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1 | /* |
2 | * Jexer - Java Text User Interface | |
3 | * | |
4 | * The MIT License (MIT) | |
5 | * | |
6 | * Copyright (C) 2017 Kevin Lamonte | |
7 | * | |
8 | * Permission is hereby granted, free of charge, to any person obtaining a | |
9 | * copy of this software and associated documentation files (the "Software"), | |
10 | * to deal in the Software without restriction, including without limitation | |
11 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, | |
12 | * and/or sell copies of the Software, and to permit persons to whom the | |
13 | * Software is furnished to do so, subject to the following conditions: | |
14 | * | |
15 | * The above copyright notice and this permission notice shall be included in | |
16 | * all copies or substantial portions of the Software. | |
17 | * | |
18 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
19 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
20 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
21 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
22 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
23 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER | |
24 | * DEALINGS IN THE SOFTWARE. | |
25 | * | |
26 | * @author Kevin Lamonte [kevin.lamonte@gmail.com] | |
27 | * @version 1 | |
28 | */ | |
29 | package jexer.io; | |
30 | ||
31 | import java.io.IOException; | |
32 | import java.io.InputStream; | |
33 | ||
34 | /** | |
35 | * This class provides an optional millisecond timeout on its read() | |
36 | * operations. This permits callers to bail out rather than block. | |
37 | */ | |
38 | public class TimeoutInputStream extends InputStream { | |
39 | ||
40 | /** | |
41 | * The wrapped stream. | |
42 | */ | |
43 | private InputStream stream; | |
44 | ||
45 | /** | |
46 | * The timeout value in millis. If it takes longer than this for bytes | |
47 | * to be available for read then a ReadTimeoutException is thrown. A | |
48 | * value of 0 means to block as a normal InputStream would. | |
49 | */ | |
50 | private int timeoutMillis; | |
51 | ||
52 | /** | |
53 | * If true, the current read() will timeout soon. | |
54 | */ | |
55 | private volatile boolean cancel = false; | |
56 | ||
57 | /** | |
58 | * Request that the current read() operation timeout immediately. | |
59 | */ | |
60 | public synchronized void cancelRead() { | |
61 | cancel = true; | |
62 | } | |
63 | ||
64 | /** | |
65 | * Public constructor, at the default timeout of 10000 millis (10 | |
66 | * seconds). | |
67 | * | |
68 | * @param stream the wrapped InputStream | |
69 | */ | |
70 | public TimeoutInputStream(final InputStream stream) { | |
71 | this.stream = stream; | |
72 | this.timeoutMillis = 10000; | |
73 | } | |
74 | ||
75 | /** | |
76 | * Public constructor, using the default 10 bits per byte. | |
77 | * | |
78 | * @param stream the wrapped InputStream | |
79 | * @param timeoutMillis the timeout value in millis. If it takes longer | |
80 | * than this for bytes to be available for read then a | |
81 | * ReadTimeoutException is thrown. A value of 0 means to block as a | |
82 | * normal InputStream would. | |
83 | */ | |
84 | public TimeoutInputStream(final InputStream stream, | |
85 | final int timeoutMillis) { | |
86 | ||
87 | if (timeoutMillis < 0) { | |
88 | throw new IllegalArgumentException("Invalid timeoutMillis value, " + | |
89 | "must be >= 0"); | |
90 | } | |
91 | ||
92 | this.stream = stream; | |
93 | this.timeoutMillis = timeoutMillis; | |
94 | } | |
95 | ||
96 | /** | |
97 | * Reads the next byte of data from the input stream. | |
98 | * | |
99 | * @return the next byte of data, or -1 if there is no more data because | |
100 | * the end of the stream has been reached. | |
101 | * @throws IOException if an I/O error occurs | |
102 | */ | |
103 | @Override | |
104 | public int read() throws IOException { | |
105 | ||
106 | if (timeoutMillis == 0) { | |
107 | // Block on the read(). | |
108 | return stream.read(); | |
109 | } | |
110 | ||
111 | if (stream.available() > 0) { | |
112 | // A byte is available now, return it. | |
113 | return stream.read(); | |
114 | } | |
115 | ||
116 | // We will wait up to timeoutMillis to see if a byte is available. | |
117 | // If not, we throw ReadTimeoutException. | |
118 | long checkTime = System.currentTimeMillis(); | |
119 | while (stream.available() == 0) { | |
120 | long now = System.currentTimeMillis(); | |
121 | synchronized (this) { | |
122 | if ((now - checkTime > timeoutMillis) || (cancel == true)) { | |
123 | if (cancel == true) { | |
124 | cancel = false; | |
125 | } | |
126 | throw new ReadTimeoutException("Timeout on read(): " + | |
127 | (int) (now - checkTime) + " millis and still no data"); | |
128 | } | |
129 | } | |
130 | try { | |
131 | // How long do we sleep for, eh? For now we will go with 2 | |
132 | // millis. | |
133 | Thread.currentThread().sleep(2); | |
134 | } catch (InterruptedException e) { | |
135 | // SQUASH | |
136 | } | |
137 | } | |
138 | ||
139 | if (stream.available() > 0) { | |
140 | // A byte is available now, return it. | |
141 | return stream.read(); | |
142 | } | |
143 | ||
144 | throw new IOException("InputStream claimed a byte was available, but " + | |
145 | "now it is not. What is going on?"); | |
146 | } | |
147 | ||
148 | /** | |
149 | * Reads some number of bytes from the input stream and stores them into | |
150 | * the buffer array b. | |
151 | * | |
152 | * @param b the buffer into which the data is read. | |
153 | * @return the total number of bytes read into the buffer, or -1 if there | |
154 | * is no more data because the end of the stream has been reached. | |
155 | * @throws IOException if an I/O error occurs | |
156 | */ | |
157 | @Override | |
158 | public int read(final byte[] b) throws IOException { | |
159 | if (timeoutMillis == 0) { | |
160 | // Block on the read(). | |
161 | return stream.read(b); | |
162 | } | |
163 | ||
164 | int remaining = b.length; | |
165 | ||
166 | if (stream.available() >= remaining) { | |
167 | // Enough bytes are available now, return them. | |
168 | return stream.read(b); | |
169 | } | |
170 | ||
171 | while (remaining > 0) { | |
172 | ||
173 | // We will wait up to timeoutMillis to see if a byte is | |
174 | // available. If not, we throw ReadTimeoutException. | |
175 | long checkTime = System.currentTimeMillis(); | |
176 | while (stream.available() == 0) { | |
177 | long now = System.currentTimeMillis(); | |
178 | ||
179 | synchronized (this) { | |
180 | if ((now - checkTime > timeoutMillis) || (cancel == true)) { | |
181 | if (cancel == true) { | |
182 | cancel = false; | |
183 | } | |
184 | throw new ReadTimeoutException("Timeout on read(): " + | |
185 | (int) (now - checkTime) + " millis and still no " + | |
186 | "data"); | |
187 | } | |
188 | } | |
189 | try { | |
190 | // How long do we sleep for, eh? For now we will go with | |
191 | // 2 millis. | |
192 | Thread.currentThread().sleep(2); | |
193 | } catch (InterruptedException e) { | |
194 | // SQUASH | |
195 | } | |
196 | } | |
197 | ||
198 | if (stream.available() > 0) { | |
199 | // At least one byte is available now, read it. | |
200 | int n = stream.available(); | |
201 | if (remaining < n) { | |
202 | n = remaining; | |
203 | } | |
204 | int rc = stream.read(b, b.length - remaining, n); | |
205 | if (rc == -1) { | |
206 | // This shouldn't happen. | |
207 | throw new IOException("InputStream claimed bytes were " + | |
208 | "available, but read() returned -1. What is going " + | |
209 | "on?"); | |
210 | } | |
211 | remaining -= rc; | |
212 | return rc; | |
213 | } | |
214 | } | |
215 | ||
216 | throw new IOException("InputStream claimed all bytes were available, " + | |
217 | "but now it is not. What is going on?"); | |
218 | } | |
219 | ||
220 | /** | |
221 | * Reads up to len bytes of data from the input stream into an array of | |
222 | * bytes. | |
223 | * | |
224 | * @param b the buffer into which the data is read. | |
225 | * @param off the start offset in array b at which the data is written. | |
226 | * @param len the maximum number of bytes to read. | |
227 | * @return the total number of bytes read into the buffer, or -1 if there | |
228 | * is no more data because the end of the stream has been reached. | |
229 | * @throws IOException if an I/O error occurs | |
230 | */ | |
231 | @Override | |
232 | public int read(final byte[] b, final int off, | |
233 | final int len) throws IOException { | |
234 | ||
235 | if (timeoutMillis == 0) { | |
236 | // Block on the read(). | |
237 | return stream.read(b); | |
238 | } | |
239 | ||
240 | int remaining = len; | |
241 | ||
242 | if (stream.available() >= remaining) { | |
243 | // Enough bytes are available now, return them. | |
244 | return stream.read(b, off, remaining); | |
245 | } | |
246 | ||
247 | while (remaining > 0) { | |
248 | ||
249 | // We will wait up to timeoutMillis to see if a byte is | |
250 | // available. If not, we throw ReadTimeoutException. | |
251 | long checkTime = System.currentTimeMillis(); | |
252 | while (stream.available() == 0) { | |
253 | long now = System.currentTimeMillis(); | |
254 | synchronized (this) { | |
255 | if ((now - checkTime > timeoutMillis) || (cancel == true)) { | |
256 | if (cancel == true) { | |
257 | cancel = false; | |
258 | } | |
259 | throw new ReadTimeoutException("Timeout on read(): " + | |
260 | (int) (now - checkTime) + " millis and still no " + | |
261 | "data"); | |
262 | } | |
263 | } | |
264 | try { | |
265 | // How long do we sleep for, eh? For now we will go with | |
266 | // 2 millis. | |
267 | Thread.currentThread().sleep(2); | |
268 | } catch (InterruptedException e) { | |
269 | // SQUASH | |
270 | } | |
271 | } | |
272 | ||
273 | if (stream.available() > 0) { | |
274 | // At least one byte is available now, read it. | |
275 | int n = stream.available(); | |
276 | if (remaining < n) { | |
277 | n = remaining; | |
278 | } | |
279 | int rc = stream.read(b, off + len - remaining, n); | |
280 | if (rc == -1) { | |
281 | // This shouldn't happen. | |
282 | throw new IOException("InputStream claimed bytes were " + | |
283 | "available, but read() returned -1. What is going " + | |
284 | "on?"); | |
285 | } | |
286 | return rc; | |
287 | } | |
288 | } | |
289 | ||
290 | throw new IOException("InputStream claimed all bytes were available, " + | |
291 | "but now it is not. What is going on?"); | |
292 | } | |
293 | ||
294 | /** | |
295 | * Returns an estimate of the number of bytes that can be read (or | |
296 | * skipped over) from this input stream without blocking by the next | |
297 | * invocation of a method for this input stream. | |
298 | * | |
299 | * @return an estimate of the number of bytes that can be read (or | |
300 | * skipped over) from this input stream without blocking or 0 when it | |
301 | * reaches the end of the input stream. | |
302 | * @throws IOException if an I/O error occurs | |
303 | */ | |
304 | @Override | |
305 | public int available() throws IOException { | |
306 | return stream.available(); | |
307 | } | |
308 | ||
309 | /** | |
310 | * Closes this input stream and releases any system resources associated | |
311 | * with the stream. | |
312 | * | |
313 | * @throws IOException if an I/O error occurs | |
314 | */ | |
315 | @Override | |
316 | public void close() throws IOException { | |
317 | stream.close(); | |
318 | } | |
319 | ||
320 | /** | |
321 | * Marks the current position in this input stream. | |
322 | * | |
323 | * @param readLimit the maximum limit of bytes that can be read before | |
324 | * the mark position becomes invalid | |
325 | */ | |
326 | @Override | |
327 | public void mark(final int readLimit) { | |
328 | stream.mark(readLimit); | |
329 | } | |
330 | ||
331 | /** | |
332 | * Tests if this input stream supports the mark and reset methods. | |
333 | * | |
334 | * @return true if this stream instance supports the mark and reset | |
335 | * methods; false otherwise | |
336 | */ | |
337 | @Override | |
338 | public boolean markSupported() { | |
339 | return stream.markSupported(); | |
340 | } | |
341 | ||
342 | /** | |
343 | * Repositions this stream to the position at the time the mark method | |
344 | * was last called on this input stream. | |
345 | * | |
346 | * @throws IOException if an I/O error occurs | |
347 | */ | |
348 | @Override | |
349 | public void reset() throws IOException { | |
350 | stream.reset(); | |
351 | } | |
352 | ||
353 | /** | |
354 | * Skips over and discards n bytes of data from this input stream. | |
355 | * | |
356 | * @param n the number of bytes to be skipped | |
357 | * @return the actual number of bytes skipped | |
358 | * @throws IOException if an I/O error occurs | |
359 | */ | |
360 | @Override | |
361 | public long skip(final long n) throws IOException { | |
362 | return stream.skip(n); | |
363 | } | |
364 | ||
365 | } |