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.
78 lines
2.6 KiB
Java
78 lines
2.6 KiB
Java
/*
|
|
* Copyright 2012 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;
|
|
|
|
import static io.netty.util.internal.ObjectUtil.checkPositive;
|
|
|
|
import io.netty.buffer.ByteBuf;
|
|
import io.netty.channel.ChannelHandlerContext;
|
|
|
|
/**
|
|
* A decoder that splits the received {@link ByteBuf}s by the fixed number
|
|
* of bytes. For example, if you received the following four fragmented packets:
|
|
* <pre>
|
|
* +---+----+------+----+
|
|
* | A | BC | DEFG | HI |
|
|
* +---+----+------+----+
|
|
* </pre>
|
|
* A {@link FixedLengthFrameDecoder}{@code (3)} will decode them into the
|
|
* following three packets with the fixed length:
|
|
* <pre>
|
|
* +-----+-----+-----+
|
|
* | ABC | DEF | GHI |
|
|
* +-----+-----+-----+
|
|
* </pre>
|
|
*/
|
|
public class FixedLengthFrameDecoder extends ByteToMessageDecoder {
|
|
|
|
private final int frameLength;
|
|
|
|
/**
|
|
* Creates a new instance.
|
|
*
|
|
* @param frameLength the length of the frame
|
|
*/
|
|
public FixedLengthFrameDecoder(int frameLength) {
|
|
checkPositive(frameLength, "frameLength");
|
|
this.frameLength = frameLength;
|
|
}
|
|
|
|
@Override
|
|
protected final void decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
|
|
Object decoded = decode0(ctx, in);
|
|
if (decoded != null) {
|
|
ctx.fireChannelRead(decoded);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Create a frame out of the {@link ByteBuf} and return it.
|
|
*
|
|
* @param ctx the {@link ChannelHandlerContext} which this {@link ByteToMessageDecoder} belongs to
|
|
* @param in the {@link ByteBuf} from which to read data
|
|
* @return frame the {@link ByteBuf} which represent the frame or {@code null} if no frame could
|
|
* be created.
|
|
*/
|
|
protected Object decode0(
|
|
@SuppressWarnings("UnusedParameters") ChannelHandlerContext ctx, ByteBuf in) throws Exception {
|
|
if (in.readableBytes() < frameLength) {
|
|
return null;
|
|
} else {
|
|
return in.readRetainedSlice(frameLength);
|
|
}
|
|
}
|
|
}
|