tweise commented on a change in pull request #15924: URL: https://github.com/apache/flink/pull/15924#discussion_r643516999
########## File path: flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/source/hybrid/HybridSource.java ########## @@ -0,0 +1,216 @@ +/* + * 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.annotation.PublicEvolving; +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. */ +@PublicEvolving +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()); + for (int i = 0; i < sourceChain.sources.size() - 1; i++) { + Preconditions.checkArgument( + Boundedness.BOUNDED.equals(sourceChain.sources.get(i).f0.getBoundedness()), + "All sources except the final source need to be bounded."); + } + 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 { + try (ByteArrayInputStream bais = new ByteArrayInputStream(serialized); + DataInputStream in = new DataInputStream(bais)) { + int sourceIndex = in.readInt(); + int nestedVersion = in.readInt(); + int length = in.readInt(); + byte[] splitBytes = new byte[length]; + in.readFully(splitBytes); + SourceSplit split = + serializerOf(sourceIndex).deserialize(nestedVersion, splitBytes); + return new HybridSourceSplit(sourceIndex, split); + } + } + + private SimpleVersionedSerializer<SourceSplit> serializerOf(int sourceIndex) { + Preconditions.checkArgument(sourceIndex < serializers.size()); + return serializers.get(sourceIndex); + } + } + + /** + * Converts checkpoint between sources to transfer end position to next source's start position. + * Only required for dynamic position transfer at time of switching, otherwise source can be + * preconfigured with a start position during job submission. + */ + public interface CheckpointConverter<InCheckpointT, OutCheckpointT> + extends Function<InCheckpointT, OutCheckpointT>, Serializable {} + + /** Chain of sources with option to convert start position at switch-time. */ + public static class SourceChain<T, SplitT extends SourceSplit, EnumChkT> Review comment: The type parameters are required to provide compile time checking so that only source with compatible record type and state type can be combined. The state type should also match of the user provided a converter function. I removed `SplitT`, it wasn't needed. -- 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: us...@infra.apache.org
