Motivation: 1. Some encoders used a `ByteBuf#writeBytes` to write short constant byte array (2-3 bytes). This can be replaced with more faster `ByteBuf#writeShort` or `ByteBuf#writeMedium` which do not access the memory. 2. Two chained calls of the `ByteBuf#setByte` with constants can be replaced with one `ByteBuf#setShort` to reduce index checks. 3. The signature of method `HttpHeadersEncoder#encoderHeader` has an unnecessary `throws`. Modifications: 1. Use `ByteBuf#writeShort` or `ByteBuf#writeMedium` instead of `ByteBuf#writeBytes` for the constants. 2. Use `ByteBuf#setShort` instead of chained call of the `ByteBuf#setByte` with constants. 3. Remove an unnecessary `throws` from `HttpHeadersEncoder#encoderHeader`. Result: A bit faster writes constants into buffers.
242 lines
9.5 KiB
Java
Executable File
242 lines
9.5 KiB
Java
Executable File
/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.http;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.ByteBufUtil;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.FileRegion;
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import io.netty.handler.codec.MessageToMessageEncoder;
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import io.netty.util.CharsetUtil;
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import io.netty.util.internal.StringUtil;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map.Entry;
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import static io.netty.buffer.Unpooled.EMPTY_BUFFER;
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import static io.netty.buffer.Unpooled.directBuffer;
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import static io.netty.buffer.Unpooled.unreleasableBuffer;
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import static io.netty.handler.codec.http.HttpConstants.CR;
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import static io.netty.handler.codec.http.HttpConstants.LF;
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/**
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* Encodes an {@link HttpMessage} or an {@link HttpContent} into
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* a {@link ByteBuf}.
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*
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* <h3>Extensibility</h3>
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*
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* Please note that this encoder is designed to be extended to implement
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* a protocol derived from HTTP, such as
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* <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
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* <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
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* To implement the encoder of such a derived protocol, extend this class and
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* implement all abstract methods properly.
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*/
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public abstract class HttpObjectEncoder<H extends HttpMessage> extends MessageToMessageEncoder<Object> {
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static final int CRLF_SHORT = (CR << 8) | LF;
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private static final int ZERO_CRLF_MEDIUM = ('0' << 16) | CRLF_SHORT;
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private static final byte[] ZERO_CRLF_CRLF = { '0', CR, LF, CR, LF };
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private static final ByteBuf CRLF_BUF = unreleasableBuffer(directBuffer(2).writeByte(CR).writeByte(LF));
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private static final ByteBuf ZERO_CRLF_CRLF_BUF = unreleasableBuffer(directBuffer(ZERO_CRLF_CRLF.length)
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.writeBytes(ZERO_CRLF_CRLF));
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private static final int ST_INIT = 0;
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private static final int ST_CONTENT_NON_CHUNK = 1;
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private static final int ST_CONTENT_CHUNK = 2;
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private static final int ST_CONTENT_ALWAYS_EMPTY = 3;
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@SuppressWarnings("RedundantFieldInitialization")
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private int state = ST_INIT;
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@Override
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protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
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ByteBuf buf = null;
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if (msg instanceof HttpMessage) {
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if (state != ST_INIT) {
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throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
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}
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@SuppressWarnings({ "unchecked", "CastConflictsWithInstanceof" })
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H m = (H) msg;
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buf = ctx.alloc().buffer();
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// Encode the message.
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encodeInitialLine(buf, m);
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encodeHeaders(m.headers(), buf);
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ByteBufUtil.writeShortBE(buf, CRLF_SHORT);
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state = isContentAlwaysEmpty(m) ? ST_CONTENT_ALWAYS_EMPTY :
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HttpUtil.isTransferEncodingChunked(m) ? ST_CONTENT_CHUNK : ST_CONTENT_NON_CHUNK;
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}
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// Bypass the encoder in case of an empty buffer, so that the following idiom works:
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//
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// ch.write(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
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//
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// See https://github.com/netty/netty/issues/2983 for more information.
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if (msg instanceof ByteBuf && !((ByteBuf) msg).isReadable()) {
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out.add(EMPTY_BUFFER);
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return;
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}
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if (msg instanceof HttpContent || msg instanceof ByteBuf || msg instanceof FileRegion) {
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switch (state) {
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case ST_INIT:
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throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
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case ST_CONTENT_NON_CHUNK:
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final long contentLength = contentLength(msg);
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if (contentLength > 0) {
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if (buf != null && buf.writableBytes() >= contentLength && msg instanceof HttpContent) {
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// merge into other buffer for performance reasons
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buf.writeBytes(((HttpContent) msg).content());
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out.add(buf);
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} else {
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if (buf != null) {
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out.add(buf);
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}
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out.add(encodeAndRetain(msg));
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}
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if (msg instanceof LastHttpContent) {
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state = ST_INIT;
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}
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break;
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}
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// fall-through!
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case ST_CONTENT_ALWAYS_EMPTY:
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if (buf != null) {
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// We allocated a buffer so add it now.
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out.add(buf);
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} else {
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// Need to produce some output otherwise an
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// IllegalStateException will be thrown
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out.add(EMPTY_BUFFER);
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}
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break;
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case ST_CONTENT_CHUNK:
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if (buf != null) {
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// We allocated a buffer so add it now.
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out.add(buf);
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}
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encodeChunkedContent(ctx, msg, contentLength(msg), out);
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break;
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default:
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throw new Error();
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}
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if (msg instanceof LastHttpContent) {
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state = ST_INIT;
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}
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} else if (buf != null) {
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out.add(buf);
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}
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}
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/**
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* Encode the {@link HttpHeaders} into a {@link ByteBuf}.
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*/
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protected void encodeHeaders(HttpHeaders headers, ByteBuf buf) {
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Iterator<Entry<CharSequence, CharSequence>> iter = headers.iteratorCharSequence();
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while (iter.hasNext()) {
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Entry<CharSequence, CharSequence> header = iter.next();
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HttpHeadersEncoder.encoderHeader(header.getKey(), header.getValue(), buf);
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}
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}
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private void encodeChunkedContent(ChannelHandlerContext ctx, Object msg, long contentLength, List<Object> out) {
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if (contentLength > 0) {
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String lengthHex = Long.toHexString(contentLength);
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ByteBuf buf = ctx.alloc().buffer(lengthHex.length() + 2);
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buf.writeCharSequence(lengthHex, CharsetUtil.US_ASCII);
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ByteBufUtil.writeShortBE(buf, CRLF_SHORT);
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out.add(buf);
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out.add(encodeAndRetain(msg));
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out.add(CRLF_BUF.duplicate());
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}
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if (msg instanceof LastHttpContent) {
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HttpHeaders headers = ((LastHttpContent) msg).trailingHeaders();
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if (headers.isEmpty()) {
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out.add(ZERO_CRLF_CRLF_BUF.duplicate());
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} else {
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ByteBuf buf = ctx.alloc().buffer();
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ByteBufUtil.writeMediumBE(buf, ZERO_CRLF_MEDIUM);
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encodeHeaders(headers, buf);
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ByteBufUtil.writeShortBE(buf, CRLF_SHORT);
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out.add(buf);
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}
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} else if (contentLength == 0) {
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// Need to produce some output otherwise an
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// IllegalStateException will be thrown
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out.add(EMPTY_BUFFER);
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}
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}
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/**
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* Determine whether a message has a content or not. Some message may have headers indicating
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* a content without having an actual content, e.g the response to an HEAD or CONNECT request.
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*
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* @param msg the message to test
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* @return {@code true} to signal the message has no content
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*/
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protected boolean isContentAlwaysEmpty(@SuppressWarnings("unused") H msg) {
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return false;
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}
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@Override
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public boolean acceptOutboundMessage(Object msg) throws Exception {
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return msg instanceof HttpObject || msg instanceof ByteBuf || msg instanceof FileRegion;
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}
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private static Object encodeAndRetain(Object msg) {
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if (msg instanceof ByteBuf) {
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return ((ByteBuf) msg).retain();
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}
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if (msg instanceof HttpContent) {
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return ((HttpContent) msg).content().retain();
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}
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if (msg instanceof FileRegion) {
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return ((FileRegion) msg).retain();
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}
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throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
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}
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private static long contentLength(Object msg) {
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if (msg instanceof HttpContent) {
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return ((HttpContent) msg).content().readableBytes();
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}
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if (msg instanceof ByteBuf) {
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return ((ByteBuf) msg).readableBytes();
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}
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if (msg instanceof FileRegion) {
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return ((FileRegion) msg).count();
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}
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throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
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}
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@Deprecated
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protected static void encodeAscii(String s, ByteBuf buf) {
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buf.writeCharSequence(s, CharsetUtil.US_ASCII);
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}
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protected abstract void encodeInitialLine(ByteBuf buf, H message) throws Exception;
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}
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