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Table of Contents

Status

Current stateVotingAccepted

Discussion thread: here
JIRA:

Jira
serverASF JIRA
columnskey,summary,type,created,updated,due,assignee,reporter,priority,status,resolution
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyKAFKA-7277
Jira
serverASF JIRA
columnskey,summary,type,created,updated,due,assignee,reporter,priority,status,resolution
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyKAFKA-7477

Motivation

  1. KAFKA-7277:

    Right now Streams API

...

  1. universally represents time as ms-since-unix-epoch.
    There's nothing wrong, per se, with this, but Duration is more ergonomic for an API.
    What we don't want is to present a heterogeneous API, so we need to make sure the whole Streams API is in terms of Duration.

  2. KAFKA-7477:
    Improve of semantics of KafkaStreams#close(Duration)

Public Interfaces

We need to add following method to public API.

...

Code Block
languagejava
firstline0
titlePublic API changes
class Window {
	//New methods.
	Instant startTime();
	Instant endTime();
}

JoinWindows {
    //Existing methods. Will be deprecated.
    static JoinWindows of(final long timeDifferenceMs) throws IllegalArgumentException;
    JoinWindows before(final long timeDifferenceMs) throws IllegalArgumentException;
    JoinWindows after(final long timeDifferenceMs) throws IllegalArgumentException;	

	//Existing method. Will be removed.
	JoinWindows grace(final long millisAfterWindowEnd);

    //New methods.
    static JoinWindows of(final Duration timeDifference) throws IllegalArgumentException;
    JoinWindows before(final Duration timeDifference) throws IllegalArgumentException;
    JoinWindows after(final Duration timeDifference) throws IllegalArgumentException;
	JoinWindows grace(final Duration afterWindowEnd) throws IllegalArgumentException;
}

Materialized {
	//Existing method. Will be removed.
	Materialized<K, V, S> withRetention(final long retentionMs);

	//New method.
	Materialized<K, V, S> withRetention(final Duration retention) throws IllegalArgumentException;
}

SessionWindows {
	//Existing methods. Will be deprecated.
    static SessionWindows with(final long inactivityGapMs);

	//Existing methods. Will be removed.
	SessionWindows grace(final long millisAfterWindowEnd);

	//New methods.
    static SessionWindows with(final Duration inactivityGap) throws IllegalArgumentException;
	SessionWindows grace(final Duration afterWindowEnd) throws IllegalArgumentException;
}

TimeWindows {
	//Existing methods. Will be deprecated.
	static TimeWindows of(final long sizeMs) throws IllegalArgumentException;
	TimeWindows advanceBy(final long advanceMs);

	//Existing method. Will be removed.
	TimeWindows grace(final long millisAfterWindowEnd);

	//New methods.
	static TimeWindows of(final Duration size) throws IllegalArgumentException;
	TimeWindows advanceBy(final Duration advance);
	TimeWindows grace(final Duration afterWindowEnd);
}

UnlimitedWindows {
	//Existing methods. Will be deprecated.
    UnlimitedWindows startOn(final long startMs) throws IllegalArgumentException;

	//Existing method. Will be removed.
	UnlimitedWindows grace(final long millisAfterWindowEnd);

	//New methods.
    UnlimitedWindows startOn(final Instant start) throws IllegalArgumentException;
	UnlimitedWindows grace(final Duration afterWindowEnd);
}

ProcessorContext {
    //Existing method. Will be deprecated.
    Cancellable schedule(final long intervalMs,
                         final PunctuationType type,
                         final Punctuator callback);

	//New method.
    Cancellable schedule(final Duration interval,
                         final PunctuationType type,
                         final Punctuator callback) throws IllegalArgumentException;
}

ReadOnlyWindowStore<K, V> {
	    //ExistingDeprecated methods. Will be deprecated.



    WindowStoreIterator<V> fetch(K key, long timeFrom, long timeTo);
    KeyValueIterator<Windowed<K>, V> fetch(K from, K to, long timeFrom, long timeTo);
    KeyValueIterator<Windowed<K>, V> fetchAll(long timeFrom, long timeTo);

	//New methods.
	//This changed after initial KIP voting based on [PR discussion](https://github.com/apache/kafka/pull/5682#discussion_r222494244)
    WindowStoreIterator<V> fetch(K key, Instant from, DurationInstant durationto) throws IllegalArgumentException;
    KeyValueIterator<Windowed<K>, V> fetch(K from, K to, Instant from, DurationInstant durationto) throws IllegalArgumentException;
    KeyValueIterator<Windowed<K>, V> fetchAll(Instant from, Duration duration) Instant to) throws IllegalArgumentException;
}

WindowStore {
	//New methods with default implementation that checks arguments and pass it to existing fetch methods.
    WindowStoreIterator<V> fetch(K key, long timeFrom, long timeTo) throws IllegalArgumentException;
    KeyValueIterator<Windowed<K>, V> fetch(K from, K to, long timeFrom, long timeTo) throws IllegalArgumentException;
    KeyValueIterator<Windowed<K>, V> fetchAll(long timeFrom, long timeTo) throws IllegalArgumentException;
}

Stores {
	//Existing methods. Will be deprecated.
	static WindowBytesStoreSupplier persistentWindowStore(final String name,
    	                                                  final long retentionPeriodMs,
        	                                              final long windowSizeMs,
                                                          final boolean retainDuplicates);


	static WindowBytesStoreSupplier persistentWindowStore//This method added after KIP voting. Based on John Roesler comment(https://github.com/apache/kafka/pull/5682#discussion_r221472187)
	static SessionBytesStoreSupplier persistentSessionStore(final String name,
                                                               final long retentionPeriodMsretentionPeriod);

	static WindowBytesStoreSupplier persistentWindowStore(final String name,
                                                          final long windowSizeMsretentionPeriodMs,
                                                          final booleanlong retainDuplicateswindowSizeMs,
                                                          final long segmentIntervalMs);

	static SessionBytesStoreSupplier persistentSessionStore(final String nameboolean retainDuplicates,
                                                            final long retentionPeriodMssegmentIntervalMs);

	//New methods.
	static WindowBytesStoreSupplier persistentWindowStore(final String name,
    	                                                  final Duration retentionPeriod,
        	                                              final Duration windowSize,
                                                          final boolean retainDuplicates) throws IllegalArgumentException;

	static SessionBytesStoreSupplier persistentSessionStore(final String name,
                                                            final Duration retentionPeriod) throws IllegalArgumentException;
}

KafkaStreams {
	//Existing method. Will be deprecated.
	public synchronized boolean close(final long timeout, final TimeUnit timeUnit);

	//New method
	public synchronized boolean close(final Duration timeout) throws IllegalArgumentException;
}


Proposed Changes

New methods in public API are proposed. See "Public Interfaces" section.

...

  1. In this scope keep existing methods as is.
    Try to reduce the visibility of methods in next tickets.
  2. Introduce finer methods with Instant and Duration

Changes in KafkaStream#close semantics:

  1. reject negative numbers
  2. make 0 just signal and return immediately (after checking the state once)

Default implementation of fetch methods in WindowStore.

Compatibility, Deprecation, and Migration Plan

...