(Working in Progress)
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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.
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public class StateStoreClosedExceptionStreamsNotStartedException extends InvalidStateStoreException public class StateStoreMigratedExceptionStreamsRebalancingException extends InvalidStateStoreException public class StateStoreRetryableExceptionStateStoreMigratedException extends InvalidStateStoreException public class StateStoreFailException extends InvalidStateStoreException |
Call Trace
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title | Call trace 6: ReadOnlySessionStore#fetch(key) |
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- 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
- Segments#getSegment()
- return
- Segments#segments()
- return new SegmentIterator()
- SessionKeySchema#segmentsToSearch()
- return new WrappedSessionStoreIterator()
- RocksDBSegmentedBytesStore#fetch()
- return
- RocksDBSessionStore.findSessions(from, to)
- return
- RocksDBSessionStore.findSessions(k)
- return new MergedSortedCacheSessionStoreIterator()
- return new MeteredWindowedKeyValueIterator()
- CachingSessionStore#findSessions()
- return
- MeteredSessionStore#findSessions()
- 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
- Segment.range(from, to)
- return
- SegmentIterator#hasNext()
- return
- return iterator(MeteredWindowedKeyValueIterator)
- MergedSortedCacheSessionStoreIterator#hasNext()
- WrappingStoreProvider#stores() (v)
- 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
- Segment.range(from, to)
- return
- SegmentIterator#hasNext()
- MergedSortedCacheSessionStoreIterator#nextStoreValue()
AbstractMergedSortedCacheStoreIterator#nextStoreValue()- WrappedSessionStoreIterator#next()
- SegmentIterator#next()
- RocksDBRangeIterator#next()
RocksDbIterator#next()- RocksDbIterator#getKeyValue()
- RocksIterator#next()
- return entry
- return
- RocksDBRangeIterator#next()
- return
- SegmentIterator#next()
- return
- WrappedSessionStoreIterator#next()
- return
- return
- MergedSortedCacheSessionStoreIterator#next()
StateStoreNotAvailableException extends InvalidStateStoreException
public class UnknownStateStoreException extends InvalidStateStoreException
public class InvalidStateStorePartitionException extends InvalidStateStoreException
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- 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)
Info |
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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 |
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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.
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Changed Classes
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public <T> T store(final String storeName, final QueryableStoreType<T> queryableStoreType) {
validateIsRunning();
return queryableStoreProvider.getStore(storeName, queryableStoreType);
} |
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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);
} |
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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);
} |
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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("the state store, " + storeName + ", may have migrated to another instance.");
}
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("the state store, " + storeName + ", may have migrated to another instance.");
}
stores.add((T) store);
}
}
return stores;
} |
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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;
} |
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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;
} |
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void validateStoreOpen() {
if (!innerState.isOpen()) {
throw new InvalidStateStoreException("Store " + innerState.name() + " is currently closed.");
}
} |
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private void validateStoreOpen() {
if (!open) {
throw new InvalidStateStoreException("Store " + this.name + " is currently closed");
}
} |
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public synchronized boolean hasNext() {
if (!open) {
throw new InvalidStateStoreException(String.format("RocksDB store %s has closed", storeName));
}
return iter.isValid();
} |
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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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