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/*
* 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.compression;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.channel.ChannelPromiseNotifier;
import io.netty.util.concurrent.EventExecutor;
import java.util.concurrent.TimeUnit;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
/**
* Compresses a {@link ByteBuf} using the deflate algorithm.
*/
public class JdkZlibEncoder extends ZlibEncoder {
private final ZlibWrapper wrapper;
private final Deflater deflater;
private volatile boolean finished;
private volatile ChannelHandlerContext ctx;
/*
* GZIP support
*/
private final CRC32 crc = new CRC32();
private static final byte[] gzipHeader = {0x1f, (byte) 0x8b, Deflater.DEFLATED, 0, 0, 0, 0, 0, 0, 0};
private boolean writeHeader = true;
/**
* Creates a new zlib encoder with the default compression level ({@code 6})
* and the default wrapper ({@link ZlibWrapper#ZLIB}).
*
* @throws CompressionException if failed to initialize zlib
*/
public JdkZlibEncoder() {
this(6);
}
/**
* Creates a new zlib encoder with the specified {@code compressionLevel}
* and the default wrapper ({@link ZlibWrapper#ZLIB}).
*
* @param compressionLevel
* {@code 1} yields the fastest compression and {@code 9} yields the
* best compression. {@code 0} means no compression. The default
* compression level is {@code 6}.
*
* @throws CompressionException if failed to initialize zlib
*/
public JdkZlibEncoder(int compressionLevel) {
this(ZlibWrapper.ZLIB, compressionLevel);
}
/**
* Creates a new zlib encoder with the default compression level ({@code 6})
* and the specified wrapper.
*
* @throws CompressionException if failed to initialize zlib
*/
public JdkZlibEncoder(ZlibWrapper wrapper) {
this(wrapper, 6);
}
/**
* Creates a new zlib encoder with the specified {@code compressionLevel}
* and the specified wrapper.
*
* @param compressionLevel
* {@code 1} yields the fastest compression and {@code 9} yields the
* best compression. {@code 0} means no compression. The default
* compression level is {@code 6}.
*
* @throws CompressionException if failed to initialize zlib
*/
public JdkZlibEncoder(ZlibWrapper wrapper, int compressionLevel) {
if (compressionLevel < 0 || compressionLevel > 9) {
throw new IllegalArgumentException(
"compressionLevel: " + compressionLevel + " (expected: 0-9)");
}
if (wrapper == null) {
throw new NullPointerException("wrapper");
}
if (wrapper == ZlibWrapper.ZLIB_OR_NONE) {
throw new IllegalArgumentException(
"wrapper '" + ZlibWrapper.ZLIB_OR_NONE + "' is not " +
"allowed for compression.");
}
this.wrapper = wrapper;
deflater = new Deflater(compressionLevel, wrapper != ZlibWrapper.ZLIB);
}
/**
* Creates a new zlib encoder with the default compression level ({@code 6})
* and the specified preset dictionary. The wrapper is always
* {@link ZlibWrapper#ZLIB} because it is the only format that supports
* the preset dictionary.
*
* @param dictionary the preset dictionary
*
* @throws CompressionException if failed to initialize zlib
*/
public JdkZlibEncoder(byte[] dictionary) {
this(6, dictionary);
}
/**
* Creates a new zlib encoder with the specified {@code compressionLevel}
* and the specified preset dictionary. The wrapper is always
* {@link ZlibWrapper#ZLIB} because it is the only format that supports
* the preset dictionary.
*
* @param compressionLevel
* {@code 1} yields the fastest compression and {@code 9} yields the
* best compression. {@code 0} means no compression. The default
* compression level is {@code 6}.
* @param dictionary the preset dictionary
*
* @throws CompressionException if failed to initialize zlib
*/
public JdkZlibEncoder(int compressionLevel, byte[] dictionary) {
if (compressionLevel < 0 || compressionLevel > 9) {
throw new IllegalArgumentException(
"compressionLevel: " + compressionLevel + " (expected: 0-9)");
}
if (dictionary == null) {
throw new NullPointerException("dictionary");
}
wrapper = ZlibWrapper.ZLIB;
deflater = new Deflater(compressionLevel);
deflater.setDictionary(dictionary);
}
@Override
public ChannelFuture close() {
return close(ctx().newPromise());
}
@Override
public ChannelFuture close(final ChannelPromise promise) {
ChannelHandlerContext ctx = ctx();
EventExecutor executor = ctx.executor();
if (executor.inEventLoop()) {
return finishEncode(ctx, promise);
} else {
final ChannelPromise p = ctx.newPromise();
executor.execute(new Runnable() {
@Override
public void run() {
ChannelFuture f = finishEncode(ctx(), p);
f.addListener(new ChannelPromiseNotifier(promise));
}
});
return p;
}
}
private ChannelHandlerContext ctx() {
ChannelHandlerContext ctx = this.ctx;
if (ctx == null) {
throw new IllegalStateException("not added to a pipeline");
}
return ctx;
}
@Override
public boolean isClosed() {
return finished;
}
@Override
protected void encode(ChannelHandlerContext ctx, ByteBuf uncompressed, ByteBuf out) throws Exception {
if (finished) {
out.writeBytes(uncompressed);
return;
}
int len = uncompressed.readableBytes();
if (len == 0) {
return;
}
int offset;
byte[] inAry;
if (uncompressed.hasArray()) {
// if it is backed by an array we not need to to do a copy at all
inAry = uncompressed.array();
offset = uncompressed.arrayOffset() + uncompressed.readerIndex();
// skip all bytes as we will consume all of them
uncompressed.skipBytes(len);
} else {
inAry = new byte[len];
uncompressed.readBytes(inAry);
offset = 0;
}
if (writeHeader) {
writeHeader = false;
if (wrapper == ZlibWrapper.GZIP) {
out.writeBytes(gzipHeader);
}
}
if (wrapper == ZlibWrapper.GZIP) {
crc.update(inAry, offset, len);
}
deflater.setInput(inAry, offset, len);
while (!deflater.needsInput()) {
deflate(out);
}
}
@Override
protected final ByteBuf allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg,
boolean preferDirect) throws Exception {
int sizeEstimate = (int) Math.ceil(msg.readableBytes() * 1.001) + 12;
if (writeHeader) {
switch (wrapper) {
case GZIP:
sizeEstimate += gzipHeader.length;
break;
case ZLIB:
sizeEstimate += 2; // first two magic bytes
break;
}
}
return ctx.alloc().heapBuffer(sizeEstimate);
}
@Override
public void close(final ChannelHandlerContext ctx, final ChannelPromise promise) throws Exception {
ChannelFuture f = finishEncode(ctx, ctx.newPromise());
f.addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture f) throws Exception {
ctx.close(promise);
}
});
if (!f.isDone()) {
// Ensure the channel is closed even if the write operation completes in time.
ctx.executor().schedule(new Runnable() {
@Override
public void run() {
ctx.close(promise);
}
}, 10, TimeUnit.SECONDS); // FIXME: Magic number
}
}
private ChannelFuture finishEncode(final ChannelHandlerContext ctx, ChannelPromise promise) {
if (finished) {
promise.setSuccess();
return promise;
}
finished = true;
ByteBuf footer = ctx.alloc().heapBuffer();
if (writeHeader && wrapper == ZlibWrapper.GZIP) {
// Write the GZIP header first if not written yet. (i.e. user wrote nothing.)
writeHeader = false;
footer.writeBytes(gzipHeader);
}
deflater.finish();
while (!deflater.finished()) {
deflate(footer);
if (!footer.isWritable()) {
// no more space so write it to the channel and continue
ctx.write(footer);
footer = ctx.alloc().heapBuffer();
}
}
if (wrapper == ZlibWrapper.GZIP) {
int crcValue = (int) crc.getValue();
int uncBytes = deflater.getTotalIn();
footer.writeByte(crcValue);
footer.writeByte(crcValue >>> 8);
footer.writeByte(crcValue >>> 16);
footer.writeByte(crcValue >>> 24);
footer.writeByte(uncBytes);
footer.writeByte(uncBytes >>> 8);
footer.writeByte(uncBytes >>> 16);
footer.writeByte(uncBytes >>> 24);
}
deflater.end();
return ctx.writeAndFlush(footer, promise);
}
private void deflate(ByteBuf out) {
int numBytes;
do {
int writerIndex = out.writerIndex();
numBytes = deflater.deflate(
out.array(), out.arrayOffset() + writerIndex, out.writableBytes(), Deflater.SYNC_FLUSH);
out.writerIndex(writerIndex + numBytes);
} while (numBytes > 0);
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
this.ctx = ctx;
}
}