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Make SplitIterator an outer class and fix parallelism (#863)
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...s-geoparquet/src/main/java/org/apache/baremaps/geoparquet/GeoParquetGroupSpliterator.java
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| /* | ||
| * 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. | ||
| */ | ||
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| package org.apache.baremaps.geoparquet; | ||
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| import java.io.IOException; | ||
| import java.util.Map; | ||
| import java.util.Queue; | ||
| import java.util.Spliterator; | ||
| import java.util.concurrent.ArrayBlockingQueue; | ||
| import java.util.function.Consumer; | ||
| import org.apache.baremaps.geoparquet.data.GeoParquetGroup; | ||
| import org.apache.baremaps.geoparquet.hadoop.GeoParquetGroupReadSupport; | ||
| import org.apache.hadoop.fs.FileStatus; | ||
| import org.apache.parquet.hadoop.ParquetReader; | ||
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| public class GeoParquetGroupSpliterator implements Spliterator<GeoParquetGroup> { | ||
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| private final GeoParquetReader geoParquetReader; | ||
| private final Queue<FileStatus> queue; | ||
| private final Map<FileStatus, GeoParquetReader.FileInfo> files; | ||
| private FileStatus fileStatus = null; | ||
| private ParquetReader<GeoParquetGroup> reader; | ||
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| GeoParquetGroupSpliterator(GeoParquetReader geoParquetReader, | ||
| Map<FileStatus, GeoParquetReader.FileInfo> files) { | ||
| this.geoParquetReader = geoParquetReader; | ||
| this.files = files; | ||
| this.queue = new ArrayBlockingQueue<>(files.keySet().size(), false, files.keySet()); | ||
| } | ||
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| @Override | ||
| public boolean tryAdvance(Consumer<? super GeoParquetGroup> action) { | ||
| try { | ||
| // Poll the next file | ||
| if (fileStatus == null) { | ||
| fileStatus = queue.poll(); | ||
| } | ||
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| // If there are no more files, return false | ||
| if (fileStatus == null) { | ||
| return false; | ||
| } | ||
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| // Create a new reader if it does not exist | ||
| if (reader == null) { | ||
| reader = createParquetReader(fileStatus); | ||
| } | ||
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| // Read the next group | ||
| GeoParquetGroup group = reader.read(); | ||
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| // If the group is null, close the resources and set the variables to null | ||
| if (group == null) { | ||
| reader.close(); | ||
| reader = null; | ||
| fileStatus = null; | ||
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| // Try to advance again | ||
| return tryAdvance(action); | ||
| } | ||
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| // Accept the group and tell the caller that there are more groups to read | ||
| action.accept(group); | ||
| return true; | ||
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| } catch (IOException e) { | ||
| // If an exception occurs, try to close the resources and throw a runtime exception | ||
| if (reader != null) { | ||
| try { | ||
| reader.close(); | ||
| } catch (IOException e2) { | ||
| // Ignore the exception as the original exception is more important | ||
| } | ||
| reader = null; | ||
| } | ||
| throw new GeoParquetException("IOException caught while trying to read the next file.", e); | ||
| } | ||
| } | ||
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| private ParquetReader<GeoParquetGroup> createParquetReader(FileStatus file) | ||
| throws IOException { | ||
| return ParquetReader | ||
| .builder(new GeoParquetGroupReadSupport(), file.getPath()) | ||
| .withConf(geoParquetReader.configuration) | ||
| .build(); | ||
| } | ||
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| @Override | ||
| public Spliterator<GeoParquetGroup> trySplit() { | ||
| if (queue.size() < 2) { | ||
| // There is nothing left to split | ||
| return null; | ||
| } | ||
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| // Create a new spliterator by polling the next polledFileStatus | ||
| FileStatus polledFileStatus = queue.poll(); | ||
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| // If there are no more files, tell the caller that there is nothing to split anymore | ||
| if (polledFileStatus == null) { | ||
| return null; | ||
| } | ||
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| // Return a new spliterator with the polledFileStatus | ||
| return new GeoParquetGroupSpliterator(geoParquetReader, | ||
| Map.of(polledFileStatus, files.get(polledFileStatus))); | ||
| } | ||
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| @Override | ||
| public long estimateSize() { | ||
| return files.values().stream() | ||
| .map(GeoParquetReader.FileInfo::recordCount) | ||
| .reduce(0L, Long::sum); | ||
| } | ||
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| @Override | ||
| public int characteristics() { | ||
| // The spliterator is not ordered, or sorted | ||
| return NONNULL | IMMUTABLE | SIZED | DISTINCT; | ||
| } | ||
| } |
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