(Working in Progress)

Table of Contents

Status

Current state: Under Discussion Accepted(vote)

Discussion thread: here

JIRA:

Jira

server	ASF JIRA
columns	key,summary,type,created,updated,due,assignee,reporter,priority,status,resolution
serverId	5aa69414-a9e9-3523-82ec-879b028fb15b
key	KAFKA-5876

...

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

There append three new exceptions: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.

Code Block

language	java

public class StreamsNotStartedException extends InvalidStateStoreException
public class StateStoreClosedExceptionStreamsRebalancingException extends InvalidStateStoreException
public class StateStoreMigratedException extends InvalidStateStoreException
public class StateStoreRetryableExceptionStateStoreNotAvailableException extends InvalidStateStoreException
public class UnknownStateStoreException extends InvalidStateStoreException
public class StateStoreFailExceptionInvalidStateStorePartitionException extends InvalidStateStoreException

Three categories exception throw to user

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 REBALANCINGStateStoreRetriableException: The application instance in the state of rebalancing, the user just need retry and wait until rebalance finished (RUNNING).
StateStoreMigratedException: The store got migrated and not hosted in application instance, the users need to rediscover the store.
StateStoreFailException: Fatal error when access state store, the user cannot retry or rediscover.

...

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 method methods that users will call to get state store instance:

KafkaStreams
- stores()
ReadOnlyKeyValueStore(CompositeReadOnlyKeyValueStore)
- get(k)
- range(from, to)
- all()
- approximateNumEntries()
ReadOnlySessionStore(CompositeReadOnlySessionStore)
- fetch(k)
- fetch(from, to)
ReadOnlyWindowStore(CompositeReadOnlyWindowStore)
- fetch(k, rf, tt)
- fetch(from, to, rf, tt)
- all()
- fetchAll()
KeyValueIterator(DelegatingPeekingKeyValueIterator)
- next()
- hasNext()
- peekNextKey()

During user call one of above methods, we should check KafkaStreams state by the following rule when InvalidStateStoreException is thrown:

If state is RUNNING or REBALANCING
- StateStoreClosedException: should be wrapped to StateStoreRetriableException
- StateStoreMigratedException: should not be wrapped, directly thrown
if state is PENDING_SHUTDOW or ERROR or NOT_RUNNING
- wrap InvalidStateStoreException to StateStoreFailException

Call Trace

Expand

title	Call trace 1: KafkaStreams#store()

KafkaStreams#store() (v)
- QueryableStoreProvider#getStore() (v)
  - GlobalStateStoreProvider#stores() (v)
  - StreamThreadStateStroeProvider#stores() (v)

Expand

title	Call trace 2: ReadOnlyKeyValueStore#get()

CompositeReadOnlyKeyValueStore#get() (v)
- WrappingStoreProvider#stores() (v)
  - StreamThreadStateStoreProvider#stores() (v)
- MeteredKeyValueBytesStore#get()
  - InnerMeteredKeyValueStore#get()
    - CachingKeyValueStore#get()
      - AbstractStateStore#validateStoreOpen() (v)
        RocksDBStore#isOpen()
    - CachingKeyValueStore#getInternal()
      - ChangeLoggingKeyValueBytesStore#get()
        RocksDBStore#get()
        RocksDBStore#validateStoreOpen() (v)
        RocksDBStore#getInternal()

Expand

title	Call trace 3: ReadOnlyKeyValueStore#range()

CompositeReadOnlyKeyValueStore#range() (v)
- WrappingStoreProvider#stores() (v)
  - StreamThreadStateStoreProvider#stores() (v)
- return new DelegatingPeekingKeyValueIterator<>()
DelegatingPeekingKeyValueIterator#hasNext() (v)
- CompositKeyValueIterator#hasNext()
  - NextIteratorFunction#apply() (v)
    - MeteredKeyValueBytesStore#range()
      - InnerMeteredKeyValueStore#range()
        CachingKeyValueStore#range()
        AbstractStateStore#validateStoreOpen() (v)
        ChangeLoggingKeyValueBytesStore#range()
        RocksDBStore#range()
        RocksDBStore#validateStoreOpen() (v)
        return new RocksDBRangeIterator()
        return new MergedSortedCacheKeyValueBytesStoreIterator()
        return new MeteredKeyValueIterator()
      - return
    - return
  - return
- CompositKeyValueIterator#next()
  - MeteredKeyValueIterator#next()
    - MergedSortedCacheKeyValueBytesStoreIterator#next()
      AbstractMergedSortedCacheStoreIterator#next()

- - - - RocksDBRangeIterator#hasNext()
        RocksDBIterator#hasNext() (v)
        RocksIterator#isValid()
      - AbstractMergedStortedCacheStoreIterator#nextSrtoreValue()
        RocksDBRangeIterator#next()
        RocksDBIterator#next()
        RocksDbIterator#hasNext() (v)
        RocksDbIterator#getKeyValue()
        RocksIterator#next()
        return keyvalue entry
        return
      - return
    - return outerkeyvalue
  - return
- return
DelegatingPeekingKeyValueIterator#next()
- return keyvalue

Expand

title	Call trace 4: ReadOnlyKeyValueStore#all()

CompositeReadOnlyKeyValueStore#all() (v)
- WrappingStoreProvider#stores() (v)
  - StreamThreadStateStoreProvider#stores() (v)
- return new DelegatingPeekingKeyValueIterator<>()
DelegatingPeekingKeyValueIterator#hasNext() (v)
- CompositKeyValueIterator#hasNext()
  - NextIteratorFunction#apply() (v)
    - MeteredKeyValueBytesStore#all()
      - InnerMeteredKeyValueStore#all()
        CachingKeyValueStore#all()
        AbstractStateStore#validateStoreOpen() (v)
        ChangeLoggingKeyValueBytesStore#all()
        RocksDBStore#all()
        RocksDBStore#validateStoreOpen() (v)
        return new RocksDBIterator()
        return
        return new MergedSortedCacheKeyValueBytesStoreIterator()
        return new MeteredKeyValueIterator()
      - return
    - return
  - return
- CompositKeyValueIterator#next()
  - MeteredKeyValueIterator#next()
    - MergedSortedCacheKeyValueBytesStoreIterator#next()
      AbstractMergedSortedCacheStoreIterator#next()
      - MemoryLRUCacheBytesIterator.hasNext()
      - DelegatingPeekingKeyValueIterator.hasNext() (v)
      - AbstractMergedSortedCacheStoreIterator#nextStoreValue()
        DelegatingPeekingKeyValueIterator#next()
        DelegatingPeekingKeyValueIterator#hasNext() (v)
        return
      - return
    - return outerkeyvalue
  - return
- return
DelegatingPeekingKeyValueIterator#next()
- return keyvalue

Expand

title	Call trace 5: ReadOnlyKeyValueStore#approximateNumEntries()

CompositeReadOnlyKeyValueStore#approximateNumEntries() (v)
- WrappingStoreProvider#stores() (v)
  - StreamThreadStateStoreProvider#stores() (v)
- MeteredKeyValueBytesStore#approximateNumEntries()
  - InnerMeteredKeyValueStore#approximateNumEntries()
    - CachingKeyValueStore#approximateNumEntries()
      - AbstractStateStore#validateStoreOpen() (v)
        RocksDBStore#isOpen()
      - RocksDBStore#approximateNumEntries()
        RocksDBStore#validateStoreOpen() (v)
        return value
      - return
    - return
  - return
- return total

...

title	Call trace 6: ReadOnlySessionStore#fetch(key)

- @Deprecated store(storeName, queryableStoreType)
- store(storeQureyParams)

Info

All the above methods could be throw exceptions:

StreamsNotStartedException, StreamsRebalancingException, StateStoreMigratedException, StateStoreNotAvailableException, UnknownStateStoreException, InvalidStateStorePartitionException

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()

Info

All the above methods could be throw following exceptions:

StreamsRebalancingException, StateStoreMigratedException, StateStoreNotAvailableException, InvalidStateStorePartitionException

Compatibility, Deprecation, and Migration Plan

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

Rejected Alternatives

None.

CompositeReadOnlySessionStore#fetch(key) (v)
- WrappingStoreProvider#stores() (v)
  - StreamThreadStateStoreProvider#stores() (v)
- MeteredSessionStore#fetch(key)
  - MeteredSessionStore#findSessions()
    - CachingSessionStore#findSessions()
      - AbstractStateStore#validateStoreOpen() (v)
      - ChangeLoggingSessionBytesStore#findSessions()
        RocksDBSessionStore.findSessions(k)
        RocksDBSessionStore.findSessions(from, to)
        RocksDBSegmentedBytesStore#fetch()
        SessionKeySchema#segmentsToSearch()
        Segments#segments()
        Segments#getSegment()
        ConcurrentHashMap#get()
        Segments#isSegment()
        return segment
        retiurn segments
        return
        return new SegmentIterator()
        return new WrappedSessionStoreIterator()
        return
        return
      - return new MergedSortedCacheSessionStoreIterator()
    - return new MeteredWindowedKeyValueIterator()
  - return
- MeteredWindowedKeyValueIterator#hasNext()
  - MergedSortedCacheSessionStoreIterator#hasNext()
    AbstraceMergedSortedCacheStoreIterator#hasNext()
    - FilteredCacheIterator#hasNext()
    - WrappedSessionStoreIterator#hasNext()
      - SegmentIterator#hasNext()
        Segment.range(from, to)
        RocksDBStore.range(from, to)
        RocksDBStore.validateStoreOpen() (v)
        return new RocksDBRangeIterator()
        return
      - return
    - return
  - return iterator(MeteredWindowedKeyValueIterator)
MeteredWindowedKeyValueIterator#next()
- MergedSortedCacheSessionStoreIterator#next()
  AbstractMergedSortedCacheStoreIterator#next()
  - AbstractMergedSortedCacheStoreIterator#hasNext()
  - FilteredCacheIterator#hasNext()
  - WrappedSessionStoreIterator#hasNext()
    - SegmentIterator#hasNext()
      - Segment.range(from, to)
        RocksDBStore.range(from, to)
        RocksDBStore.validateStoreOpen() (v)
        return new RocksDBRangeIterator()
      - return
    - return
  - MergedSortedCacheSessionStoreIterator#nextStoreValue()
    AbstractMergedSortedCacheStoreIterator#nextStoreValue()
    - WrappedSessionStoreIterator#next()
      - SegmentIterator#next()
        RocksDBRangeIterator#next()
        RocksDbIterator#next()
        RocksDbIterator#getKeyValue()
        RocksIterator#next()
        return entry
        return
      - return
    - return
  - return
- return

...

Expand

title	Call trace 7: ReadOnlySessionStore#fetch(from, to)

CompositeReadOnlySessionStore#fetch(from, to) (v)
- WrappingStoreProvider#stores() (v)
  - StreamThreadStateStoreProvider#stores() (v)
- return new DelegatingPeekingKeyValueIterator<>()
DelegatingPeekingKeyValueIterator#hasNext() (v)
- CompositKeyValueIterator#hasNext()
  - NextIteratorFunction#apply(store)
    - MeteredSessionStore#fetch(from, to)
      - MeteredSessionStore#findSession(from, to, 0, t)
        CachingSessionStore#findSession(from, to, 0, t)
        CachingSessionStore#validStoreOpen()
        AbstractStateStore#validStoreOpen() (v)
        ChangeLoggingSessionBytesStore#isOpen()
        RocksDBSessionStore#isOpen()
        AbstractStateStore#isOpen()
        RocksDBSegmentedBytesStore#isOpen()
        return
        return
        return
        ChangeLoggingSessionBytesStore#findSesisons()
        RocksDBSessionStore#findSessions()
        RocksDBSegmentedBytesStore#fetch()
        SessionKeySchema#segmentsToSearch()
        Segments#segments() (v)
        RocksDBStore#isOpen()
        return new SegmentIterator()
        return new WrappedSessionStoreIterator()
        return
        return
        return new MergedSortedCacheSessionStoreIterator()
        return MeteredWindowedKeyValueIterator()
      - return
    - return
  - MeteredWindowedKeyValueIterator#hasNext()
    - MergedSortedCacheSessionStoreIterator#hasNext()
      AbstractMergedSortedCacheStoreIterator#hasNext()
      - FilteredCacheIterator#hasNext()
      - WrappedSessionStoreIterator#hasNext()
        SegmentIterator#hasNext()
        Segment.range(from, to)
        RocksDBStore.range(from, to)

- - - - RocksDBStore.validateStoreOpen() (v)
        return new RocksDBRangeIterator()
        return
        return
      - return
    - return
  - return
- CompositeKeyValueIterator#next()
- return
DelegatingPeekingKeyValueIterator#next()
- return keyvalue

Changed Classes

Code Block

language	java

public interface QueryableStoreType<T> {
    T create(final KafkaStreams streams, final StateStoreProvider storeProvider, final String storeName);
}

Code Block

language	java
title	KafkaStreams#store()
collapse	true

public <T> T store(final String storeName, final QueryableStoreType<T> queryableStoreType) {
    validateIsRunning();
    return queryableStoreProvider.getStore(storeName, queryableStoreType);
}

Code Block

language	java
title	QueryableStoreProvider#getStore()
collapse	true

public <T> T getStore(final String storeName, final QueryableStoreType<T> queryableStoreType) {
    final List<T> globalStore = globalStoreProvider.stores(storeName, queryableStoreType);
    if (!globalStore.isEmpty()) {
        return queryableStoreType.create(new WrappingStoreProvider(Collections.<StateStoreProvider>singletonList(globalStoreProvider)), storeName);
    }
    final List<T> allStores = new ArrayList<>();
    for (StateStoreProvider storeProvider : storeProviders) {
        allStores.addAll(storeProvider.stores(storeName, queryableStoreType));
    }
    if (allStores.isEmpty()) {
        throw new InvalidStateStoreException("the state store, " + storeName + ", may have migrated to another instance.");
    }
    return queryableStoreType.create(
            new WrappingStoreProvider(storeProviders),
            storeName);
}

Code Block

language	java
title	GlobalStateStoreProvider#stores()
collapse	true

public <T> List<T> stores(final String storeName, final QueryableStoreType<T> queryableStoreType) {
    final StateStore store = globalStateStores.get(storeName);
    if (store == null || !queryableStoreType.accepts(store)) {
        return Collections.emptyList();
    }
    if (!store.isOpen()) {
        throw new InvalidStateStoreException("the state store, " + storeName + ", is not open.");
    }
    return (List<T>) Collections.singletonList(store);
}

Code Block

language	java
title	StreamThreadStateStoreProvider#stores()
collapse	true

 public <T> List<T> stores(final String storeName, final QueryableStoreType<T> queryableStoreType) {
    if (streamThread.state() == StreamThread.State.DEAD) {
        return Collections.emptyList();
    }
    if (!streamThread.isRunningAndNotRebalancing()) {
        throw new InvalidStateStoreException("Cannot get state store " + storeName + " because the stream thread is " +
                streamThread.state() + ", not RUNNING");
    }
    final List<T> stores = new ArrayList<>();
    for (Task streamTask : streamThread.tasks().values()) {
        final StateStore store = streamTask.getStore(storeName);
        if (store != null && queryableStoreType.accepts(store)) {
            if (!store.isOpen()) {
                throw new InvalidStateStoreException("Cannot get state store " + storeName + " for task " + streamTask +
                        " because the store is not open. The state store may have migrated to another instances.");
            }
            stores.add((T) store);
        }
    }
    return stores;
}

Code Block

language	java
title	WrappingStoreProvider#stores()
collapse	true

public <T> List<T> stores(final String storeName, QueryableStoreType<T> type) {
    final List<T> allStores = new ArrayList<>();
    for (StateStoreProvider provider : storeProviders) {
        final List<T> stores =
            provider.stores(storeName, type);
        allStores.addAll(stores);
    }
    if (allStores.isEmpty()) {
        throw new InvalidStateStoreException("the state store, " + storeName + ", may have migrated to another instance.");
    }
    return allStores;
}

Code Block

language	java
title	CompositeReadOnlyKeyValueStore
collapse	true

public V get(final K key) {
    Objects.requireNonNull(key);
    final List<ReadOnlyKeyValueStore<K, V>> stores = storeProvider.stores(storeName, storeType);
    for (ReadOnlyKeyValueStore<K, V> store : stores) {
        try {
            final V result = store.get(key);
            if (result != null) {
                return result;
            }
        } catch (InvalidStateStoreException e) {
            throw new InvalidStateStoreException("State store is not available anymore and may have been migrated to another instance; please re-discover its location from the state metadata.");
        }

    }
    return null;
}
 
public KeyValueIterator<K, V> range(final K from, final K to) {
    Objects.requireNonNull(from);
    Objects.requireNonNull(to);
    final NextIteratorFunction<K, V, ReadOnlyKeyValueStore<K, V>> nextIteratorFunction = new NextIteratorFunction<K, V, ReadOnlyKeyValueStore<K, V>>() {
        @Override
        public KeyValueIterator<K, V> apply(final ReadOnlyKeyValueStore<K, V> store) {
            try {
                return store.range(from, to);
            } catch (InvalidStateStoreException e) {
                throw new InvalidStateStoreException("State store is not available anymore and may have been migrated to another instance; please re-discover its location from the state metadata.");
            }
        }
    };
    final List<ReadOnlyKeyValueStore<K, V>> stores = storeProvider.stores(storeName, storeType);
    return new DelegatingPeekingKeyValueIterator<>(storeName, new CompositeKeyValueIterator<>(stores.iterator(), nextIteratorFunction));
}

public KeyValueIterator<K, V> all() {
    final NextIteratorFunction<K, V, ReadOnlyKeyValueStore<K, V>> nextIteratorFunction = new NextIteratorFunction<K, V, ReadOnlyKeyValueStore<K, V>>() {
        @Override
        public KeyValueIterator<K, V> apply(final ReadOnlyKeyValueStore<K, V> store) {
            try {
                return store.all();
            } catch (InvalidStateStoreException e) {
                throw new InvalidStateStoreException("State store is not available anymore and may have been migrated to another instance; please re-discover its location from the state metadata.");
            }
        }
    };
    final List<ReadOnlyKeyValueStore<K, V>> stores = storeProvider.stores(storeName, storeType);
    return new DelegatingPeekingKeyValueIterator<>(storeName, new CompositeKeyValueIterator<>(stores.iterator(), nextIteratorFunction));
}
 
public long approximateNumEntries() {
    final List<ReadOnlyKeyValueStore<K, V>> stores = storeProvider.stores(storeName, storeType);
    long total = 0;
    for (ReadOnlyKeyValueStore<K, V> store : stores) {
        total += store.approximateNumEntries();
        if (total < 0) {
            return Long.MAX_VALUE;
        }
    }
    return total;
}

Code Block

language	java
title	AbstractStateStore#validateStoreOpen()
collapse	true

void validateStoreOpen() {
    if (!innerState.isOpen()) {
        throw new InvalidStateStoreException("Store " + innerState.name() + " is currently closed.");
    }
}

Code Block

language	java
title	RocksDBStore#validateStoreOpen()
collapse	true

private void validateStoreOpen() {
    if (!open) {
        throw new InvalidStateStoreException("Store " + this.name + " is currently closed");
    }
}

Code Block

language	java
title	RocksDBIterator#hasNext()
collapse	true

public synchronized boolean hasNext() {
    if (!open) {
        throw new InvalidStateStoreException(String.format("RocksDB store %s has closed", storeName));
    }

    return iter.isValid();
}

Code Block

language	java
title	DelegatingPeekingKeyValueIterator#hasNext()
collapse	true

public synchronized boolean hasNext() {
    if (!open) {
        throw new InvalidStateStoreException(String.format("Store %s has closed", storeName));
    }
    if (next != null) {
        return true;
    }

    if (!underlying.hasNext()) {
        return false;
    }

    next = underlying.next();
    return true;
}

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Key

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Motivation

Proposed Changes

Call Trace

Compatibility, Deprecation, and Migration Plan

Rejected Alternatives

Changed Classes

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Versions Compared

Old Version 24

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Key

Status

Motivation

Proposed Changes

Call Trace

Compatibility, Deprecation, and Migration Plan

Rejected Alternatives

Changed Classes