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 17package com.android.volley.toolbox; 18 19import android.os.SystemClock; 20 21import com.android.volley.Cache; 22import com.android.volley.VolleyLog; 23 24import java.io.EOFException; 25import java.io.File; 26import java.io.FileInputStream; 27import java.io.FileOutputStream; 28import java.io.FilterInputStream; 29import java.io.IOException; 30import java.io.InputStream; 31import java.io.OutputStream; 32import java.util.Collections; 33import java.util.HashMap; 34import java.util.Iterator; 35import java.util.LinkedHashMap; 36import java.util.Map; 37 38/** 39 * Cache implementation that caches files directly onto the hard disk in the specified 40 * directory. The default disk usage size is 5MB, but is configurable. 41 */ 42public class DiskBasedCache implements Cache { 43 44 /** Map of the Key, CacheHeader pairs */ 45 private final Map<String, CacheHeader> mEntries = 46 new LinkedHashMap<String, CacheHeader>(16, .75f, true); 47 48 /** Total amount of space currently used by the cache in bytes. */ 49 private long mTotalSize = 0; 50 51 /** The root directory to use for the cache. */ 52 private final File mRootDirectory; 53 54 /** The maximum size of the cache in bytes. */ 55 private final int mMaxCacheSizeInBytes; 56 57 /** Default maximum disk usage in bytes. */ 58 private static final int DEFAULT_DISK_USAGE_BYTES = 5 * 1024 * 1024; 59 60 /** High water mark percentage for the cache */ 61 private static final float HYSTERESIS_FACTOR = 0.9f; 62 63 /** Magic number for current version of cache file format. */ 64 private static final int CACHE_MAGIC = 0x20140623; 65 66 /** 67 * Constructs an instance of the DiskBasedCache at the specified directory. 68 * @param rootDirectory The root directory of the cache. 69 * @param maxCacheSizeInBytes The maximum size of the cache in bytes. 70 */ 71 public DiskBasedCache(File rootDirectory, int maxCacheSizeInBytes) { 72 mRootDirectory = rootDirectory; 73 mMaxCacheSizeInBytes = maxCacheSizeInBytes; 74 } 75 76 /** 77 * Constructs an instance of the DiskBasedCache at the specified directory using 78 * the default maximum cache size of 5MB. 79 * @param rootDirectory The root directory of the cache. 80 */ 81 public DiskBasedCache(File rootDirectory) { 82 this(rootDirectory, DEFAULT_DISK_USAGE_BYTES); 83 } 84 85 /** 86 * Clears the cache. Deletes all cached files from disk. 87 */ 88 @Override 89 public synchronized void clear() { 90 File[] files = mRootDirectory.listFiles(); 91 if (files != null) { 92 for (File file : files) { 93 file.delete(); 94 } 95 } 96 mEntries.clear(); 97 mTotalSize = 0; 98 VolleyLog.d("Cache cleared."); 99 } 100 101 /** 102 * Returns the cache entry with the specified key if it exists, null otherwise. 103 */ 104 @Override 105 public synchronized Entry get(String key) { 106 CacheHeader entry = mEntries.get(key); 107 // if the entry does not exist, return. 108 if (entry == null) { 109 return null; 110 } 111 112 File file = getFileForKey(key); 113 CountingInputStream cis = null; 114 try { 115 cis = new CountingInputStream(new FileInputStream(file)); 116 CacheHeader.readHeader(cis); // eat header 117 byte[] data = streamToBytes(cis, (int) (file.length() - cis.bytesRead)); 118 return entry.toCacheEntry(data); 119 } catch (IOException e) { 120 VolleyLog.d("%s: %s", file.getAbsolutePath(), e.toString()); 121 remove(key); 122 return null; 123 } finally { 124 if (cis != null) { 125 try { 126 cis.close(); 127 } catch (IOException ioe) { 128 return null; 129 } 130 } 131 } 132 } 133 134 /** 135 * Initializes the DiskBasedCache by scanning for all files currently in the 136 * specified root directory. Creates the root directory if necessary. 137 */ 138 @Override 139 public synchronized void initialize() { 140 if (!mRootDirectory.exists()) { 141 if (!mRootDirectory.mkdirs()) { 142 VolleyLog.e("Unable to create cache dir %s", mRootDirectory.getAbsolutePath()); 143 } 144 return; 145 } 146 147 File[] files = mRootDirectory.listFiles(); 148 if (files == null) { 149 return; 150 } 151 for (File file : files) { 152 FileInputStream fis = null; 153 try { 154 fis = new FileInputStream(file); 155 CacheHeader entry = CacheHeader.readHeader(fis); 156 entry.size = file.length(); 157 putEntry(entry.key, entry); 158 } catch (IOException e) { 159 if (file != null) { 160 file.delete(); 161 } 162 } finally { 163 try { 164 if (fis != null) { 165 fis.close(); 166 } 167 } catch (IOException ignored) { } 168 } 169 } 170 } 171 172 /** 173 * Invalidates an entry in the cache. 174 * @param key Cache key 175 * @param fullExpire True to fully expire the entry, false to soft expire 176 */ 177 @Override 178 public synchronized void invalidate(String key, boolean fullExpire) { 179 Entry entry = get(key); 180 if (entry != null) { 181 entry.softTtl = 0; 182 if (fullExpire) { 183 entry.ttl = 0; 184 } 185 put(key, entry); 186 } 187 188 } 189 190 /** 191 * Puts the entry with the specified key into the cache. 192 */ 193 @Override 194 public synchronized void put(String key, Entry entry) { 195 pruneIfNeeded(entry.data.length); 196 File file = getFileForKey(key); 197 try { 198 FileOutputStream fos = new FileOutputStream(file); 199 CacheHeader e = new CacheHeader(key, entry); 200 boolean success = e.writeHeader(fos); 201 if (!success) { 202 fos.close(); 203 VolleyLog.d("Failed to write header for %s", file.getAbsolutePath()); 204 throw new IOException(); 205 } 206 fos.write(entry.data); 207 fos.close(); 208 putEntry(key, e); 209 return; 210 } catch (IOException e) { 211 } 212 boolean deleted = file.delete(); 213 if (!deleted) { 214 VolleyLog.d("Could not clean up file %s", file.getAbsolutePath()); 215 } 216 } 217 218 /** 219 * Removes the specified key from the cache if it exists. 220 */ 221 @Override 222 public synchronized void remove(String key) { 223 boolean deleted = getFileForKey(key).delete(); 224 removeEntry(key); 225 if (!deleted) { 226 VolleyLog.d("Could not delete cache entry for key=%s, filename=%s", 227 key, getFilenameForKey(key)); 228 } 229 } 230 231 /** 232 * Creates a pseudo-unique filename for the specified cache key. 233 * @param key The key to generate a file name for. 234 * @return A pseudo-unique filename. 235 */ 236 private String getFilenameForKey(String key) { 237 int firstHalfLength = key.length() / 2; 238 String localFilename = String.valueOf(key.substring(0, firstHalfLength).hashCode()); 239 localFilename += String.valueOf(key.substring(firstHalfLength).hashCode()); 240 return localFilename; 241 } 242 243 /** 244 * Returns a file object for the given cache key. 245 */ 246 public File getFileForKey(String key) { 247 return new File(mRootDirectory, getFilenameForKey(key)); 248 } 249 250 /** 251 * Prunes the cache to fit the amount of bytes specified. 252 * @param neededSpace The amount of bytes we are trying to fit into the cache. 253 */ 254 private void pruneIfNeeded(int neededSpace) { 255 if ((mTotalSize + neededSpace) < mMaxCacheSizeInBytes) { 256 return; 257 } 258 if (VolleyLog.DEBUG) { 259 VolleyLog.v("Pruning old cache entries."); 260 } 261 262 long before = mTotalSize; 263 int prunedFiles = 0; 264 long startTime = SystemClock.elapsedRealtime(); 265 266 Iterator<Map.Entry<String, CacheHeader>> iterator = mEntries.entrySet().iterator(); 267 while (iterator.hasNext()) { 268 Map.Entry<String, CacheHeader> entry = iterator.next(); 269 CacheHeader e = entry.getValue(); 270 boolean deleted = getFileForKey(e.key).delete(); 271 if (deleted) { 272 mTotalSize -= e.size; 273 } else { 274 VolleyLog.d("Could not delete cache entry for key=%s, filename=%s", 275 e.key, getFilenameForKey(e.key)); 276 } 277 iterator.remove(); 278 prunedFiles++; 279 280 if ((mTotalSize + neededSpace) < mMaxCacheSizeInBytes * HYSTERESIS_FACTOR) { 281 break; 282 } 283 } 284 285 if (VolleyLog.DEBUG) { 286 VolleyLog.v("pruned %d files, %d bytes, %d ms", 287 prunedFiles, (mTotalSize - before), SystemClock.elapsedRealtime() - startTime); 288 } 289 } 290 291 /** 292 * Puts the entry with the specified key into the cache. 293 * @param key The key to identify the entry by. 294 * @param entry The entry to cache. 295 */ 296 private void putEntry(String key, CacheHeader entry) { 297 if (!mEntries.containsKey(key)) { 298 mTotalSize += entry.size; 299 } else { 300 CacheHeader oldEntry = mEntries.get(key); 301 mTotalSize += (entry.size - oldEntry.size); 302 } 303 mEntries.put(key, entry); 304 } 305 306 /** 307 * Removes the entry identified by 'key' from the cache. 308 */ 309 private void removeEntry(String key) { 310 CacheHeader entry = mEntries.get(key); 311 if (entry != null) { 312 mTotalSize -= entry.size; 313 mEntries.remove(key); 314 } 315 } 316 317 /** 318 * Reads the contents of an InputStream into a byte[]. 319 * */ 320 private static byte[] streamToBytes(InputStream in, int length) throws IOException { 321 byte[] bytes = new byte[length]; 322 int count; 323 int pos = 0; 324 while (pos < length && ((count = in.read(bytes, pos, length - pos)) != -1)) { 325 pos += count; 326 } 327 if (pos != length) { 328 throw new IOException("Expected " + length + " bytes, read " + pos + " bytes"); 329 } 330 return bytes; 331 } 332 333 /** 334 * Handles holding onto the cache headers for an entry. 335 */ 336 // Visible for testing. 337 static class CacheHeader { 338 /** The size of the data identified by this CacheHeader. (This is not 339 * serialized to disk. */ 340 public long size; 341 342 /** The key that identifies the cache entry. */ 343 public String key; 344 345 /** ETag for cache coherence. */ 346 public String etag; 347 348 /** Date of this response as reported by the server. */ 349 public long serverDate; 350 351 /** TTL for this record. */ 352 public long ttl; 353 354 /** Soft TTL for this record. */ 355 public long softTtl; 356 357 /** Headers from the response resulting in this cache entry. */ 358 public Map<String, String> responseHeaders; 359 360 private CacheHeader() { } 361 362 /** 363 * Instantiates a new CacheHeader object 364 * @param key The key that identifies the cache entry 365 * @param entry The cache entry. 366 */ 367 public CacheHeader(String key, Entry entry) { 368 this.key = key; 369 this.size = entry.data.length; 370 this.etag = entry.etag; 371 this.serverDate = entry.serverDate; 372 this.ttl = entry.ttl; 373 this.softTtl = entry.softTtl; 374 this.responseHeaders = entry.responseHeaders; 375 } 376 377 /** 378 * Reads the header off of an InputStream and returns a CacheHeader object. 379 * @param is The InputStream to read from. 380 * @throws IOException 381 */ 382 public static CacheHeader readHeader(InputStream is) throws IOException { 383 CacheHeader entry = new CacheHeader(); 384 int magic = readInt(is); 385 if (magic != CACHE_MAGIC) { 386 // don't bother deleting, it'll get pruned eventually 387 throw new IOException(); 388 } 389 entry.key = readString(is); 390 entry.etag = readString(is); 391 if (entry.etag.equals("")) { 392 entry.etag = null; 393 } 394 entry.serverDate = readLong(is); 395 entry.ttl = readLong(is); 396 entry.softTtl = readLong(is); 397 entry.responseHeaders = readStringStringMap(is); 398 return entry; 399 } 400 401 /** 402 * Creates a cache entry for the specified data. 403 */ 404 public Entry toCacheEntry(byte[] data) { 405 Entry e = new Entry(); 406 e.data = data; 407 e.etag = etag; 408 e.serverDate = serverDate; 409 e.ttl = ttl; 410 e.softTtl = softTtl; 411 e.responseHeaders = responseHeaders; 412 return e; 413 } 414 415 416 /** 417 * Writes the contents of this CacheHeader to the specified OutputStream. 418 */ 419 public boolean writeHeader(OutputStream os) { 420 try { 421 writeInt(os, CACHE_MAGIC); 422 writeString(os, key); 423 writeString(os, etag == null ? "" : etag); 424 writeLong(os, serverDate); 425 writeLong(os, ttl); 426 writeLong(os, softTtl); 427 writeStringStringMap(responseHeaders, os); 428 os.flush(); 429 return true; 430 } catch (IOException e) { 431 VolleyLog.d("%s", e.toString()); 432 return false; 433 } 434 } 435 436 } 437 438 private static class CountingInputStream extends FilterInputStream { 439 private int bytesRead = 0; 440 441 private CountingInputStream(InputStream in) { 442 super(in); 443 } 444 445 @Override 446 public int read() throws IOException { 447 int result = super.read(); 448 if (result != -1) { 449 bytesRead++; 450 } 451 return result; 452 } 453 454 @Override 455 public int read(byte[] buffer, int offset, int count) throws IOException { 456 int result = super.read(buffer, offset, count); 457 if (result != -1) { 458 bytesRead += result; 459 } 460 return result; 461 } 462 } 463 464 /* 465 * Homebrewed simple serialization system used for reading and writing cache 466 * headers on disk. Once upon a time, this used the standard Java 467 * Object{Input,Output}Stream, but the default implementation relies heavily 468 * on reflection (even for standard types) and generates a ton of garbage. 469 */ 470 471 /** 472 * Simple wrapper around {@link InputStream#read()} that throws EOFException 473 * instead of returning -1. 474 */ 475 private static int read(InputStream is) throws IOException { 476 int b = is.read(); 477 if (b == -1) { 478 throw new EOFException(); 479 } 480 return b; 481 } 482 483 static void writeInt(OutputStream os, int n) throws IOException { 484 os.write((n >> 0) & 0xff); 485 os.write((n >> 8) & 0xff); 486 os.write((n >> 16) & 0xff); 487 os.write((n >> 24) & 0xff); 488 } 489 490 static int readInt(InputStream is) throws IOException { 491 int n = 0; 492 n |= (read(is) << 0); 493 n |= (read(is) << 8); 494 n |= (read(is) << 16); 495 n |= (read(is) << 24); 496 return n; 497 } 498 499 static void writeLong(OutputStream os, long n) throws IOException { 500 os.write((byte)(n >>> 0)); 501 os.write((byte)(n >>> 8)); 502 os.write((byte)(n >>> 16)); 503 os.write((byte)(n >>> 24)); 504 os.write((byte)(n >>> 32)); 505 os.write((byte)(n >>> 40)); 506 os.write((byte)(n >>> 48)); 507 os.write((byte)(n >>> 56)); 508 } 509 510 static long readLong(InputStream is) throws IOException { 511 long n = 0; 512 n |= ((read(is) & 0xFFL) << 0); 513 n |= ((read(is) & 0xFFL) << 8); 514 n |= ((read(is) & 0xFFL) << 16); 515 n |= ((read(is) & 0xFFL) << 24); 516 n |= ((read(is) & 0xFFL) << 32); 517 n |= ((read(is) & 0xFFL) << 40); 518 n |= ((read(is) & 0xFFL) << 48); 519 n |= ((read(is) & 0xFFL) << 56); 520 return n; 521 } 522 523 static void writeString(OutputStream os, String s) throws IOException { 524 byte[] b = s.getBytes("UTF-8"); 525 writeLong(os, b.length); 526 os.write(b, 0, b.length); 527 } 528 529 static String readString(InputStream is) throws IOException { 530 int n = (int) readLong(is); 531 byte[] b = streamToBytes(is, n); 532 return new String(b, "UTF-8"); 533 } 534 535 static void writeStringStringMap(Map<String, String> map, OutputStream os) throws IOException { 536 if (map != null) { 537 writeInt(os, map.size()); 538 for (Map.Entry<String, String> entry : map.entrySet()) { 539 writeString(os, entry.getKey()); 540 writeString(os, entry.getValue()); 541 } 542 } else { 543 writeInt(os, 0); 544 } 545 } 546 547 static Map<String, String> readStringStringMap(InputStream is) throws IOException { 548 int size = readInt(is); 549 Map<String, String> result = (size == 0) 550 ? Collections.<String, String>emptyMap() 551 : new HashMap<String, String>(size); 552 for (int i = 0; i < size; i++) { 553 String key = readString(is).intern(); 554 String value = readString(is).intern(); 555 result.put(key, value); 556 } 557 return result; 558 } 559 560 561} 562