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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.compression;
17  
18  import com.jcraft.jzlib.Deflater;
19  import com.jcraft.jzlib.JZlib;
20  import io.netty.buffer.ByteBuf;
21  import io.netty.buffer.Unpooled;
22  import io.netty.channel.ChannelFuture;
23  import io.netty.channel.ChannelFutureListener;
24  import io.netty.channel.ChannelHandlerContext;
25  import io.netty.channel.ChannelPromise;
26  import io.netty.channel.ChannelPromiseNotifier;
27  import io.netty.util.concurrent.EventExecutor;
28  import io.netty.util.internal.EmptyArrays;
29  
30  import java.util.concurrent.TimeUnit;
31  
32  /**
33   * Compresses a {@link ByteBuf} using the deflate algorithm.
34   */
35  public class JZlibEncoder extends ZlibEncoder {
36  
37      private final int wrapperOverhead;
38      private final Deflater z = new Deflater();
39      private volatile boolean finished;
40      private volatile ChannelHandlerContext ctx;
41  
42      /**
43       * Creates a new zlib encoder with the default compression level ({@code 6}),
44       * default window bits ({@code 15}), default memory level ({@code 8}),
45       * and the default wrapper ({@link ZlibWrapper#ZLIB}).
46       *
47       * @throws CompressionException if failed to initialize zlib
48       */
49      public JZlibEncoder() {
50          this(6);
51      }
52  
53      /**
54       * Creates a new zlib encoder with the specified {@code compressionLevel},
55       * default window bits ({@code 15}), default memory level ({@code 8}),
56       * and the default wrapper ({@link ZlibWrapper#ZLIB}).
57       *
58       * @param compressionLevel
59       *        {@code 1} yields the fastest compression and {@code 9} yields the
60       *        best compression.  {@code 0} means no compression.  The default
61       *        compression level is {@code 6}.
62       *
63       * @throws CompressionException if failed to initialize zlib
64       */
65      public JZlibEncoder(int compressionLevel) {
66          this(ZlibWrapper.ZLIB, compressionLevel);
67      }
68  
69      /**
70       * Creates a new zlib encoder with the default compression level ({@code 6}),
71       * default window bits ({@code 15}), default memory level ({@code 8}),
72       * and the specified wrapper.
73       *
74       * @throws CompressionException if failed to initialize zlib
75       */
76      public JZlibEncoder(ZlibWrapper wrapper) {
77          this(wrapper, 6);
78      }
79  
80      /**
81       * Creates a new zlib encoder with the specified {@code compressionLevel},
82       * default window bits ({@code 15}), default memory level ({@code 8}),
83       * and the specified wrapper.
84       *
85       * @param compressionLevel
86       *        {@code 1} yields the fastest compression and {@code 9} yields the
87       *        best compression.  {@code 0} means no compression.  The default
88       *        compression level is {@code 6}.
89       *
90       * @throws CompressionException if failed to initialize zlib
91       */
92      public JZlibEncoder(ZlibWrapper wrapper, int compressionLevel) {
93          this(wrapper, compressionLevel, 15, 8);
94      }
95  
96      /**
97       * Creates a new zlib encoder with the specified {@code compressionLevel},
98       * the specified {@code windowBits}, the specified {@code memLevel}, and
99       * the specified wrapper.
100      *
101      * @param compressionLevel
102      *        {@code 1} yields the fastest compression and {@code 9} yields the
103      *        best compression.  {@code 0} means no compression.  The default
104      *        compression level is {@code 6}.
105      * @param windowBits
106      *        The base two logarithm of the size of the history buffer.  The
107      *        value should be in the range {@code 9} to {@code 15} inclusive.
108      *        Larger values result in better compression at the expense of
109      *        memory usage.  The default value is {@code 15}.
110      * @param memLevel
111      *        How much memory should be allocated for the internal compression
112      *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
113      *        memory.  Larger values result in better and faster compression
114      *        at the expense of memory usage.  The default value is {@code 8}
115      *
116      * @throws CompressionException if failed to initialize zlib
117      */
118     public JZlibEncoder(ZlibWrapper wrapper, int compressionLevel, int windowBits, int memLevel) {
119 
120         if (compressionLevel < 0 || compressionLevel > 9) {
121             throw new IllegalArgumentException(
122                     "compressionLevel: " + compressionLevel +
123                     " (expected: 0-9)");
124         }
125         if (windowBits < 9 || windowBits > 15) {
126             throw new IllegalArgumentException(
127                     "windowBits: " + windowBits + " (expected: 9-15)");
128         }
129         if (memLevel < 1 || memLevel > 9) {
130             throw new IllegalArgumentException(
131                     "memLevel: " + memLevel + " (expected: 1-9)");
132         }
133         if (wrapper == null) {
134             throw new NullPointerException("wrapper");
135         }
136         if (wrapper == ZlibWrapper.ZLIB_OR_NONE) {
137             throw new IllegalArgumentException(
138                     "wrapper '" + ZlibWrapper.ZLIB_OR_NONE + "' is not " +
139                     "allowed for compression.");
140         }
141 
142         int resultCode = z.init(
143                 compressionLevel, windowBits, memLevel,
144                 ZlibUtil.convertWrapperType(wrapper));
145         if (resultCode != JZlib.Z_OK) {
146             ZlibUtil.fail(z, "initialization failure", resultCode);
147         }
148 
149         wrapperOverhead = ZlibUtil.wrapperOverhead(wrapper);
150     }
151 
152     /**
153      * Creates a new zlib encoder with the default compression level ({@code 6}),
154      * default window bits ({@code 15}), default memory level ({@code 8}),
155      * and the specified preset dictionary.  The wrapper is always
156      * {@link ZlibWrapper#ZLIB} because it is the only format that supports
157      * the preset dictionary.
158      *
159      * @param dictionary  the preset dictionary
160      *
161      * @throws CompressionException if failed to initialize zlib
162      */
163     public JZlibEncoder(byte[] dictionary) {
164         this(6, dictionary);
165     }
166 
167     /**
168      * Creates a new zlib encoder with the specified {@code compressionLevel},
169      * default window bits ({@code 15}), default memory level ({@code 8}),
170      * and the specified preset dictionary.  The wrapper is always
171      * {@link ZlibWrapper#ZLIB} because it is the only format that supports
172      * the preset dictionary.
173      *
174      * @param compressionLevel
175      *        {@code 1} yields the fastest compression and {@code 9} yields the
176      *        best compression.  {@code 0} means no compression.  The default
177      *        compression level is {@code 6}.
178      * @param dictionary  the preset dictionary
179      *
180      * @throws CompressionException if failed to initialize zlib
181      */
182     public JZlibEncoder(int compressionLevel, byte[] dictionary) {
183         this(compressionLevel, 15, 8, dictionary);
184     }
185 
186     /**
187      * Creates a new zlib encoder with the specified {@code compressionLevel},
188      * the specified {@code windowBits}, the specified {@code memLevel},
189      * and the specified preset dictionary.  The wrapper is always
190      * {@link ZlibWrapper#ZLIB} because it is the only format that supports
191      * the preset dictionary.
192      *
193      * @param compressionLevel
194      *        {@code 1} yields the fastest compression and {@code 9} yields the
195      *        best compression.  {@code 0} means no compression.  The default
196      *        compression level is {@code 6}.
197      * @param windowBits
198      *        The base two logarithm of the size of the history buffer.  The
199      *        value should be in the range {@code 9} to {@code 15} inclusive.
200      *        Larger values result in better compression at the expense of
201      *        memory usage.  The default value is {@code 15}.
202      * @param memLevel
203      *        How much memory should be allocated for the internal compression
204      *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
205      *        memory.  Larger values result in better and faster compression
206      *        at the expense of memory usage.  The default value is {@code 8}
207      * @param dictionary  the preset dictionary
208      *
209      * @throws CompressionException if failed to initialize zlib
210      */
211     public JZlibEncoder(int compressionLevel, int windowBits, int memLevel, byte[] dictionary) {
212         if (compressionLevel < 0 || compressionLevel > 9) {
213             throw new IllegalArgumentException("compressionLevel: " + compressionLevel + " (expected: 0-9)");
214         }
215         if (windowBits < 9 || windowBits > 15) {
216             throw new IllegalArgumentException(
217                     "windowBits: " + windowBits + " (expected: 9-15)");
218         }
219         if (memLevel < 1 || memLevel > 9) {
220             throw new IllegalArgumentException(
221                     "memLevel: " + memLevel + " (expected: 1-9)");
222         }
223         if (dictionary == null) {
224             throw new NullPointerException("dictionary");
225         }
226         int resultCode;
227         resultCode = z.deflateInit(
228                 compressionLevel, windowBits, memLevel,
229                 JZlib.W_ZLIB); // Default: ZLIB format
230         if (resultCode != JZlib.Z_OK) {
231             ZlibUtil.fail(z, "initialization failure", resultCode);
232         } else {
233             resultCode = z.deflateSetDictionary(dictionary, dictionary.length);
234             if (resultCode != JZlib.Z_OK) {
235                 ZlibUtil.fail(z, "failed to set the dictionary", resultCode);
236             }
237         }
238 
239         wrapperOverhead = ZlibUtil.wrapperOverhead(ZlibWrapper.ZLIB);
240     }
241 
242     @Override
243     public ChannelFuture close() {
244         return close(ctx().channel().newPromise());
245     }
246 
247     @Override
248     public ChannelFuture close(final ChannelPromise promise) {
249         ChannelHandlerContext ctx = ctx();
250         EventExecutor executor = ctx.executor();
251         if (executor.inEventLoop()) {
252             return finishEncode(ctx, promise);
253         } else {
254             final ChannelPromise p = ctx.newPromise();
255             executor.execute(new Runnable() {
256                 @Override
257                 public void run() {
258                     ChannelFuture f = finishEncode(ctx(), p);
259                     f.addListener(new ChannelPromiseNotifier(promise));
260                 }
261             });
262             return p;
263         }
264     }
265 
266     private ChannelHandlerContext ctx() {
267         ChannelHandlerContext ctx = this.ctx;
268         if (ctx == null) {
269             throw new IllegalStateException("not added to a pipeline");
270         }
271         return ctx;
272     }
273 
274     @Override
275     public boolean isClosed() {
276         return finished;
277     }
278 
279     @Override
280     protected void encode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out) throws Exception {
281         if (finished) {
282             out.writeBytes(in);
283             return;
284         }
285 
286         int inputLength = in.readableBytes();
287         if (inputLength == 0) {
288             return;
289         }
290 
291         try {
292             // Configure input.
293             boolean inHasArray = in.hasArray();
294             z.avail_in = inputLength;
295             if (inHasArray) {
296                 z.next_in = in.array();
297                 z.next_in_index = in.arrayOffset() + in.readerIndex();
298             } else {
299                 byte[] array = new byte[inputLength];
300                 in.getBytes(in.readerIndex(), array);
301                 z.next_in = array;
302                 z.next_in_index = 0;
303             }
304             int oldNextInIndex = z.next_in_index;
305 
306             // Configure output.
307             int maxOutputLength = (int) Math.ceil(inputLength * 1.001) + 12 + wrapperOverhead;
308             out.ensureWritable(maxOutputLength);
309             z.avail_out = maxOutputLength;
310             z.next_out = out.array();
311             z.next_out_index = out.arrayOffset() + out.writerIndex();
312             int oldNextOutIndex = z.next_out_index;
313 
314             // Note that Z_PARTIAL_FLUSH has been deprecated.
315             int resultCode;
316             try {
317                 resultCode = z.deflate(JZlib.Z_SYNC_FLUSH);
318             } finally {
319                 in.skipBytes(z.next_in_index - oldNextInIndex);
320             }
321 
322             if (resultCode != JZlib.Z_OK) {
323                 ZlibUtil.fail(z, "compression failure", resultCode);
324             }
325 
326             int outputLength = z.next_out_index - oldNextOutIndex;
327             if (outputLength > 0) {
328                 out.writerIndex(out.writerIndex() + outputLength);
329             }
330         } finally {
331             // Deference the external references explicitly to tell the VM that
332             // the allocated byte arrays are temporary so that the call stack
333             // can be utilized.
334             // I'm not sure if the modern VMs do this optimization though.
335             z.next_in = null;
336             z.next_out = null;
337         }
338     }
339 
340     @Override
341     public void close(
342             final ChannelHandlerContext ctx,
343             final ChannelPromise promise) {
344         ChannelFuture f = finishEncode(ctx, ctx.newPromise());
345         f.addListener(new ChannelFutureListener() {
346             @Override
347             public void operationComplete(ChannelFuture f) throws Exception {
348                 ctx.close(promise);
349             }
350         });
351 
352         if (!f.isDone()) {
353             // Ensure the channel is closed even if the write operation completes in time.
354             ctx.executor().schedule(new Runnable() {
355                 @Override
356                 public void run() {
357                     ctx.close(promise);
358                 }
359             }, 10, TimeUnit.SECONDS); // FIXME: Magic number
360         }
361     }
362 
363     private ChannelFuture finishEncode(ChannelHandlerContext ctx, ChannelPromise promise) {
364         if (finished) {
365             promise.setSuccess();
366             return promise;
367         }
368         finished = true;
369 
370         ByteBuf footer;
371         try {
372             // Configure input.
373             z.next_in = EmptyArrays.EMPTY_BYTES;
374             z.next_in_index = 0;
375             z.avail_in = 0;
376 
377             // Configure output.
378             byte[] out = new byte[32]; // room for ADLER32 + ZLIB / CRC32 + GZIP header
379             z.next_out = out;
380             z.next_out_index = 0;
381             z.avail_out = out.length;
382 
383             // Write the ADLER32 checksum (stream footer).
384             int resultCode = z.deflate(JZlib.Z_FINISH);
385             if (resultCode != JZlib.Z_OK && resultCode != JZlib.Z_STREAM_END) {
386                 promise.setFailure(ZlibUtil.deflaterException(z, "compression failure", resultCode));
387                 return promise;
388             } else if (z.next_out_index != 0) {
389                 footer = Unpooled.wrappedBuffer(out, 0, z.next_out_index);
390             } else {
391                 footer = Unpooled.EMPTY_BUFFER;
392             }
393         } finally {
394             z.deflateEnd();
395 
396             // Deference the external references explicitly to tell the VM that
397             // the allocated byte arrays are temporary so that the call stack
398             // can be utilized.
399             // I'm not sure if the modern VMs do this optimization though.
400             z.next_in = null;
401             z.next_out = null;
402         }
403         return ctx.writeAndFlush(footer, promise);
404     }
405 
406     @Override
407     public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
408         this.ctx = ctx;
409     }
410 }