/*
* Copyright 2013 The Netty Project
*
* The Netty Project 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 io.netty.handler.codec.memcache;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.FileRegion;
import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.util.internal.StringUtil;
import io.netty.util.internal.UnstableApi;
import java.util.List;
/**
* A general purpose {@link AbstractMemcacheObjectEncoder} that encodes {@link MemcacheMessage}s.
* <p/>
* <p>Note that this class is designed to be extended, especially because both the binary and ascii protocol
* require different treatment of their messages. Since the content chunk writing is the same for both, the encoder
* abstracts this right away.</p>
*/
@UnstableApi
public abstract class AbstractMemcacheObjectEncoder<M extends MemcacheMessage> extends MessageToMessageEncoder<Object> {
private boolean expectingMoreContent;
@Override
protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
if (msg instanceof MemcacheMessage) {
if (expectingMoreContent) {
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
@SuppressWarnings({ "unchecked", "CastConflictsWithInstanceof" })
final M m = (M) msg;
out.add(encodeMessage(ctx, m));
}
if (msg instanceof MemcacheContent || msg instanceof ByteBuf || msg instanceof FileRegion) {
int contentLength = contentLength(msg);
if (contentLength > 0) {
out.add(encodeAndRetain(msg));
} else {
out.add(Unpooled.EMPTY_BUFFER);
}
expectingMoreContent = !(msg instanceof LastMemcacheContent);
}
}
@Override
public boolean acceptOutboundMessage(Object msg) throws Exception {
return msg instanceof MemcacheObject || msg instanceof ByteBuf || msg instanceof FileRegion;
}
/**
* Take the given {@link MemcacheMessage} and encode it into a writable {@link ByteBuf}.
*
* @param ctx the channel handler context.
* @param msg the message to encode.
* @return the {@link ByteBuf} representation of the message.
*/
protected abstract ByteBuf encodeMessage(ChannelHandlerContext ctx, M msg);
/**
* Determine the content length of the given object.
*
* @param msg the object to determine the length of.
* @return the determined content length.
*/
private static int contentLength(Object msg) {
if (msg instanceof MemcacheContent) {
return ((MemcacheContent) msg).content().readableBytes();
}
if (msg instanceof ByteBuf) {
return ((ByteBuf) msg).readableBytes();
}
if (msg instanceof FileRegion) {
return (int) ((FileRegion) msg).count();
}
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
/**
* Encode the content, depending on the object type.
*
* @param msg the object to encode.
* @return the encoded object.
*/
private static Object encodeAndRetain(Object msg) {
if (msg instanceof ByteBuf) {
return ((ByteBuf) msg).retain();
}
if (msg instanceof MemcacheContent) {
return ((MemcacheContent) msg).content().retain();
}
if (msg instanceof FileRegion) {
return ((FileRegion) msg).retain();
}
throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
}
}