0e4c073bcf
Motivation: ByteToMessageDecoder requires using an intermediate List to put results into. This intermediate list adds overhead (memory/CPU) which grows as the number of objects increases. This overhead can be avoided by directly propagating events through the ChannelPipeline via ctx.fireChannelRead(...). This also makes the semantics more clear and allows us to keep track if we need to call ctx.read() in all cases. Modifications: - Remove List from the method signature of ByteToMessageDecoder.decode(...) and decodeLast(...) - Adjust all sub-classes - Adjust unit tests - Fix javadocs. Result: Adjust ByteToMessageDecoder as noted in https://github.com/netty/netty/issues/8525.
73 lines
2.6 KiB
Java
73 lines
2.6 KiB
Java
/*
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* Copyright 2019 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.dns;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
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import io.netty.util.internal.UnstableApi;
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import java.net.SocketAddress;
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@UnstableApi
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public final class TcpDnsResponseDecoder extends LengthFieldBasedFrameDecoder {
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private final DnsResponseDecoder<SocketAddress> responseDecoder;
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/**
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* Creates a new decoder with {@linkplain DnsRecordDecoder#DEFAULT the default record decoder}.
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*/
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public TcpDnsResponseDecoder() {
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this(DnsRecordDecoder.DEFAULT, 64 * 1024);
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}
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/**
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* Creates a new decoder with the specified {@code recordDecoder} and {@code maxFrameLength}
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*/
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public TcpDnsResponseDecoder(DnsRecordDecoder recordDecoder, int maxFrameLength) {
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// Length is two octets as defined by RFC-7766
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// See https://tools.ietf.org/html/rfc7766#section-8
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super(maxFrameLength, 0, 2, 0, 2);
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this.responseDecoder = new DnsResponseDecoder<SocketAddress>(recordDecoder) {
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@Override
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protected DnsResponse newResponse(SocketAddress sender, SocketAddress recipient,
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int id, DnsOpCode opCode, DnsResponseCode responseCode) {
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return new DefaultDnsResponse(id, opCode, responseCode);
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}
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};
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}
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@Override
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protected Object decode0(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
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ByteBuf frame = (ByteBuf) super.decode0(ctx, in);
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if (frame == null) {
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return null;
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}
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try {
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return responseDecoder.decode(ctx.channel().remoteAddress(), ctx.channel().localAddress(), frame.slice());
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} finally {
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frame.release();
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}
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}
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@Override
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protected ByteBuf extractFrame(ChannelHandlerContext ctx, ByteBuf buffer, int index, int length) {
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return buffer.copy(index, length);
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}
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}
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