1 /*
2 * Hunt - A refined core library for D programming language.
3 *
4 * Copyright (C) 2018-2019 HuntLabs
5 *
6 * Website: https://www.huntlabs.net/
7 *
8 * Licensed under the Apache-2.0 License.
9 *
10 */11 12 modulehunt.stream.BufferedInputStream;
13 14 importhunt.stream.Common;
15 importhunt.stream.FilterInputStream;
16 importhunt.Exceptions;
17 18 version(HUNT_DEBUG) {
19 importhunt.logging;
20 }
21 22 /**
23 * A <code>BufferedInputStream</code> adds
24 * functionality to another input stream-namely,
25 * the ability to buffer the input and to
26 * support the <code>mark</code> and <code>reset</code>
27 * methods. When the <code>BufferedInputStream</code>
28 * is created, an internal buffer array is
29 * created. As bytes from the stream are read
30 * or skipped, the internal buffer is refilled
31 * as necessary from the contained input stream,
32 * many bytes at a time. The <code>mark</code>
33 * operation remembers a point in the input
34 * stream and the <code>reset</code> operation
35 * causes all the bytes read since the most
36 * recent <code>mark</code> operation to be
37 * reread before new bytes are taken from
38 * the contained input stream.
39 *
40 * @author Arthur van Hoff
41 */42 classBufferedInputStream : FilterInputStream {
43 44 privateenumintDEFAULT_BUFFER_SIZE = 8192;
45 46 /**
47 * The maximum size of array to allocate.
48 * Some VMs reserve some header words in an array.
49 * Attempts to allocate larger arrays may result in
50 * OutOfMemoryError: Requested array size exceeds VM limit
51 */52 privateenumintMAX_BUFFER_SIZE = int.max - 8;
53 54 /**
55 * As this class is used early during bootstrap, it's motivated to use
56 * Unsafe.compareAndSetObject instead of AtomicReferenceFieldUpdater
57 * (or VarHandles) to reduce dependencies and improve startup time.
58 */59 // private static final Unsafe U = Unsafe.getUnsafe();60 61 // private static final long BUF_OFFSET62 // = U.objectFieldOffset(BufferedInputStream.class, "buf");63 64 /**
65 * The internal buffer array where the data is stored. When necessary,
66 * it may be replaced by another array of
67 * a different size.
68 */69 /*
70 * We null this out with a CAS on close(), which is necessary since
71 * closes can be asynchronous. We use nullness of buf[] as primary
72 * indicator that this stream is closed. (The "in" field is also
73 * nulled out on close.)
74 */75 protectedbyte[] buf;
76 77 /**
78 * The index one greater than the index of the last valid byte in
79 * the buffer.
80 * This value is always
81 * in the range <code>0</code> through <code>buf.length</code>;
82 * elements <code>buf[0]</code> through <code>buf[count-1]
83 * </code>contain buffered input data obtained
84 * from the underlying input stream.
85 */86 protectedintcount;
87 88 /**
89 * The current position in the buffer. This is the index of the next
90 * character to be read from the <code>buf</code> array.
91 * <p>
92 * This value is always in the range <code>0</code>
93 * through <code>count</code>. If it is less
94 * than <code>count</code>, then <code>buf[pos]</code>
95 * is the next byte to be supplied as input;
96 * if it is equal to <code>count</code>, then
97 * the next <code>read</code> or <code>skip</code>
98 * operation will require more bytes to be
99 * read from the contained input stream.
100 *
101 * @see java.io.BufferedInputStream#buf
102 */103 protectedintpos;
104 105 /**
106 * The value of the <code>pos</code> field at the time the last
107 * <code>mark</code> method was called.
108 * <p>
109 * This value is always
110 * in the range <code>-1</code> through <code>pos</code>.
111 * If there is no marked position in the input
112 * stream, this field is <code>-1</code>. If
113 * there is a marked position in the input
114 * stream, then <code>buf[markpos]</code>
115 * is the first byte to be supplied as input
116 * after a <code>reset</code> operation. If
117 * <code>markpos</code> is not <code>-1</code>,
118 * then all bytes from positions <code>buf[markpos]</code>
119 * through <code>buf[pos-1]</code> must remain
120 * in the buffer array (though they may be
121 * moved to another place in the buffer array,
122 * with suitable adjustments to the values
123 * of <code>count</code>, <code>pos</code>,
124 * and <code>markpos</code>); they may not
125 * be discarded unless and until the difference
126 * between <code>pos</code> and <code>markpos</code>
127 * exceeds <code>marklimit</code>.
128 *
129 * @see java.io.BufferedInputStream#mark(int)
130 * @see java.io.BufferedInputStream#pos
131 */132 protectedintmarkpos = -1;
133 134 /**
135 * The maximum read ahead allowed after a call to the
136 * <code>mark</code> method before subsequent calls to the
137 * <code>reset</code> method fail.
138 * Whenever the difference between <code>pos</code>
139 * and <code>markpos</code> exceeds <code>marklimit</code>,
140 * then the mark may be dropped by setting
141 * <code>markpos</code> to <code>-1</code>.
142 *
143 * @see java.io.BufferedInputStream#mark(int)
144 * @see java.io.BufferedInputStream#reset()
145 */146 protectedintmarklimit;
147 148 /**
149 * Creates a <code>BufferedInputStream</code>
150 * and saves its argument, the input stream
151 * <code>inputStream</code>, for later use. An internal
152 * buffer array is created and stored in <code>buf</code>.
153 *
154 * @param inputStream the underlying input stream.
155 */156 this(InputStreaminputStream) {
157 this(inputStream, DEFAULT_BUFFER_SIZE);
158 }
159 160 /**
161 * Creates a <code>BufferedInputStream</code>
162 * with the specified buffer size,
163 * and saves its argument, the input stream
164 * <code>inputStream</code>, for later use. An internal
165 * buffer array of length <code>size</code>
166 * is created and stored in <code>buf</code>.
167 *
168 * @param inputStream the underlying input stream.
169 * @param size the buffer size.
170 * @exception IllegalArgumentException if {@code size <= 0}.
171 */172 this(InputStreaminputStream, intsize) {
173 super(inputStream);
174 if (size <= 0) {
175 thrownewIllegalArgumentException("Buffer size <= 0");
176 }
177 buf = newbyte[size];
178 }
179 180 /**
181 * Check to make sure that underlying input stream has not been
182 * nulled out due to close; if not return it;
183 */184 privateInputStreamgetInIfOpen() {
185 InputStreaminput = inputStream;
186 if (inputisnull)
187 thrownewIOException("Stream closed");
188 returninput;
189 }
190 191 /**
192 * Check to make sure that buffer has not been nulled out due to
193 * close; if not return it;
194 */195 privatebyte[] getBufIfOpen() {
196 byte[] buffer = buf;
197 if (bufferisnull)
198 thrownewIOException("Stream closed");
199 returnbuffer;
200 }
201 202 /**
203 * Fills the buffer with more data, taking into account
204 * shuffling and other tricks for dealing with marks.
205 * Assumes that it is being called by a synchronized method.
206 * This method also assumes that all data has already been read in,
207 * hence pos > count.
208 */209 privatevoidfill() {
210 byte[] buffer = getBufIfOpen();
211 if (markpos < 0)
212 pos = 0; /* no mark: throw away the buffer */213 elseif (pos >= buffer.length) { /* no room left in buffer */214 if (markpos > 0) { /* can throw away early part of the buffer */215 intsz = pos - markpos;
216 // System.arraycopy(buffer, markpos, buffer, 0, sz);217 for(inti=0; i<sz; i++) {
218 buffer[i] = buffer[markpos+i];
219 }
220 pos = sz;
221 markpos = 0;
222 } elseif (buffer.length >= marklimit) {
223 markpos = -1; /* buffer got too big, invalidate mark */224 pos = 0; /* drop buffer contents */225 } elseif (buffer.length >= MAX_BUFFER_SIZE) {
226 thrownewOutOfMemoryError("Required array size too large");
227 } else { /* grow buffer */228 intnsz = (pos <= MAX_BUFFER_SIZE - pos) ?
229 pos * 2 : MAX_BUFFER_SIZE;
230 if (nsz > marklimit)
231 nsz = marklimit;
232 byte[] nbuf = buffer[0..pos].dup;
233 // byte[] nbuf = new byte[nsz];234 // System.arraycopy(buffer, 0, nbuf, 0, pos);235 // if (!U.compareAndSetObject(this, BUF_OFFSET, buffer, nbuf))236 if(this.buf !isbuffer) {
237 // Can't replace buf if there was an async close.238 // Note: This would need to be changed if fill()239 // is ever made accessible to multiple threads.240 // But for now, the only way CAS can fail is via close.241 // assert buf is null;242 thrownewIOException("Stream closed");
243 }
244 buffer = nbuf;
245 }
246 }
247 count = pos;
248 intn = getInIfOpen().read(buffer, pos, cast(int)buffer.length - pos);
249 if (n > 0)
250 count = n + pos;
251 }
252 253 /**
254 * See
255 * the general contract of the <code>read</code>
256 * method of <code>InputStream</code>.
257 *
258 * @return the next byte of data, or <code>-1</code> if the end of the
259 * stream is reached.
260 * @exception IOException if this input stream has been closed by
261 * invoking its {@link #close()} method,
262 * or an I/O error occurs.
263 * @see java.io.FilterInputStream#inputStream
264 */265 overrideintread() {
266 if (pos >= count) {
267 fill();
268 if (pos >= count)
269 return -1;
270 }
271 returngetBufIfOpen()[pos++] & 0xff;
272 }
273 274 /**
275 * Read characters into a portion of an array, reading from the underlying
276 * stream at most once if necessary.
277 */278 privateintread1(byte[] b, intoff, intlen) {
279 intavail = count - pos;
280 if (avail <= 0) {
281 /* If the requested length is at least as large as the buffer, and
282 if there is no mark/reset activity, do not bother to copy the
283 bytes into the local buffer. In this way buffered streams will
284 cascade harmlessly. */285 if (len >= getBufIfOpen().length && markpos < 0) {
286 returngetInIfOpen().read(b, off, len);
287 }
288 fill();
289 avail = count - pos;
290 if (avail <= 0) return -1;
291 }
292 intcnt = (avail < len) ? avail : len;
293 b[off.. off+cnt] = getBufIfOpen()[pos .. pos+cnt];
294 // System.arraycopy(getBufIfOpen(), pos, b, off, cnt);295 pos += cnt;
296 returncnt;
297 }
298 299 /**
300 * Reads bytes from this byte-input stream into the specified byte array,
301 * starting at the given offset.
302 *
303 * <p> This method implements the general contract of the corresponding
304 * <code>{@link InputStream#read(byte[], int, int) read}</code> method of
305 * the <code>{@link InputStream}</code> class. As an additional
306 * convenience, it attempts to read as many bytes as possible by repeatedly
307 * invoking the <code>read</code> method of the underlying stream. This
308 * iterated <code>read</code> continues until one of the following
309 * conditions becomes true: <ul>
310 *
311 * <li> The specified number of bytes have been read,
312 *
313 * <li> The <code>read</code> method of the underlying stream returns
314 * <code>-1</code>, indicating end-of-file, or
315 *
316 * <li> The <code>available</code> method of the underlying stream
317 * returns zero, indicating that further input requests would block.
318 *
319 * </ul> If the first <code>read</code> on the underlying stream returns
320 * <code>-1</code> to indicate end-of-file then this method returns
321 * <code>-1</code>. Otherwise this method returns the number of bytes
322 * actually read.
323 *
324 * <p> Subclasses of this class are encouraged, but not required, to
325 * attempt to read as many bytes as possible in the same fashion.
326 *
327 * @param b destination buffer.
328 * @param off offset at which to start storing bytes.
329 * @param len maximum number of bytes to read.
330 * @return the number of bytes read, or <code>-1</code> if the end of
331 * the stream has been reached.
332 * @exception IOException if this input stream has been closed by
333 * invoking its {@link #close()} method,
334 * or an I/O error occurs.
335 */336 overrideintread(byte[] b, intoff, intlen) {
337 getBufIfOpen(); // Check for closed stream338 if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
339 thrownewIndexOutOfBoundsException();
340 } elseif (len == 0) {
341 return0;
342 }
343 344 intn = 0;
345 for (;;) {
346 intnread = read1(b, off + n, len - n);
347 if (nread <= 0)
348 return (n == 0) ? nread : n;
349 n += nread;
350 if (n >= len)
351 returnn;
352 // if not closed but no bytes available, return353 InputStreaminput = inputStream;
354 if (input !isnull && input.available() <= 0)
355 returnn;
356 }
357 }
358 359 /**
360 * See the general contract of the <code>skip</code>
361 * method of <code>InputStream</code>.
362 *
363 * @throws IOException if this input stream has been closed by
364 * invoking its {@link #close()} method,
365 * {@code inputStream.skip(n)} throws an IOException,
366 * or an I/O error occurs.
367 */368 overridelongskip(longn) {
369 getBufIfOpen(); // Check for closed stream370 if (n <= 0) {
371 return0;
372 }
373 longavail = count - pos;
374 375 if (avail <= 0) {
376 // If no mark position set then don't keep in buffer377 if (markpos <0)
378 returngetInIfOpen().skip(n);
379 380 // Fill in buffer to save bytes for reset381 fill();
382 avail = count - pos;
383 if (avail <= 0)
384 return0;
385 }
386 387 longskipped = (avail < n) ? avail : n;
388 pos += skipped;
389 returnskipped;
390 }
391 392 /**
393 * Returns an estimate of the number of bytes that can be read (or
394 * skipped over) from this input stream without blocking by the next
395 * invocation of a method for this input stream. The next invocation might be
396 * the same thread or another thread. A single read or skip of this
397 * many bytes will not block, but may read or skip fewer bytes.
398 * <p>
399 * This method returns the sum of the number of bytes remaining to be read in
400 * the buffer (<code>count - pos</code>) and the result of calling the
401 * {@link java.io.FilterInputStream#inputStream inputStream}.available().
402 *
403 * @return an estimate of the number of bytes that can be read (or skipped
404 * over) from this input stream without blocking.
405 * @exception IOException if this input stream has been closed by
406 * invoking its {@link #close()} method,
407 * or an I/O error occurs.
408 */409 overrideintavailable() {
410 intn = count - pos;
411 intavail = getInIfOpen().available();
412 returnn > (int.max - avail) ? int.max : n + avail;
413 }
414 415 /**
416 * See the general contract of the <code>mark</code>
417 * method of <code>InputStream</code>.
418 *
419 * @param readlimit the maximum limit of bytes that can be read before
420 * the mark position becomes invalid.
421 * @see java.io.BufferedInputStream#reset()
422 */423 overridevoidmark(intreadlimit) {
424 marklimit = readlimit;
425 markpos = pos;
426 }
427 428 /**
429 * See the general contract of the <code>reset</code>
430 * method of <code>InputStream</code>.
431 * <p>
432 * If <code>markpos</code> is <code>-1</code>
433 * (no mark has been set or the mark has been
434 * invalidated), an <code>IOException</code>
435 * is thrown. Otherwise, <code>pos</code> is
436 * set equal to <code>markpos</code>.
437 *
438 * @exception IOException if this stream has not been marked or,
439 * if the mark has been invalidated, or the stream
440 * has been closed by invoking its {@link #close()}
441 * method, or an I/O error occurs.
442 * @see java.io.BufferedInputStream#mark(int)
443 */444 overridevoidreset() {
445 getBufIfOpen(); // Cause exception if closed446 if (markpos < 0)
447 thrownewIOException("Resetting to invalid mark");
448 pos = markpos;
449 }
450 451 overridevoidposition(intindex) {
452 getBufIfOpen(); // Cause exception if closed453 if(index < 0 || index > count + inputStream.available())
454 thrownewIOException("Out of range");
455 456 if(index >= count) {
457 inputStream.position(index - count);
458 pos = count;
459 } else {
460 inputStream.position(0);
461 pos = index;
462 }
463 }
464 465 466 /**
467 * Tests if this input stream supports the <code>mark</code>
468 * and <code>reset</code> methods. The <code>markSupported</code>
469 * method of <code>BufferedInputStream</code> returns
470 * <code>true</code>.
471 *
472 * @return a <code>bool</code> indicating if this stream type supports
473 * the <code>mark</code> and <code>reset</code> methods.
474 * @see java.io.InputStream#mark(int)
475 * @see java.io.InputStream#reset()
476 */477 overrideboolmarkSupported() {
478 returntrue;
479 }
480 481 /**
482 * Closes this input stream and releases any system resources
483 * associated with the stream.
484 * Once the stream has been closed, further read(), available(), reset(),
485 * or skip() invocations will throw an IOException.
486 * Closing a previously closed stream has no effect.
487 *
488 * @exception IOException if an I/O error occurs.
489 */490 overridevoidclose() {
491 byte[] buffer;
492 while ( (buffer = buf) !isnull) {
493 // if (U.compareAndSetObject(this, BUF_OFFSET, buffer, null))494 if(this.bufisbuffer) {
495 this.buf = null;
496 InputStreaminput = inputStream;
497 inputStream = null;
498 if (input !isnull)
499 input.close();
500 return;
501 }
502 // Else retry in case a new buf was CASed in fill()503 }
504 }
505 }