org.apache.flink.contrib.streaming.state

Class RocksDBKeyedStateBackend<K>

java.lang.Object

org.apache.flink.runtime.state.AbstractKeyedStateBackend<K>

org.apache.flink.contrib.streaming.state.RocksDBKeyedStateBackend<K>

All Implemented Interfaces:

Closeable, AutoCloseable, CheckpointListener, InternalCheckpointListener, CheckpointableKeyedStateBackend<K>, InternalKeyContext<K>, KeyedStateBackend<K>, KeyedStateFactory, PriorityQueueSetFactory, Snapshotable<SnapshotResult<KeyedStateHandle>>, TestableKeyedStateBackend<K>, Disposable

public class RocksDBKeyedStateBackend<K>
extends AbstractKeyedStateBackend<K>

An AbstractKeyedStateBackend that stores its state in RocksDB and serializes state to streams provided by a CheckpointStreamFactory upon checkpointing. This state backend can store very large state that exceeds memory and spills to disk. Except for the snapshotting, this class should be accessed as if it is not threadsafe.

This class follows the rules for closing/releasing native RocksDB resources as described in + this document.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RocksDBKeyedStateBackend.RocksDbKvStateInfo Rocks DB specific information about the k/v states.

Nested classes/interfaces inherited from class org.apache.flink.runtime.state.AbstractKeyedStateBackend

AbstractKeyedStateBackend.PartitionStateFactory

Nested classes/interfaces inherited from interface org.apache.flink.runtime.state.KeyedStateBackend

KeyedStateBackend.KeySelectionListener<K>

Field Summary

Fields

Modifier and Type	Field and Description
protected org.rocksdb.RocksDB	db Our RocksDB database, this is used by the actual subclasses of AbstractRocksDBState to store state.
static String	MERGE_OPERATOR_NAME The name of the merge operator in RocksDB.

Fields inherited from class org.apache.flink.runtime.state.AbstractKeyedStateBackend

cancelStreamRegistry, keyContext, keyGroupCompressionDecorator, keyGroupRange, keySerializer, kvStateRegistry, latencyTrackingStateConfig, numberOfKeyGroups, ttlTimeProvider, userCodeClassLoader

Constructor Summary

Constructors

Constructor and Description

RocksDBKeyedStateBackend(ClassLoader userCodeClassLoader, File instanceBasePath, RocksDBResourceContainer optionsContainer, Function<String,org.rocksdb.ColumnFamilyOptions> columnFamilyOptionsFactory, TaskKvStateRegistry kvStateRegistry, TypeSerializer<K> keySerializer, ExecutionConfig executionConfig, TtlTimeProvider ttlTimeProvider, LatencyTrackingStateConfig latencyTrackingStateConfig, org.rocksdb.RocksDB db, LinkedHashMap<String,RocksDBKeyedStateBackend.RocksDbKvStateInfo> kvStateInformation, Map<String,HeapPriorityQueueSnapshotRestoreWrapper<?>> registeredPQStates, int keyGroupPrefixBytes, CloseableRegistry cancelStreamRegistry, StreamCompressionDecorator keyGroupCompressionDecorator, ResourceGuard rocksDBResourceGuard, RocksDBSnapshotStrategyBase<K,?> checkpointSnapshotStrategy, RocksDBWriteBatchWrapper writeBatchWrapper, org.rocksdb.ColumnFamilyHandle defaultColumnFamilyHandle, RocksDBNativeMetricMonitor nativeMetricMonitor, SerializedCompositeKeyBuilder<K> sharedRocksKeyBuilder, PriorityQueueSetFactory priorityQueueFactory, RocksDbTtlCompactFiltersManager ttlCompactFiltersManager, InternalKeyContext<K> keyContext, long writeBatchSize, CompletableFuture<Void> asyncCompactFuture, RocksDBManualCompactionManager rocksDBManualCompactionManager)

Method Summary

Modifier and Type	Method and Description
void	compactState(StateDescriptor<?,?> stateDesc)
<T extends HeapPriorityQueueElement & PriorityComparable<? super T> & Keyed<?>> KeyGroupedInternalPriorityQueue<T>	create(String stateName, TypeSerializer<T> byteOrderedElementSerializer) Creates a KeyGroupedInternalPriorityQueue.
<T extends HeapPriorityQueueElement & PriorityComparable<? super T> & Keyed<?>> KeyGroupedInternalPriorityQueue<T>	create(String stateName, TypeSerializer<T> byteOrderedElementSerializer, boolean allowFutureMetadataUpdates) Creates a KeyGroupedInternalPriorityQueue.
<N,SV,SEV,S extends State,IS extends S> IS	createOrUpdateInternalState(TypeSerializer<N> namespaceSerializer, StateDescriptor<S,SV> stateDesc, StateSnapshotTransformer.StateSnapshotTransformFactory<SEV> snapshotTransformFactory) Creates or updates internal state and returns a new InternalKvState.
<N,SV,SEV,S extends State,IS extends S> IS	createOrUpdateInternalState(TypeSerializer<N> namespaceSerializer, StateDescriptor<S,SV> stateDesc, StateSnapshotTransformer.StateSnapshotTransformFactory<SEV> snapshotTransformFactory, boolean allowFutureMetadataUpdates) Creates or updates internal state and returns a new InternalKvState.
void	dispose() Should only be called by one thread, and only after all accesses to the DB happened.
Optional<CompletableFuture<Void>>	getAsyncCompactAfterRestoreFuture()
int	getKeyGroupPrefixBytes()
<N> Stream<K>	getKeys(String state, N namespace)
<N> Stream<Tuple2<K,N>>	getKeysAndNamespaces(String state)
org.rocksdb.ReadOptions	getReadOptions()
org.rocksdb.WriteOptions	getWriteOptions()
boolean	isSafeToReuseKVState() Whether it's safe to reuse key-values from the state-backend, e.g for the purpose of optimization.
void	notifyCheckpointAborted(long checkpointId) This method is called as a notification once a distributed checkpoint has been aborted.
void	notifyCheckpointComplete(long completedCheckpointId) Notifies the listener that the checkpoint with the given checkpointId completed and was committed.
int	numKeyValueStateEntries() Returns the total number of state entries across all keys/namespaces.
boolean	requiresLegacySynchronousTimerSnapshots(SnapshotType checkpointType)
SavepointResources<K>	savepoint() Returns a SavepointResources that can be used by SavepointSnapshotStrategy to write out a savepoint in the common/unified format.
void	setCurrentKey(K newKey) Sets the current key that is used for partitioned state.
RunnableFuture<SnapshotResult<KeyedStateHandle>>	snapshot(long checkpointId, long timestamp, CheckpointStreamFactory streamFactory, CheckpointOptions checkpointOptions) Triggers an asynchronous snapshot of the keyed state backend from RocksDB.

Methods inherited from class org.apache.flink.runtime.state.AbstractKeyedStateBackend

applyToAllKeys, applyToAllKeys, close, deregisterKeySelectionListener, getCurrentKey, getCurrentKeyGroupIndex, getKeyContext, getKeyGroupCompressionDecorator, getKeyGroupRange, getKeySerializer, getLatencyTrackingStateConfig, getNumberOfKeyGroups, getOrCreateKeyedState, getPartitionedState, notifyCheckpointSubsumed, numKeyValueStatesByName, publishQueryableStateIfEnabled, registerKeySelectionListener, setCurrentKeyGroupIndex

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.flink.runtime.state.TestableKeyedStateBackend

getDelegatedKeyedStateBackend

Methods inherited from interface org.apache.flink.runtime.state.KeyedStateBackend

isStateImmutableInStateBackend

Methods inherited from interface org.apache.flink.runtime.state.KeyedStateFactory

createOrUpdateInternalState

Field Detail

MERGE_OPERATOR_NAME

public static final String MERGE_OPERATOR_NAME

The name of the merge operator in RocksDB. Do not change except you know exactly what you do.

See Also:

Constant Field Values

db

protected final org.rocksdb.RocksDB db

Our RocksDB database, this is used by the actual subclasses of AbstractRocksDBState to store state. The different k/v states that we have don't each have their own RocksDB instance. They all write to this instance but to their own column family.

Constructor Detail

RocksDBKeyedStateBackend

public RocksDBKeyedStateBackend(ClassLoader userCodeClassLoader,
                                File instanceBasePath,
                                RocksDBResourceContainer optionsContainer,
                                Function<String,org.rocksdb.ColumnFamilyOptions> columnFamilyOptionsFactory,
                                TaskKvStateRegistry kvStateRegistry,
                                TypeSerializer<K> keySerializer,
                                ExecutionConfig executionConfig,
                                TtlTimeProvider ttlTimeProvider,
                                LatencyTrackingStateConfig latencyTrackingStateConfig,
                                org.rocksdb.RocksDB db,
                                LinkedHashMap<String,RocksDBKeyedStateBackend.RocksDbKvStateInfo> kvStateInformation,
                                Map<String,HeapPriorityQueueSnapshotRestoreWrapper<?>> registeredPQStates,
                                int keyGroupPrefixBytes,
                                CloseableRegistry cancelStreamRegistry,
                                StreamCompressionDecorator keyGroupCompressionDecorator,
                                ResourceGuard rocksDBResourceGuard,
                                RocksDBSnapshotStrategyBase<K,?> checkpointSnapshotStrategy,
                                RocksDBWriteBatchWrapper writeBatchWrapper,
                                org.rocksdb.ColumnFamilyHandle defaultColumnFamilyHandle,
                                RocksDBNativeMetricMonitor nativeMetricMonitor,
                                SerializedCompositeKeyBuilder<K> sharedRocksKeyBuilder,
                                PriorityQueueSetFactory priorityQueueFactory,
                                RocksDbTtlCompactFiltersManager ttlCompactFiltersManager,
                                InternalKeyContext<K> keyContext,
                                @Nonnegative
                                long writeBatchSize,
                                @Nullable
                                CompletableFuture<Void> asyncCompactFuture,
                                RocksDBManualCompactionManager rocksDBManualCompactionManager)

Method Detail

getKeys

public <N> Stream<K> getKeys(String state,
                             N namespace)

Parameters:

state - State variable for which existing keys will be returned.

namespace - Namespace for which existing keys will be returned.

Returns:

A stream of all keys for the given state and namespace. Modifications to the state during iterating over it keys are not supported.

getKeysAndNamespaces

public <N> Stream<Tuple2<K,N>> getKeysAndNamespaces(String state)

Parameters:

state - State variable for which existing keys will be returned.

Returns:

A stream of all keys for the given state and namespace. Modifications to the state during iterating over it keys are not supported. Implementations go not make any ordering guarantees about the returned tupes. Two records with the same key or namespace may not be returned near each other in the stream.

setCurrentKey

public void setCurrentKey(K newKey)

Description copied from interface: KeyedStateBackend

Sets the current key that is used for partitioned state.

Specified by:

setCurrentKey in interface InternalKeyContext<K>

Specified by:

setCurrentKey in interface KeyedStateBackend<K>

Overrides:

setCurrentKey in class AbstractKeyedStateBackend<K>

Parameters:

newKey - The new current key.

See Also:

KeyedStateBackend

dispose

public void dispose()

Should only be called by one thread, and only after all accesses to the DB happened.

Specified by:

dispose in interface KeyedStateBackend<K>

Specified by:

dispose in interface Disposable

Overrides:

dispose in class AbstractKeyedStateBackend<K>

create

@Nonnull
public <T extends HeapPriorityQueueElement & PriorityComparable<? super T> & Keyed<?>> KeyGroupedInternalPriorityQueue<T> create(@Nonnull
                                                                                                                                          String stateName,
                                                                                                                                          @Nonnull
                                                                                                                                          TypeSerializer<T> byteOrderedElementSerializer)

Description copied from interface: PriorityQueueSetFactory

Creates a KeyGroupedInternalPriorityQueue.

Type Parameters:

T - type of the stored elements.

Parameters:

stateName - unique name for associated with this queue.

byteOrderedElementSerializer - a serializer that with a format that is lexicographically ordered in alignment with elementPriorityComparator.

Returns:

the queue with the specified unique name.

create

public <T extends HeapPriorityQueueElement & PriorityComparable<? super T> & Keyed<?>> KeyGroupedInternalPriorityQueue<T> create(@Nonnull
                                                                                                                                 String stateName,
                                                                                                                                 @Nonnull
                                                                                                                                 TypeSerializer<T> byteOrderedElementSerializer,
                                                                                                                                 boolean allowFutureMetadataUpdates)

Description copied from interface: PriorityQueueSetFactory

Creates a KeyGroupedInternalPriorityQueue.

Type Parameters:

T - type of the stored elements.

Parameters:

stateName - unique name for associated with this queue.

byteOrderedElementSerializer - a serializer that with a format that is lexicographically ordered in alignment with elementPriorityComparator.

allowFutureMetadataUpdates - whether allow metadata to update in the future or not.

Returns:

the queue with the specified unique name.

getKeyGroupPrefixBytes

public int getKeyGroupPrefixBytes()

getWriteOptions

public org.rocksdb.WriteOptions getWriteOptions()

getReadOptions

public org.rocksdb.ReadOptions getReadOptions()

snapshot

@Nonnull
public RunnableFuture<SnapshotResult<KeyedStateHandle>> snapshot(long checkpointId,
                                                                          long timestamp,
                                                                          @Nonnull
                                                                          CheckpointStreamFactory streamFactory,
                                                                          @Nonnull
                                                                          CheckpointOptions checkpointOptions)
                                                                   throws Exception

Triggers an asynchronous snapshot of the keyed state backend from RocksDB. This snapshot can be canceled and is also stopped when the backend is closed through dispose(). For each backend, this method must always be called by the same thread.

Parameters:

checkpointId - The Id of the checkpoint.

timestamp - The timestamp of the checkpoint.

streamFactory - The factory that we can use for writing our state to streams.

checkpointOptions - Options for how to perform this checkpoint.

Returns:

Future to the state handle of the snapshot data.

Throws:

Exception - indicating a problem in the synchronous part of the checkpoint.

savepoint

@Nonnull
public SavepointResources<K> savepoint()
                                         throws Exception

Description copied from interface: CheckpointableKeyedStateBackend

Returns a SavepointResources that can be used by SavepointSnapshotStrategy to write out a savepoint in the common/unified format.

Throws:

Exception

notifyCheckpointComplete

public void notifyCheckpointComplete(long completedCheckpointId)
                              throws Exception

Description copied from interface: CheckpointListener

Notifies the listener that the checkpoint with the given checkpointId completed and was committed.

These notifications are "best effort", meaning they can sometimes be skipped. To behave properly, implementers need to follow the "Checkpoint Subsuming Contract". Please see the class-level JavaDocs for details.

Please note that checkpoints may generally overlap, so you cannot assume that the notifyCheckpointComplete() call is always for the latest prior checkpoint (or snapshot) that was taken on the function/operator implementing this interface. It might be for a checkpoint that was triggered earlier. Implementing the "Checkpoint Subsuming Contract" (see above) properly handles this situation correctly as well.

Please note that throwing exceptions from this method will not cause the completed checkpoint to be revoked. Throwing exceptions will typically cause task/job failure and trigger recovery.

Parameters:

completedCheckpointId - The ID of the checkpoint that has been completed.

Throws:

Exception - This method can propagate exceptions, which leads to a failure/recovery for the task. Note that this will NOT lead to the checkpoint being revoked.

notifyCheckpointAborted

public void notifyCheckpointAborted(long checkpointId)
                             throws Exception

Description copied from interface: CheckpointListener

This method is called as a notification once a distributed checkpoint has been aborted.

Important: The fact that a checkpoint has been aborted does NOT mean that the data and artifacts produced between the previous checkpoint and the aborted checkpoint are to be discarded. The expected behavior is as if this checkpoint was never triggered in the first place, and the next successful checkpoint simply covers a longer time span. See the "Checkpoint Subsuming Contract" in the class-level JavaDocs for details.

These notifications are "best effort", meaning they can sometimes be skipped.

This method is very rarely necessary to implement. The "best effort" guarantee, together with the fact that this method should not result in discarding any data (per the "Checkpoint Subsuming Contract") means it is mainly useful for earlier cleanups of auxiliary resources. One example is to pro-actively clear a local per-checkpoint state cache upon checkpoint failure.

Parameters:

checkpointId - The ID of the checkpoint that has been aborted.

Throws:

Exception - This method can propagate exceptions, which leads to a failure/recovery for the task or job.

createOrUpdateInternalState

@Nonnull
public <N,SV,SEV,S extends State,IS extends S> IS createOrUpdateInternalState(@Nonnull
                                                                                       TypeSerializer<N> namespaceSerializer,
                                                                                       @Nonnull
                                                                                       StateDescriptor<S,SV> stateDesc,
                                                                                       @Nonnull
                                                                                       StateSnapshotTransformer.StateSnapshotTransformFactory<SEV> snapshotTransformFactory)
                                                                                throws Exception

Description copied from interface: KeyedStateFactory

Creates or updates internal state and returns a new InternalKvState.

Type Parameters:

N - The type of the namespace.

SV - The type of the stored state value.

SEV - The type of the stored state value or entry for collection types (list or map).

S - The type of the public API state.

IS - The type of internal state.

Parameters:

namespaceSerializer - TypeSerializer for the state namespace.

stateDesc - The StateDescriptor that contains the name of the state.

snapshotTransformFactory - factory of state snapshot transformer.

Throws:

Exception

createOrUpdateInternalState

@Nonnull
public <N,SV,SEV,S extends State,IS extends S> IS createOrUpdateInternalState(@Nonnull
                                                                                       TypeSerializer<N> namespaceSerializer,
                                                                                       @Nonnull
                                                                                       StateDescriptor<S,SV> stateDesc,
                                                                                       @Nonnull
                                                                                       StateSnapshotTransformer.StateSnapshotTransformFactory<SEV> snapshotTransformFactory,
                                                                                       boolean allowFutureMetadataUpdates)
                                                                                throws Exception

Description copied from interface: KeyedStateFactory

Creates or updates internal state and returns a new InternalKvState.

Type Parameters:

N - The type of the namespace.

SV - The type of the stored state value.

SEV - The type of the stored state value or entry for collection types (list or map).

S - The type of the public API state.

IS - The type of internal state.

Parameters:

namespaceSerializer - TypeSerializer for the state namespace.

stateDesc - The StateDescriptor that contains the name of the state.

snapshotTransformFactory - factory of state snapshot transformer.

allowFutureMetadataUpdates - whether allow metadata to update in the future or not.

Throws:

Exception

numKeyValueStateEntries

@VisibleForTesting
public int numKeyValueStateEntries()

Description copied from interface: TestableKeyedStateBackend

Returns the total number of state entries across all keys/namespaces.

requiresLegacySynchronousTimerSnapshots

public boolean requiresLegacySynchronousTimerSnapshots(SnapshotType checkpointType)

Overrides:

requiresLegacySynchronousTimerSnapshots in class AbstractKeyedStateBackend<K>

isSafeToReuseKVState

public boolean isSafeToReuseKVState()

Description copied from interface: KeyedStateBackend

Whether it's safe to reuse key-values from the state-backend, e.g for the purpose of optimization.

NOTE: this method should not be used to check for InternalPriorityQueue, as the priority queue could be stored on different locations, e.g RocksDB state-backend could store that on JVM heap if configuring HEAP as the time-service factory.

Returns:

returns ture if safe to reuse the key-values from the state-backend.

compactState

@VisibleForTesting
public void compactState(StateDescriptor<?,?> stateDesc)
                                     throws org.rocksdb.RocksDBException

Throws:

org.rocksdb.RocksDBException

getAsyncCompactAfterRestoreFuture

public Optional<CompletableFuture<Void>> getAsyncCompactAfterRestoreFuture()