org.apache.hadoop.mapred.SequenceFileAsBinaryInputFormat.java Source code

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Here is the source code for org.apache.hadoop.mapred.SequenceFileAsBinaryInputFormat.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.hadoop.mapred;

import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.SequenceFile;

/**
 * InputFormat reading keys, values from SequenceFiles in binary (raw)
 * format.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class SequenceFileAsBinaryInputFormat extends SequenceFileInputFormat<BytesWritable, BytesWritable> {

    public SequenceFileAsBinaryInputFormat() {
        super();
    }

    public RecordReader<BytesWritable, BytesWritable> getRecordReader(InputSplit split, JobConf job,
            Reporter reporter) throws IOException {
        return new SequenceFileAsBinaryRecordReader(job, (FileSplit) split);
    }

    /**
     * Read records from a SequenceFile as binary (raw) bytes.
     */
    public static class SequenceFileAsBinaryRecordReader implements RecordReader<BytesWritable, BytesWritable> {
        private SequenceFile.Reader in;
        private long start;
        private long end;
        private boolean done = false;
        private DataOutputBuffer buffer = new DataOutputBuffer();
        private SequenceFile.ValueBytes vbytes;

        public SequenceFileAsBinaryRecordReader(Configuration conf, FileSplit split) throws IOException {
            Path path = split.getPath();
            FileSystem fs = path.getFileSystem(conf);
            this.in = new SequenceFile.Reader(fs, path, conf);
            this.end = split.getStart() + split.getLength();
            if (split.getStart() > in.getPosition())
                in.sync(split.getStart()); // sync to start
            this.start = in.getPosition();
            vbytes = in.createValueBytes();
            done = start >= end;
        }

        public BytesWritable createKey() {
            return new BytesWritable();
        }

        public BytesWritable createValue() {
            return new BytesWritable();
        }

        /**
         * Retrieve the name of the key class for this SequenceFile.
         * @see org.apache.hadoop.io.SequenceFile.Reader#getKeyClassName
         */
        public String getKeyClassName() {
            return in.getKeyClassName();
        }

        /**
         * Retrieve the name of the value class for this SequenceFile.
         * @see org.apache.hadoop.io.SequenceFile.Reader#getValueClassName
         */
        public String getValueClassName() {
            return in.getValueClassName();
        }

        /**
         * Read raw bytes from a SequenceFile.
         */
        public synchronized boolean next(BytesWritable key, BytesWritable val) throws IOException {
            if (done)
                return false;
            long pos = in.getPosition();
            boolean eof = -1 == in.nextRawKey(buffer);
            if (!eof) {
                key.set(buffer.getData(), 0, buffer.getLength());
                buffer.reset();
                in.nextRawValue(vbytes);
                vbytes.writeUncompressedBytes(buffer);
                val.set(buffer.getData(), 0, buffer.getLength());
                buffer.reset();
            }
            return !(done = (eof || (pos >= end && in.syncSeen())));
        }

        public long getPos() throws IOException {
            return in.getPosition();
        }

        public void close() throws IOException {
            in.close();
        }

        /**
         * Return the progress within the input split
         * @return 0.0 to 1.0 of the input byte range
         */
        public float getProgress() throws IOException {
            if (end == start) {
                return 0.0f;
            } else {
                return Math.min(1.0f, (float) ((in.getPosition() - start) / (double) (end - start)));
            }
        }
    }
}