gyfora commented on code in PR #28837: URL: https://github.com/apache/flink/pull/28837#discussion_r3776205170
########## flink-libraries/flink-state-processing-api/src/main/java/org/apache/flink/state/api/input/deserializer/PojoToRowDataDeserializer.java: ########## @@ -0,0 +1,330 @@ +/* + * 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.state.api.input.deserializer; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.common.typeutils.TypeSerializerSnapshot; +import org.apache.flink.api.java.typeutils.runtime.PojoDeserializerCompatibilitySnapshot; +import org.apache.flink.api.java.typeutils.runtime.PojoSerializerSnapshot; +import org.apache.flink.core.memory.DataInputView; +import org.apache.flink.core.memory.DataOutputView; +import org.apache.flink.state.api.schema.SerializerSnapshotToLogicalTypeConverter; +import org.apache.flink.table.data.GenericRowData; +import org.apache.flink.table.data.RowData; +import org.apache.flink.table.types.logical.LogicalType; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.IOException; +import java.util.AbstractMap; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; + +/** + * A {@link TypeSerializer} that reads the POJO binary format written by {@link + * org.apache.flink.api.java.typeutils.runtime.PojoSerializer} and produces {@link GenericRowData}. + * + * <p>This deserializer does <em>not</em> require the user POJO class to be on the classpath. It + * mirrors the exact binary protocol of {@code PojoSerializer}: + * + * <pre>{@code + * 1 byte: flags (bitmask) + * 0x01 IS_NULL → value is null, return null + * 0x02 NO_SUBCLASS → exact POJO class: read numFields × (isNull boolean + field bytes) + * 0x08 IS_TAGGED_SUBCLASS → 1 byte subclass tag; delegate to registered subclass deserializer + * 0x04 IS_SUBCLASS → UTF class name (must be read); Kryo not supported → throws IOException + * }</pre> + * + * <p>Use {@link #create(PojoSerializerSnapshot)} to build an instance from a savepoint snapshot. + */ +@Internal +public final class PojoToRowDataDeserializer extends TypeSerializer<RowData> { + + private static final long serialVersionUID = 1L; + + private static final Logger LOG = LoggerFactory.getLogger(PojoToRowDataDeserializer.class); + + // Mirrors constants in PojoSerializer + static final int IS_NULL = 0x01; + static final int NO_SUBCLASS = 0x02; + static final int IS_SUBCLASS = 0x04; + static final int IS_TAGGED_SUBCLASS = 0x08; + + private final int numFields; + private final TypeSerializer<?>[] fieldDeserializers; + private final LogicalType[] fieldTypes; + private final String[] fieldNames; + private final List<PojoToRowDataDeserializer> registeredSubclassDeserializers; + + /** + * Builds a {@link PojoToRowDataDeserializer} from a {@link PojoSerializerSnapshot}. + * + * <p>For each field: + * + * <ul> + * <li>If the field snapshot is itself a {@link PojoSerializerSnapshot}, this method recurses + * to build a nested {@link PojoToRowDataDeserializer}. + * <li>For all other field types, the field's original serializer is restored via {@link + * TypeSerializerSnapshot#restoreSerializer()}. + * </ul> + * + * <p>Registered subclasses are handled by building a deserializer for each registered subclass + * snapshot in order (matching the tag index used in the binary format). + * + * @throws IllegalStateException if a required field serializer snapshot is absent + */ + public static PojoToRowDataDeserializer create(PojoSerializerSnapshot<?> snapshot) { + List<AbstractMap.SimpleEntry<String, TypeSerializerSnapshot<?>>> fieldEntries = + snapshot.getFieldSnapshotEntries(); + + List<TypeSerializer<?>> fieldDeserializerList = new ArrayList<>(fieldEntries.size()); + List<LogicalType> fieldTypeList = new ArrayList<>(fieldEntries.size()); + List<String> fieldNameList = new ArrayList<>(fieldEntries.size()); + + for (AbstractMap.SimpleEntry<String, TypeSerializerSnapshot<?>> entry : fieldEntries) { + String fieldName = entry.getKey(); + TypeSerializerSnapshot<?> fieldSnapshot = entry.getValue(); + + if (fieldSnapshot == null) { Review Comment: Good catch, added enum support -- This is an automated message from the Apache Git Service. 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