afedulov commented on code in PR #23553: URL: https://github.com/apache/flink/pull/23553#discussion_r1370875073
########## flink-connectors/flink-connector-datagen/src/main/java/org/apache/flink/connector/datagen/functions/FromElementsGeneratorFunction.java: ########## @@ -0,0 +1,211 @@ +/* + * 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.datagen.functions; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.api.common.ExecutionConfig; +import org.apache.flink.api.common.typeinfo.TypeInformation; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.connector.source.SourceReaderContext; +import org.apache.flink.api.java.typeutils.OutputTypeConfigurable; +import org.apache.flink.connector.datagen.source.GeneratorFunction; +import org.apache.flink.core.memory.DataInputView; +import org.apache.flink.core.memory.DataInputViewStreamWrapper; +import org.apache.flink.core.memory.DataOutputViewStreamWrapper; +import org.apache.flink.util.Preconditions; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; + +import java.io.ByteArrayInputStream; +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.io.UncheckedIOException; +import java.util.Arrays; +import java.util.Collection; +import java.util.Objects; + +/** + * A stream generator function that returns a sequence of elements. + * + * <p>This generator function serializes the elements using Flink's type information. That way, any + * object transport using Java serialization will not be affected by the serializability of the + * elements. + * + * <p><b>NOTE:</b> This source has a parallelism of 1. + * + * @param <OUT> The type of elements returned by this function. + */ +@Internal +public class FromElementsGeneratorFunction<OUT> + implements GeneratorFunction<Long, OUT>, OutputTypeConfigurable<OUT> { + + private static final long serialVersionUID = 1L; + + private static final Logger LOG = LoggerFactory.getLogger(FromElementsGeneratorFunction.class); + + /** The (de)serializer to be used for the data elements. */ + private @Nullable TypeSerializer<OUT> serializer; + + /** The actual data elements, in serialized form. */ + private byte[] elementsSerialized; + + /** The number of elements emitted already. */ + private int numElementsEmitted; + + private final transient Iterable<OUT> elements; + private transient DataInputView input; + + public FromElementsGeneratorFunction(TypeSerializer<OUT> serializer, OUT... elements) + throws IOException { + this(serializer, Arrays.asList(elements)); + } + + public FromElementsGeneratorFunction(TypeSerializer<OUT> serializer, Iterable<OUT> elements) + throws IOException { + this.serializer = Preconditions.checkNotNull(serializer); + this.elements = elements; + serializeElements(); + } + + @SafeVarargs + public FromElementsGeneratorFunction(OUT... elements) { + this(Arrays.asList(elements)); + } + + public FromElementsGeneratorFunction(Iterable<OUT> elements) { + this.serializer = null; + this.elements = elements; + checkIterable(elements, Object.class); + } + + @VisibleForTesting + @Nullable + public TypeSerializer<OUT> getSerializer() { + return serializer; + } + + private void serializeElements() throws IOException { + Preconditions.checkState(serializer != null, "serializer not set"); + LOG.info("Serializing elements using " + serializer); + ByteArrayOutputStream baos = new ByteArrayOutputStream(); + DataOutputViewStreamWrapper wrapper = new DataOutputViewStreamWrapper(baos); + + try { + for (OUT element : elements) { + serializer.serialize(element, wrapper); + } + } catch (Exception e) { + throw new IOException("Serializing the source elements failed: " + e.getMessage(), e); + } + this.elementsSerialized = baos.toByteArray(); + } + + @Override + public void open(SourceReaderContext readerContext) throws Exception { + ByteArrayInputStream bais = new ByteArrayInputStream(elementsSerialized); + this.input = new DataInputViewStreamWrapper(bais); + } + + @Override + public OUT map(Long nextIndex) throws Exception { + // Move iterator to the required position in case of failure recovery + while (numElementsEmitted < nextIndex) { + numElementsEmitted++; + tryDeserialize(serializer, input); + } + numElementsEmitted++; + return tryDeserialize(serializer, input); + } + + private OUT tryDeserialize(TypeSerializer<OUT> serializer, DataInputView input) + throws IOException { + try { + return serializer.deserialize(input); + } catch (Exception e) { + throw new IOException( + "Failed to deserialize an element from the source. " + + "If you are using user-defined serialization (Value and Writable types), check the " + + "serialization functions.\nSerializer is " + + serializer, + e); Review Comment: Hmmm, I am not quite sure I follow. The underlying `GeneratingIteratorSourceReader` will blow up with a `FlinkRuntimeException` and terminate. Is not this what we want? -- 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. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
