Package org.apache.flink.contrib.streaming.state

Class RocksDBKeyedStateBackend<K>

    • 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.

    • 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.

      • 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.

      • 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.

      • 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