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1   /*
2    * Copyright (C) 2009-2010, Google Inc.
3    * and other copyright owners as documented in the project's IP log.
4    *
5    * This program and the accompanying materials are made available
6    * under the terms of the Eclipse Distribution License v1.0 which
7    * accompanies this distribution, is reproduced below, and is
8    * available at http://www.eclipse.org/org/documents/edl-v10.php
9    *
10   * All rights reserved.
11   *
12   * Redistribution and use in source and binary forms, with or
13   * without modification, are permitted provided that the following
14   * conditions are met:
15   *
16   * - Redistributions of source code must retain the above copyright
17   *   notice, this list of conditions and the following disclaimer.
18   *
19   * - Redistributions in binary form must reproduce the above
20   *   copyright notice, this list of conditions and the following
21   *   disclaimer in the documentation and/or other materials provided
22   *   with the distribution.
23   *
24   * - Neither the name of the Eclipse Foundation, Inc. nor the
25   *   names of its contributors may be used to endorse or promote
26   *   products derived from this software without specific prior
27   *   written permission.
28   *
29   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42   */
43  
44  package org.eclipse.jgit.util.io;
45  
46  import java.io.IOException;
47  import java.io.InputStream;
48  import java.io.InterruptedIOException;
49  import java.io.OutputStream;
50  import java.util.concurrent.atomic.AtomicInteger;
51  
52  /** Thread to copy from an input stream to an output stream. */
53  public class StreamCopyThread extends Thread {
54  	private static final int BUFFER_SIZE = 1024;
55  
56  	private final InputStream src;
57  
58  	private final OutputStream dst;
59  
60  	private volatile boolean done;
61  
62  	private final AtomicInteger flushCount = new AtomicInteger(0);
63  
64  	/**
65  	 * Create a thread to copy data from an input stream to an output stream.
66  	 *
67  	 * @param i
68  	 *            stream to copy from. The thread terminates when this stream
69  	 *            reaches EOF. The thread closes this stream before it exits.
70  	 * @param o
71  	 *            stream to copy into. The destination stream is automatically
72  	 *            closed when the thread terminates.
73  	 */
74  	public StreamCopyThread(final InputStream i, final OutputStream o) {
75  		setName(Thread.currentThread().getName() + "-StreamCopy"); //$NON-NLS-1$
76  		src = i;
77  		dst = o;
78  	}
79  
80  	/**
81  	 * Request the thread to flush the output stream as soon as possible.
82  	 * <p>
83  	 * This is an asynchronous request to the thread. The actual flush will
84  	 * happen at some future point in time, when the thread wakes up to process
85  	 * the request.
86  	 */
87  	public void flush() {
88  		flushCount.incrementAndGet();
89  		interrupt();
90  	}
91  
92  	/**
93  	 * Request that the thread terminate, and wait for it.
94  	 * <p>
95  	 * This method signals to the copy thread that it should stop as soon as
96  	 * there is no more IO occurring.
97  	 *
98  	 * @throws InterruptedException
99  	 *             the calling thread was interrupted.
100 	 */
101 	public void halt() throws InterruptedException {
102 		for (;;) {
103 			join(250 /* milliseconds */);
104 			if (isAlive()) {
105 				done = true;
106 				interrupt();
107 			} else
108 				break;
109 		}
110 	}
111 
112 	@Override
113 	public void run() {
114 		try {
115 			final byte[] buf = new byte[BUFFER_SIZE];
116 			int flushCountBeforeRead = 0;
117 			boolean readInterrupted = false;
118 			for (;;) {
119 				try {
120 					if (readInterrupted) {
121 						dst.flush();
122 						readInterrupted = false;
123 						if (!flushCount.compareAndSet(flushCountBeforeRead, 0)) {
124 							// There was a flush() call since last blocked read.
125 							// Set interrupt status, so next blocked read will throw
126 							// an InterruptedIOException and we will flush again.
127 							interrupt();
128 						}
129 					}
130 
131 					if (done)
132 						break;
133 
134 					flushCountBeforeRead = flushCount.get();
135 					final int n;
136 					try {
137 						n = src.read(buf);
138 					} catch (InterruptedIOException wakey) {
139 						readInterrupted = true;
140 						continue;
141 					}
142 					if (n < 0)
143 						break;
144 
145 					boolean writeInterrupted = false;
146 					for (;;) {
147 						try {
148 							dst.write(buf, 0, n);
149 						} catch (InterruptedIOException wakey) {
150 							writeInterrupted = true;
151 							continue;
152 						}
153 
154 						// set interrupt status, which will be checked
155 						// when we block in src.read
156 						if (writeInterrupted || flushCount.get() > 0)
157 							interrupt();
158 						break;
159 					}
160 				} catch (IOException e) {
161 					break;
162 				}
163 			}
164 		} finally {
165 			try {
166 				src.close();
167 			} catch (IOException e) {
168 				// Ignore IO errors on close
169 			}
170 			try {
171 				dst.close();
172 			} catch (IOException e) {
173 				// Ignore IO errors on close
174 			}
175 		}
176 	}
177 }