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.
63 lines
2.1 KiB
Java
63 lines
2.1 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.example.factorial;
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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.ByteToMessageDecoder;
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import io.netty.handler.codec.CorruptedFrameException;
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import java.math.BigInteger;
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/**
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* Decodes the binary representation of a {@link BigInteger} prepended
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* with a magic number ('F' or 0x46) and a 32-bit integer length prefix into a
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* {@link BigInteger} instance. For example, { 'F', 0, 0, 0, 1, 42 } will be
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* decoded into new BigInteger("42").
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*/
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public class BigIntegerDecoder extends ByteToMessageDecoder {
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@Override
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protected void decode(ChannelHandlerContext ctx, ByteBuf in) {
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// Wait until the length prefix is available.
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if (in.readableBytes() < 5) {
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return;
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}
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int readerIndex = in.readerIndex();
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// Check the magic number.
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int magicNumber = in.readUnsignedByte();
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if (magicNumber != 'F') {
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in.readerIndex(readerIndex);
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throw new CorruptedFrameException("Invalid magic number: " + magicNumber);
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}
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// Wait until the whole data is available.
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int dataLength = in.readInt();
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if (in.readableBytes() < dataLength) {
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in.readerIndex(readerIndex);
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return;
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}
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// Convert the received data into a new BigInteger.
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byte[] decoded = new byte[dataLength];
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in.readBytes(decoded);
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ctx.fireChannelRead(new BigInteger(decoded));
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}
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}
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