leftJoin(final KStream<K, VO> otherStream, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final JoinWindows windows, final Serde<K> keySerde, final Serde<V> thisValSerde, final Serde<VO> otherValueSerde); <VO, VR> KStream<K, VR> outerJoin(final KStream<K, VO> otherStream, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final JoinWindows windows); <VO, VR> KStream<K, VR> outerJoin(final KStream<K, VO> otherStream, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final JoinWindows windows, final Serde<K> keySerde, final Serde<V> thisValueSerde, final Serde<VO> otherValueSerde); <VT, VR> KStream<K, VR> join(final KTable<K, VT> table, final RichValueJoiner<? super V, ? super VT, ? extends VR> joiner); <VT, VR> KStream<K, VR> join(final KTable<K, VT> table, final RichValueJoiner<? super V, ? super VT, ? extends VR> joiner, final Serde<K> keySerde, final Serde<V> valSerde); <VT, VR> KStream<K, VR> leftJoin(final KTable<K, VT> table, final RichValueJoiner<? super V, ? super VT, ? extends VR> joiner); <VT, VR> KStream<K, VR> leftJoin(final KTable<K, VT> table, final RichValueJoiner<? super V, ? super VT, ? extends VR> joiner, final Serde<K> keySerde, final Serde<V> valSerde); <GK, GV, RV> KStream<K, RV> join(final GlobalKTable<GK, GV> globalKTable, final RichKeyValueMapper<? super K, ? super V, ? extends GK> keyValueMapper, final RichValueJoiner<? super V, ? super GV, ? extends RV> joiner); <GK, GV, RV> KStream<K, RV> leftJoin(final GlobalKTable<GK, GV> globalKTable, final RichKeyValueMapper<? super K, ? super V, ? extends GK> keyValueMapper, final RichValueJoiner<? super V, ? super GV, ? extends RV> valueJoiner);
KTable.java
KTable<K, V> filter(final RichPredicate<? super K, ? super V> predicate); KTable<K, V> filter(final RichPredicate<? super K, ? super V> predicate, final String queryableStoreName); KTable<K, V> filter(final RichPredicate<? super K, ? super V> predicate, final StateStoreSupplier<KeyValueStore> storeSupplier); KTable<K, V> filterNot(final RichPredicate<? super K, ? super V> predicate); KTable<K, V> filterNot(final RichPredicate<? super K, ? super V> predicate, final StateStoreSupplier<KeyValueStore> storeSupplier); KTable<K, V> filterNot(final RichPredicate<? super K, ? super V> predicate, final String queryableStoreName); <VR> KTable<K, VR> mapValues(final RichValueMapper<? super V, ? extends VR> mapper); <VR> KTable<K, VR> mapValues(final RichValueMapper<? super V, ? extends VR> mapper, final Serde<VR> valueSerde, final String queryableStoreName); <VR> KTable<K, VR> mapValues(final RichValueMapper<? super V, ? extends VR> mapper, final Serde<VR> valueSerde, final StateStoreSupplier<KeyValueStore> storeSupplier); void foreach(final RichForeachAction<? super K, ? super V> action); <KR> KStream<KR, V> toStream(final RichKeyValueMapper<? super K, ? super V, ? extends KR> mapper); <KR, VR> KGroupedTable<KR, VR> groupBy(final RichKeyValueMapper<? super K, ? super V, KeyValue<KR, VR>> selector); <KR, VR> KGroupedTable<KR, VR> groupBy(final RichKeyValueMapper<? super K, ? super V, KeyValue<KR, VR>> selector, final Serde<KR> keySerde, final Serde<VR> valueSerde); <VO, VR> KTable<K, VR> join(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner); <VO, VR> KTable<K, VR> join(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final Serde<VR> joinSerde, final String queryableStoreName); <VO, VR> KTable<K, VR> join(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final StateStoreSupplier<KeyValueStore> storeSupplier); <VO, VR> KTable<K, VR> leftJoin(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner); <VO, VR> KTable<K, VR> leftJoin(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final Serde<VR> joinSerde, final String queryableStoreName); <VO, VR> KTable<K, VR> leftJoin(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final StateStoreSupplier<KeyValueStore> storeSupplier); <VO, VR> KTable<K, VR> outerJoin(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner); <VO, VR> KTable<K, VR> outerJoin(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final Serde<VR> joinSerde, final String queryableStoreName); <VO, VR> KTable<K, VR> outerJoin(final KTable<K, VO> other, final RichValueJoiner<? super V, ? super VO, ? extends VR> joiner, final StateStoreSupplier<KeyValueStore> storeSupplier);
KGroupedStream
KTable<K, V> reduce(final RichReducer<V> reducer); KTable<K, V> reduce(final RichReducer<V> reducer, final String queryableStoreName); KTable<K, V> reduce(final RichReducer<V> reducer, final StateStoreSupplier<KeyValueStore> storeSupplier); <W extends Window> KTable<Windowed<K>, V> reduce(final RichReducer<V> reducer, final Windows<W> windows, final String queryableStoreName); <W extends Window> KTable<Windowed<K>, V> reduce(final RichReducer<V> reducer, final Windows<W> windows); <W extends Window> KTable<Windowed<K>, V> reduce(final RichReducer<V> reducer, final Windows<W> windows, final StateStoreSupplier<WindowStore> storeSupplier); KTable<Windowed<K>, V> reduce(final RichReducer<V> reducer, final SessionWindows sessionWindows, final String queryableStoreName); KTable<Windowed<K>, V> reduce(final RichReducer<V> reducer, final SessionWindows sessionWindows); KTable<Windowed<K>, V> reduce(final RichReducer<V> reducer, final SessionWindows sessionWindows, final StateStoreSupplier<SessionStore> storeSupplier); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Serde<VR> aggValueSerde, final String queryableStoreName); <VR> KTable<K, VR> aggregate(final Initializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Serde<VR> aggValueSerde, final String queryableStoreName); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Serde<VR> aggValueSerde, final String queryableStoreName); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Serde<VR> aggValueSerde); <VR> KTable<K, VR> aggregate(final Initializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Serde<VR> aggValueSerde); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Serde<VR> aggValueSerde); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final StateStoreSupplier<KeyValueStore> storeSupplier); <VR> KTable<K, VR> aggregate(final Initializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final StateStoreSupplier<KeyValueStore> storeSupplier); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final StateStoreSupplier<KeyValueStore> storeSupplier); <W extends Window, VR> KTable<Windowed<K>, VR> aggregate(final RichInitializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Windows<W> windows, final Serde<VR> aggValueSerde, final String queryableStoreName); <W extends Window, VR> KTable<Windowed<K>, VR> aggregate(final Initializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Windows<W> windows, final Serde<VR> aggValueSerde, final String queryableStoreName); <W extends Window, VR> KTable<Windowed<K>, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Windows<W> windows, final Serde<VR> aggValueSerde, final String queryableStoreName); <W extends Window, VR> KTable<Windowed<K>, VR> aggregate(final RichInitializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Windows<W> windows, final StateStoreSupplier<WindowStore> storeSupplier); <W extends Window, VR> KTable<Windowed<K>, VR> aggregate(final Initializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Windows<W> windows, final StateStoreSupplier<WindowStore> storeSupplier); <W extends Window, VR> KTable<Windowed<K>, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> aggregator, final Windows<W> windows, final StateStoreSupplier<WindowStore> storeSupplier); <T> KTable<Windowed<K>, T> aggregate(final RichInitializer<T> initializer, final Aggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde, final String queryableStoreName); <T> KTable<Windowed<K>, T> aggregate(final Initializer<T> initializer, final RichAggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde, final String queryableStoreName); <T> KTable<Windowed<K>, T> aggregate(final RichInitializer<T> initializer, final RichAggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde, final String queryableStoreName); <T> KTable<Windowed<K>, T> aggregate(final RichInitializer<T> initializer, final Aggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde); <T> KTable<Windowed<K>, T> aggregate(final Initializer<T> initializer, final RichAggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde); <T> KTable<Windowed<K>, T> aggregate(final RichInitializer<T> initializer, final RichAggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde); <T> KTable<Windowed<K>, T> aggregate(final Initializer<T> initializer, final RichAggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde, final StateStoreSupplier<SessionStore> storeSupplier); <T> KTable<Windowed<K>, T> aggregate(final RichInitializer<T> initializer, final Aggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde, final StateStoreSupplier<SessionStore> storeSupplier); <T> KTable<Windowed<K>, T> aggregate(final RichInitializer<T> initializer, final RichAggregator<? super K, ? super V, T> aggregator, final Merger<? super K, T> sessionMerger, final SessionWindows sessionWindows, final Serde<T> aggValueSerde, final StateStoreSupplier<SessionStore> storeSupplier);
KGroupedTable
KTable<K, V> reduce(final RichReducer<V> adder, final Reducer<V> subtractor, final String queryableStoreName); KTable<K, V> reduce(final Reducer<V> adder, final RichReducer<V> subtractor, final String queryableStoreName); KTable<K, V> reduce(final RichReducer<V> adder, final RichReducer<V> subtractor, final String queryableStoreName); KTable<K, V> reduce(final RichReducer<V> adder, final Reducer<V> subtractor); KTable<K, V> reduce(final Reducer<V> adder, final RichReducer<V> subtractor); KTable<K, V> reduce(final RichReducer<V> adder, final RichReducer<V> subtractor); KTable<K, V> reduce(final RichReducer<V> adder, final Reducer<V> subtractor, final StateStoreSupplier<KeyValueStore> storeSupplier); KTable<K, V> reduce(final Reducer<V> adder, final RichReducer<V> subtractor, final StateStoreSupplier<KeyValueStore> storeSupplier); KTable<K, V> reduce(final RichReducer<V> adder, final RichReducer<V> subtractor, final StateStoreSupplier<KeyValueStore> storeSupplier); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> adder, final RichAggregator<? super K, ? super V, VR> subtractor, final String queryableStoreName); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> adder, final RichAggregator<? super K, ? super V, VR> subtractor); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> adder, final RichAggregator<? super K, ? super V, VR> subtractor, final Serde<VR> aggValueSerde, final String queryableStoreName); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> adder, final RichAggregator<? super K, ? super V, VR> subtractor, final Serde<VR> aggValueSerde); <VR> KTable<K, VR> aggregate(final RichInitializer<VR> initializer, final RichAggregator<? super K, ? super V, VR> adder, final RichAggregator<? super K, ? super V, VR> subtractor, final StateStoreSupplier<KeyValueStore> storeSupplier);
Proposed changes
Limiting the ProcessorContext - RecordContext interface
We create a subset of features from ProcessorContext
and put into RecordContext
interface
public interface RecordContext { String applicationId(); TaskId taskId(); StreamsMetrics metrics(); String topic(); int partition(); void commit(); long offset(); long timestamp(); Map<String, Object> appConfigs(); Map<String, Object> appConfigsWithPrefix(String prefix); } public interface ProcessorContext extends RecordContext { // all methods but the ones in RecordContext }
Once we need a conversion from ProcessorContext
and RecordContext, we just cast:
private class KStreamMapProcessor extends AbstractProcessor<K, V> { @Override public void init(ProcessorContext processorContext) { super.init(processorContext); richMapper.init((RecordContext) processorContext); // HERE WE MAKE A CAST } @Override public void process(final K key, final V value) { V1 newValue = mapper.apply(key, value); context().forward(key, newValue); } @Override public void close() { super.close(); mapper.close(); } }
Rich Interfaces
public interface RichValueMapper<V, VR> { VR apply(final V value, final RecordContext recordContext); } public interface RichValueJoiner<V1, V2, VR> { VR apply(final V1 value1, final V2 value2, final RecordContext recordContext); } public interface RichKeyValueMapper<K, V, VR> { VR apply(final K key, final V value, final RecordContext recordContext); } public interface RichReducer<V> { V apply(final V value1, final V value2, final RecordContext recordContext); } public interface RichInitializer<VA> { VA apply(final RecordContext recordContext); } public interface RichAggregator<K, V, VA> { VA apply(final K key, final V value, final VA aggregate, final RecordContext recordContext); } public interface RichForeachAction<K, V> { void apply(final K key, final V value, final RecordContext recordContext); } public interface RichPredicate<K, V> { boolean test(final K key, final V value, final RecordContext recordContext); }
Rejected Alternatives
Not yet.