StefanRRichter commented on a change in pull request #6707: [FLINK-10157] [State TTL] Allow `null` user values in map state with TTL URL: https://github.com/apache/flink/pull/6707#discussion_r218485176
########## File path: flink-core/src/main/java/org/apache/flink/api/java/typeutils/runtime/NullableSerializer.java ########## @@ -0,0 +1,221 @@ +/* + * 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.api.java.typeutils.runtime; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.api.common.typeutils.CompatibilityResult; +import org.apache.flink.api.common.typeutils.CompatibilityUtil; +import org.apache.flink.api.common.typeutils.CompositeTypeSerializerConfigSnapshot; +import org.apache.flink.api.common.typeutils.TypeDeserializerAdapter; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.common.typeutils.TypeSerializerConfigSnapshot; +import org.apache.flink.api.common.typeutils.UnloadableDummyTypeSerializer; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.core.memory.DataInputView; +import org.apache.flink.core.memory.DataOutputSerializer; +import org.apache.flink.core.memory.DataOutputView; +import org.apache.flink.util.Preconditions; + +import java.io.IOException; +import java.util.List; + +/** + * Serializer wrapper to add support of null value serialization. + * + * <p>If the target serializer does not support null values of its type, + * you can use this class to wrap this serializer. + * This is a generic treatment of null value serialization + * which comes with the cost of additional byte in the final serialized value. + * The {@code NullableSerializer} will intercept null value serialization case + * and prepend the target serialized value with a boolean flag marking whether it is null or not. + * <pre> {@code + * TypeSerializer<T> originalSerializer = ...; + * TypeSerializer<T> serializerWithNullValueSupport = NullableSerializer.wrap(originalSerializer); + * // or + * TypeSerializer<T> serializerWithNullValueSupport = NullableSerializer.wrapIfNullIsNotSupported(originalSerializer); + * }}</pre> + * + * @param <T> type to serialize + */ +public class NullableSerializer<T> extends TypeSerializer<T> { + private static final long serialVersionUID = 3335569358214720033L; + + private final TypeSerializer<T> originalSerializer; + + private NullableSerializer(TypeSerializer<T> originalSerializer) { + Preconditions.checkNotNull(originalSerializer, "The original serializer cannot be null"); Review comment: For my personal taste, I would prefer `@Nonnull` on the field. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
