Alexander Lucas | 97842ff | 2014-03-07 14:56:55 -0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2011 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.example.android.displayingbitmaps.util; |
| 18 | |
| 19 | import java.io.BufferedInputStream; |
| 20 | import java.io.BufferedWriter; |
| 21 | import java.io.Closeable; |
| 22 | import java.io.EOFException; |
| 23 | import java.io.File; |
| 24 | import java.io.FileInputStream; |
| 25 | import java.io.FileNotFoundException; |
| 26 | import java.io.FileOutputStream; |
| 27 | import java.io.FileWriter; |
| 28 | import java.io.FilterOutputStream; |
| 29 | import java.io.IOException; |
| 30 | import java.io.InputStream; |
| 31 | import java.io.InputStreamReader; |
| 32 | import java.io.OutputStream; |
| 33 | import java.io.OutputStreamWriter; |
| 34 | import java.io.Reader; |
| 35 | import java.io.StringWriter; |
| 36 | import java.io.Writer; |
| 37 | import java.lang.reflect.Array; |
| 38 | import java.nio.charset.Charset; |
| 39 | import java.util.ArrayList; |
| 40 | import java.util.Arrays; |
| 41 | import java.util.Iterator; |
| 42 | import java.util.LinkedHashMap; |
| 43 | import java.util.Map; |
| 44 | import java.util.concurrent.Callable; |
| 45 | import java.util.concurrent.ExecutorService; |
| 46 | import java.util.concurrent.LinkedBlockingQueue; |
| 47 | import java.util.concurrent.ThreadPoolExecutor; |
| 48 | import java.util.concurrent.TimeUnit; |
| 49 | |
| 50 | /** |
| 51 | ****************************************************************************** |
| 52 | * Taken from the JB source code, can be found in: |
| 53 | * libcore/luni/src/main/java/libcore/io/DiskLruCache.java |
| 54 | * or direct link: |
| 55 | * https://android.googlesource.com/platform/libcore/+/android-4.1.1_r1/luni/src/main/java/libcore/io/DiskLruCache.java |
| 56 | ****************************************************************************** |
| 57 | * |
| 58 | * A cache that uses a bounded amount of space on a filesystem. Each cache |
| 59 | * entry has a string key and a fixed number of values. Values are byte |
| 60 | * sequences, accessible as streams or files. Each value must be between {@code |
| 61 | * 0} and {@code Integer.MAX_VALUE} bytes in length. |
| 62 | * |
| 63 | * <p>The cache stores its data in a directory on the filesystem. This |
| 64 | * directory must be exclusive to the cache; the cache may delete or overwrite |
| 65 | * files from its directory. It is an error for multiple processes to use the |
| 66 | * same cache directory at the same time. |
| 67 | * |
| 68 | * <p>This cache limits the number of bytes that it will store on the |
| 69 | * filesystem. When the number of stored bytes exceeds the limit, the cache will |
| 70 | * remove entries in the background until the limit is satisfied. The limit is |
| 71 | * not strict: the cache may temporarily exceed it while waiting for files to be |
| 72 | * deleted. The limit does not include filesystem overhead or the cache |
| 73 | * journal so space-sensitive applications should set a conservative limit. |
| 74 | * |
| 75 | * <p>Clients call {@link #edit} to create or update the values of an entry. An |
| 76 | * entry may have only one editor at one time; if a value is not available to be |
| 77 | * edited then {@link #edit} will return null. |
| 78 | * <ul> |
| 79 | * <li>When an entry is being <strong>created</strong> it is necessary to |
| 80 | * supply a full set of values; the empty value should be used as a |
| 81 | * placeholder if necessary. |
| 82 | * <li>When an entry is being <strong>edited</strong>, it is not necessary |
| 83 | * to supply data for every value; values default to their previous |
| 84 | * value. |
| 85 | * </ul> |
| 86 | * Every {@link #edit} call must be matched by a call to {@link Editor#commit} |
| 87 | * or {@link Editor#abort}. Committing is atomic: a read observes the full set |
| 88 | * of values as they were before or after the commit, but never a mix of values. |
| 89 | * |
| 90 | * <p>Clients call {@link #get} to read a snapshot of an entry. The read will |
| 91 | * observe the value at the time that {@link #get} was called. Updates and |
| 92 | * removals after the call do not impact ongoing reads. |
| 93 | * |
| 94 | * <p>This class is tolerant of some I/O errors. If files are missing from the |
| 95 | * filesystem, the corresponding entries will be dropped from the cache. If |
| 96 | * an error occurs while writing a cache value, the edit will fail silently. |
| 97 | * Callers should handle other problems by catching {@code IOException} and |
| 98 | * responding appropriately. |
| 99 | */ |
| 100 | public final class DiskLruCache implements Closeable { |
| 101 | static final String JOURNAL_FILE = "journal"; |
| 102 | static final String JOURNAL_FILE_TMP = "journal.tmp"; |
| 103 | static final String MAGIC = "libcore.io.DiskLruCache"; |
| 104 | static final String VERSION_1 = "1"; |
| 105 | static final long ANY_SEQUENCE_NUMBER = -1; |
| 106 | private static final String CLEAN = "CLEAN"; |
| 107 | private static final String DIRTY = "DIRTY"; |
| 108 | private static final String REMOVE = "REMOVE"; |
| 109 | private static final String READ = "READ"; |
| 110 | |
| 111 | private static final Charset UTF_8 = Charset.forName("UTF-8"); |
| 112 | private static final int IO_BUFFER_SIZE = 8 * 1024; |
| 113 | |
| 114 | /* |
| 115 | * This cache uses a journal file named "journal". A typical journal file |
| 116 | * looks like this: |
| 117 | * libcore.io.DiskLruCache |
| 118 | * 1 |
| 119 | * 100 |
| 120 | * 2 |
| 121 | * |
| 122 | * CLEAN 3400330d1dfc7f3f7f4b8d4d803dfcf6 832 21054 |
| 123 | * DIRTY 335c4c6028171cfddfbaae1a9c313c52 |
| 124 | * CLEAN 335c4c6028171cfddfbaae1a9c313c52 3934 2342 |
| 125 | * REMOVE 335c4c6028171cfddfbaae1a9c313c52 |
| 126 | * DIRTY 1ab96a171faeeee38496d8b330771a7a |
| 127 | * CLEAN 1ab96a171faeeee38496d8b330771a7a 1600 234 |
| 128 | * READ 335c4c6028171cfddfbaae1a9c313c52 |
| 129 | * READ 3400330d1dfc7f3f7f4b8d4d803dfcf6 |
| 130 | * |
| 131 | * The first five lines of the journal form its header. They are the |
| 132 | * constant string "libcore.io.DiskLruCache", the disk cache's version, |
| 133 | * the application's version, the value count, and a blank line. |
| 134 | * |
| 135 | * Each of the subsequent lines in the file is a record of the state of a |
| 136 | * cache entry. Each line contains space-separated values: a state, a key, |
| 137 | * and optional state-specific values. |
| 138 | * o DIRTY lines track that an entry is actively being created or updated. |
| 139 | * Every successful DIRTY action should be followed by a CLEAN or REMOVE |
| 140 | * action. DIRTY lines without a matching CLEAN or REMOVE indicate that |
| 141 | * temporary files may need to be deleted. |
| 142 | * o CLEAN lines track a cache entry that has been successfully published |
| 143 | * and may be read. A publish line is followed by the lengths of each of |
| 144 | * its values. |
| 145 | * o READ lines track accesses for LRU. |
| 146 | * o REMOVE lines track entries that have been deleted. |
| 147 | * |
| 148 | * The journal file is appended to as cache operations occur. The journal may |
| 149 | * occasionally be compacted by dropping redundant lines. A temporary file named |
| 150 | * "journal.tmp" will be used during compaction; that file should be deleted if |
| 151 | * it exists when the cache is opened. |
| 152 | */ |
| 153 | |
| 154 | private final File directory; |
| 155 | private final File journalFile; |
| 156 | private final File journalFileTmp; |
| 157 | private final int appVersion; |
| 158 | private final long maxSize; |
| 159 | private final int valueCount; |
| 160 | private long size = 0; |
| 161 | private Writer journalWriter; |
| 162 | private final LinkedHashMap<String, Entry> lruEntries |
| 163 | = new LinkedHashMap<String, Entry>(0, 0.75f, true); |
| 164 | private int redundantOpCount; |
| 165 | |
| 166 | /** |
| 167 | * To differentiate between old and current snapshots, each entry is given |
| 168 | * a sequence number each time an edit is committed. A snapshot is stale if |
| 169 | * its sequence number is not equal to its entry's sequence number. |
| 170 | */ |
| 171 | private long nextSequenceNumber = 0; |
| 172 | |
| 173 | /* From java.util.Arrays */ |
| 174 | @SuppressWarnings("unchecked") |
| 175 | private static <T> T[] copyOfRange(T[] original, int start, int end) { |
| 176 | final int originalLength = original.length; // For exception priority compatibility. |
| 177 | if (start > end) { |
| 178 | throw new IllegalArgumentException(); |
| 179 | } |
| 180 | if (start < 0 || start > originalLength) { |
| 181 | throw new ArrayIndexOutOfBoundsException(); |
| 182 | } |
| 183 | final int resultLength = end - start; |
| 184 | final int copyLength = Math.min(resultLength, originalLength - start); |
| 185 | final T[] result = (T[]) Array |
| 186 | .newInstance(original.getClass().getComponentType(), resultLength); |
| 187 | System.arraycopy(original, start, result, 0, copyLength); |
| 188 | return result; |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * Returns the remainder of 'reader' as a string, closing it when done. |
| 193 | */ |
| 194 | public static String readFully(Reader reader) throws IOException { |
| 195 | try { |
| 196 | StringWriter writer = new StringWriter(); |
| 197 | char[] buffer = new char[1024]; |
| 198 | int count; |
| 199 | while ((count = reader.read(buffer)) != -1) { |
| 200 | writer.write(buffer, 0, count); |
| 201 | } |
| 202 | return writer.toString(); |
| 203 | } finally { |
| 204 | reader.close(); |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Returns the ASCII characters up to but not including the next "\r\n", or |
| 210 | * "\n". |
| 211 | * |
| 212 | * @throws java.io.EOFException if the stream is exhausted before the next newline |
| 213 | * character. |
| 214 | */ |
| 215 | public static String readAsciiLine(InputStream in) throws IOException { |
| 216 | // TODO: support UTF-8 here instead |
| 217 | |
| 218 | StringBuilder result = new StringBuilder(80); |
| 219 | while (true) { |
| 220 | int c = in.read(); |
| 221 | if (c == -1) { |
| 222 | throw new EOFException(); |
| 223 | } else if (c == '\n') { |
| 224 | break; |
| 225 | } |
| 226 | |
| 227 | result.append((char) c); |
| 228 | } |
| 229 | int length = result.length(); |
| 230 | if (length > 0 && result.charAt(length - 1) == '\r') { |
| 231 | result.setLength(length - 1); |
| 232 | } |
| 233 | return result.toString(); |
| 234 | } |
| 235 | |
| 236 | /** |
| 237 | * Closes 'closeable', ignoring any checked exceptions. Does nothing if 'closeable' is null. |
| 238 | */ |
| 239 | public static void closeQuietly(Closeable closeable) { |
| 240 | if (closeable != null) { |
| 241 | try { |
| 242 | closeable.close(); |
| 243 | } catch (RuntimeException rethrown) { |
| 244 | throw rethrown; |
| 245 | } catch (Exception ignored) { |
| 246 | } |
| 247 | } |
| 248 | } |
| 249 | |
| 250 | /** |
| 251 | * Recursively delete everything in {@code dir}. |
| 252 | */ |
| 253 | // TODO: this should specify paths as Strings rather than as Files |
| 254 | public static void deleteContents(File dir) throws IOException { |
| 255 | File[] files = dir.listFiles(); |
| 256 | if (files == null) { |
| 257 | throw new IllegalArgumentException("not a directory: " + dir); |
| 258 | } |
| 259 | for (File file : files) { |
| 260 | if (file.isDirectory()) { |
| 261 | deleteContents(file); |
| 262 | } |
| 263 | if (!file.delete()) { |
| 264 | throw new IOException("failed to delete file: " + file); |
| 265 | } |
| 266 | } |
| 267 | } |
| 268 | |
| 269 | /** This cache uses a single background thread to evict entries. */ |
| 270 | private final ExecutorService executorService = new ThreadPoolExecutor(0, 1, |
| 271 | 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); |
| 272 | private final Callable<Void> cleanupCallable = new Callable<Void>() { |
| 273 | @Override public Void call() throws Exception { |
| 274 | synchronized (DiskLruCache.this) { |
| 275 | if (journalWriter == null) { |
| 276 | return null; // closed |
| 277 | } |
| 278 | trimToSize(); |
| 279 | if (journalRebuildRequired()) { |
| 280 | rebuildJournal(); |
| 281 | redundantOpCount = 0; |
| 282 | } |
| 283 | } |
| 284 | return null; |
| 285 | } |
| 286 | }; |
| 287 | |
| 288 | private DiskLruCache(File directory, int appVersion, int valueCount, long maxSize) { |
| 289 | this.directory = directory; |
| 290 | this.appVersion = appVersion; |
| 291 | this.journalFile = new File(directory, JOURNAL_FILE); |
| 292 | this.journalFileTmp = new File(directory, JOURNAL_FILE_TMP); |
| 293 | this.valueCount = valueCount; |
| 294 | this.maxSize = maxSize; |
| 295 | } |
| 296 | |
| 297 | /** |
| 298 | * Opens the cache in {@code directory}, creating a cache if none exists |
| 299 | * there. |
| 300 | * |
| 301 | * @param directory a writable directory |
| 302 | * @param appVersion |
| 303 | * @param valueCount the number of values per cache entry. Must be positive. |
| 304 | * @param maxSize the maximum number of bytes this cache should use to store |
| 305 | * @throws java.io.IOException if reading or writing the cache directory fails |
| 306 | */ |
| 307 | public static DiskLruCache open(File directory, int appVersion, int valueCount, long maxSize) |
| 308 | throws IOException { |
| 309 | if (maxSize <= 0) { |
| 310 | throw new IllegalArgumentException("maxSize <= 0"); |
| 311 | } |
| 312 | if (valueCount <= 0) { |
| 313 | throw new IllegalArgumentException("valueCount <= 0"); |
| 314 | } |
| 315 | |
| 316 | // prefer to pick up where we left off |
| 317 | DiskLruCache cache = new DiskLruCache(directory, appVersion, valueCount, maxSize); |
| 318 | if (cache.journalFile.exists()) { |
| 319 | try { |
| 320 | cache.readJournal(); |
| 321 | cache.processJournal(); |
| 322 | cache.journalWriter = new BufferedWriter(new FileWriter(cache.journalFile, true), |
| 323 | IO_BUFFER_SIZE); |
| 324 | return cache; |
| 325 | } catch (IOException journalIsCorrupt) { |
| 326 | // System.logW("DiskLruCache " + directory + " is corrupt: " |
| 327 | // + journalIsCorrupt.getMessage() + ", removing"); |
| 328 | cache.delete(); |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | // create a new empty cache |
| 333 | directory.mkdirs(); |
| 334 | cache = new DiskLruCache(directory, appVersion, valueCount, maxSize); |
| 335 | cache.rebuildJournal(); |
| 336 | return cache; |
| 337 | } |
| 338 | |
| 339 | private void readJournal() throws IOException { |
| 340 | InputStream in = new BufferedInputStream(new FileInputStream(journalFile), IO_BUFFER_SIZE); |
| 341 | try { |
| 342 | String magic = readAsciiLine(in); |
| 343 | String version = readAsciiLine(in); |
| 344 | String appVersionString = readAsciiLine(in); |
| 345 | String valueCountString = readAsciiLine(in); |
| 346 | String blank = readAsciiLine(in); |
| 347 | if (!MAGIC.equals(magic) |
| 348 | || !VERSION_1.equals(version) |
| 349 | || !Integer.toString(appVersion).equals(appVersionString) |
| 350 | || !Integer.toString(valueCount).equals(valueCountString) |
| 351 | || !"".equals(blank)) { |
| 352 | throw new IOException("unexpected journal header: [" |
| 353 | + magic + ", " + version + ", " + valueCountString + ", " + blank + "]"); |
| 354 | } |
| 355 | |
| 356 | while (true) { |
| 357 | try { |
| 358 | readJournalLine(readAsciiLine(in)); |
| 359 | } catch (EOFException endOfJournal) { |
| 360 | break; |
| 361 | } |
| 362 | } |
| 363 | } finally { |
| 364 | closeQuietly(in); |
| 365 | } |
| 366 | } |
| 367 | |
| 368 | private void readJournalLine(String line) throws IOException { |
| 369 | String[] parts = line.split(" "); |
| 370 | if (parts.length < 2) { |
| 371 | throw new IOException("unexpected journal line: " + line); |
| 372 | } |
| 373 | |
| 374 | String key = parts[1]; |
| 375 | if (parts[0].equals(REMOVE) && parts.length == 2) { |
| 376 | lruEntries.remove(key); |
| 377 | return; |
| 378 | } |
| 379 | |
| 380 | Entry entry = lruEntries.get(key); |
| 381 | if (entry == null) { |
| 382 | entry = new Entry(key); |
| 383 | lruEntries.put(key, entry); |
| 384 | } |
| 385 | |
| 386 | if (parts[0].equals(CLEAN) && parts.length == 2 + valueCount) { |
| 387 | entry.readable = true; |
| 388 | entry.currentEditor = null; |
| 389 | entry.setLengths(copyOfRange(parts, 2, parts.length)); |
| 390 | } else if (parts[0].equals(DIRTY) && parts.length == 2) { |
| 391 | entry.currentEditor = new Editor(entry); |
| 392 | } else if (parts[0].equals(READ) && parts.length == 2) { |
| 393 | // this work was already done by calling lruEntries.get() |
| 394 | } else { |
| 395 | throw new IOException("unexpected journal line: " + line); |
| 396 | } |
| 397 | } |
| 398 | |
| 399 | /** |
| 400 | * Computes the initial size and collects garbage as a part of opening the |
| 401 | * cache. Dirty entries are assumed to be inconsistent and will be deleted. |
| 402 | */ |
| 403 | private void processJournal() throws IOException { |
| 404 | deleteIfExists(journalFileTmp); |
| 405 | for (Iterator<Entry> i = lruEntries.values().iterator(); i.hasNext(); ) { |
| 406 | Entry entry = i.next(); |
| 407 | if (entry.currentEditor == null) { |
| 408 | for (int t = 0; t < valueCount; t++) { |
| 409 | size += entry.lengths[t]; |
| 410 | } |
| 411 | } else { |
| 412 | entry.currentEditor = null; |
| 413 | for (int t = 0; t < valueCount; t++) { |
| 414 | deleteIfExists(entry.getCleanFile(t)); |
| 415 | deleteIfExists(entry.getDirtyFile(t)); |
| 416 | } |
| 417 | i.remove(); |
| 418 | } |
| 419 | } |
| 420 | } |
| 421 | |
| 422 | /** |
| 423 | * Creates a new journal that omits redundant information. This replaces the |
| 424 | * current journal if it exists. |
| 425 | */ |
| 426 | private synchronized void rebuildJournal() throws IOException { |
| 427 | if (journalWriter != null) { |
| 428 | journalWriter.close(); |
| 429 | } |
| 430 | |
| 431 | Writer writer = new BufferedWriter(new FileWriter(journalFileTmp), IO_BUFFER_SIZE); |
| 432 | writer.write(MAGIC); |
| 433 | writer.write("\n"); |
| 434 | writer.write(VERSION_1); |
| 435 | writer.write("\n"); |
| 436 | writer.write(Integer.toString(appVersion)); |
| 437 | writer.write("\n"); |
| 438 | writer.write(Integer.toString(valueCount)); |
| 439 | writer.write("\n"); |
| 440 | writer.write("\n"); |
| 441 | |
| 442 | for (Entry entry : lruEntries.values()) { |
| 443 | if (entry.currentEditor != null) { |
| 444 | writer.write(DIRTY + ' ' + entry.key + '\n'); |
| 445 | } else { |
| 446 | writer.write(CLEAN + ' ' + entry.key + entry.getLengths() + '\n'); |
| 447 | } |
| 448 | } |
| 449 | |
| 450 | writer.close(); |
| 451 | journalFileTmp.renameTo(journalFile); |
| 452 | journalWriter = new BufferedWriter(new FileWriter(journalFile, true), IO_BUFFER_SIZE); |
| 453 | } |
| 454 | |
| 455 | private static void deleteIfExists(File file) throws IOException { |
| 456 | // try { |
| 457 | // Libcore.os.remove(file.getPath()); |
| 458 | // } catch (ErrnoException errnoException) { |
| 459 | // if (errnoException.errno != OsConstants.ENOENT) { |
| 460 | // throw errnoException.rethrowAsIOException(); |
| 461 | // } |
| 462 | // } |
| 463 | if (file.exists() && !file.delete()) { |
| 464 | throw new IOException(); |
| 465 | } |
| 466 | } |
| 467 | |
| 468 | /** |
| 469 | * Returns a snapshot of the entry named {@code key}, or null if it doesn't |
| 470 | * exist is not currently readable. If a value is returned, it is moved to |
| 471 | * the head of the LRU queue. |
| 472 | */ |
| 473 | public synchronized Snapshot get(String key) throws IOException { |
| 474 | checkNotClosed(); |
| 475 | validateKey(key); |
| 476 | Entry entry = lruEntries.get(key); |
| 477 | if (entry == null) { |
| 478 | return null; |
| 479 | } |
| 480 | |
| 481 | if (!entry.readable) { |
| 482 | return null; |
| 483 | } |
| 484 | |
| 485 | /* |
| 486 | * Open all streams eagerly to guarantee that we see a single published |
| 487 | * snapshot. If we opened streams lazily then the streams could come |
| 488 | * from different edits. |
| 489 | */ |
| 490 | InputStream[] ins = new InputStream[valueCount]; |
| 491 | try { |
| 492 | for (int i = 0; i < valueCount; i++) { |
| 493 | ins[i] = new FileInputStream(entry.getCleanFile(i)); |
| 494 | } |
| 495 | } catch (FileNotFoundException e) { |
| 496 | // a file must have been deleted manually! |
| 497 | return null; |
| 498 | } |
| 499 | |
| 500 | redundantOpCount++; |
| 501 | journalWriter.append(READ + ' ' + key + '\n'); |
| 502 | if (journalRebuildRequired()) { |
| 503 | executorService.submit(cleanupCallable); |
| 504 | } |
| 505 | |
| 506 | return new Snapshot(key, entry.sequenceNumber, ins); |
| 507 | } |
| 508 | |
| 509 | /** |
| 510 | * Returns an editor for the entry named {@code key}, or null if another |
| 511 | * edit is in progress. |
| 512 | */ |
| 513 | public Editor edit(String key) throws IOException { |
| 514 | return edit(key, ANY_SEQUENCE_NUMBER); |
| 515 | } |
| 516 | |
| 517 | private synchronized Editor edit(String key, long expectedSequenceNumber) throws IOException { |
| 518 | checkNotClosed(); |
| 519 | validateKey(key); |
| 520 | Entry entry = lruEntries.get(key); |
| 521 | if (expectedSequenceNumber != ANY_SEQUENCE_NUMBER |
| 522 | && (entry == null || entry.sequenceNumber != expectedSequenceNumber)) { |
| 523 | return null; // snapshot is stale |
| 524 | } |
| 525 | if (entry == null) { |
| 526 | entry = new Entry(key); |
| 527 | lruEntries.put(key, entry); |
| 528 | } else if (entry.currentEditor != null) { |
| 529 | return null; // another edit is in progress |
| 530 | } |
| 531 | |
| 532 | Editor editor = new Editor(entry); |
| 533 | entry.currentEditor = editor; |
| 534 | |
| 535 | // flush the journal before creating files to prevent file leaks |
| 536 | journalWriter.write(DIRTY + ' ' + key + '\n'); |
| 537 | journalWriter.flush(); |
| 538 | return editor; |
| 539 | } |
| 540 | |
| 541 | /** |
| 542 | * Returns the directory where this cache stores its data. |
| 543 | */ |
| 544 | public File getDirectory() { |
| 545 | return directory; |
| 546 | } |
| 547 | |
| 548 | /** |
| 549 | * Returns the maximum number of bytes that this cache should use to store |
| 550 | * its data. |
| 551 | */ |
| 552 | public long maxSize() { |
| 553 | return maxSize; |
| 554 | } |
| 555 | |
| 556 | /** |
| 557 | * Returns the number of bytes currently being used to store the values in |
| 558 | * this cache. This may be greater than the max size if a background |
| 559 | * deletion is pending. |
| 560 | */ |
| 561 | public synchronized long size() { |
| 562 | return size; |
| 563 | } |
| 564 | |
| 565 | private synchronized void completeEdit(Editor editor, boolean success) throws IOException { |
| 566 | Entry entry = editor.entry; |
| 567 | if (entry.currentEditor != editor) { |
| 568 | throw new IllegalStateException(); |
| 569 | } |
| 570 | |
| 571 | // if this edit is creating the entry for the first time, every index must have a value |
| 572 | if (success && !entry.readable) { |
| 573 | for (int i = 0; i < valueCount; i++) { |
| 574 | if (!entry.getDirtyFile(i).exists()) { |
| 575 | editor.abort(); |
| 576 | throw new IllegalStateException("edit didn't create file " + i); |
| 577 | } |
| 578 | } |
| 579 | } |
| 580 | |
| 581 | for (int i = 0; i < valueCount; i++) { |
| 582 | File dirty = entry.getDirtyFile(i); |
| 583 | if (success) { |
| 584 | if (dirty.exists()) { |
| 585 | File clean = entry.getCleanFile(i); |
| 586 | dirty.renameTo(clean); |
| 587 | long oldLength = entry.lengths[i]; |
| 588 | long newLength = clean.length(); |
| 589 | entry.lengths[i] = newLength; |
| 590 | size = size - oldLength + newLength; |
| 591 | } |
| 592 | } else { |
| 593 | deleteIfExists(dirty); |
| 594 | } |
| 595 | } |
| 596 | |
| 597 | redundantOpCount++; |
| 598 | entry.currentEditor = null; |
| 599 | if (entry.readable | success) { |
| 600 | entry.readable = true; |
| 601 | journalWriter.write(CLEAN + ' ' + entry.key + entry.getLengths() + '\n'); |
| 602 | if (success) { |
| 603 | entry.sequenceNumber = nextSequenceNumber++; |
| 604 | } |
| 605 | } else { |
| 606 | lruEntries.remove(entry.key); |
| 607 | journalWriter.write(REMOVE + ' ' + entry.key + '\n'); |
| 608 | } |
| 609 | |
| 610 | if (size > maxSize || journalRebuildRequired()) { |
| 611 | executorService.submit(cleanupCallable); |
| 612 | } |
| 613 | } |
| 614 | |
| 615 | /** |
| 616 | * We only rebuild the journal when it will halve the size of the journal |
| 617 | * and eliminate at least 2000 ops. |
| 618 | */ |
| 619 | private boolean journalRebuildRequired() { |
| 620 | final int REDUNDANT_OP_COMPACT_THRESHOLD = 2000; |
| 621 | return redundantOpCount >= REDUNDANT_OP_COMPACT_THRESHOLD |
| 622 | && redundantOpCount >= lruEntries.size(); |
| 623 | } |
| 624 | |
| 625 | /** |
| 626 | * Drops the entry for {@code key} if it exists and can be removed. Entries |
| 627 | * actively being edited cannot be removed. |
| 628 | * |
| 629 | * @return true if an entry was removed. |
| 630 | */ |
| 631 | public synchronized boolean remove(String key) throws IOException { |
| 632 | checkNotClosed(); |
| 633 | validateKey(key); |
| 634 | Entry entry = lruEntries.get(key); |
| 635 | if (entry == null || entry.currentEditor != null) { |
| 636 | return false; |
| 637 | } |
| 638 | |
| 639 | for (int i = 0; i < valueCount; i++) { |
| 640 | File file = entry.getCleanFile(i); |
| 641 | if (!file.delete()) { |
| 642 | throw new IOException("failed to delete " + file); |
| 643 | } |
| 644 | size -= entry.lengths[i]; |
| 645 | entry.lengths[i] = 0; |
| 646 | } |
| 647 | |
| 648 | redundantOpCount++; |
| 649 | journalWriter.append(REMOVE + ' ' + key + '\n'); |
| 650 | lruEntries.remove(key); |
| 651 | |
| 652 | if (journalRebuildRequired()) { |
| 653 | executorService.submit(cleanupCallable); |
| 654 | } |
| 655 | |
| 656 | return true; |
| 657 | } |
| 658 | |
| 659 | /** |
| 660 | * Returns true if this cache has been closed. |
| 661 | */ |
| 662 | public boolean isClosed() { |
| 663 | return journalWriter == null; |
| 664 | } |
| 665 | |
| 666 | private void checkNotClosed() { |
| 667 | if (journalWriter == null) { |
| 668 | throw new IllegalStateException("cache is closed"); |
| 669 | } |
| 670 | } |
| 671 | |
| 672 | /** |
| 673 | * Force buffered operations to the filesystem. |
| 674 | */ |
| 675 | public synchronized void flush() throws IOException { |
| 676 | checkNotClosed(); |
| 677 | trimToSize(); |
| 678 | journalWriter.flush(); |
| 679 | } |
| 680 | |
| 681 | /** |
| 682 | * Closes this cache. Stored values will remain on the filesystem. |
| 683 | */ |
| 684 | public synchronized void close() throws IOException { |
| 685 | if (journalWriter == null) { |
| 686 | return; // already closed |
| 687 | } |
| 688 | for (Entry entry : new ArrayList<Entry>(lruEntries.values())) { |
| 689 | if (entry.currentEditor != null) { |
| 690 | entry.currentEditor.abort(); |
| 691 | } |
| 692 | } |
| 693 | trimToSize(); |
| 694 | journalWriter.close(); |
| 695 | journalWriter = null; |
| 696 | } |
| 697 | |
| 698 | private void trimToSize() throws IOException { |
| 699 | while (size > maxSize) { |
| 700 | // Map.Entry<String, Entry> toEvict = lruEntries.eldest(); |
| 701 | final Map.Entry<String, Entry> toEvict = lruEntries.entrySet().iterator().next(); |
| 702 | remove(toEvict.getKey()); |
| 703 | } |
| 704 | } |
| 705 | |
| 706 | /** |
| 707 | * Closes the cache and deletes all of its stored values. This will delete |
| 708 | * all files in the cache directory including files that weren't created by |
| 709 | * the cache. |
| 710 | */ |
| 711 | public void delete() throws IOException { |
| 712 | close(); |
| 713 | deleteContents(directory); |
| 714 | } |
| 715 | |
| 716 | private void validateKey(String key) { |
| 717 | if (key.contains(" ") || key.contains("\n") || key.contains("\r")) { |
| 718 | throw new IllegalArgumentException( |
| 719 | "keys must not contain spaces or newlines: \"" + key + "\""); |
| 720 | } |
| 721 | } |
| 722 | |
| 723 | private static String inputStreamToString(InputStream in) throws IOException { |
| 724 | return readFully(new InputStreamReader(in, UTF_8)); |
| 725 | } |
| 726 | |
| 727 | /** |
| 728 | * A snapshot of the values for an entry. |
| 729 | */ |
| 730 | public final class Snapshot implements Closeable { |
| 731 | private final String key; |
| 732 | private final long sequenceNumber; |
| 733 | private final InputStream[] ins; |
| 734 | |
| 735 | private Snapshot(String key, long sequenceNumber, InputStream[] ins) { |
| 736 | this.key = key; |
| 737 | this.sequenceNumber = sequenceNumber; |
| 738 | this.ins = ins; |
| 739 | } |
| 740 | |
| 741 | /** |
| 742 | * Returns an editor for this snapshot's entry, or null if either the |
| 743 | * entry has changed since this snapshot was created or if another edit |
| 744 | * is in progress. |
| 745 | */ |
| 746 | public Editor edit() throws IOException { |
| 747 | return DiskLruCache.this.edit(key, sequenceNumber); |
| 748 | } |
| 749 | |
| 750 | /** |
| 751 | * Returns the unbuffered stream with the value for {@code index}. |
| 752 | */ |
| 753 | public InputStream getInputStream(int index) { |
| 754 | return ins[index]; |
| 755 | } |
| 756 | |
| 757 | /** |
| 758 | * Returns the string value for {@code index}. |
| 759 | */ |
| 760 | public String getString(int index) throws IOException { |
| 761 | return inputStreamToString(getInputStream(index)); |
| 762 | } |
| 763 | |
| 764 | @Override public void close() { |
| 765 | for (InputStream in : ins) { |
| 766 | closeQuietly(in); |
| 767 | } |
| 768 | } |
| 769 | } |
| 770 | |
| 771 | /** |
| 772 | * Edits the values for an entry. |
| 773 | */ |
| 774 | public final class Editor { |
| 775 | private final Entry entry; |
| 776 | private boolean hasErrors; |
| 777 | |
| 778 | private Editor(Entry entry) { |
| 779 | this.entry = entry; |
| 780 | } |
| 781 | |
| 782 | /** |
| 783 | * Returns an unbuffered input stream to read the last committed value, |
| 784 | * or null if no value has been committed. |
| 785 | */ |
| 786 | public InputStream newInputStream(int index) throws IOException { |
| 787 | synchronized (DiskLruCache.this) { |
| 788 | if (entry.currentEditor != this) { |
| 789 | throw new IllegalStateException(); |
| 790 | } |
| 791 | if (!entry.readable) { |
| 792 | return null; |
| 793 | } |
| 794 | return new FileInputStream(entry.getCleanFile(index)); |
| 795 | } |
| 796 | } |
| 797 | |
| 798 | /** |
| 799 | * Returns the last committed value as a string, or null if no value |
| 800 | * has been committed. |
| 801 | */ |
| 802 | public String getString(int index) throws IOException { |
| 803 | InputStream in = newInputStream(index); |
| 804 | return in != null ? inputStreamToString(in) : null; |
| 805 | } |
| 806 | |
| 807 | /** |
| 808 | * Returns a new unbuffered output stream to write the value at |
| 809 | * {@code index}. If the underlying output stream encounters errors |
| 810 | * when writing to the filesystem, this edit will be aborted when |
| 811 | * {@link #commit} is called. The returned output stream does not throw |
| 812 | * IOExceptions. |
| 813 | */ |
| 814 | public OutputStream newOutputStream(int index) throws IOException { |
| 815 | synchronized (DiskLruCache.this) { |
| 816 | if (entry.currentEditor != this) { |
| 817 | throw new IllegalStateException(); |
| 818 | } |
| 819 | return new FaultHidingOutputStream(new FileOutputStream(entry.getDirtyFile(index))); |
| 820 | } |
| 821 | } |
| 822 | |
| 823 | /** |
| 824 | * Sets the value at {@code index} to {@code value}. |
| 825 | */ |
| 826 | public void set(int index, String value) throws IOException { |
| 827 | Writer writer = null; |
| 828 | try { |
| 829 | writer = new OutputStreamWriter(newOutputStream(index), UTF_8); |
| 830 | writer.write(value); |
| 831 | } finally { |
| 832 | closeQuietly(writer); |
| 833 | } |
| 834 | } |
| 835 | |
| 836 | /** |
| 837 | * Commits this edit so it is visible to readers. This releases the |
| 838 | * edit lock so another edit may be started on the same key. |
| 839 | */ |
| 840 | public void commit() throws IOException { |
| 841 | if (hasErrors) { |
| 842 | completeEdit(this, false); |
| 843 | remove(entry.key); // the previous entry is stale |
| 844 | } else { |
| 845 | completeEdit(this, true); |
| 846 | } |
| 847 | } |
| 848 | |
| 849 | /** |
| 850 | * Aborts this edit. This releases the edit lock so another edit may be |
| 851 | * started on the same key. |
| 852 | */ |
| 853 | public void abort() throws IOException { |
| 854 | completeEdit(this, false); |
| 855 | } |
| 856 | |
| 857 | private class FaultHidingOutputStream extends FilterOutputStream { |
| 858 | private FaultHidingOutputStream(OutputStream out) { |
| 859 | super(out); |
| 860 | } |
| 861 | |
| 862 | @Override public void write(int oneByte) { |
| 863 | try { |
| 864 | out.write(oneByte); |
| 865 | } catch (IOException e) { |
| 866 | hasErrors = true; |
| 867 | } |
| 868 | } |
| 869 | |
| 870 | @Override public void write(byte[] buffer, int offset, int length) { |
| 871 | try { |
| 872 | out.write(buffer, offset, length); |
| 873 | } catch (IOException e) { |
| 874 | hasErrors = true; |
| 875 | } |
| 876 | } |
| 877 | |
| 878 | @Override public void close() { |
| 879 | try { |
| 880 | out.close(); |
| 881 | } catch (IOException e) { |
| 882 | hasErrors = true; |
| 883 | } |
| 884 | } |
| 885 | |
| 886 | @Override public void flush() { |
| 887 | try { |
| 888 | out.flush(); |
| 889 | } catch (IOException e) { |
| 890 | hasErrors = true; |
| 891 | } |
| 892 | } |
| 893 | } |
| 894 | } |
| 895 | |
| 896 | private final class Entry { |
| 897 | private final String key; |
| 898 | |
| 899 | /** Lengths of this entry's files. */ |
| 900 | private final long[] lengths; |
| 901 | |
| 902 | /** True if this entry has ever been published */ |
| 903 | private boolean readable; |
| 904 | |
| 905 | /** The ongoing edit or null if this entry is not being edited. */ |
| 906 | private Editor currentEditor; |
| 907 | |
| 908 | /** The sequence number of the most recently committed edit to this entry. */ |
| 909 | private long sequenceNumber; |
| 910 | |
| 911 | private Entry(String key) { |
| 912 | this.key = key; |
| 913 | this.lengths = new long[valueCount]; |
| 914 | } |
| 915 | |
| 916 | public String getLengths() throws IOException { |
| 917 | StringBuilder result = new StringBuilder(); |
| 918 | for (long size : lengths) { |
| 919 | result.append(' ').append(size); |
| 920 | } |
| 921 | return result.toString(); |
| 922 | } |
| 923 | |
| 924 | /** |
| 925 | * Set lengths using decimal numbers like "10123". |
| 926 | */ |
| 927 | private void setLengths(String[] strings) throws IOException { |
| 928 | if (strings.length != valueCount) { |
| 929 | throw invalidLengths(strings); |
| 930 | } |
| 931 | |
| 932 | try { |
| 933 | for (int i = 0; i < strings.length; i++) { |
| 934 | lengths[i] = Long.parseLong(strings[i]); |
| 935 | } |
| 936 | } catch (NumberFormatException e) { |
| 937 | throw invalidLengths(strings); |
| 938 | } |
| 939 | } |
| 940 | |
| 941 | private IOException invalidLengths(String[] strings) throws IOException { |
| 942 | throw new IOException("unexpected journal line: " + Arrays.toString(strings)); |
| 943 | } |
| 944 | |
| 945 | public File getCleanFile(int i) { |
| 946 | return new File(directory, key + "." + i); |
| 947 | } |
| 948 | |
| 949 | public File getDirtyFile(int i) { |
| 950 | return new File(directory, key + "." + i + ".tmp"); |
| 951 | } |
| 952 | } |
| 953 | } |