stevenzwu commented on a change in pull request #15924: URL: https://github.com/apache/flink/pull/15924#discussion_r639413522
########## File path: flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/source/hybrid/HybridSource.java ########## @@ -0,0 +1,209 @@ +/* + * 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.connector.base.source.hybrid; + +import org.apache.flink.api.connector.source.Boundedness; +import org.apache.flink.api.connector.source.Source; +import org.apache.flink.api.connector.source.SourceReader; +import org.apache.flink.api.connector.source.SourceReaderContext; +import org.apache.flink.api.connector.source.SourceSplit; +import org.apache.flink.api.connector.source.SplitEnumerator; +import org.apache.flink.api.connector.source.SplitEnumeratorContext; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.core.io.SimpleVersionedSerializer; +import org.apache.flink.util.Preconditions; + +import java.io.ByteArrayInputStream; +import java.io.ByteArrayOutputStream; +import java.io.DataInputStream; +import java.io.DataOutputStream; +import java.io.IOException; +import java.io.Serializable; +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; +import java.util.function.Function; + +/** Hybrid source that switches underlying sources based on configurable source chain. */ +public class HybridSource<T> implements Source<T, HybridSourceSplit, HybridSourceEnumState> { + + private final SourceChain<T, ? extends SourceSplit, ?> sourceChain; + + public HybridSource(SourceChain<T, ? extends SourceSplit, ?> sourceChain) { + Preconditions.checkArgument(!sourceChain.sources.isEmpty()); + this.sourceChain = sourceChain; + } + + @Override + public Boundedness getBoundedness() { + return sourceChain.sources.get(sourceChain.sources.size() - 1).f0.getBoundedness(); + } + + @Override + public SourceReader<T, HybridSourceSplit> createReader(SourceReaderContext readerContext) + throws Exception { + List<SourceReader<?, ? extends SourceSplit>> readers = new ArrayList<>(); + for (Tuple2<Source<T, ? extends SourceSplit, ?>, ?> source : sourceChain.sources) { + readers.add(source.f0.createReader(readerContext)); + } + return new HybridSourceReader(readerContext, readers); + } + + @Override + public SplitEnumerator<HybridSourceSplit, HybridSourceEnumState> createEnumerator( + SplitEnumeratorContext<HybridSourceSplit> enumContext) { + return new HybridSourceSplitEnumerator(enumContext, sourceChain); + } + + @Override + public SplitEnumerator<HybridSourceSplit, HybridSourceEnumState> restoreEnumerator( + SplitEnumeratorContext<HybridSourceSplit> enumContext, HybridSourceEnumState checkpoint) + throws Exception { + return new HybridSourceSplitEnumerator( + enumContext, sourceChain, checkpoint.getCurrentSourceIndex()); + } + + @Override + public SimpleVersionedSerializer<HybridSourceSplit> getSplitSerializer() { + List<SimpleVersionedSerializer<SourceSplit>> serializers = new ArrayList<>(); + sourceChain.sources.forEach( + t -> serializers.add(castSerializer(t.f0.getSplitSerializer()))); + return new SplitSerializerWrapper<>(serializers); + } + + @Override + public SimpleVersionedSerializer<HybridSourceEnumState> getEnumeratorCheckpointSerializer() { + List<SimpleVersionedSerializer<Object>> serializers = new ArrayList<>(); + sourceChain.sources.forEach( + t -> serializers.add(castSerializer(t.f0.getEnumeratorCheckpointSerializer()))); + return new HybridSourceEnumStateSerializer(serializers); + } + + private static <T> SimpleVersionedSerializer<T> castSerializer( + SimpleVersionedSerializer<? extends T> s) { + @SuppressWarnings("rawtypes") + SimpleVersionedSerializer s1 = s; + return s1; + } + + /** Serializes splits by delegating to the source-indexed split serializer. */ + public static class SplitSerializerWrapper<SplitT extends SourceSplit> + implements SimpleVersionedSerializer<HybridSourceSplit> { + + final List<SimpleVersionedSerializer<SourceSplit>> serializers; + + public SplitSerializerWrapper(List<SimpleVersionedSerializer<SourceSplit>> serializers) { + this.serializers = serializers; + } + + @Override + public int getVersion() { + return 0; + } + + @Override + public byte[] serialize(HybridSourceSplit split) throws IOException { + try (ByteArrayOutputStream baos = new ByteArrayOutputStream(); + DataOutputStream out = new DataOutputStream(baos)) { + out.writeInt(split.sourceIndex()); + out.writeInt(serializerOf(split.sourceIndex()).getVersion()); + byte[] serializedSplit = + serializerOf(split.sourceIndex()).serialize(split.getWrappedSplit()); + out.writeInt(serializedSplit.length); + out.write(serializedSplit); + return baos.toByteArray(); + } + } + + @Override + public HybridSourceSplit deserialize(int version, byte[] serialized) throws IOException { Review comment: we can also move the remaining code to a `deserializeV0` method -- This is an automated message from the Apache Git Service. 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