tillrohrmann commented on a change in pull request #9501: [FLINK-12697] [State Backends] Support on-disk state storage for spill-able heap backend URL: https://github.com/apache/flink/pull/9501#discussion_r320714521
########## File path: flink-state-backends/flink-statebackend-heap-spillable/src/main/java/org/apache/flink/runtime/state/heap/CopyOnWriteSkipListStateMapSnapshot.java ########## @@ -0,0 +1,229 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * 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, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * 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.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.core.memory.DataOutputView; +import org.apache.flink.runtime.state.StateSnapshotTransformer; +import org.apache.flink.util.ResourceGuard; + +import javax.annotation.Nonnegative; +import javax.annotation.Nonnull; +import javax.annotation.Nullable; + +import java.io.IOException; +import java.util.Iterator; +import java.util.NoSuchElementException; + +import static org.apache.flink.runtime.state.heap.SkipListUtils.HEAD_NODE; +import static org.apache.flink.runtime.state.heap.SkipListUtils.NIL_NODE; +import static org.apache.flink.runtime.state.heap.SkipListUtils.NIL_VALUE_POINTER; + +/** + * This class represents the snapshot of a {@link CopyOnWriteSkipListStateMap}. + * + * @param <K> type of key + * @param <N> type of namespace + * @param <S> type of state + */ +public class CopyOnWriteSkipListStateMapSnapshot<K, N, S> + extends StateMapSnapshot<K, N, S, CopyOnWriteSkipListStateMap<K, N, S>> { + + /** + * Version of the {@link CopyOnWriteSkipListStateMap} when this snapshot was created. This can be used to release the snapshot. + */ + private final int snapshotVersion; + + /** The number of (non-null) entries in snapshotData. */ + @Nonnegative + private final int numberOfEntriesInSnapshotData; + + /** + * This lease protects the state map resources. + */ + private final ResourceGuard.Lease lease; + + /** + * Creates a new {@link CopyOnWriteSkipListStateMap}. + * + * @param owningStateMap the {@link CopyOnWriteSkipListStateMap} for which this object represents a snapshot. + * @param lease the lease protects the state map resources. + */ + CopyOnWriteSkipListStateMapSnapshot( + CopyOnWriteSkipListStateMap<K, N, S> owningStateMap, + ResourceGuard.Lease lease) { + super(owningStateMap); + + this.snapshotVersion = owningStateMap.getStateMapVersion(); + this.numberOfEntriesInSnapshotData = owningStateMap.size(); + this.lease = lease; + } + + /** + * Returns the internal version of the when this snapshot was created. + */ + int getSnapshotVersion() { + return snapshotVersion; + } + + @Override + public void release() { + owningStateMap.releaseSnapshot(this); + lease.close(); + } + + @Override + public void writeState( + TypeSerializer<K> keySerializer, + TypeSerializer<N> namespaceSerializer, + TypeSerializer<S> stateSerializer, + @Nonnull DataOutputView dov, + @Nullable StateSnapshotTransformer<S> stateSnapshotTransformer) throws IOException { + if (stateSnapshotTransformer == null) { + writeStateWithNoTransform(dov); + } else { + writeStateWithTransform(stateSerializer, dov, stateSnapshotTransformer); + } + } + + private void writeStateWithNoTransform(@Nonnull DataOutputView dov) throws IOException { + dov.writeInt(numberOfEntriesInSnapshotData); + SnapshotNodeIterator nodeIterator = new SnapshotNodeIterator(true); + while (nodeIterator.hasNext()) { + Tuple2<Long, Long> tuple = nodeIterator.next(); + writeKeyAndNamespace(tuple.f0, dov); + writeValue(tuple.f1, dov); + } + } + + private void writeStateWithTransform( + TypeSerializer<S> stateSerializer, + @Nonnull DataOutputView dov, + @Nonnull StateSnapshotTransformer<S> stateSnapshotTransformer) throws IOException { + SkipListValueSerializer<S> skipListValueSerializer = + new SkipListValueSerializer<>(stateSerializer); + + // 1. iterates nodes to get size after transform + SnapshotNodeIterator transformNodeIterator = new SnapshotNodeIterator(true); + int size = 0; + while (transformNodeIterator.hasNext()) { + Tuple2<Long, Long> tuple = transformNodeIterator.next(); + S oldState = owningStateMap.helpGetState(tuple.f1, skipListValueSerializer); + S newState = stateSnapshotTransformer.filterOrTransform(oldState); + if (newState != null) { + size++; + } + } + + dov.writeInt(size); Review comment: Not sure whether this is supported or not but couldn't we also write a `null` placeholder if `newState == null`? That way we would not have to pass over the state data twice at the cost of a slightly increased snapshot. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
