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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 org.jboss.netty.handler.codec.compression;
17  
18  import org.jboss.netty.buffer.ChannelBuffer;
19  import org.jboss.netty.buffer.ChannelBuffers;
20  import org.jboss.netty.channel.Channel;
21  import org.jboss.netty.channel.ChannelEvent;
22  import org.jboss.netty.channel.ChannelFuture;
23  import org.jboss.netty.channel.ChannelFutureListener;
24  import org.jboss.netty.channel.ChannelHandlerContext;
25  import org.jboss.netty.channel.ChannelStateEvent;
26  import org.jboss.netty.channel.Channels;
27  import org.jboss.netty.channel.LifeCycleAwareChannelHandler;
28  import org.jboss.netty.handler.codec.oneone.OneToOneStrictEncoder;
29  import org.jboss.netty.util.internal.jzlib.JZlib;
30  import org.jboss.netty.util.internal.jzlib.ZStream;
31  
32  import java.util.concurrent.atomic.AtomicBoolean;
33  
34  
35  /**
36   * Compresses a {@link ChannelBuffer} using the deflate algorithm.
37   * @apiviz.landmark
38   * @apiviz.has org.jboss.netty.handler.codec.compression.ZlibWrapper
39   */
40  public class ZlibEncoder extends OneToOneStrictEncoder implements LifeCycleAwareChannelHandler {
41  
42      private static final byte[] EMPTY_ARRAY = new byte[0];
43  
44      private final int wrapperOverhead;
45      private final ZStream z = new ZStream();
46      private final AtomicBoolean finished = new AtomicBoolean();
47      private volatile ChannelHandlerContext ctx;
48  
49      /**
50       * Creates a new zlib encoder with the default compression level ({@code 6}),
51       * default window bits ({@code 15}), default memory level ({@code 8}),
52       * and the default wrapper ({@link ZlibWrapper#ZLIB}).
53       *
54       * @throws CompressionException if failed to initialize zlib
55       */
56      public ZlibEncoder() {
57          this(6);
58      }
59  
60      /**
61       * Creates a new zlib encoder with the specified {@code compressionLevel},
62       * default window bits ({@code 15}), default memory level ({@code 8}),
63       * and the default wrapper ({@link ZlibWrapper#ZLIB}).
64       *
65       * @param compressionLevel
66       *        {@code 1} yields the fastest compression and {@code 9} yields the
67       *        best compression.  {@code 0} means no compression.  The default
68       *        compression level is {@code 6}.
69       *
70       * @throws CompressionException if failed to initialize zlib
71       */
72      public ZlibEncoder(int compressionLevel) {
73          this(ZlibWrapper.ZLIB, compressionLevel);
74      }
75  
76      /**
77       * Creates a new zlib encoder with the default compression level ({@code 6}),
78       * default window bits ({@code 15}), default memory level ({@code 8}),
79       * and the specified wrapper.
80       *
81       * @throws CompressionException if failed to initialize zlib
82       */
83      public ZlibEncoder(ZlibWrapper wrapper) {
84          this(wrapper, 6);
85      }
86  
87      /**
88       * Creates a new zlib encoder with the specified {@code compressionLevel},
89       * default window bits ({@code 15}), default memory level ({@code 8}),
90       * and the specified wrapper.
91       *
92       * @param compressionLevel
93       *        {@code 1} yields the fastest compression and {@code 9} yields the
94       *        best compression.  {@code 0} means no compression.  The default
95       *        compression level is {@code 6}.
96       *
97       * @throws CompressionException if failed to initialize zlib
98       */
99      public ZlibEncoder(ZlibWrapper wrapper, int compressionLevel) {
100         this(wrapper, compressionLevel, 15, 8);
101     }
102 
103     /**
104      * Creates a new zlib encoder with the specified {@code compressionLevel},
105      * the specified {@code windowBits}, the specified {@code memLevel}, and
106      * the specified wrapper.
107      *
108      * @param compressionLevel
109      *        {@code 1} yields the fastest compression and {@code 9} yields the
110      *        best compression.  {@code 0} means no compression.  The default
111      *        compression level is {@code 6}.
112      * @param windowBits
113      *        The base two logarithm of the size of the history buffer.  The
114      *        value should be in the range {@code 9} to {@code 15} inclusive.
115      *        Larger values result in better compression at the expense of
116      *        memory usage.  The default value is {@code 15}.
117      * @param memLevel
118      *        How much memory should be allocated for the internal compression
119      *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
120      *        memory.  Larger values result in better and faster compression
121      *        at the expense of memory usage.  The default value is {@code 8}
122      *
123      * @throws CompressionException if failed to initialize zlib
124      */
125     public ZlibEncoder(ZlibWrapper wrapper, int compressionLevel, int windowBits, int memLevel) {
126         if (compressionLevel < 0 || compressionLevel > 9) {
127             throw new IllegalArgumentException(
128                     "compressionLevel: " + compressionLevel + " (expected: 0-9)");
129         }
130         if (windowBits < 9 || windowBits > 15) {
131             throw new IllegalArgumentException(
132                     "windowBits: " + windowBits + " (expected: 9-15)");
133         }
134         if (memLevel < 1 || memLevel > 9) {
135             throw new IllegalArgumentException(
136                     "memLevel: " + memLevel + " (expected: 1-9)");
137         }
138         if (wrapper == null) {
139             throw new NullPointerException("wrapper");
140         }
141         if (wrapper == ZlibWrapper.ZLIB_OR_NONE) {
142             throw new IllegalArgumentException(
143                     "wrapper '" + ZlibWrapper.ZLIB_OR_NONE + "' is not " +
144                     "allowed for compression.");
145         }
146 
147         wrapperOverhead = ZlibUtil.wrapperOverhead(wrapper);
148 
149         synchronized (z) {
150             int resultCode = z.deflateInit(compressionLevel, windowBits, memLevel,
151                     ZlibUtil.convertWrapperType(wrapper));
152             if (resultCode != JZlib.Z_OK) {
153                 ZlibUtil.fail(z, "initialization failure", resultCode);
154             }
155         }
156     }
157 
158     /**
159      * Creates a new zlib encoder with the default compression level ({@code 6}),
160      * default window bits ({@code 15}), default memory level ({@code 8}),
161      * and the specified preset dictionary.  The wrapper is always
162      * {@link ZlibWrapper#ZLIB} because it is the only format that supports
163      * the preset dictionary.
164      *
165      * @param dictionary  the preset dictionary
166      *
167      * @throws CompressionException if failed to initialize zlib
168      */
169     public ZlibEncoder(byte[] dictionary) {
170         this(6, dictionary);
171     }
172 
173     /**
174      * Creates a new zlib encoder with the specified {@code compressionLevel},
175      * default window bits ({@code 15}), default memory level ({@code 8}),
176      * and the specified preset dictionary.  The wrapper is always
177      * {@link ZlibWrapper#ZLIB} because it is the only format that supports
178      * the preset dictionary.
179      *
180      * @param compressionLevel
181      *        {@code 1} yields the fastest compression and {@code 9} yields the
182      *        best compression.  {@code 0} means no compression.  The default
183      *        compression level is {@code 6}.
184      * @param dictionary  the preset dictionary
185      *
186      * @throws CompressionException if failed to initialize zlib
187      */
188     public ZlibEncoder(int compressionLevel, byte[] dictionary) {
189         this(compressionLevel, 15, 8, dictionary);
190     }
191 
192     /**
193      * Creates a new zlib encoder with the specified {@code compressionLevel},
194      * the specified {@code windowBits}, the specified {@code memLevel},
195      * and the specified preset dictionary.  The wrapper is always
196      * {@link ZlibWrapper#ZLIB} because it is the only format that supports
197      * the preset dictionary.
198      *
199      * @param compressionLevel
200      *        {@code 1} yields the fastest compression and {@code 9} yields the
201      *        best compression.  {@code 0} means no compression.  The default
202      *        compression level is {@code 6}.
203      * @param windowBits
204      *        The base two logarithm of the size of the history buffer.  The
205      *        value should be in the range {@code 9} to {@code 15} inclusive.
206      *        Larger values result in better compression at the expense of
207      *        memory usage.  The default value is {@code 15}.
208      * @param memLevel
209      *        How much memory should be allocated for the internal compression
210      *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
211      *        memory.  Larger values result in better and faster compression
212      *        at the expense of memory usage.  The default value is {@code 8}
213      * @param dictionary  the preset dictionary
214      *
215      * @throws CompressionException if failed to initialize zlib
216      */
217     public ZlibEncoder(int compressionLevel, int windowBits, int memLevel, byte[] dictionary) {
218         if (compressionLevel < 0 || compressionLevel > 9) {
219             throw new IllegalArgumentException(
220                     "compressionLevel: " + compressionLevel + " (expected: 0-9)");
221         }
222         if (windowBits < 9 || windowBits > 15) {
223             throw new IllegalArgumentException(
224                     "windowBits: " + windowBits + " (expected: 9-15)");
225         }
226         if (memLevel < 1 || memLevel > 9) {
227             throw new IllegalArgumentException(
228                     "memLevel: " + memLevel + " (expected: 1-9)");
229         }
230         if (dictionary == null) {
231             throw new NullPointerException("dictionary");
232         }
233 
234         wrapperOverhead = ZlibUtil.wrapperOverhead(ZlibWrapper.ZLIB);
235 
236         synchronized (z) {
237             int resultCode;
238             resultCode = z.deflateInit(compressionLevel, windowBits, memLevel,
239                     JZlib.W_ZLIB); // Default: ZLIB format
240             if (resultCode != JZlib.Z_OK) {
241                 ZlibUtil.fail(z, "initialization failure", resultCode);
242             } else {
243                 resultCode = z.deflateSetDictionary(dictionary, dictionary.length);
244                 if (resultCode != JZlib.Z_OK) {
245                     ZlibUtil.fail(z, "failed to set the dictionary", resultCode);
246                 }
247             }
248         }
249     }
250 
251     public ChannelFuture close() {
252         ChannelHandlerContext ctx = this.ctx;
253         if (ctx == null) {
254             throw new IllegalStateException("not added to a pipeline");
255         }
256         return finishEncode(ctx, null);
257     }
258 
259     public boolean isClosed() {
260         return finished.get();
261     }
262 
263     @Override
264     protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
265         if (!(msg instanceof ChannelBuffer) || finished.get()) {
266             return msg;
267         }
268 
269         final ChannelBuffer result;
270         synchronized (z) {
271             try {
272                 // Configure input.
273                 final ChannelBuffer uncompressed = (ChannelBuffer) msg;
274                 final int uncompressedLen = uncompressed.readableBytes();
275                 if (uncompressedLen == 0) {
276                     return uncompressed;
277                 }
278 
279                 final byte[] in = new byte[uncompressedLen];
280                 uncompressed.readBytes(in);
281                 z.next_in = in;
282                 z.next_in_index = 0;
283                 z.avail_in = uncompressedLen;
284 
285                 // Configure output.
286                 final byte[] out = new byte[(int) Math.ceil(uncompressedLen * 1.001) + 12 + wrapperOverhead];
287                 z.next_out = out;
288                 z.next_out_index = 0;
289                 z.avail_out = out.length;
290 
291                 // Note that Z_PARTIAL_FLUSH has been deprecated.
292                 final int resultCode = z.deflate(JZlib.Z_SYNC_FLUSH);
293                 if (resultCode != JZlib.Z_OK) {
294                     ZlibUtil.fail(z, "compression failure", resultCode);
295                 }
296 
297                 if (z.next_out_index != 0) {
298                     result = ctx.getChannel().getConfig().getBufferFactory().getBuffer(
299                             uncompressed.order(), out, 0, z.next_out_index);
300                 } else {
301                     result = ChannelBuffers.EMPTY_BUFFER;
302                 }
303             } finally {
304                 // Deference the external references explicitly to tell the VM that
305                 // the allocated byte arrays are temporary so that the call stack
306                 // can be utilized.
307                 // I'm not sure if the modern VMs do this optimization though.
308                 z.next_in = null;
309                 z.next_out = null;
310             }
311         }
312 
313         return result;
314     }
315 
316     @Override
317     public void handleDownstream(ChannelHandlerContext ctx, ChannelEvent evt)
318             throws Exception {
319         if (evt instanceof ChannelStateEvent) {
320             ChannelStateEvent e = (ChannelStateEvent) evt;
321             switch (e.getState()) {
322             case OPEN:
323             case CONNECTED:
324             case BOUND:
325                 if (Boolean.FALSE.equals(e.getValue()) || e.getValue() == null) {
326                     finishEncode(ctx, evt);
327                     return;
328                 }
329             }
330         }
331 
332         super.handleDownstream(ctx, evt);
333     }
334 
335     private ChannelFuture finishEncode(final ChannelHandlerContext ctx, final ChannelEvent evt) {
336         if (!finished.compareAndSet(false, true)) {
337             if (evt != null) {
338                 ctx.sendDownstream(evt);
339             }
340             return Channels.succeededFuture(ctx.getChannel());
341         }
342 
343         ChannelBuffer footer;
344         ChannelFuture future;
345         synchronized (z) {
346             try {
347                 // Configure input.
348                 z.next_in = EMPTY_ARRAY;
349                 z.next_in_index = 0;
350                 z.avail_in = 0;
351 
352                 // Configure output.
353                 byte[] out = new byte[32]; // room for ADLER32 + ZLIB / CRC32 + GZIP header
354                 z.next_out = out;
355                 z.next_out_index = 0;
356                 z.avail_out = out.length;
357 
358                 // Write the ADLER32 checksum (stream footer).
359                 int resultCode = z.deflate(JZlib.Z_FINISH);
360                 if (resultCode != JZlib.Z_OK && resultCode != JZlib.Z_STREAM_END) {
361                     future = Channels.failedFuture(
362                             ctx.getChannel(),
363                             ZlibUtil.exception(z, "compression failure", resultCode));
364                     footer = null;
365                 } else if (z.next_out_index != 0) {
366                     future = Channels.future(ctx.getChannel());
367                     footer =
368                         ctx.getChannel().getConfig().getBufferFactory().getBuffer(
369                                 out, 0, z.next_out_index);
370                 } else {
371                     // Note that we should never use a SucceededChannelFuture
372                     // here just in case any downstream handler or a sink wants
373                     // to notify a write error.
374                     future = Channels.future(ctx.getChannel());
375                     footer = ChannelBuffers.EMPTY_BUFFER;
376                 }
377             } finally {
378                 z.deflateEnd();
379 
380                 // Deference the external references explicitly to tell the VM that
381                 // the allocated byte arrays are temporary so that the call stack
382                 // can be utilized.
383                 // I'm not sure if the modern VMs do this optimization though.
384                 z.next_in = null;
385                 z.next_out = null;
386             }
387         }
388 
389         if (footer != null) {
390             Channels.write(ctx, future, footer);
391         }
392 
393         if (evt != null) {
394             future.addListener(new ChannelFutureListener() {
395                 public void operationComplete(ChannelFuture future) throws Exception {
396                     ctx.sendDownstream(evt);
397                 }
398             });
399         }
400 
401         return future;
402     }
403 
404     public void beforeAdd(ChannelHandlerContext ctx) throws Exception {
405         this.ctx = ctx;
406     }
407 
408     public void afterAdd(ChannelHandlerContext ctx) throws Exception {
409         // Unused
410     }
411 
412     public void beforeRemove(ChannelHandlerContext ctx) throws Exception {
413         // Unused
414     }
415 
416     public void afterRemove(ChannelHandlerContext ctx) throws Exception {
417         // Unused
418     }
419 }