Showing the changes to java/pkg/javax/imageio/stream/MemoryCache.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,364 @@ | ||
| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package javax.imageio.stream; | |
| 27 | + | |
| 28 | +import java.util.ArrayList; | |
| 29 | +import java.io.InputStream; | |
| 30 | +import java.io.OutputStream; | |
| 31 | +import java.io.IOException; | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * Package-visible class consolidating common code for | |
| 35 | + * <code>MemoryCacheImageInputStream</code> and | |
| 36 | + * <code>MemoryCacheImageOutputStream</code>. | |
| 37 | + * This class keeps an <code>ArrayList</code> of 8K blocks, | |
| 38 | + * loaded sequentially. Blocks may only be disposed of | |
| 39 | + * from the index 0 forward. As blocks are freed, the | |
| 40 | + * corresponding entries in the array list are set to | |
| 41 | + * <code>null</code>, but no compacting is performed. | |
| 42 | + * This allows the index for each block to never change, | |
| 43 | + * and the length of the cache is always the same as the | |
| 44 | + * total amount of data ever cached. Cached data is | |
| 45 | + * therefore always contiguous from the point of last | |
| 46 | + * disposal to the current length. | |
| 47 | + * | |
| 48 | + * <p> The total number of blocks resident in the cache must not | |
| 49 | + * exceed <code>Integer.MAX_VALUE</code>. In practice, the limit of | |
| 50 | + * available memory will be exceeded long before this becomes an | |
| 51 | + * issue, since a full cache would contain 8192*2^31 = 16 terabytes of | |
| 52 | + * data. | |
| 53 | + * | |
| 54 | + * A <code>MemoryCache</code> may be reused after a call | |
| 55 | + * to <code>reset()</code>. | |
| 56 | + */ | |
| 57 | +class MemoryCache { | |
| 58 | + | |
| 59 | + private static final int BUFFER_LENGTH = 8192; | |
| 60 | + | |
| 61 | + private ArrayList cache = new ArrayList(); | |
| 62 | + | |
| 63 | + private long cacheStart = 0L; | |
| 64 | + | |
| 65 | + /** | |
| 66 | + * The largest position ever written to the cache. | |
| 67 | + */ | |
| 68 | + private long length = 0L; | |
| 69 | + | |
| 70 | + private byte[] getCacheBlock(long blockNum) throws IOException { | |
| 71 | + long blockOffset = blockNum - cacheStart; | |
| 72 | + if (blockOffset > Integer.MAX_VALUE) { | |
| 73 | + // This can only happen when the cache hits 16 terabytes of | |
| 74 | + // contiguous data... | |
| 75 | + throw new IOException("Cache addressing limit exceeded!"); | |
| 76 | + } | |
| 77 | + return (byte[])cache.get((int)blockOffset); | |
| 78 | + } | |
| 79 | + | |
| 80 | + /** | |
| 81 | + * Ensures that at least <code>pos</code> bytes are cached, | |
| 82 | + * or the end of the source is reached. The return value | |
| 83 | + * is equal to the smaller of <code>pos</code> and the | |
| 84 | + * length of the source. | |
| 85 | + */ | |
| 86 | + public long loadFromStream(InputStream stream, long pos) | |
| 87 | + throws IOException { | |
| 88 | + // We've already got enough data cached | |
| 89 | + if (pos < length) { | |
| 90 | + return pos; | |
| 91 | + } | |
| 92 | + | |
| 93 | + int offset = (int)(length % BUFFER_LENGTH); | |
| 94 | + byte [] buf = null; | |
| 95 | + | |
| 96 | + long len = pos - length; | |
| 97 | + if (offset != 0) { | |
| 98 | + buf = getCacheBlock(length/BUFFER_LENGTH); | |
| 99 | + } | |
| 100 | + | |
| 101 | + while (len > 0) { | |
| 102 | + if (buf == null) { | |
| 103 | + try { | |
| 104 | + buf = new byte[BUFFER_LENGTH]; | |
| 105 | + } catch (OutOfMemoryError e) { | |
| 106 | + throw new IOException("No memory left for cache!"); | |
| 107 | + } | |
| 108 | + offset = 0; | |
| 109 | + } | |
| 110 | + | |
| 111 | + int left = BUFFER_LENGTH - offset; | |
| 112 | + int nbytes = (int)Math.min(len, (long)left); | |
| 113 | + nbytes = stream.read(buf, offset, nbytes); | |
| 114 | + if (nbytes == -1) { | |
| 115 | + return length; // EOF | |
| 116 | + } | |
| 117 | + | |
| 118 | + if (offset == 0) { | |
| 119 | + cache.add(buf); | |
| 120 | + } | |
| 121 | + | |
| 122 | + len -= nbytes; | |
| 123 | + length += nbytes; | |
| 124 | + offset += nbytes; | |
| 125 | + | |
| 126 | + if (offset >= BUFFER_LENGTH) { | |
| 127 | + // we've filled the current buffer, so a new one will be | |
| 128 | + // allocated next time around (and offset will be reset to 0) | |
| 129 | + buf = null; | |
| 130 | + } | |
| 131 | + } | |
| 132 | + | |
| 133 | + return pos; | |
| 134 | + } | |
| 135 | + | |
| 136 | + /** | |
| 137 | + * Writes out a portion of the cache to an <code>OutputStream</code>. | |
| 138 | + * This method preserves no state about the output stream, and does | |
| 139 | + * not dispose of any blocks containing bytes written. To dispose | |
| 140 | + * blocks, use {@link #disposeBefore <code>disposeBefore()</code>}. | |
| 141 | + * | |
| 142 | + * @exception IndexOutOfBoundsException if any portion of | |
| 143 | + * the requested data is not in the cache (including if <code>pos</code> | |
| 144 | + * is in a block already disposed), or if either <code>pos</code> or | |
| 145 | + * <code>len</code> is < 0. | |
| 146 | + */ | |
| 147 | + public void writeToStream(OutputStream stream, long pos, long len) | |
| 148 | + throws IOException { | |
| 149 | + if (pos + len > length) { | |
| 150 | + throw new IndexOutOfBoundsException("Argument out of cache"); | |
| 151 | + } | |
| 152 | + if ((pos < 0) || (len < 0)) { | |
| 153 | + throw new IndexOutOfBoundsException("Negative pos or len"); | |
| 154 | + } | |
| 155 | + if (len == 0) { | |
| 156 | + return; | |
| 157 | + } | |
| 158 | + | |
| 159 | + long bufIndex = pos/BUFFER_LENGTH; | |
| 160 | + if (bufIndex < cacheStart) { | |
| 161 | + throw new IndexOutOfBoundsException("pos already disposed"); | |
| 162 | + } | |
| 163 | + int offset = (int)(pos % BUFFER_LENGTH); | |
| 164 | + | |
| 165 | + byte[] buf = getCacheBlock(bufIndex++); | |
| 166 | + while (len > 0) { | |
| 167 | + if (buf == null) { | |
| 168 | + buf = getCacheBlock(bufIndex++); | |
| 169 | + offset = 0; | |
| 170 | + } | |
| 171 | + int nbytes = (int)Math.min(len, (long)(BUFFER_LENGTH - offset)); | |
| 172 | + stream.write(buf, offset, nbytes); | |
| 173 | + buf = null; | |
| 174 | + len -= nbytes; | |
| 175 | + } | |
| 176 | + } | |
| 177 | + | |
| 178 | + /** | |
| 179 | + * Ensure that there is space to write a byte at the given position. | |
| 180 | + */ | |
| 181 | + private void pad(long pos) throws IOException { | |
| 182 | + long currIndex = cacheStart + cache.size() - 1; | |
| 183 | + long lastIndex = pos/BUFFER_LENGTH; | |
| 184 | + long numNewBuffers = lastIndex - currIndex; | |
| 185 | + for (long i = 0; i < numNewBuffers; i++) { | |
| 186 | + try { | |
| 187 | + cache.add(new byte[BUFFER_LENGTH]); | |
| 188 | + } catch (OutOfMemoryError e) { | |
| 189 | + throw new IOException("No memory left for cache!"); | |
| 190 | + } | |
| 191 | + } | |
| 192 | + } | |
| 193 | + | |
| 194 | + /** | |
| 195 | + * Overwrites and/or appends the cache from a byte array. | |
| 196 | + * The length of the cache will be extended as needed to hold | |
| 197 | + * the incoming data. | |
| 198 | + * | |
| 199 | + * @param b an array of bytes containing data to be written. | |
| 200 | + * @param off the starting offset withing the data array. | |
| 201 | + * @param len the number of bytes to be written. | |
| 202 | + * @param pos the cache position at which to begin writing. | |
| 203 | + * | |
| 204 | + * @exception NullPointerException if <code>b</code> is <code>null</code>. | |
| 205 | + * @exception IndexOutOfBoundsException if <code>off</code>, | |
| 206 | + * <code>len</code>, or <code>pos</code> are negative, | |
| 207 | + * or if <code>off+len > b.length</code>. | |
| 208 | + */ | |
| 209 | + public void write(byte[] b, int off, int len, long pos) | |
| 210 | + throws IOException { | |
| 211 | + if (b == null) { | |
| 212 | + throw new NullPointerException("b == null!"); | |
| 213 | + } | |
| 214 | + // Fix 4430357 - if off + len < 0, overflow occurred | |
| 215 | + if ((off < 0) || (len < 0) || (pos < 0) || | |
| 216 | + (off + len > b.length) || (off + len < 0)) { | |
| 217 | + throw new IndexOutOfBoundsException(); | |
| 218 | + } | |
| 219 | + | |
| 220 | + // Ensure there is space for the incoming data | |
| 221 | + long lastPos = pos + len - 1; | |
| 222 | + if (lastPos >= length) { | |
| 223 | + pad(lastPos); | |
| 224 | + length = lastPos + 1; | |
| 225 | + } | |
| 226 | + | |
| 227 | + // Copy the data into the cache, block by block | |
| 228 | + int offset = (int)(pos % BUFFER_LENGTH); | |
| 229 | + while (len > 0) { | |
| 230 | + byte[] buf = getCacheBlock(pos/BUFFER_LENGTH); | |
| 231 | + int nbytes = Math.min(len, BUFFER_LENGTH - offset); | |
| 232 | + System.arraycopy(b, off, buf, offset, nbytes); | |
| 233 | + | |
| 234 | + pos += nbytes; | |
| 235 | + off += nbytes; | |
| 236 | + len -= nbytes; | |
| 237 | + offset = 0; // Always after the first time | |
| 238 | + } | |
| 239 | + } | |
| 240 | + | |
| 241 | + /** | |
| 242 | + * Overwrites or appends a single byte to the cache. | |
| 243 | + * The length of the cache will be extended as needed to hold | |
| 244 | + * the incoming data. | |
| 245 | + * | |
| 246 | + * @param b an <code>int</code> whose 8 least significant bits | |
| 247 | + * will be written. | |
| 248 | + * @param pos the cache position at which to begin writing. | |
| 249 | + * | |
| 250 | + * @exception IndexOutOfBoundsException if <code>pos</code> is negative. | |
| 251 | + */ | |
| 252 | + public void write(int b, long pos) throws IOException { | |
| 253 | + if (pos < 0) { | |
| 254 | + throw new ArrayIndexOutOfBoundsException("pos < 0"); | |
| 255 | + } | |
| 256 | + | |
| 257 | + // Ensure there is space for the incoming data | |
| 258 | + if (pos >= length) { | |
| 259 | + pad(pos); | |
| 260 | + length = pos + 1; | |
| 261 | + } | |
| 262 | + | |
| 263 | + // Insert the data. | |
| 264 | + byte[] buf = getCacheBlock(pos/BUFFER_LENGTH); | |
| 265 | + int offset = (int)(pos % BUFFER_LENGTH); | |
| 266 | + buf[offset] = (byte)b; | |
| 267 | + } | |
| 268 | + | |
| 269 | + /** | |
| 270 | + * Returns the total length of data that has been cached, | |
| 271 | + * regardless of whether any early blocks have been disposed. | |
| 272 | + * This value will only ever increase. | |
| 273 | + */ | |
| 274 | + public long getLength() { | |
| 275 | + return length; | |
| 276 | + } | |
| 277 | + | |
| 278 | + /** | |
| 279 | + * Returns the single byte at the given position, as an | |
| 280 | + * <code>int</code>. Returns -1 if this position has | |
| 281 | + * not been cached or has been disposed. | |
| 282 | + */ | |
| 283 | + public int read(long pos) throws IOException { | |
| 284 | + if (pos >= length) { | |
| 285 | + return -1; | |
| 286 | + } | |
| 287 | + | |
| 288 | + byte[] buf = getCacheBlock(pos/BUFFER_LENGTH); | |
| 289 | + if (buf == null) { | |
| 290 | + return -1; | |
| 291 | + } | |
| 292 | + | |
| 293 | + return buf[(int)(pos % BUFFER_LENGTH)] & 0xff; | |
| 294 | + } | |
| 295 | + | |
| 296 | + /** | |
| 297 | + * Copy <code>len</code> bytes from the cache, starting | |
| 298 | + * at cache position <code>pos</code>, into the array | |
| 299 | + * <code>b</code> at offset <code>off</code>. | |
| 300 | + * | |
| 301 | + * @exception NullPointerException if b is <code>null</code> | |
| 302 | + * @exception IndexOutOfBoundsException if <code>off</code>, | |
| 303 | + * <code>len</code> or <code>pos</code> are negative or if | |
| 304 | + * <code>off + len > b.length</code> or if any portion of the | |
| 305 | + * requested data is not in the cache (including if | |
| 306 | + * <code>pos</code> is in a block that has already been disposed). | |
| 307 | + */ | |
| 308 | + public void read(byte[] b, int off, int len, long pos) | |
| 309 | + throws IOException { | |
| 310 | + if (b == null) { | |
| 311 | + throw new NullPointerException("b == null!"); | |
| 312 | + } | |
| 313 | + // Fix 4430357 - if off + len < 0, overflow occurred | |
| 314 | + if ((off < 0) || (len < 0) || (pos < 0) || | |
| 315 | + (off + len > b.length) || (off + len < 0)) { | |
| 316 | + throw new IndexOutOfBoundsException(); | |
| 317 | + } | |
| 318 | + if (pos + len > length) { | |
| 319 | + throw new IndexOutOfBoundsException(); | |
| 320 | + } | |
| 321 | + | |
| 322 | + long index = pos/BUFFER_LENGTH; | |
| 323 | + int offset = (int)pos % BUFFER_LENGTH; | |
| 324 | + while (len > 0) { | |
| 325 | + int nbytes = Math.min(len, BUFFER_LENGTH - offset); | |
| 326 | + byte[] buf = getCacheBlock(index++); | |
| 327 | + System.arraycopy(buf, offset, b, off, nbytes); | |
| 328 | + | |
| 329 | + len -= nbytes; | |
| 330 | + off += nbytes; | |
| 331 | + offset = 0; // Always after the first time | |
| 332 | + } | |
| 333 | + } | |
| 334 | + | |
| 335 | + /** | |
| 336 | + * Free the blocks up to the position <code>pos</code>. | |
| 337 | + * The byte at <code>pos</code> remains available. | |
| 338 | + * | |
| 339 | + * @exception IndexOutOfBoundsException if <code>pos</code> | |
| 340 | + * is in a block that has already been disposed. | |
| 341 | + */ | |
| 342 | + public void disposeBefore(long pos) { | |
| 343 | + long index = pos/BUFFER_LENGTH; | |
| 344 | + if (index < cacheStart) { | |
| 345 | + throw new IndexOutOfBoundsException("pos already disposed"); | |
| 346 | + } | |
| 347 | + long numBlocks = Math.min(index - cacheStart, cache.size()); | |
| 348 | + for (long i = 0; i < numBlocks; i++) { | |
| 349 | + cache.remove(0); | |
| 350 | + } | |
| 351 | + this.cacheStart = index; | |
| 352 | + } | |
| 353 | + | |
| 354 | + /** | |
| 355 | + * Erase the entire cache contents and reset the length to 0. | |
| 356 | + * The cache object may subsequently be reused as though it had just | |
| 357 | + * been allocated. | |
| 358 | + */ | |
| 359 | + public void reset() { | |
| 360 | + cache.clear(); | |
| 361 | + cacheStart = 0; | |
| 362 | + length = 0L; | |
| 363 | + } | |
| 364 | + } | |