org.apache.mahout.math.hadoop.stochasticsvd.SplitPartitionedWritable.java Source code

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Here is the source code for org.apache.mahout.math.hadoop.stochasticsvd.SplitPartitionedWritable.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.mahout.math.hadoop.stochasticsvd;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.Serializable;

import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.math.Varint;

/**
 * a key for vectors allowing to identify them by their coordinates in original
 * split of A.
 * 
 * We assume all passes over A results in the same splits, thus, we can always
 * prepare side files that come into contact with A, sp that they are sorted and
 * partitioned same way.
 * <P>
 * 
 * Hashcode is defined the way that all records of the same split go to the same
 * reducer.
 * <P>
 * 
 * In addition, we are defining a grouping comparator allowing group one split
 * into the same reducer group.
 * <P>
 * 
 */
public class SplitPartitionedWritable implements WritableComparable<SplitPartitionedWritable> {

    private int taskId;
    private long taskItemOrdinal;

    public SplitPartitionedWritable(Mapper<?, ?, ?, ?>.Context mapperContext) {
        // this is basically a split # if i understand it right
        taskId = mapperContext.getTaskAttemptID().getTaskID().getId();
    }

    public SplitPartitionedWritable() {
    }

    public int getTaskId() {
        return taskId;
    }

    public long getTaskItemOrdinal() {
        return taskItemOrdinal;
    }

    public void incrementItemOrdinal() {
        taskItemOrdinal++;
    }

    public void setTaskItemOrdinal(long taskItemOrdinal) {
        this.taskItemOrdinal = taskItemOrdinal;
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        taskId = Varint.readUnsignedVarInt(in);
        taskItemOrdinal = Varint.readUnsignedVarLong(in);
    }

    @Override
    public void write(DataOutput out) throws IOException {
        Varint.writeUnsignedVarInt(taskId, out);
        Varint.writeUnsignedVarLong(taskItemOrdinal, out);
    }

    @Override
    public int hashCode() {
        int prime = 31;
        int result = 1;
        result = prime * result + taskId;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        SplitPartitionedWritable other = (SplitPartitionedWritable) obj;
        return taskId == other.taskId;
    }

    @Override
    public int compareTo(SplitPartitionedWritable o) {
        if (taskId < o.taskId) {
            return -1;
        }
        if (taskId > o.taskId) {
            return 1;
        }
        if (taskItemOrdinal < o.taskItemOrdinal) {
            return -1;
        }
        if (taskItemOrdinal > o.taskItemOrdinal) {
            return 1;
        }
        return 0;
    }

    public static final class SplitGroupingComparator extends WritableComparator implements Serializable {

        public SplitGroupingComparator() {
            super(SplitPartitionedWritable.class, true);
        }

        @Override
        public int compare(Object a, Object b) {
            SplitPartitionedWritable o1 = (SplitPartitionedWritable) a;
            SplitPartitionedWritable o2 = (SplitPartitionedWritable) b;

            if (o1.taskId < o2.taskId) {
                return -1;
            }
            if (o1.taskId > o2.taskId) {
                return 1;
            }
            return 0;
        }

    }

}