Package org.apache.kafka.streams.processor.internals

Class StoreChangelogReader

java.lang.Object

org.apache.kafka.streams.processor.internals.StoreChangelogReader

All Implemented Interfaces:

ChangelogReader, ChangelogRegister

public class StoreChangelogReader
extends java.lang.Object
implements ChangelogReader

ChangelogReader is created and maintained by the stream thread and used for both updating standby tasks and restoring active tasks. It manages the restore consumer, including its assigned partitions, when to pause / resume these partitions, etc.

The reader also maintains the source of truth for restoration state: only active tasks restoring changelog could be completed, while standby tasks updating changelog would always be in restoring state after being initialized.

Constructor Summary

Constructors

Constructor	Description
StoreChangelogReader(org.apache.kafka.common.utils.Time time, StreamsConfig config, org.apache.kafka.common.utils.LogContext logContext, org.apache.kafka.clients.admin.Admin adminClient, org.apache.kafka.clients.consumer.Consumer<byte[],byte[]> restoreConsumer, StateRestoreListener stateRestoreListener)

Method Summary

Modifier and Type	Method	Description
void	clear()	Clear all partitions
java.util.Set<org.apache.kafka.common.TopicPartition>	completedChangelogs()
void	enforceRestoreActive()	Transit to restore active changelogs mode
boolean	isEmpty()
void	register(org.apache.kafka.common.TopicPartition partition, ProcessorStateManager stateManager)	Since it is shared for multiple tasks and hence multiple state managers, the registration would take its corresponding state manager as well for restoring.
void	restore()	Restore all registered state stores by reading from their changelogs
java.lang.String	toString()
void	transitToUpdateStandby()	Transit to update standby changelogs mode
void	unregister(java.util.Collection<org.apache.kafka.common.TopicPartition> revokedChangelogs)	Unregisters and removes the passed in partitions from the set of changelogs

Methods inherited from class java.lang.Object

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

Constructor Detail

StoreChangelogReader

public StoreChangelogReader(org.apache.kafka.common.utils.Time time,
                            StreamsConfig config,
                            org.apache.kafka.common.utils.LogContext logContext,
                            org.apache.kafka.clients.admin.Admin adminClient,
                            org.apache.kafka.clients.consumer.Consumer<byte[],byte[]> restoreConsumer,
                            StateRestoreListener stateRestoreListener)

Method Detail

enforceRestoreActive

public void enforceRestoreActive()

Description copied from interface: ChangelogReader

Transit to restore active changelogs mode

Specified by:

enforceRestoreActive in interface ChangelogReader

transitToUpdateStandby

public void transitToUpdateStandby()

Description copied from interface: ChangelogReader

Transit to update standby changelogs mode

Specified by:

transitToUpdateStandby in interface ChangelogReader

register

public void register(org.apache.kafka.common.TopicPartition partition,
                     ProcessorStateManager stateManager)

Since it is shared for multiple tasks and hence multiple state managers, the registration would take its corresponding state manager as well for restoring.

Specified by:

register in interface ChangelogRegister

Parameters:

partition - the state store's changelog partition for restoring

stateManager - the state manager used for restoring (one per task)

completedChangelogs

public java.util.Set<org.apache.kafka.common.TopicPartition> completedChangelogs()

Specified by:

completedChangelogs in interface ChangelogReader

Returns:

the changelog partitions that have been completed restoring

restore

public void restore()

Description copied from interface: ChangelogReader

Restore all registered state stores by reading from their changelogs

Specified by:

restore in interface ChangelogReader

unregister

public void unregister(java.util.Collection<org.apache.kafka.common.TopicPartition> revokedChangelogs)

Description copied from interface: ChangelogRegister

Unregisters and removes the passed in partitions from the set of changelogs

Specified by:

unregister in interface ChangelogRegister

Parameters:

revokedChangelogs - the set of partitions to remove

clear

public void clear()

Description copied from interface: ChangelogReader

Clear all partitions

Specified by:

clear in interface ChangelogReader

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface ChangelogReader

Returns:

whether the changelog reader has just been cleared or is uninitialized

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object