Github user shixiaogang commented on a diff in the pull request: https://github.com/apache/flink/pull/3336#discussion_r102125062 --- Diff: flink-contrib/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBMapState.java --- @@ -0,0 +1,579 @@ +/* + * 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 + * <p/> + * http://www.apache.org/licenses/LICENSE-2.0 + * <p/> + * 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.contrib.streaming.state; + +import org.apache.flink.api.common.state.MapState; +import org.apache.flink.api.common.state.MapStateDescriptor; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.api.java.tuple.Tuple3; +import org.apache.flink.api.java.tuple.Tuple4; +import org.apache.flink.core.memory.ByteArrayInputStreamWithPos; +import org.apache.flink.core.memory.ByteArrayOutputStreamWithPos; +import org.apache.flink.core.memory.DataInputViewStreamWrapper; +import org.apache.flink.core.memory.DataOutputViewStreamWrapper; +import org.apache.flink.runtime.query.netty.message.KvStateRequestSerializer; +import org.apache.flink.runtime.state.KeyGroupRangeAssignment; +import org.apache.flink.runtime.state.internal.InternalMapState; +import org.apache.flink.util.Preconditions; +import org.rocksdb.ColumnFamilyHandle; +import org.rocksdb.RocksDB; +import org.rocksdb.RocksDBException; +import org.rocksdb.RocksIterator; +import org.rocksdb.WriteOptions; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Iterator; +import java.util.Map; + +/** + * {@link MapState} implementation that stores state in RocksDB. + * <p> + * <p>{@link RocksDBStateBackend} must ensure that we set the + * {@link org.rocksdb.StringAppendOperator} on the column family that we use for our state since + * we use the {@code merge()} call. + * + * @param <K> The type of the key. + * @param <N> The type of the namespace. + * @param <UK> The type of the keys in the map state. + * @param <UV> The type of the values in the map state. + */ +public class RocksDBMapState<K, N, UK, UV> + extends AbstractRocksDBState<K, N, MapState<UK, UV>, MapStateDescriptor<UK, UV>, Map<UK, UV>> + implements InternalMapState<N, UK, UV> { + + /** Serializer for the keys and values */ + private final TypeSerializer<UK> userKeySerializer; + private final TypeSerializer<UV> userValueSerializer; + + /** + * We disable writes to the write-ahead-log here. We can't have these in the base class + * because JNI segfaults for some reason if they are. + */ + private final WriteOptions writeOptions; --- End diff -- To be honest, i have no idea why we can't put `writeOptions` in base class. We put it in `AbstractRocksDBState` and do not come across any problem in our production environment. Maybe @aljoscha is more familiar with the problem.
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