eagle-core/eagle-query/eagle-query-base/src/main/java/org/apache/eagle/query/aggregate/raw/GroupbyValue.java

/*
 * 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.eagle.query.aggregate.raw;

import org.apache.eagle.common.ByteUtil;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.Writable;

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

/**
 * <h3>Strucutre</h3>
 * <pre>
 * {
 *   value: List[byte[],...],
 *   meta : List[byte[],...] // byte[] may be serialized value
 *                           // of any type of value like:
 *                           // Integer,Double or Object
 *                           // and so on
 * }
 * </pre>
 *
 * TODO: Add self-described serializer or deserializer for meta bytes array, so that any side of the RPC will know how to read/write meta information
 *
 * @since : 11/4/14,2014
 */
public class GroupbyValue implements Writable {
    private final WritableList<DoubleWritable> value;
    private WritableList<BytesWritable> meta;
    private int initialCapacity = 1;

    public GroupbyValue() {
        this(1);
    }

    /**
     * Constructs an empty list with the specified initial capacity.
     *
     * @param   initialCapacity   the initial capacity of the list
     * @exception IllegalArgumentException if the specified initial capacity
     *            is negative
     */
    public GroupbyValue(int initialCapacity) {
        this.initialCapacity = initialCapacity;
        this.value = new WritableList<DoubleWritable>(DoubleWritable.class,this.initialCapacity);
        this.meta = new WritableList<BytesWritable>(BytesWritable.class,this.initialCapacity);
    }

    public WritableList<DoubleWritable> getValue() {
        return this.value;
    }

    public DoubleWritable get(int index) {
        return this.value.get(index);
    }

    public WritableList<BytesWritable> getMeta() {
        return this.meta;
    }

    public BytesWritable getMeta(int index) {
        if (this.meta == null) {
            return null;
        }
        return this.meta.get(index);
    }

    // Values
    public void add(DoubleWritable value) {
        this.value.add(value);
    }

    public void add(Double value) {
        this.value.add(new DoubleWritable(value));
    }

    public void set(int index,DoubleWritable value) {
        this.value.set(index, value);
    }

    //////////////
    // Meta
    /////////////
    public void addMeta(BytesWritable meta) {
        this.meta.add(meta);
    }

    public void addMeta(int meta) {
        this.meta.add(new BytesWritable(ByteUtil.intToBytes(meta)));
    }

    public void setMeta(int index,BytesWritable meta) {
        this.meta.set(index,meta);
    }

    public void setMeta(int index,int meta) {
        this.meta.set(index, new BytesWritable(ByteUtil.intToBytes(meta)));
    }

    /**
     * Serialize the fields of this object to <code>out</code>.
     *
     * @param out <code>DataOuput</code> to serialize this object into.
     * @throws java.io.IOException
     */
    @Override
    public void write(DataOutput out) throws IOException {
        out.writeInt(this.initialCapacity);
        this.value.write(out);
        this.meta.write(out);
    }

    /**
     * Deserialize the fields of this object from <code>in</code>.
     * <p/>
     * <p>For efficiency, implementations should attempt to re-use storage in the
     * existing object where possible.</p>
     *
     * @param in <code>DataInput</code> to deseriablize this object from.
     * @throws java.io.IOException
     */
    @Override
    public void readFields(DataInput in) throws IOException {
        this.initialCapacity = in.readInt();
        this.value.readFields(in);
        this.meta.readFields(in);
    }
}