Package org.apache.kafka.streams.state.internals

Class InMemorySessionStore

java.lang.Object

org.apache.kafka.streams.state.internals.InMemorySessionStore

All Implemented Interfaces:

StateStore, ReadOnlySessionStore<org.apache.kafka.common.utils.Bytes,byte[]>, SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

public class InMemorySessionStore
extends java.lang.Object
implements SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Method Summary

Modifier and Type	Method	Description
void	close()	Close the storage engine.
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	fetch(org.apache.kafka.common.utils.Bytes key)	Retrieve all aggregated sessions for the provided key.
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	fetch(org.apache.kafka.common.utils.Bytes from, org.apache.kafka.common.utils.Bytes to)	Retrieve all aggregated sessions for the given range of keys.
byte[]	fetchSession(org.apache.kafka.common.utils.Bytes key, long startTime, long endTime)	Get the value of key from a single session.
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	findSessions(org.apache.kafka.common.utils.Bytes key, long earliestSessionEndTime, long latestSessionStartTime)	Deprecated.
KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]>	findSessions(org.apache.kafka.common.utils.Bytes keyFrom, org.apache.kafka.common.utils.Bytes keyTo, long earliestSessionEndTime, long latestSessionStartTime)	Deprecated.
void	flush()	Flush any cached data
void	init(ProcessorContext context, StateStore root)	Initializes this state store.
boolean	isOpen()	Is this store open for reading and writing
java.lang.String	name()	The name of this store.
boolean	persistent()	Return if the storage is persistent or not.
void	put(Windowed<org.apache.kafka.common.utils.Bytes> sessionKey, byte[] aggregate)	Write the aggregated value for the provided key to the store
void	remove(Windowed<org.apache.kafka.common.utils.Bytes> sessionKey)	Remove the session aggregated with provided Windowed key from the store

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

name

public java.lang.String name()

Description copied from interface: StateStore

The name of this store.

Specified by:

name in interface StateStore

Returns:

the storage name

init

public void init(ProcessorContext context,
                 StateStore root)

Description copied from interface: StateStore

Initializes this state store.

The implementation of this function must register the root store in the context via the ProcessorContext.register(StateStore, StateRestoreCallback) function, where the first StateStore parameter should always be the passed-in root object, and the second parameter should be an object of user's implementation of the StateRestoreCallback interface used for restoring the state store from the changelog.

Note that if the state store engine itself supports bulk writes, users can implement another interface BatchingStateRestoreCallback which extends StateRestoreCallback to let users implement bulk-load restoration logic instead of restoring one record at a time.

Specified by:

init in interface StateStore

put

public void put(Windowed<org.apache.kafka.common.utils.Bytes> sessionKey,
                byte[] aggregate)

Description copied from interface: SessionStore

Write the aggregated value for the provided key to the store

Specified by:

put in interface SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

sessionKey - key of the session to write

aggregate - the aggregated value for the session, it can be null; if the serialized bytes are also null it is interpreted as deletes

remove

public void remove(Windowed<org.apache.kafka.common.utils.Bytes> sessionKey)

Description copied from interface: SessionStore

Remove the session aggregated with provided Windowed key from the store

Specified by:

remove in interface SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

sessionKey - key of the session to remove

fetchSession

public byte[] fetchSession(org.apache.kafka.common.utils.Bytes key,
                           long startTime,
                           long endTime)

Description copied from interface: SessionStore

Get the value of key from a single session.

Specified by:

fetchSession in interface SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - the key to fetch

startTime - start timestamp of the session

endTime - end timestamp of the session

Returns:

The value or null if no session associated with the key can be found

findSessions

@Deprecated
public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> findSessions(org.apache.kafka.common.utils.Bytes key,
                                                                                                 long earliestSessionEndTime,
                                                                                                 long latestSessionStartTime)

Deprecated.

Description copied from interface: SessionStore

Fetch any sessions with the matching key and the sessions end is ≥ earliestSessionEndTime and the sessions start is ≤ latestSessionStartTime This iterator must be closed after use.

Specified by:

findSessions in interface SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - the key to return sessions for

earliestSessionEndTime - the end timestamp of the earliest session to search for

latestSessionStartTime - the end timestamp of the latest session to search for

Returns:

iterator of sessions with the matching key and aggregated values

findSessions

@Deprecated
public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> findSessions(org.apache.kafka.common.utils.Bytes keyFrom,
                                                                                                 org.apache.kafka.common.utils.Bytes keyTo,
                                                                                                 long earliestSessionEndTime,
                                                                                                 long latestSessionStartTime)

Deprecated.

Description copied from interface: SessionStore

Fetch any sessions in the given range of keys and the sessions end is ≥ earliestSessionEndTime and the sessions start is ≤ latestSessionStartTime This iterator must be closed after use.

Specified by:

findSessions in interface SessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

keyFrom - The first key that could be in the range

keyTo - The last key that could be in the range

earliestSessionEndTime - the end timestamp of the earliest session to search for

latestSessionStartTime - the end timestamp of the latest session to search for

Returns:

iterator of sessions with the matching keys and aggregated values

fetch

public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> fetch(org.apache.kafka.common.utils.Bytes key)

Description copied from interface: ReadOnlySessionStore

Retrieve all aggregated sessions for the provided key. This iterator must be closed after use. For each key, the iterator guarantees ordering of sessions, starting from the oldest/earliest available session to the newest/latest session.

Specified by:

fetch in interface ReadOnlySessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

key - record key to find aggregated session values for

Returns:

KeyValueIterator containing all sessions for the provided key.

fetch

public KeyValueIterator<Windowed<org.apache.kafka.common.utils.Bytes>,byte[]> fetch(org.apache.kafka.common.utils.Bytes from,
                                                                                          org.apache.kafka.common.utils.Bytes to)

Description copied from interface: ReadOnlySessionStore

Retrieve all aggregated sessions for the given range of keys. This iterator must be closed after use. For each key, the iterator guarantees ordering of sessions, starting from the oldest/earliest available session to the newest/latest session.

Specified by:

fetch in interface ReadOnlySessionStore<org.apache.kafka.common.utils.Bytes,byte[]>

Parameters:

from - first key in the range to find aggregated session values for

to - last key in the range to find aggregated session values for

Returns:

KeyValueIterator containing all sessions for the provided key.

persistent

public boolean persistent()

Description copied from interface: StateStore

Return if the storage is persistent or not.

Specified by:

persistent in interface StateStore

Returns:

true if the storage is persistent—false otherwise

isOpen

public boolean isOpen()

Description copied from interface: StateStore

Is this store open for reading and writing

Specified by:

isOpen in interface StateStore

Returns:

true if the store is open

flush

public void flush()

Description copied from interface: StateStore

Flush any cached data

Specified by:

flush in interface StateStore

close

public void close()

Description copied from interface: StateStore

Close the storage engine. Note that this function needs to be idempotent since it may be called several times on the same state store.

Users only need to implement this function but should NEVER need to call this api explicitly as it will be called by the library automatically when necessary

Specified by:

close in interface StateStore