org.apache.crunch.io.orc.OrcFileReaderFactory.java Source code

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Here is the source code for org.apache.crunch.io.orc.OrcFileReaderFactory.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.
 */
package org.apache.crunch.io.orc;

import java.util.Iterator;

import org.apache.crunch.CrunchRuntimeException;
import org.apache.crunch.MapFn;
import org.apache.crunch.io.FileReaderFactory;
import org.apache.crunch.types.PType;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.io.orc.OrcInputFormat;
import org.apache.hadoop.hive.ql.io.orc.OrcStruct;
import org.apache.hadoop.hive.serde2.ColumnProjectionUtils;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;

import com.google.common.collect.UnmodifiableIterator;

public class OrcFileReaderFactory<T> implements FileReaderFactory<T> {

    private MapFn<Object, T> inputFn;
    private OrcInputFormat inputFormat = new OrcInputFormat();
    private int[] readColumns;

    public OrcFileReaderFactory(PType<T> ptype) {
        this(ptype, null);
    }

    public OrcFileReaderFactory(PType<T> ptype, int[] readColumns) {
        inputFn = ptype.getInputMapFn();
        this.readColumns = readColumns;
    }

    @Override
    public Iterator<T> read(FileSystem fs, final Path path) {
        try {
            if (!fs.isFile(path)) {
                throw new CrunchRuntimeException("Not a file: " + path);
            }

            inputFn.initialize();

            FileStatus status = fs.getFileStatus(path);
            FileSplit split = new FileSplit(path, 0, status.getLen(), new String[0]);

            JobConf conf = new JobConf();
            if (readColumns != null) {
                conf.setBoolean(OrcFileSource.HIVE_READ_ALL_COLUMNS, false);
                conf.set(ColumnProjectionUtils.READ_COLUMN_IDS_CONF_STR,
                        OrcFileSource.getColumnIdsStr(readColumns));
            }
            final RecordReader<NullWritable, OrcStruct> reader = inputFormat.getRecordReader(split, conf,
                    Reporter.NULL);

            return new UnmodifiableIterator<T>() {

                private boolean checked = false;
                private boolean hasNext;
                private OrcStruct value;
                private OrcWritable writable = new OrcWritable();

                @Override
                public boolean hasNext() {
                    try {
                        if (value == null) {
                            value = reader.createValue();
                        }
                        if (!checked) {
                            hasNext = reader.next(NullWritable.get(), value);
                            checked = true;
                        }
                        return hasNext;
                    } catch (Exception e) {
                        throw new CrunchRuntimeException("Error while reading local file: " + path, e);
                    }
                }

                @Override
                public T next() {
                    try {
                        if (value == null) {
                            value = reader.createValue();
                        }
                        if (!checked) {
                            reader.next(NullWritable.get(), value);
                        }
                        checked = false;
                        writable.set(value);
                        return inputFn.map(writable);
                    } catch (Exception e) {
                        throw new CrunchRuntimeException("Error while reading local file: " + path, e);
                    }
                }

            };
        } catch (Exception e) {
            throw new CrunchRuntimeException("Error while reading local file: " + path, e);
        }
    }

}