RowDataPacket.java

/*
 * Copyright (c) 2013, OpenCloudDB/MyCAT and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software;Designed and Developed mainly by many Chinese 
 * opensource volunteers. you can redistribute it and/or modify it under the 
 * terms of the GNU General Public License version 2 only, as published by the
 * Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 * 
 * Any questions about this component can be directed to it's project Web address 
 * https://code.google.com/p/opencloudb/.
 *
 */
package io.mycat.server.packet;

import io.mycat.net.BufferArray;
import io.mycat.net.Connection;
import io.mycat.net.NetSystem;
import io.mycat.server.packet.util.BufferUtil;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

/**
 * From server to client. One packet for each row in the result set.
 * 
 * <pre>
 * Bytes                   Name
 * -----                   ----
 * n (Length Coded String) (column value)
 * ...
 * 
 * (column value):         The data in the column, as a character string.
 *                         If a column is defined as non-character, the
 *                         server converts the value into a character
 *                         before sending it. Since the value is a Length
 *                         Coded String, a NULL can be represented with a
 *                         single byte containing 251(see the description
 *                         of Length Coded Strings in section "Elements" above).
 * 
 * @see http://forge.mysql.com/wiki/MySQL_Internals_ClientServer_Protocol#Row_Data_Packet
 * </pre>
 * 
 * @author mycat
 */
public class RowDataPacket extends MySQLPacket {
	private static final byte NULL_MARK = (byte) 251;
	private static final byte EMPTY_MARK = (byte) 0;
	public int fieldCount;
	public final List<byte[]> fieldValues;

	public RowDataPacket(int fieldCount) {
		this.fieldCount = fieldCount;
		this.fieldValues = new ArrayList<byte[]>(fieldCount);
	}

	public void add(byte[] value) {
		// 这里应该修改value
		fieldValues.add(value);
	}

	public void addFieldCount(int add) {
		// 这里应该修改field
		fieldCount = fieldCount + add;
	}

	public void read(byte[] data) {
		MySQLMessage mm = new MySQLMessage(data);
		packetLength = mm.readUB3();
		packetId = mm.read();
		for (int i = 0; i < fieldCount; i++) {
			fieldValues.add(mm.readBytesWithLength());
		}
	}

	@Override
	public void write(BufferArray bufferArray) {
		int size = calcPacketSize();
		ByteBuffer buffer = bufferArray.checkWriteBuffer(packetHeaderSize
				+ size);
		BufferUtil.writeUB3(buffer, size);
		buffer.put(packetId);
		for (int i = 0; i < fieldCount; i++) {
			byte[] fv = fieldValues.get(i);
			if (fv == null) {
				buffer = bufferArray.checkWriteBuffer(1);
				buffer.put(RowDataPacket.NULL_MARK);
			} else if (fv.length == 0) {
				buffer = bufferArray.checkWriteBuffer(1);
				buffer.put(RowDataPacket.EMPTY_MARK);
			} else {
				buffer = bufferArray.checkWriteBuffer(BufferUtil
						.getLength(fv.length));
				BufferUtil.writeLength(buffer, fv.length);
				bufferArray.write(fv);
			}
		}
	}

	public void write(Connection conn) {
		int size = calcPacketSize();
		int totalSize = size + packetHeaderSize;
		if (NetSystem.getInstance().getBufferPool().getChunkSize() >= totalSize) {
			ByteBuffer buffer = NetSystem.getInstance().getBufferPool()
					.allocate();
			BufferUtil.writeUB3(buffer, size);
			buffer.put(packetId);
			for (int i = 0; i < fieldCount; i++) {
				byte[] fv = fieldValues.get(i);
				if (fv == null) {
					buffer.put(RowDataPacket.NULL_MARK);
				} else if (fv.length == 0) {
					buffer.put(RowDataPacket.EMPTY_MARK);
				} else {
					BufferUtil.writeLength(buffer, fv.length);
					buffer.put(fv);
				}
			}
			conn.write(buffer);
		} else {
			BufferArray bufArray = NetSystem.getInstance().getBufferPool()
					.allocateArray();
			write(bufArray);
			conn.write(bufArray);
		}

	}

	@Override
	public int calcPacketSize() {
		int size = 0;
		for (int i = 0; i < fieldCount; i++) {
			byte[] v = fieldValues.get(i);
			size += (v == null || v.length == 0) ? 1 : BufferUtil.getLength(v);
		}
		return size;
	}

	@Override
	protected String getPacketInfo() {
		return "MySQL RowData Packet";
	}

}