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Status
Current state: Under Discussion Adopted (1.0)
Discussion thread: [DISCUS] KIP-182: Reduce Streams DSL overloads and allow easier use of custom storage engineshere [Change the link from the KIP proposal email archive to your own email thread]
JIRA: KAFKA-5651
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
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<KR, VR> KGroupedTable<KR, VR> groupBy(final KeyValueMapper<? super K, ? super V, KeyValue<KR, VR>> selector, Serialized<KR, VR> serialized); KTable<K, V> filter(final Predicate<? super K, ? super V> predicate, final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized); KTable<K, V> filterNot(final Predicate<? super K, ? super V> predicate, final Materialized<K, V, KeyValueStore<Bytes[], byte[]>> materialized); <VR> KTable<K, VR> mapValues(final ValueMapper<? super V, ? extends VR> mapper, final Materialized<K, V, KeyValueStore<Bytes[], byte[]>> materialized); void to(final String topic, final Produced<K, V> options); KTable<K, V> through(final Serde<K> keySerde, final Produced<K, V> produced) KTable<K, V> through(final String topic, final Produced<K, V> produced, final Materialized<K, V, KeyValueStore<Bytes, byte[]> options); <VO, VR> KTable<K, VR> join(final KTable<K, VO> other, <VO, VR> KTable<K, VR> join(final KTable<K, VO> other, final ValueJoiner<? super V, ? super VO, ? extends VR> joiner, final Materialized<K, VR, KeyValueStore<Bytes, byte[]>> materialized); <VO, VR> KTable<K, VR> leftJoin(final KTable<K, VO> other, final ValueJoiner<? super V, ? super VO, ? extends VR> joiner, final Materialized<K, VR, KeyValueStore<Bytes, byte[]>> materialized); <VO, VR> KTable<K, VR> outerJoin(final KTable<K, VO> other, final ValueJoiner<? super V, ? super VO, ? extends VR> joiner, final Materialized<K, VR, KeyValueStore<Bytes, byte[]>> materialized); |
We add some new helper methods to Stores so people can conveniently and quickly create basic StateStoreSuppliers for use in the DSL or PAPI. We will also deprecate the existing Stores.create(...)
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<W extends Window> WindowedKStream<KTimeWindowedKStream<K, V> windowedBy(Windows<W> timeWindows); SessionWindowedKStream<K, V> windowedBy(SessionWindows sessionWindows); KTable<K, Long> count(final Materialized<K, Long> materialized); KTable<K, V> reduce(final Reducer<V> reducer, final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized); <VR> KTable<K, VR> aggregate(final Initializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Serde<VR>Materialized<K, aggValueSerdeVR, final Materialized<K, VR, KeyValueStore<Bytes, byteKeyValueStore<Bytes, byte[]>> materialized); |
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KTable<K, Long> count(final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized); KTable<K, V> reduce(final Reducer<V> adder, final Reducer<V> subtractor, final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized); <VR> KTable<K, VR> aggregate(final Initializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Aggregator<? super K, ? super V, VR> subtractor, final Materialized<K, VR, KeyValueStore<Bytes, byte[]>> materialized); |
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public synchronized <K, V> KStream<K, V> stream(final String topic) public synchronized <K, V> KStream<K, V> stream(final String topic, final Consumed<K, V> options) public synchronized <K, V> KStream<K, V> stream(final Collection<String> topic, final Consumed<K, V> options) public synchronized <K, V> KStream<K, V> stream(final Collection<String> topic) public synchronized <K, V> KStream<K, V> stream(final Pattern pattern, final Consumed<K, V> options) public synchronized <K, V> KTable<K, V> table(final String topic, final Consumed<K, V> consumed) public synchronized <K, V> KTable<K, V> table(final String topic, final Consumed<K, V> consumed, final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized) public synchronized <K, V> GlobalKTable<KKTable<K, V> globalTabletable(final String topic, final Consumed<KMaterialized<K, V, KeyValueStore<Bytes, V> consumedbyte[]>> materialized) public synchronized <K, V> GlobalKTable<K, V> globalTable(final String topic, final Consumed<K, V> consumed, final ) public synchronized <K, V> GlobalKTable<K, V> globalTable(final String topic, final Consumed<K, V> consumed, final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized) public synchronized <K, V> GlobalKTable<K, V> globalTable(final String topic, final Materialized<K, V, KeyValueStore<Bytes, byte[]>> materialized) |
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public interface WindowedKStream<KTimeWindowedKStream<K, V> { KTable<Windowed<K>, Long> count(); KTable<Windowed<K>, Long> count(final Materialized<K, Long, WindowStore<Bytes, byte[]>> materializedAs); <VR> KTable<Windowed<K>, VR> aggregate(final Initializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator); <VR> KTable<Windowed<K>, VR> aggregate(final Initializer<VR> initializer, final Aggregator<? super K, ? super V, VR> aggregator, final Materialized<K, VR, WindowStore<Bytes, byte[]>> materializedAs); KTable<Windowed<K>, V> reduce(final Reducer<V> reducer); KTable<Windowed<K>, V> reduce(final Reducer<V> reducer, final Materialized<K, V, WindowStore<Bytes, byte[]>> materializedAs); } |
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/** * Used when materializing a state store, i.e, during an aggregation operation or KTable operations */ public class Materialized<K, V, S extends StateStore> { public static <K, V> Materialized<K, V, KeyValueStore<Bytes, byte[]>> asKeyValueStore(final String storeName) public static <K, V> S extends StateStore> Materialized<K, V, WindowStore<Bytes, byte[]>> asWindowStore(final String storeName) public static <K, V> Materialized<K, V, SessionStore<Bytes, byte[]>> asSessionStoreS> as(final String storeName) public static <K, V> Materialized<K, V, WindowStore<Bytes, byte[]>> as(final WindowBytesStoreSupplier supplier); public static <K, V> Materialized<K, V, SessionStore<Bytes, byte[]>> as(final SessionBytesStoreSupplier supplier); public static <K, V> Materialized<K, V, KeyValueStore<Bytes, byte[]>> as(final KeyValueBytesStoreSupplier supplier) public Materialized<K, V, S> withValueSerde(final Serde<V> valueSerde) public Materialized<K, V, S> withKeySerde(final Serde<K> valueSerde) public Materialized<K, V, S> withLoggingEnabled(final Map<String, String> topicConfig) public Materialized<K, V, S> withLoggingDisabled() public Materialized<K, V, S> withCachingEnabled() public Materialized<K, V, public Materialized<K, V, S> withCachingDisabled() public StateStoreBuilder storeBuilderS> withCachingDisabled() public String storeName(); public StoreSupplier<S> storeSupplier() public Serde<K> keySerde() public Serde<V> valueSerde() public boolean loggingEnabled() public Map<String, String> logConfig() public boolean cachingEnabled() } |
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/** * Optional params that can be passed to groupBy and groupByKey operations */ public class Serialized<K, V> { public static <K, V> Serialized<K, V> with(final Serde<K> keySerde, final Serde<V> valueSerde) public Serialized<K, V> withKeySerde(final Serde<K> keySerde) public Serialized<K, V> withValueSerde(final Serde valueSerde) public Serde<K> keySerde() public Serde<V> valueSerde() } |
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/** * Options for consuming a topic as a KStream or KTable */ public class Consumed<K, V> { public static <K, V> Consumed<K, V> with(final Serde<K> keySerde, final Serde<V> valueSerde, final TimestampExtractor extractor, final Topology.AutoOffsetReset resetPolicy) public static <K, V> Consumed<K, V> with(final Serde<K> keySerde, final Serde<V> valueSerde) public static <K, V> Consumed<K, V> with(final TimestampExtractor extractor) public static <K, V> Consumed<K, V> with(final Topology.AutoOffsetReset resetPolicy) public Consumed<K, V> withKeySerde(final Serde<K> keySerde) public Consumed<K, V> withValueSerde(final(final Serde<V> valueSerde) public Consumed<K, V> withTimestampExtractor(final TimestampExtractor timestampExtractor) public Consumed<K, V> withOffsetResetPolicy(final Topology.AutoOffsetReset resetPolicy) public Serde<K> keySerde() public Serde<V> valueSerde() public Consumed<K, V> withTimestampExtractor(final public TimestampExtractor timestampExtractor() public Consumed<K, V> withOffsetResetPolicy(final TopologyToploogy.AutoOffsetReset resetPolicyoffsetResetPolicy() } |
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/** * Implementations of this will provide the ability to wrap a given StateStore * with or without caching/loggging etc. */ public interface StateStoreBuilder<TStoreBuilder<T extends StateStore> { StateStoreBuilder<T>StoreBuilder<T> withCachingEnabled(); StateStoreBuilder<T>StoreBuilder<T> withLoggingEnabled(Map<String, String> config); StoreBuilder<T> withLoggingDisabled() T build(); Map<String, String> logConfig(); boolean loggingEnabled(); } |
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/** * A store supplier that can be used to create one or more {@link SessionStore} instances of type <Byte, byte[]> */ public interface SessionBytesStoreSupplier extends StoreSupplier<SessionStore<Bytes, byte[]>> { /** * The size of a segment, in milliseconds. Used when caching is enabled to segment the cache * and reduce the amount of data that needs to be scanned when performing range queries * * @return segmentInterval in milliseconds */ long segmentIntervalsegmentIntervalMs(); } |
Proposed Changes
Add the above methods, interfaces, classes to the DSL. Deprecate existing overloads on KStream, KTable, and KGroupedStream that take more than the required parameters, for example, KTable#filter(Predicate, String) and KTable#filter(Predicate, StateStoreSupplier) will be deprecated. StateStoreSupplier will also be deprecated deprecated. All versions of KTable#through and KTable#to will be deprecated in favour of using KTable#toStream()#through and KTable#toStream()#to
The new Interface BytesStoreSupplier supersedes the existing StateStoreSupplier (which will remain untouched). This so we can provide a convenient way for users creating custom state stores to wrap them with caching/logging etc if they chose. In order to do this we need to force the inner most store, i.e, the custom store, to be a store of type `<Bytes, byte[]>`.
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