MemcachedDecoder.java

/**
 *Copyright [2009-2010] [dennis zhuang(killme2008@gmail.com)]
 *Licensed 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 net.rubyeye.xmemcached.codec;

import net.rubyeye.xmemcached.command.Command;
import net.rubyeye.xmemcached.impl.MemcachedTCPSession;
import net.rubyeye.xmemcached.utils.ByteUtils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.code.yanf4j.buffer.IoBuffer;
import com.google.code.yanf4j.core.Session;
import com.google.code.yanf4j.core.CodecFactory.Decoder;
import com.google.code.yanf4j.util.ByteBufferMatcher;
import com.google.code.yanf4j.util.ShiftAndByteBufferMatcher;

/**
 * Memcached protocol decoder
 * 
 * @author dennis
 * 
 */
public class MemcachedDecoder implements Decoder {

	public static final Logger log = LoggerFactory
			.getLogger(MemcachedDecoder.class);

	public MemcachedDecoder() {
		super();
	}

	/**
	 * shift-and algorithm for ByteBuffer's match
	 */
	public static final ByteBufferMatcher SPLIT_MATCHER = new ShiftAndByteBufferMatcher(
			IoBuffer.wrap(ByteUtils.SPLIT));

	public Object decode(IoBuffer buffer, Session origSession) {
		MemcachedTCPSession session = (MemcachedTCPSession) origSession;
		if (session.getCurrentCommand() != null) {
			return decode0(buffer, session);
		} else {
			session.takeCurrentCommand();
			if (session.getCurrentCommand() == null)
				return null;
			return decode0(buffer, session);
		}
	}

	private Object decode0(IoBuffer buffer, MemcachedTCPSession session) {
		if (session.getCurrentCommand().decode(session, buffer.buf())) {
			final Command command = session.getCurrentCommand();
			session.setCurrentCommand(null);
			return command;
		}
		return null;
	}
}