b57d9f307f
- write() now accepts a ChannelPromise and returns ChannelFuture as most users expected. It makes the user's life much easier because it is now much easier to get notified when a specific message has been written. - flush() does not create a ChannelPromise nor returns ChannelFuture. It is now similar to what read() looks like.
310 lines
12 KiB
Java
310 lines
12 KiB
Java
/*
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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.ByteBufHolder;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.embedded.EmbeddedChannel;
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import io.netty.handler.codec.MessageToMessageCodec;
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import io.netty.handler.codec.http.HttpHeaders.Names;
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import io.netty.handler.codec.http.HttpHeaders.Values;
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import io.netty.util.ReferenceCountUtil;
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import java.util.ArrayDeque;
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import java.util.List;
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import java.util.Queue;
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/**
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* Encodes the content of the outbound {@link HttpResponse} and {@link HttpContent}.
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* The original content is replaced with the new content encoded by the
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* {@link EmbeddedChannel}, which is created by {@link #beginEncode(HttpResponse, String)}.
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* Once encoding is finished, the value of the <tt>'Content-Encoding'</tt> header
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* is set to the target content encoding, as returned by
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* {@link #beginEncode(HttpResponse, String)}.
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* Also, the <tt>'Content-Length'</tt> header is updated to the length of the
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* encoded content. If there is no supported or allowed encoding in the
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* corresponding {@link HttpRequest}'s {@code "Accept-Encoding"} header,
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* {@link #beginEncode(HttpResponse, String)} should return {@code null} so that
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* no encoding occurs (i.e. pass-through).
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* <p>
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* Please note that this is an abstract class. You have to extend this class
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* and implement {@link #beginEncode(HttpResponse, String)} properly to make
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* this class functional. For example, refer to the source code of
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* {@link HttpContentCompressor}.
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* <p>
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* This handler must be placed after {@link HttpObjectEncoder} in the pipeline
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* so that this handler can intercept HTTP responses before {@link HttpObjectEncoder}
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* converts them into {@link ByteBuf}s.
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*/
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public abstract class HttpContentEncoder extends MessageToMessageCodec<HttpRequest, HttpObject> {
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private enum State {
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PASS_THROUGH,
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AWAIT_HEADERS,
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AWAIT_CONTENT
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}
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private final Queue<String> acceptEncodingQueue = new ArrayDeque<String>();
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private String acceptEncoding;
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private EmbeddedChannel encoder;
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private State state = State.AWAIT_HEADERS;
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@Override
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public boolean acceptOutboundMessage(Object msg) throws Exception {
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return msg instanceof HttpContent || msg instanceof HttpResponse;
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}
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@Override
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protected void decode(ChannelHandlerContext ctx, HttpRequest msg, List<Object> out)
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throws Exception {
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String acceptedEncoding = msg.headers().get(HttpHeaders.Names.ACCEPT_ENCODING);
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if (acceptedEncoding == null) {
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acceptedEncoding = HttpHeaders.Values.IDENTITY;
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}
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acceptEncodingQueue.add(acceptedEncoding);
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out.add(ReferenceCountUtil.retain(msg));
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}
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@Override
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protected void encode(ChannelHandlerContext ctx, HttpObject msg, List<Object> out) throws Exception {
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final boolean isFull = msg instanceof HttpResponse && msg instanceof LastHttpContent;
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switch (state) {
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case AWAIT_HEADERS: {
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ensureHeaders(msg);
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assert encoder == null;
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final HttpResponse res = (HttpResponse) msg;
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if (res.getStatus().code() == 100) {
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if (isFull) {
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out.add(ReferenceCountUtil.retain(res));
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} else {
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out.add(res);
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// Pass through all following contents.
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state = State.PASS_THROUGH;
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}
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break;
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}
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// Get the list of encodings accepted by the peer.
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acceptEncoding = acceptEncodingQueue.poll();
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if (acceptEncoding == null) {
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throw new IllegalStateException("cannot send more responses than requests");
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}
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if (isFull) {
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// Pass through the full response with empty content and continue waiting for the the next resp.
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if (!((ByteBufHolder) res).content().isReadable()) {
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// Set the content length to 0.
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res.headers().remove(Names.TRANSFER_ENCODING);
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res.headers().set(Names.CONTENT_LENGTH, "0");
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out.add(ReferenceCountUtil.retain(res));
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break;
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}
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}
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// Prepare to encode the content.
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final Result result = beginEncode(res, acceptEncoding);
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// If unable to encode, pass through.
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if (result == null) {
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if (isFull) {
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// As an unchunked response
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res.headers().remove(Names.TRANSFER_ENCODING);
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res.headers().set(Names.CONTENT_LENGTH, ((ByteBufHolder) res).content().readableBytes());
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out.add(ReferenceCountUtil.retain(res));
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} else {
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// As a chunked response
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res.headers().remove(Names.CONTENT_LENGTH);
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res.headers().set(Names.TRANSFER_ENCODING, Values.CHUNKED);
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out.add(res);
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state = State.PASS_THROUGH;
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}
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break;
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}
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encoder = result.contentEncoder();
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// Encode the content and remove or replace the existing headers
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// so that the message looks like a decoded message.
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res.headers().set(Names.CONTENT_ENCODING, result.targetContentEncoding());
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// Make the response chunked to simplify content transformation.
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res.headers().remove(Names.CONTENT_LENGTH);
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res.headers().set(Names.TRANSFER_ENCODING, Values.CHUNKED);
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// Output the rewritten response.
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if (isFull) {
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// Convert full message into unfull one.
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HttpResponse newRes = new DefaultHttpResponse(res.getProtocolVersion(), res.getStatus());
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newRes.headers().set(res.headers());
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out.add(newRes);
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// Fall through to encode the content of the full response.
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} else {
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out.add(res);
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state = State.AWAIT_CONTENT;
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break;
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}
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}
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case AWAIT_CONTENT: {
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ensureContent(msg);
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encodeContent((HttpContent) msg, out);
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if (msg instanceof LastHttpContent) {
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state = State.AWAIT_HEADERS;
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}
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break;
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}
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case PASS_THROUGH: {
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ensureContent(msg);
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out.add(ReferenceCountUtil.retain(msg));
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// Passed through all following contents of the current response.
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if (msg instanceof LastHttpContent) {
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state = State.AWAIT_HEADERS;
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}
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break;
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}
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}
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}
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private static void ensureHeaders(HttpObject msg) {
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if (!(msg instanceof HttpResponse)) {
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throw new IllegalStateException(
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"unexpected message type: " +
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msg.getClass().getName() + " (expected: " + HttpResponse.class.getSimpleName() + ')');
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}
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}
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private static void ensureContent(HttpObject msg) {
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if (!(msg instanceof HttpContent)) {
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throw new IllegalStateException(
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"unexpected message type: " +
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msg.getClass().getName() + " (expected: " + HttpContent.class.getSimpleName() + ')');
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}
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}
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private void encodeContent(HttpContent c, List<Object> out) {
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ByteBuf content = c.content();
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encode(content, out);
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if (c instanceof LastHttpContent) {
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finishEncode(out);
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// Generate an additional chunk if the decoder produced
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// the last product on closure,
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out.add(LastHttpContent.EMPTY_LAST_CONTENT);
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}
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}
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/**
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* Prepare to encode the HTTP message content.
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*
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* @param headers
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* the headers
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* @param acceptEncoding
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* the value of the {@code "Accept-Encoding"} header
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*
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* @return the result of preparation, which is composed of the determined
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* target content encoding and a new {@link EmbeddedChannel} that
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* encodes the content into the target content encoding.
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* {@code null} if {@code acceptEncoding} is unsupported or rejected
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* and thus the content should be handled as-is (i.e. no encoding).
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*/
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protected abstract Result beginEncode(HttpResponse headers, String acceptEncoding) throws Exception;
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@Override
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public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
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cleanup();
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super.handlerRemoved(ctx);
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}
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@Override
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public void channelInactive(ChannelHandlerContext ctx) throws Exception {
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cleanup();
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super.channelInactive(ctx);
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}
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private void cleanup() {
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if (encoder != null) {
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// Clean-up the previous encoder if not cleaned up correctly.
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if (encoder.finish()) {
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for (;;) {
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ByteBuf buf = (ByteBuf) encoder.readOutbound();
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if (buf == null) {
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break;
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}
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// Release the buffer
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// https://github.com/netty/netty/issues/1524
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buf.release();
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}
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}
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encoder = null;
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}
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}
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private void encode(ByteBuf in, List<Object> out) {
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// call retain here as it will call release after its written to the channel
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encoder.writeOutbound(in.retain());
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fetchEncoderOutput(out);
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}
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private void finishEncode(List<Object> out) {
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if (encoder.finish()) {
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fetchEncoderOutput(out);
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}
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encoder = null;
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}
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private void fetchEncoderOutput(List<Object> out) {
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for (;;) {
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ByteBuf buf = (ByteBuf) encoder.readOutbound();
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if (buf == null) {
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break;
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}
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if (!buf.isReadable()) {
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continue;
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}
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out.add(new DefaultHttpContent(buf));
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}
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}
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public static final class Result {
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private final String targetContentEncoding;
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private final EmbeddedChannel contentEncoder;
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public Result(String targetContentEncoding, EmbeddedChannel contentEncoder) {
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if (targetContentEncoding == null) {
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throw new NullPointerException("targetContentEncoding");
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}
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if (contentEncoder == null) {
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throw new NullPointerException("contentEncoder");
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}
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this.targetContentEncoding = targetContentEncoding;
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this.contentEncoder = contentEncoder;
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}
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public String targetContentEncoding() {
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return targetContentEncoding;
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}
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public EmbeddedChannel contentEncoder() {
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return contentEncoder;
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}
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}
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}
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