io.netty.handler.codec.compression.ZlibDecoder Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* 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:
*
* https://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.compression;
import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
/**
* Decompresses a {@link ByteBuf} using the deflate algorithm.
*/
public abstract class ZlibDecoder extends ByteToMessageDecoder {
/**
* Maximum allowed size of the decompression buffer.
*/
protected final int maxAllocation;
/**
* Same as {@link #ZlibDecoder(int)} with maxAllocation = 0.
*/
public ZlibDecoder() {
this(0);
}
/**
* Construct a new ZlibDecoder.
* @param maxAllocation
* Maximum size of the decompression buffer. Must be >= 0.
* If zero, maximum size is decided by the {@link ByteBufAllocator}.
*/
public ZlibDecoder(int maxAllocation) {
this.maxAllocation = checkPositiveOrZero(maxAllocation, "maxAllocation");
}
/**
* Returns {@code true} if and only if the end of the compressed stream
* has been reached.
*/
public abstract boolean isClosed();
/**
* Allocate or expand the decompression buffer, without exceeding the maximum allocation.
* Calls {@link #decompressionBufferExhausted(ByteBuf)} if the buffer is full and cannot be expanded further.
*/
protected ByteBuf prepareDecompressBuffer(ChannelHandlerContext ctx, ByteBuf buffer, int preferredSize) {
if (buffer == null) {
if (maxAllocation == 0) {
return ctx.alloc().heapBuffer(preferredSize);
}
return ctx.alloc().heapBuffer(Math.min(preferredSize, maxAllocation), maxAllocation);
}
// this always expands the buffer if possible, even if the expansion is less than preferredSize
// we throw the exception only if the buffer could not be expanded at all
// this means that one final attempt to deserialize will always be made with the buffer at maxAllocation
if (buffer.ensureWritable(preferredSize, true) == 1) {
// buffer must be consumed so subclasses don't add it to output
// we therefore duplicate it when calling decompressionBufferExhausted() to guarantee non-interference
// but wait until after to consume it so the subclass can tell how much output is really in the buffer
decompressionBufferExhausted(buffer.duplicate());
buffer.skipBytes(buffer.readableBytes());
throw new DecompressionException("Decompression buffer has reached maximum size: " + buffer.maxCapacity());
}
return buffer;
}
/**
* Called when the decompression buffer cannot be expanded further.
* Default implementation is a no-op, but subclasses can override in case they want to
* do something before the {@link DecompressionException} is thrown, such as log the
* data that was decompressed so far.
*/
protected void decompressionBufferExhausted(ByteBuf buffer) {
}
}