org.apache.flink.runtime.state.heap.AbstractStateTableSnapshot Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.state.heap;
import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.runtime.state.StateSnapshot;
import org.apache.flink.runtime.state.StateSnapshotTransformer;
import org.apache.flink.runtime.state.metainfo.StateMetaInfoSnapshot;
import org.apache.flink.util.Preconditions;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.io.IOException;
/**
* Abstract base class for snapshots of a {@link StateTable}. Offers a way to serialize the snapshot (by key-group).
* All snapshots should be released after usage.
*/
@Internal
abstract class AbstractStateTableSnapshot
implements StateSnapshot, StateSnapshot.StateKeyGroupWriter {
/**
* The {@link StateTable} from which this snapshot was created.
*/
protected final StateTable owningStateTable;
/**
* A local duplicate of the table's key serializer.
*/
@Nonnull
protected final TypeSerializer localKeySerializer;
/**
* A local duplicate of the table's namespace serializer.
*/
@Nonnull
protected final TypeSerializer localNamespaceSerializer;
/**
* A local duplicate of the table's state serializer.
*/
@Nonnull
protected final TypeSerializer localStateSerializer;
@Nullable
protected final StateSnapshotTransformer stateSnapshotTransformer;
/**
* Creates a new {@link AbstractStateTableSnapshot} for and owned by the given table.
*
* @param owningStateTable the {@link StateTable} for which this object represents a snapshot.
*/
AbstractStateTableSnapshot(
StateTable owningStateTable,
TypeSerializer localKeySerializer,
TypeSerializer localNamespaceSerializer,
TypeSerializer localStateSerializer,
@Nullable StateSnapshotTransformer stateSnapshotTransformer) {
this.owningStateTable = Preconditions.checkNotNull(owningStateTable);
this.localKeySerializer = Preconditions.checkNotNull(localKeySerializer);
this.localNamespaceSerializer = Preconditions.checkNotNull(localNamespaceSerializer);
this.localStateSerializer = Preconditions.checkNotNull(localStateSerializer);
this.stateSnapshotTransformer = stateSnapshotTransformer;
}
/**
* Return the state map snapshot for the key group. If the snapshot does not exist, return null.
*/
protected abstract StateMapSnapshot> getStateMapSnapshotForKeyGroup(int keyGroup);
@Nonnull
@Override
public StateMetaInfoSnapshot getMetaInfoSnapshot() {
return owningStateTable.getMetaInfo().snapshot();
}
@Override
public StateKeyGroupWriter getKeyGroupWriter() {
return this;
}
/**
* Implementation note: we currently chose the same format between {@link NestedMapsStateTable} and
* {@link CopyOnWriteStateTable}.
*
* {@link NestedMapsStateTable} could naturally support a kind of
* prefix-compressed format (grouping by namespace, writing the namespace only once per group instead for each
* mapping). We might implement support for different formats later (tailored towards different state table
* implementations).
*/
@Override
public void writeStateInKeyGroup(@Nonnull DataOutputView dov, int keyGroupId) throws IOException {
StateMapSnapshot> stateMapSnapshot = getStateMapSnapshotForKeyGroup(keyGroupId);
stateMapSnapshot.writeState(localKeySerializer, localNamespaceSerializer, localStateSerializer, dov, stateSnapshotTransformer);
stateMapSnapshot.release();
}
}