Status

Current state:  Under Discussion Accepted(vote)

Discussion thread: here

JIRA: 

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Motivation

Currently, IQ throws InvalidStateStoreException for any types of error, that means a user cannot handle different types of error.

Because of that, we should throw different exceptions for each type. 

Proposed Changes

Three categories exception to user

• StateStoreRetryableException: just wait, plain retry
• StateStoreMigratedException: need rediscover
• StateStoreFailException: fatal error, cannot retry or rediscover

 To distinguish different types of error, we need to handle all InvalidStateStoreException better during these public methods invoked. The main change is to introduce new exceptions that extend from InvalidStateStoreException. InvalidStateStoreException is not thrown at all anymore, but only new sub-classes.

public class StateStoreClosedExceptionStreamsNotStartedException extends InvalidStateStoreException
public class StreamsRebalancingException extends InvalidStateStoreException
public class StateStoreMigratedException extends InvalidStateStoreException
public class StateStoreNotAvailableException extends InvalidStateStoreException
public class StateStoreRetryableExceptionUnknownStateStoreException extends InvalidStateStoreException
public class StateStoreFailExceptionInvalidStateStorePartitionException extends InvalidStateStoreException

Call Trace

• StreamsNotStartedException: will be thrown when stream thread state is CREATED, the user can retry until to RUNNING.
• StreamsRebalancingException: will be thrown when stream thread is not running and stream state is REBALANCING, the user just retry and wait until rebalance finished (RUNNING).
• StateStoreMigratedException: will be thrown when state store already closed and stream state is RUNNING. The user need to rediscover the store and cannot blindly retry as the store handle is invalid and a new store handle must be retrived.
• StateStoreNotAvailableException: will be thrown when state store closed and stream state is PENDING_SHUTDOWN / NOT_RUNNING / ERROR. The user cannot retry when this exception is thrown.
• UnknownStateStoreException: will be thrown when passing an unknown state store. The user cannot retry when this exception is thrown.
• InvalidStateStorePartitionException: will be thrown when user requested partition is not available on the stream instance.

The following is the public methods that users will call to get state store instance:

• KafkaStreams
  
  • @Deprecated store(storeName, queryableStoreType)
  • store(storeQureyParams)

The following is the public methods that users will call to get store values:

• interface ReadOnlyKeyValueStore(class CompositeReadOnlyKeyValueStore)
  • get(key)
  • range(from, to)
  • all()
  • approximateNumEntries()
• interface ReadOnlySessionStore(class CompositeReadOnlySessionStore)
  
  • fetch(key)
  • fetch(from, to)
• interface ReadOnlyWindowStore(class CompositeReadOnlyWindowStore)
  
  • fetch(key, time)

  • fetch(key, from, to)

  • fetch(from, to, fromTime, toTime)
  • all()
  • fetchAll(from, to)
  • @Deprecated fetch(key, timeFrom, timeTo)
  • @Deprecated fetch(from, to, timeFrom, timeTo)
  • @Deprecated fetchAll(timeFrom, timeTo)
• interface KeyValueIterator(class DelegatingPeekingKeyValueIterator)
  
  • next()
  • hasNext()
  • peekNextKey()

Compatibility, Deprecation, and Migration Plan

• All new exceptions extend from InvalidStateStoreException, this change will be fully backward compatible.

Rejected Alternatives

None.

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