lirui-apache commented on a change in pull request #13914: URL: https://github.com/apache/flink/pull/13914#discussion_r517130765
########## File path: flink-table/flink-table-runtime-blink/src/main/java/org/apache/flink/table/filesystem/LimitableBulkFormat.java ########## @@ -0,0 +1,133 @@ +/* + * 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.table.filesystem; + +import org.apache.flink.api.common.typeinfo.TypeInformation; +import org.apache.flink.configuration.Configuration; +import org.apache.flink.connector.file.src.FileSourceSplit; +import org.apache.flink.connector.file.src.reader.BulkFormat; +import org.apache.flink.connector.file.src.util.RecordAndPosition; + +import javax.annotation.Nullable; + +import java.io.IOException; +import java.util.concurrent.atomic.AtomicLong; + +/** + * A {@link BulkFormat} that can limit output record number. + */ +public class LimitableBulkFormat<T, SplitT extends FileSourceSplit> implements BulkFormat<T, SplitT> { + + private static final long serialVersionUID = 1L; + + private final BulkFormat<T, SplitT> format; + private final long limit; + + private transient AtomicLong numRead; + + private LimitableBulkFormat(BulkFormat<T, SplitT> format, long limit) { + this.format = format; + this.limit = limit; + } + + @Override + public Reader<T> createReader(Configuration config, SplitT split) throws IOException { + return new LimitableReader(format.createReader(config, split)); + } + + @Override + public Reader<T> restoreReader(Configuration config, SplitT split) throws IOException { + return new LimitableReader(format.restoreReader(config, split)); + } + + @Override + public boolean isSplittable() { + return format.isSplittable(); + } + + @Override + public TypeInformation<T> getProducedType() { + return format.getProducedType(); + } + + private class LimitableReader implements Reader<T> { + + private final Reader<T> reader; + + private LimitableReader(Reader<T> reader) { + this.reader = reader; + } + + @Nullable + @Override + public RecordIterator<T> readBatch() throws IOException { + if (reachLimit()) { + return null; + } + + RecordIterator<T> batch = reader.readBatch(); + return batch == null ? null : new LimitableIterator(batch); + } + + @Override + public void close() throws IOException { + reader.close(); + } + } + + private class LimitableIterator implements RecordIterator<T> { + + private final RecordIterator<T> iterator; + + private LimitableIterator(RecordIterator<T> iterator) { + this.iterator = iterator; + } + + @Nullable + @Override + public RecordAndPosition<T> next() { + if (reachLimit()) { + return null; + } + getNumRead().incrementAndGet(); + return iterator.next(); + } + + @Override + public void releaseBatch() { + iterator.releaseBatch(); + } + } + + private AtomicLong getNumRead() { + if (numRead == null) { + numRead = new AtomicLong(0); Review comment: If the init can only happen in `readBatch`, I think it's better to move it to `readBatch`. And other code can directly use `numRead`. ---------------------------------------------------------------- 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: [email protected]
