com.facebook.infrastructure.db.ReadResponse.java Source code

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Here is the source code for com.facebook.infrastructure.db.ReadResponse.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 com.facebook.infrastructure.db;

import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.Serializable;

import javax.xml.bind.annotation.XmlElement;

import com.facebook.infrastructure.io.ICompactSerializer;
import com.facebook.infrastructure.net.Message;
import com.facebook.infrastructure.net.MessagingService;
import com.facebook.infrastructure.service.StorageService;
import org.apache.commons.lang.ArrayUtils;

/*
 * The read response message is sent by the server when reading data 
 * this encapsulates the tablename and teh row that has been read.
 * The table name is needed so that we can use it to create repairs.
 * Author : Avinash Lakshman ( alakshman@facebook.com) & Prashant Malik ( pmalik@facebook.com )
 */
public class ReadResponse implements Serializable {
    private static ICompactSerializer<ReadResponse> serializer_;

    static {
        serializer_ = new ReadResponseMessageSerializer();
    }

    public static ICompactSerializer<ReadResponse> serializer() {
        return serializer_;
    }

    public static Message makeReadResponseMessage(ReadResponse readResponse) throws IOException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(bos);
        ReadResponse.serializer().serialize(readResponse, dos);
        Message message = new Message(StorageService.getLocalStorageEndPoint(), MessagingService.responseStage_,
                MessagingService.responseVerbHandler_, bos.toByteArray());
        return message;
    }

    @XmlElement(name = "Table")
    private String table_;

    @XmlElement(name = "Row")
    private Row row_;

    @XmlElement(name = "Digest")
    private byte[] digest_ = ArrayUtils.EMPTY_BYTE_ARRAY;

    @XmlElement(name = "isDigestQuery")
    private boolean isDigestQuery_ = false;

    private ReadResponse() {
    }

    public ReadResponse(String table, byte[] digest) {
        table_ = table;
        digest_ = digest;
    }

    public ReadResponse(String table, Row row) {
        table_ = table;
        row_ = row;
    }

    public String table() {
        return table_;
    }

    public Row row() {
        return row_;
    }

    public byte[] digest() {
        return digest_;
    }

    public boolean isDigestQuery() {
        return isDigestQuery_;
    }

    public void setIsDigestQuery(boolean isDigestQuery) {
        isDigestQuery_ = isDigestQuery;
    }
}

class ReadResponseMessageSerializer implements ICompactSerializer<ReadResponse> {
    public void serialize(ReadResponse rm, DataOutputStream dos) throws IOException {
        dos.writeUTF(rm.table());
        dos.writeInt(rm.digest().length);
        dos.write(rm.digest());
        dos.writeBoolean(rm.isDigestQuery());

        if (!rm.isDigestQuery() && rm.row() != null) {
            Row.serializer().serialize(rm.row(), dos);
        }
    }

    public ReadResponse deserialize(DataInputStream dis) throws IOException {
        String table = dis.readUTF();
        int digestSize = dis.readInt();
        byte[] digest = new byte[digestSize];
        dis.read(digest, 0, digestSize);
        boolean isDigest = dis.readBoolean();

        Row row = null;
        if (!isDigest) {
            row = Row.serializer().deserialize(dis);
        }

        ReadResponse rmsg = null;
        if (isDigest) {
            rmsg = new ReadResponse(table, digest);
        } else {
            rmsg = new ReadResponse(table, row);
        }
        rmsg.setIsDigestQuery(isDigest);
        return rmsg;
    }
}