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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  package org.apache.http.nio.util;
28  
29  import java.io.IOException;
30  import java.io.InterruptedIOException;
31  import java.util.concurrent.locks.Condition;
32  import java.util.concurrent.locks.ReentrantLock;
33  
34  import org.apache.http.annotation.ThreadingBehavior;
35  import org.apache.http.annotation.Contract;
36  import org.apache.http.nio.ContentEncoder;
37  import org.apache.http.nio.IOControl;
38  import org.apache.http.util.Args;
39  import org.apache.http.util.Asserts;
40  
41  /**
42   * Implementation of the {@link ContentOutputBuffer} interface that can be
43   * shared by multiple threads, usually the I/O dispatch of an I/O reactor and
44   * a worker thread.
45   * <p>
46   * The I/O dispatch thread is expected to transfer data from the buffer to
47   *   {@link ContentEncoder} by calling {@link #produceContent(ContentEncoder)}.
48   * <p>
49   * The worker thread is expected to write data to the buffer by calling
50   * {@link #write(int)}, {@link #write(byte[], int, int)} or {@link #writeCompleted()}
51   * <p>
52   * In case of an abnormal situation or when no longer needed the buffer must be
53   * shut down using {@link #shutdown()} method.
54   *
55   * @since 4.0
56   */
57  @Contract(threading = ThreadingBehavior.SAFE_CONDITIONAL)
58  public class SharedOutputBuffer extends ExpandableBuffer implements ContentOutputBuffer {
59  
60      private final ReentrantLock lock;
61      private final Condition condition;
62  
63      private volatile IOControl ioctrl;
64      private volatile boolean shutdown = false;
65      private volatile boolean endOfStream = false;
66  
67      /**
68       * @deprecated (4.3) use {@link SharedOutputBuffer#SharedOutputBuffer(int, ByteBufferAllocator)}
69       */
70      @Deprecated
71      public SharedOutputBuffer(final int buffersize, final IOControl ioctrl, final ByteBufferAllocator allocator) {
72          super(buffersize, allocator);
73          Args.notNull(ioctrl, "I/O content control");
74          this.ioctrl = ioctrl;
75          this.lock = new ReentrantLock();
76          this.condition = this.lock.newCondition();
77      }
78  
79      /**
80       * @since 4.3
81       */
82      public SharedOutputBuffer(final int buffersize, final ByteBufferAllocator allocator) {
83          super(buffersize, allocator);
84          this.lock = new ReentrantLock();
85          this.condition = this.lock.newCondition();
86      }
87  
88      /**
89       * @since 4.3
90       */
91      public SharedOutputBuffer(final int buffersize) {
92          this(buffersize, HeapByteBufferAllocator.INSTANCE);
93      }
94  
95      @Override
96      public void reset() {
97          if (this.shutdown) {
98              return;
99          }
100         this.lock.lock();
101         try {
102             clear();
103             this.endOfStream = false;
104         } finally {
105             this.lock.unlock();
106         }
107     }
108 
109     @Override
110     public boolean hasData() {
111         this.lock.lock();
112         try {
113             return super.hasData();
114         } finally {
115             this.lock.unlock();
116         }
117     }
118 
119     @Override
120     public int available() {
121         this.lock.lock();
122         try {
123             return super.available();
124         } finally {
125             this.lock.unlock();
126         }
127     }
128 
129     @Override
130     public int capacity() {
131         this.lock.lock();
132         try {
133             return super.capacity();
134         } finally {
135             this.lock.unlock();
136         }
137     }
138 
139     @Override
140     public int length() {
141         this.lock.lock();
142         try {
143             return super.length();
144         } finally {
145             this.lock.unlock();
146         }
147     }
148 
149     /**
150      * @deprecated (4.3) use {@link #produceContent(ContentEncoder, IOControl)}
151      */
152     @Override
153     @Deprecated
154     public int produceContent(final ContentEncoder encoder) throws IOException {
155         return produceContent(encoder, null);
156     }
157 
158     /**
159      * @since 4.3
160      */
161     public int produceContent(final ContentEncoder encoder, final IOControl ioctrl) throws IOException {
162         if (this.shutdown) {
163             return -1;
164         }
165         this.lock.lock();
166         try {
167             if (ioctrl != null) {
168                 this.ioctrl = ioctrl;
169             }
170             setOutputMode();
171             int bytesWritten = 0;
172             if (super.hasData()) {
173                 bytesWritten = encoder.write(this.buffer);
174                 if (encoder.isCompleted()) {
175                     this.endOfStream = true;
176                 }
177             }
178             if (!super.hasData()) {
179                 // No more buffered content
180                 // If at the end of the stream, terminate
181                 if (this.endOfStream && !encoder.isCompleted()) {
182                     encoder.complete();
183                 }
184                 if (!this.endOfStream) {
185                     // suspend output events
186                     if (this.ioctrl != null) {
187                         this.ioctrl.suspendOutput();
188                     }
189                 }
190             }
191             this.condition.signalAll();
192             return bytesWritten;
193         } finally {
194             this.lock.unlock();
195         }
196     }
197 
198     public void close() {
199         shutdown();
200     }
201 
202     public void shutdown() {
203         if (this.shutdown) {
204             return;
205         }
206         this.shutdown = true;
207         this.lock.lock();
208         try {
209             this.condition.signalAll();
210         } finally {
211             this.lock.unlock();
212         }
213     }
214 
215     @Override
216     public void write(final byte[] b, final int off, final int len) throws IOException {
217         if (b == null) {
218             return;
219         }
220         int pos = off;
221         this.lock.lock();
222         try {
223             Asserts.check(!this.shutdown && !this.endOfStream, "Buffer already closed for writing");
224             setInputMode();
225             int remaining = len;
226             while (remaining > 0) {
227                 if (!this.buffer.hasRemaining()) {
228                     flushContent();
229                     setInputMode();
230                 }
231                 final int chunk = Math.min(remaining, this.buffer.remaining());
232                 this.buffer.put(b, pos, chunk);
233                 remaining -= chunk;
234                 pos += chunk;
235             }
236         } finally {
237             this.lock.unlock();
238         }
239     }
240 
241     public void write(final byte[] b) throws IOException {
242         if (b == null) {
243             return;
244         }
245         write(b, 0, b.length);
246     }
247 
248     @Override
249     public void write(final int b) throws IOException {
250         this.lock.lock();
251         try {
252             Asserts.check(!this.shutdown && !this.endOfStream, "Buffer already closed for writing");
253             setInputMode();
254             if (!this.buffer.hasRemaining()) {
255                 flushContent();
256                 setInputMode();
257             }
258             this.buffer.put((byte)b);
259         } finally {
260             this.lock.unlock();
261         }
262     }
263 
264     @Override
265     public void flush() throws IOException {
266     }
267 
268     private void flushContent() throws IOException {
269         this.lock.lock();
270         try {
271             try {
272                 while (super.hasData()) {
273                     if (this.shutdown) {
274                         throw new InterruptedIOException("Output operation aborted");
275                     }
276                     if (this.ioctrl != null) {
277                         this.ioctrl.requestOutput();
278                     }
279                     this.condition.await();
280                 }
281             } catch (final InterruptedException ex) {
282                 throw new IOException("Interrupted while flushing the content buffer");
283             }
284         } finally {
285             this.lock.unlock();
286         }
287     }
288 
289     @Override
290     public void writeCompleted() throws IOException {
291         this.lock.lock();
292         try {
293             if (this.endOfStream) {
294                 return;
295             }
296             this.endOfStream = true;
297             if (this.ioctrl != null) {
298                 this.ioctrl.requestOutput();
299             }
300         } finally {
301             this.lock.unlock();
302         }
303     }
304 
305 }