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/*
* 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 io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.ChannelPromise;
import io.netty.handler.codec.EncoderException;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.PromiseNotifier;
import io.netty.util.internal.ObjectUtil;
import net.jpountz.lz4.LZ4Compressor;
import net.jpountz.lz4.LZ4Exception;
import net.jpountz.lz4.LZ4Factory;
import java.nio.ByteBuffer;
import java.util.zip.Checksum;
import static io.netty.handler.codec.compression.Lz4Constants.BLOCK_TYPE_COMPRESSED;
import static io.netty.handler.codec.compression.Lz4Constants.BLOCK_TYPE_NON_COMPRESSED;
import static io.netty.handler.codec.compression.Lz4Constants.CHECKSUM_OFFSET;
import static io.netty.handler.codec.compression.Lz4Constants.COMPRESSED_LENGTH_OFFSET;
import static io.netty.handler.codec.compression.Lz4Constants.COMPRESSION_LEVEL_BASE;
import static io.netty.handler.codec.compression.Lz4Constants.DECOMPRESSED_LENGTH_OFFSET;
import static io.netty.handler.codec.compression.Lz4Constants.DEFAULT_BLOCK_SIZE;
import static io.netty.handler.codec.compression.Lz4Constants.DEFAULT_SEED;
import static io.netty.handler.codec.compression.Lz4Constants.HEADER_LENGTH;
import static io.netty.handler.codec.compression.Lz4Constants.MAGIC_NUMBER;
import static io.netty.handler.codec.compression.Lz4Constants.MAX_BLOCK_SIZE;
import static io.netty.handler.codec.compression.Lz4Constants.MIN_BLOCK_SIZE;
import static io.netty.handler.codec.compression.Lz4Constants.TOKEN_OFFSET;
/**
* Compresses a {@link ByteBuf} using the LZ4 format.
*
* See original LZ4 Github project
* and LZ4 block format
* for full description.
*
* Since the original LZ4 block format does not contains size of compressed block and size of original data
* this encoder uses format like LZ4 Java library
* written by Adrien Grand and approved by Yann Collet (author of original LZ4 library).
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* * Magic * Token * Compressed * Decompressed * Checksum * + * LZ4 compressed *
* * * * length * length * * * block *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*/
public class Lz4FrameEncoder extends MessageToByteEncoder {
static final int DEFAULT_MAX_ENCODE_SIZE = Integer.MAX_VALUE;
private final int blockSize;
/**
* Underlying compressor in use.
*/
private final LZ4Compressor compressor;
/**
* Underlying checksum calculator in use.
*/
private final ByteBufChecksum checksum;
/**
* Compression level of current LZ4 encoder (depends on {@link #blockSize}).
*/
private final int compressionLevel;
/**
* Inner byte buffer for outgoing data. It's capacity will be {@link #blockSize}.
*/
private ByteBuf buffer;
/**
* Maximum size for any buffer to write encoded (compressed) data into.
*/
private final int maxEncodeSize;
/**
* Indicates if the compressed stream has been finished.
*/
private volatile boolean finished;
/**
* Used to interact with its {@link ChannelPipeline} and other handlers.
*/
private volatile ChannelHandlerContext ctx;
/**
* Creates the fastest LZ4 encoder with default block size (64 KB)
* and xxhash hashing for Java, based on Yann Collet's work available at
* Github.
*/
public Lz4FrameEncoder() {
this(false);
}
/**
* Creates a new LZ4 encoder with hight or fast compression, default block size (64 KB)
* and xxhash hashing for Java, based on Yann Collet's work available at
* Github.
*
* @param highCompressor if {@code true} codec will use compressor which requires more memory
* and is slower but compresses more efficiently
*/
public Lz4FrameEncoder(boolean highCompressor) {
this(LZ4Factory.fastestInstance(), highCompressor, DEFAULT_BLOCK_SIZE, new Lz4XXHash32(DEFAULT_SEED));
}
/**
* Creates a new customizable LZ4 encoder.
*
* @param factory user customizable {@link LZ4Factory} instance
* which may be JNI bindings to the original C implementation, a pure Java implementation
* or a Java implementation that uses the {@link sun.misc.Unsafe}
* @param highCompressor if {@code true} codec will use compressor which requires more memory
* and is slower but compresses more efficiently
* @param blockSize the maximum number of bytes to try to compress at once,
* must be >= 64 and <= 32 M
* @param checksum the {@link Checksum} instance to use to check data for integrity
*/
public Lz4FrameEncoder(LZ4Factory factory, boolean highCompressor, int blockSize, Checksum checksum) {
this(factory, highCompressor, blockSize, checksum, DEFAULT_MAX_ENCODE_SIZE);
}
/**
* Creates a new customizable LZ4 encoder.
*
* @param factory user customizable {@link LZ4Factory} instance
* which may be JNI bindings to the original C implementation, a pure Java implementation
* or a Java implementation that uses the {@link sun.misc.Unsafe}
* @param highCompressor if {@code true} codec will use compressor which requires more memory
* and is slower but compresses more efficiently
* @param blockSize the maximum number of bytes to try to compress at once,
* must be >= 64 and <= 32 M
* @param checksum the {@link Checksum} instance to use to check data for integrity
* @param maxEncodeSize the maximum size for an encode (compressed) buffer
*/
public Lz4FrameEncoder(LZ4Factory factory, boolean highCompressor, int blockSize,
Checksum checksum, int maxEncodeSize) {
ObjectUtil.checkNotNull(factory, "factory");
ObjectUtil.checkNotNull(checksum, "checksum");
compressor = highCompressor ? factory.highCompressor() : factory.fastCompressor();
this.checksum = ByteBufChecksum.wrapChecksum(checksum);
compressionLevel = compressionLevel(blockSize);
this.blockSize = blockSize;
this.maxEncodeSize = ObjectUtil.checkPositive(maxEncodeSize, "maxEncodeSize");
finished = false;
}
/**
* Calculates compression level on the basis of block size.
*/
private static int compressionLevel(int blockSize) {
if (blockSize < MIN_BLOCK_SIZE || blockSize > MAX_BLOCK_SIZE) {
throw new IllegalArgumentException(String.format(
"blockSize: %d (expected: %d-%d)", blockSize, MIN_BLOCK_SIZE, MAX_BLOCK_SIZE));
}
int compressionLevel = 32 - Integer.numberOfLeadingZeros(blockSize - 1); // ceil of log2
compressionLevel = Math.max(0, compressionLevel - COMPRESSION_LEVEL_BASE);
return compressionLevel;
}
@Override
protected ByteBuf allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg, boolean preferDirect) {
return allocateBuffer(ctx, msg, preferDirect, true);
}
private ByteBuf allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg, boolean preferDirect,
boolean allowEmptyReturn) {
int targetBufSize = 0;
int remaining = msg.readableBytes() + buffer.readableBytes();
// quick overflow check
if (remaining < 0) {
throw new EncoderException("too much data to allocate a buffer for compression");
}
while (remaining > 0) {
int curSize = Math.min(blockSize, remaining);
remaining -= curSize;
// calculate the total compressed size of the current block (including header) and add to the total
targetBufSize += compressor.maxCompressedLength(curSize) + HEADER_LENGTH;
}
// in addition to just the raw byte count, the headers (HEADER_LENGTH) per block (configured via
// #blockSize) will also add to the targetBufSize, and the combination of those would never wrap around
// again to be >= 0, this is a good check for the overflow case.
if (targetBufSize > maxEncodeSize || 0 > targetBufSize) {
throw new EncoderException(String.format("requested encode buffer size (%d bytes) exceeds the maximum " +
"allowable size (%d bytes)", targetBufSize, maxEncodeSize));
}
if (allowEmptyReturn && targetBufSize < blockSize) {
return Unpooled.EMPTY_BUFFER;
}
if (preferDirect) {
return ctx.alloc().ioBuffer(targetBufSize, targetBufSize);
} else {
return ctx.alloc().heapBuffer(targetBufSize, targetBufSize);
}
}
/**
* {@inheritDoc}
*
* Encodes the input buffer into {@link #blockSize} chunks in the output buffer. Data is only compressed and
* written once we hit the {@link #blockSize}; else, it is copied into the backing {@link #buffer} to await
* more data.
*/
@Override
protected void encode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out) throws Exception {
if (finished) {
if (!out.isWritable(in.readableBytes())) {
// out should be EMPTY_BUFFER because we should have allocated enough space above in allocateBuffer.
throw new IllegalStateException("encode finished and not enough space to write remaining data");
}
out.writeBytes(in);
return;
}
final ByteBuf buffer = this.buffer;
int length;
while ((length = in.readableBytes()) > 0) {
final int nextChunkSize = Math.min(length, buffer.writableBytes());
in.readBytes(buffer, nextChunkSize);
if (!buffer.isWritable()) {
flushBufferedData(out);
}
}
}
private void flushBufferedData(ByteBuf out) {
int flushableBytes = buffer.readableBytes();
if (flushableBytes == 0) {
return;
}
checksum.reset();
checksum.update(buffer, buffer.readerIndex(), flushableBytes);
final int check = (int) checksum.getValue();
final int bufSize = compressor.maxCompressedLength(flushableBytes) + HEADER_LENGTH;
out.ensureWritable(bufSize);
final int idx = out.writerIndex();
int compressedLength;
try {
ByteBuffer outNioBuffer = out.internalNioBuffer(idx + HEADER_LENGTH, out.writableBytes() - HEADER_LENGTH);
int pos = outNioBuffer.position();
// We always want to start at position 0 as we take care of reusing the buffer in the encode(...) loop.
compressor.compress(buffer.internalNioBuffer(buffer.readerIndex(), flushableBytes), outNioBuffer);
compressedLength = outNioBuffer.position() - pos;
} catch (LZ4Exception e) {
throw new CompressionException(e);
}
final int blockType;
if (compressedLength >= flushableBytes) {
blockType = BLOCK_TYPE_NON_COMPRESSED;
compressedLength = flushableBytes;
out.setBytes(idx + HEADER_LENGTH, buffer, buffer.readerIndex(), flushableBytes);
} else {
blockType = BLOCK_TYPE_COMPRESSED;
}
out.setLong(idx, MAGIC_NUMBER);
out.setByte(idx + TOKEN_OFFSET, (byte) (blockType | compressionLevel));
out.setIntLE(idx + COMPRESSED_LENGTH_OFFSET, compressedLength);
out.setIntLE(idx + DECOMPRESSED_LENGTH_OFFSET, flushableBytes);
out.setIntLE(idx + CHECKSUM_OFFSET, check);
out.writerIndex(idx + HEADER_LENGTH + compressedLength);
buffer.clear();
}
@Override
public void flush(final ChannelHandlerContext ctx) throws Exception {
if (buffer != null && buffer.isReadable()) {
final ByteBuf buf = allocateBuffer(ctx, Unpooled.EMPTY_BUFFER, isPreferDirect(), false);
flushBufferedData(buf);
ctx.write(buf);
}
ctx.flush();
}
private ChannelFuture finishEncode(final ChannelHandlerContext ctx, ChannelPromise promise) {
if (finished) {
promise.setSuccess();
return promise;
}
finished = true;
final ByteBuf footer = ctx.alloc().heapBuffer(
compressor.maxCompressedLength(buffer.readableBytes()) + HEADER_LENGTH);
flushBufferedData(footer);
footer.ensureWritable(HEADER_LENGTH);
final int idx = footer.writerIndex();
footer.setLong(idx, MAGIC_NUMBER);
footer.setByte(idx + TOKEN_OFFSET, (byte) (BLOCK_TYPE_NON_COMPRESSED | compressionLevel));
footer.setInt(idx + COMPRESSED_LENGTH_OFFSET, 0);
footer.setInt(idx + DECOMPRESSED_LENGTH_OFFSET, 0);
footer.setInt(idx + CHECKSUM_OFFSET, 0);
footer.writerIndex(idx + HEADER_LENGTH);
return ctx.writeAndFlush(footer, promise);
}
/**
* Returns {@code true} if and only if the compressed stream has been finished.
*/
public boolean isClosed() {
return finished;
}
/**
* Close this {@link Lz4FrameEncoder} and so finish the encoding.
*
* The returned {@link ChannelFuture} will be notified once the operation completes.
*/
public ChannelFuture close() {
return close(ctx().newPromise());
}
/**
* Close this {@link Lz4FrameEncoder} and so finish the encoding.
* The given {@link ChannelFuture} will be notified once the operation
* completes and will also be returned.
*/
public ChannelFuture close(final ChannelPromise promise) {
ChannelHandlerContext ctx = ctx();
EventExecutor executor = ctx.executor();
if (executor.inEventLoop()) {
return finishEncode(ctx, promise);
} else {
executor.execute(new Runnable() {
@Override
public void run() {
ChannelFuture f = finishEncode(ctx(), promise);
PromiseNotifier.cascade(f, promise);
}
});
return promise;
}
}
@Override
public void close(final ChannelHandlerContext ctx, final ChannelPromise promise) throws Exception {
ChannelFuture f = finishEncode(ctx, ctx.newPromise());
EncoderUtil.closeAfterFinishEncode(ctx, f, promise);
}
private ChannelHandlerContext ctx() {
ChannelHandlerContext ctx = this.ctx;
if (ctx == null) {
throw new IllegalStateException("not added to a pipeline");
}
return ctx;
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) {
this.ctx = ctx;
// Ensure we use a heap based ByteBuf.
buffer = Unpooled.wrappedBuffer(new byte[blockSize]);
buffer.clear();
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
super.handlerRemoved(ctx);
if (buffer != null) {
buffer.release();
buffer = null;
}
}
final ByteBuf getBackingBuffer() {
return buffer;
}
}
