IdAndVersionDataReader.java

package com.aconex.scrutineer.elasticsearch;

import java.io.EOFException;
import java.io.IOException;
import java.io.ObjectInputStream;

import com.aconex.scrutineer.IdAndVersion;
import com.aconex.scrutineer.IdAndVersionFactory;
import com.fasterxml.sort.DataReader;

class IdAndVersionDataReader extends DataReader<IdAndVersion> {

    private static final int BYTES_PER_CHAR = 2;
    private static final int BYTES_PER_LONG = 8;
    private static final int BYTES_PER_OBJECT_POINTER = 24;
    private static final int BYTES_PER_ARRAY_POINTER = 28;

	private final IdAndVersionFactory factory;
    private final ObjectInputStream objectInputStream;

    public IdAndVersionDataReader(IdAndVersionFactory factory, ObjectInputStream objectInputStream) {
    	this.factory = factory;
        this.objectInputStream = objectInputStream;
    }

    @Override
    public IdAndVersion readNext() throws IOException {
        try {
            return factory.readFromStream(objectInputStream);
        } catch (EOFException e) {
            return null;
        }
    }

    @Override
    public int estimateSizeInBytes(IdAndVersion item) {
        int idAndVersionContainerSize = BYTES_PER_OBJECT_POINTER;
        int versionSize = BYTES_PER_LONG;
        int idSize = BYTES_PER_OBJECT_POINTER + BYTES_PER_ARRAY_POINTER + (item.getId().length() * BYTES_PER_CHAR);
        int totalSize = idAndVersionContainerSize + versionSize + idSize;

        return totalSize;
    }

    @Override
    public void close() throws IOException {
        objectInputStream.close();
    }
}