| 1 | /* |
| 2 | * jDTAUS Core Utilities |
| 3 | * Copyright (C) 2005 Christian Schulte |
| 4 | * <cs@schulte.it> |
| 5 | * |
| 6 | * This library is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or any later version. |
| 10 | * |
| 11 | * This library is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with this library; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | * |
| 20 | */ |
| 21 | package org.jdtaus.core.io.util; |
| 22 | |
| 23 | import java.io.IOException; |
| 24 | import java.io.InputStream; |
| 25 | import java.io.OutputStream; |
| 26 | import java.util.Locale; |
| 27 | import org.jdtaus.core.container.ContainerFactory; |
| 28 | import org.jdtaus.core.io.FileOperations; |
| 29 | import org.jdtaus.core.lang.spi.MemoryManager; |
| 30 | |
| 31 | /** |
| 32 | * Read-ahead {@code FileOperations} cache. |
| 33 | * <p>This implementation implements a read-ahead cache for |
| 34 | * {@code FileOperations} implementations. The cache is controlled by |
| 35 | * configuration property {@code cacheSize} holding the number of bytes |
| 36 | * to read-ahead. By default property {@code cacheSize} is initialized to |
| 37 | * {@code 16384} leading to a cache size of 16 kB. All memory is allocated |
| 38 | * during instantiation so that an {@code OutOfMemoryError} may be thrown |
| 39 | * when constructing the cache but not when working with the instance.</p> |
| 40 | * |
| 41 | * <p><b>Note:</b><br> |
| 42 | * This implementation is not thread-safe and concurrent changes to the |
| 43 | * underlying {@code FileOperations} implementation are not supported.</p> |
| 44 | * |
| 45 | * @author <a href="mailto:cs@schulte.it">Christian Schulte</a> |
| 46 | * @version $JDTAUS: ReadAheadFileOperations.java 8641 2012-09-27 06:45:17Z schulte $ |
| 47 | */ |
| 48 | public final class ReadAheadFileOperations implements FlushableFileOperations |
| 49 | { |
| 50 | //--Dependencies------------------------------------------------------------ |
| 51 | |
| 52 | // <editor-fold defaultstate="collapsed" desc=" Generated Code ">//GEN-BEGIN:jdtausDependencies |
| 53 | // This section is managed by jdtaus-container-mojo. |
| 54 | |
| 55 | /** |
| 56 | * Gets the configured <code>MemoryManager</code> implementation. |
| 57 | * |
| 58 | * @return The configured <code>MemoryManager</code> implementation. |
| 59 | */ |
| 60 | private MemoryManager getMemoryManager() |
| 61 | { |
| 62 | return (MemoryManager) ContainerFactory.getContainer(). |
| 63 | getDependency( this, "MemoryManager" ); |
| 64 | |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Gets the configured <code>Locale</code> implementation. |
| 69 | * |
| 70 | * @return The configured <code>Locale</code> implementation. |
| 71 | */ |
| 72 | private Locale getLocale() |
| 73 | { |
| 74 | return (Locale) ContainerFactory.getContainer(). |
| 75 | getDependency( this, "Locale" ); |
| 76 | |
| 77 | } |
| 78 | |
| 79 | // </editor-fold>//GEN-END:jdtausDependencies |
| 80 | |
| 81 | //------------------------------------------------------------Dependencies-- |
| 82 | //--Properties-------------------------------------------------------------- |
| 83 | |
| 84 | // <editor-fold defaultstate="collapsed" desc=" Generated Code ">//GEN-BEGIN:jdtausProperties |
| 85 | // This section is managed by jdtaus-container-mojo. |
| 86 | |
| 87 | /** |
| 88 | * Gets the value of property <code>defaultCacheSize</code>. |
| 89 | * |
| 90 | * @return Default cache size in byte. |
| 91 | */ |
| 92 | private java.lang.Integer getDefaultCacheSize() |
| 93 | { |
| 94 | return (java.lang.Integer) ContainerFactory.getContainer(). |
| 95 | getProperty( this, "defaultCacheSize" ); |
| 96 | |
| 97 | } |
| 98 | |
| 99 | // </editor-fold>//GEN-END:jdtausProperties |
| 100 | |
| 101 | //--------------------------------------------------------------Properties-- |
| 102 | //--FileOperations---------------------------------------------------------- |
| 103 | |
| 104 | public long getLength() throws IOException |
| 105 | { |
| 106 | this.assertNotClosed(); |
| 107 | |
| 108 | return this.fileOperations.getLength(); |
| 109 | } |
| 110 | |
| 111 | public void setLength( final long newLength ) throws IOException |
| 112 | { |
| 113 | this.assertNotClosed(); |
| 114 | |
| 115 | final long oldLength = this.getLength(); |
| 116 | this.fileOperations.setLength( newLength ); |
| 117 | if ( this.filePointer > newLength ) |
| 118 | { |
| 119 | this.filePointer = newLength; |
| 120 | } |
| 121 | |
| 122 | if ( oldLength > newLength && this.cachePosition != NO_CACHEPOSITION && |
| 123 | this.cachePosition + this.cacheLength >= newLength ) |
| 124 | { // Discard the end of file cache. |
| 125 | this.cachePosition = NO_CACHEPOSITION; |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | public long getFilePointer() throws IOException |
| 130 | { |
| 131 | this.assertNotClosed(); |
| 132 | |
| 133 | return this.filePointer; |
| 134 | } |
| 135 | |
| 136 | public void setFilePointer( final long pos ) throws IOException |
| 137 | { |
| 138 | this.assertNotClosed(); |
| 139 | |
| 140 | this.filePointer = pos; |
| 141 | } |
| 142 | |
| 143 | public int read( final byte[] buf, int off, int len ) |
| 144 | throws IOException |
| 145 | { |
| 146 | if ( buf == null ) |
| 147 | { |
| 148 | throw new NullPointerException( "buf" ); |
| 149 | } |
| 150 | if ( off < 0 ) |
| 151 | { |
| 152 | throw new IndexOutOfBoundsException( Integer.toString( off ) ); |
| 153 | } |
| 154 | if ( len < 0 ) |
| 155 | { |
| 156 | throw new IndexOutOfBoundsException( Integer.toString( len ) ); |
| 157 | } |
| 158 | if ( off + len > buf.length ) |
| 159 | { |
| 160 | throw new IndexOutOfBoundsException( Integer.toString( off + len ) ); |
| 161 | } |
| 162 | |
| 163 | this.assertNotClosed(); |
| 164 | |
| 165 | int read = FileOperations.EOF; |
| 166 | |
| 167 | final long fileLength = this.getLength(); |
| 168 | |
| 169 | if ( len == 0 ) |
| 170 | { |
| 171 | read = 0; |
| 172 | } |
| 173 | else if ( this.filePointer < fileLength ) |
| 174 | { |
| 175 | if ( this.cachePosition == NO_CACHEPOSITION || |
| 176 | !( this.filePointer >= this.cachePosition && |
| 177 | this.filePointer < this.cachePosition + this.cacheLength ) ) |
| 178 | { // Cache not initialized or file pointer outside the cached area. |
| 179 | this.fillCache(); |
| 180 | } |
| 181 | |
| 182 | final long cacheStart = this.filePointer - this.cachePosition; |
| 183 | |
| 184 | assert cacheStart <= Integer.MAX_VALUE : |
| 185 | "Unexpected implementation limit reached."; |
| 186 | |
| 187 | final int cachedLength = len > this.cacheLength - |
| 188 | (int) cacheStart |
| 189 | ? this.cacheLength - (int) cacheStart |
| 190 | : len; |
| 191 | |
| 192 | System.arraycopy( this.getCache(), (int) cacheStart, buf, off, |
| 193 | cachedLength ); |
| 194 | |
| 195 | len -= cachedLength; |
| 196 | off += cachedLength; |
| 197 | read = cachedLength; |
| 198 | this.filePointer += cachedLength; |
| 199 | } |
| 200 | |
| 201 | return read; |
| 202 | } |
| 203 | |
| 204 | public void write( final byte[] buf, final int off, final int len ) |
| 205 | throws IOException |
| 206 | { |
| 207 | if ( buf == null ) |
| 208 | { |
| 209 | throw new NullPointerException( "buf" ); |
| 210 | } |
| 211 | if ( off < 0 ) |
| 212 | { |
| 213 | throw new IndexOutOfBoundsException( Integer.toString( off ) ); |
| 214 | } |
| 215 | if ( len < 0 ) |
| 216 | { |
| 217 | throw new IndexOutOfBoundsException( Integer.toString( len ) ); |
| 218 | } |
| 219 | if ( off + len > buf.length ) |
| 220 | { |
| 221 | throw new IndexOutOfBoundsException( Integer.toString( off + len ) ); |
| 222 | } |
| 223 | |
| 224 | this.assertNotClosed(); |
| 225 | |
| 226 | if ( this.cachePosition != NO_CACHEPOSITION && |
| 227 | this.filePointer >= this.cachePosition && |
| 228 | this.filePointer < this.cachePosition + this.cacheLength ) |
| 229 | { // Cache needs updating. |
| 230 | final long cacheStart = this.filePointer - this.cachePosition; |
| 231 | |
| 232 | assert cacheStart <= Integer.MAX_VALUE : |
| 233 | "Unexpected implementation limit reached."; |
| 234 | |
| 235 | final int cachedLength = len > this.cacheLength - |
| 236 | (int) cacheStart |
| 237 | ? this.cacheLength - (int) cacheStart |
| 238 | : len; |
| 239 | |
| 240 | System.arraycopy( buf, off, this.getCache(), (int) cacheStart, |
| 241 | cachedLength ); |
| 242 | |
| 243 | } |
| 244 | |
| 245 | this.fileOperations.setFilePointer( this.filePointer ); |
| 246 | this.fileOperations.write( buf, off, len ); |
| 247 | this.filePointer += len; |
| 248 | } |
| 249 | |
| 250 | public void read( final OutputStream out ) throws IOException |
| 251 | { |
| 252 | this.assertNotClosed(); |
| 253 | |
| 254 | this.fileOperations.read( out ); |
| 255 | this.filePointer = this.fileOperations.getFilePointer(); |
| 256 | } |
| 257 | |
| 258 | public void write( final InputStream in ) throws IOException |
| 259 | { |
| 260 | this.assertNotClosed(); |
| 261 | |
| 262 | this.fileOperations.write( in ); |
| 263 | this.filePointer = this.fileOperations.getFilePointer(); |
| 264 | } |
| 265 | |
| 266 | /** |
| 267 | * {@inheritDoc} |
| 268 | * Flushes the cache and closes the {@code FileOperations} implementation |
| 269 | * backing the instance. |
| 270 | * |
| 271 | * @throws IOException if closing the {@code FileOperations} implementation |
| 272 | * backing the instance fails or if the instance already is closed. |
| 273 | */ |
| 274 | public void close() throws IOException |
| 275 | { |
| 276 | this.assertNotClosed(); |
| 277 | |
| 278 | this.flush(); |
| 279 | this.getFileOperations().close(); |
| 280 | this.closed = true; |
| 281 | } |
| 282 | |
| 283 | //----------------------------------------------------------FileOperations-- |
| 284 | //--FlushableFileOperations------------------------------------------------- |
| 285 | |
| 286 | /** |
| 287 | * {@inheritDoc} |
| 288 | * This method calls the {@code flush()} method of an underlying |
| 289 | * {@code FlushableFileOperations} implementation, if any. |
| 290 | */ |
| 291 | public void flush() throws IOException |
| 292 | { |
| 293 | this.assertNotClosed(); |
| 294 | |
| 295 | if ( this.fileOperations instanceof FlushableFileOperations ) |
| 296 | { |
| 297 | ( (FlushableFileOperations) this.fileOperations ).flush(); |
| 298 | } |
| 299 | } |
| 300 | |
| 301 | //-------------------------------------------------FlushableFileOperations-- |
| 302 | //--ReadAheadFileOperations------------------------------------------------- |
| 303 | |
| 304 | /** The {@code FileOperations} backing the instance. */ |
| 305 | private final FileOperations fileOperations; |
| 306 | |
| 307 | /** Cached bytes. */ |
| 308 | private byte[] cache; |
| 309 | |
| 310 | /** Position in the file {@code cache} starts. */ |
| 311 | private long cachePosition; |
| 312 | |
| 313 | private static final long NO_CACHEPOSITION = Long.MIN_VALUE; |
| 314 | |
| 315 | /** Length of the cached data. */ |
| 316 | private int cacheLength; |
| 317 | |
| 318 | /** File pointer value. */ |
| 319 | private long filePointer; |
| 320 | |
| 321 | /** Flags the instance as beeing closed. */ |
| 322 | private boolean closed; |
| 323 | |
| 324 | /** Cache size in byte. */ |
| 325 | private Integer cacheSize; |
| 326 | |
| 327 | /** |
| 328 | * Creates a new {@code ReadAheadFileOperations} instance taking the |
| 329 | * {@code FileOperations} backing the instance. |
| 330 | * |
| 331 | * @param fileOperations the {@code FileOperations} backing the instance. |
| 332 | * |
| 333 | * @throws NullPointerException if {@code fileOperations} is {@code null}. |
| 334 | * @throws IOException if reading fails. |
| 335 | */ |
| 336 | public ReadAheadFileOperations( final FileOperations fileOperations ) |
| 337 | throws IOException |
| 338 | { |
| 339 | super(); |
| 340 | |
| 341 | if ( fileOperations == null ) |
| 342 | { |
| 343 | throw new NullPointerException( "fileOperations" ); |
| 344 | } |
| 345 | |
| 346 | this.fileOperations = fileOperations; |
| 347 | this.filePointer = fileOperations.getFilePointer(); |
| 348 | } |
| 349 | |
| 350 | /** |
| 351 | * Creates a new {@code ReadAheadFileOperations} instance taking the |
| 352 | * {@code FileOperations} backing the instance and the size of the cache. |
| 353 | * |
| 354 | * @param fileOperations the {@code FileOperations} backing the instance. |
| 355 | * @param cacheSize the number of bytes to read-ahead. |
| 356 | * |
| 357 | * @throws NullPointerException if {@code fileOperations} is {@code null}. |
| 358 | * @throws IOException if reading fails. |
| 359 | */ |
| 360 | public ReadAheadFileOperations( final FileOperations fileOperations, |
| 361 | final int cacheSize ) throws IOException |
| 362 | { |
| 363 | this( fileOperations ); |
| 364 | |
| 365 | if ( cacheSize > 0 ) |
| 366 | { |
| 367 | this.cacheSize = new Integer( cacheSize ); |
| 368 | } |
| 369 | } |
| 370 | |
| 371 | /** |
| 372 | * Gets the {@code FileOperations} implementation operations are performed |
| 373 | * with. |
| 374 | * |
| 375 | * @return the {@code FileOperations} implementation operations are |
| 376 | * performed with. |
| 377 | */ |
| 378 | public FileOperations getFileOperations() |
| 379 | { |
| 380 | return this.fileOperations; |
| 381 | } |
| 382 | |
| 383 | /** |
| 384 | * Gets the size of the cache in byte. |
| 385 | * |
| 386 | * @return the size of the cache in byte. |
| 387 | */ |
| 388 | public int getCacheSize() |
| 389 | { |
| 390 | if ( this.cacheSize == null ) |
| 391 | { |
| 392 | this.cacheSize = this.getDefaultCacheSize(); |
| 393 | } |
| 394 | |
| 395 | return this.cacheSize.intValue(); |
| 396 | } |
| 397 | |
| 398 | /** |
| 399 | * Gets the cache buffer. |
| 400 | * |
| 401 | * @return the cache buffer. |
| 402 | */ |
| 403 | private byte[] getCache() |
| 404 | { |
| 405 | if ( this.cache == null ) |
| 406 | { |
| 407 | this.cache = |
| 408 | this.getMemoryManager().allocateBytes( this.getCacheSize() ); |
| 409 | |
| 410 | } |
| 411 | |
| 412 | return this.cache; |
| 413 | } |
| 414 | |
| 415 | /** |
| 416 | * Checks that the instance is not closed. |
| 417 | * |
| 418 | * @throws IOException if the instance is closed. |
| 419 | */ |
| 420 | private void assertNotClosed() throws IOException |
| 421 | { |
| 422 | if ( this.closed ) |
| 423 | { |
| 424 | throw new IOException( this.getAlreadyClosedMessage( |
| 425 | this.getLocale() ) ); |
| 426 | |
| 427 | } |
| 428 | } |
| 429 | |
| 430 | /** |
| 431 | * Fills the cache starting at the current file pointer value. |
| 432 | * |
| 433 | * @throws IOException if reading fails. |
| 434 | */ |
| 435 | private void fillCache() throws IOException |
| 436 | { |
| 437 | final long delta = this.getLength() - this.filePointer; |
| 438 | final int toRead = delta > this.getCache().length |
| 439 | ? this.getCache().length |
| 440 | : (int) delta; |
| 441 | |
| 442 | this.cachePosition = this.filePointer; |
| 443 | |
| 444 | int totalRead = 0; |
| 445 | int readLength = toRead; |
| 446 | |
| 447 | do |
| 448 | { |
| 449 | this.fileOperations.setFilePointer( this.filePointer ); |
| 450 | final int read = this.fileOperations.read( |
| 451 | this.getCache(), totalRead, readLength ); |
| 452 | |
| 453 | assert read != FileOperations.EOF : "Unexpected end of file."; |
| 454 | |
| 455 | totalRead += read; |
| 456 | readLength -= read; |
| 457 | |
| 458 | } |
| 459 | while ( totalRead < toRead ); |
| 460 | |
| 461 | this.cacheLength = toRead; |
| 462 | } |
| 463 | |
| 464 | //-------------------------------------------------ReadAheadFileOperations-- |
| 465 | //--Messages---------------------------------------------------------------- |
| 466 | |
| 467 | // <editor-fold defaultstate="collapsed" desc=" Generated Code ">//GEN-BEGIN:jdtausMessages |
| 468 | // This section is managed by jdtaus-container-mojo. |
| 469 | |
| 470 | /** |
| 471 | * Gets the text of message <code>alreadyClosed</code>. |
| 472 | * <blockquote><pre>Instanz geschlossen - keine E/A-Operationen möglich.</pre></blockquote> |
| 473 | * <blockquote><pre>Instance closed - cannot perform I/O.</pre></blockquote> |
| 474 | * |
| 475 | * @param locale The locale of the message instance to return. |
| 476 | * |
| 477 | * @return Message stating that an instance is already closed. |
| 478 | */ |
| 479 | private String getAlreadyClosedMessage( final Locale locale ) |
| 480 | { |
| 481 | return ContainerFactory.getContainer(). |
| 482 | getMessage( this, "alreadyClosed", locale, null ); |
| 483 | |
| 484 | } |
| 485 | |
| 486 | // </editor-fold>//GEN-END:jdtausMessages |
| 487 | |
| 488 | //----------------------------------------------------------------Messages-- |
| 489 | } |