LzfEncoder.java — netty Source File

Source Code

/*
 * Copyright 2014 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 com.ning.compress.BufferRecycler;
import com.ning.compress.lzf.ChunkEncoder;
import com.ning.compress.lzf.LZFChunk;
import com.ning.compress.lzf.LZFEncoder;
import com.ning.compress.lzf.util.ChunkEncoderFactory;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.internal.PlatformDependent;

import static com.ning.compress.lzf.LZFChunk.MAX_CHUNK_LEN;

/**
 * Compresses a {@link ByteBuf} using the LZF format.
 * <p>
 * See original <a href="http://oldhome.schmorp.de/marc/liblzf.html">LZF package</a>
 * and <a href="https://github.com/ning/compress/wiki/LZFFormat">LZF format</a> for full description.
 */
public class LzfEncoder extends MessageToByteEncoder<ByteBuf> {

    /**
     * Minimum block size ready for compression. Blocks with length
     * less than {@link #MIN_BLOCK_TO_COMPRESS} will write as uncompressed.
     */
    private static final int MIN_BLOCK_TO_COMPRESS = 16;
    private static final boolean DEFAULT_SAFE = !PlatformDependent.hasUnsafe();

    /**
     * Compress threshold for LZF format. When the amount of input data is less than compressThreshold,
     * we will construct an uncompressed output according to the LZF format.
     * <p>
     * When the value is less than {@see ChunkEncoder#MIN_BLOCK_TO_COMPRESS}, since LZF will not compress data
     * that is less than {@see ChunkEncoder#MIN_BLOCK_TO_COMPRESS}, compressThreshold will not work.
     */
    private final int compressThreshold;

    /**
     * Underlying decoder in use.
     */
    private final ChunkEncoder encoder;

    /**
     * Object that handles details of buffer recycling.
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