001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.data.cache; 003 004import java.io.FileNotFoundException; 005import java.io.IOException; 006import java.net.URL; 007import java.security.SecureRandom; 008import java.util.HashSet; 009import java.util.List; 010import java.util.Map; 011import java.util.Set; 012import java.util.concurrent.ConcurrentHashMap; 013import java.util.concurrent.ConcurrentMap; 014import java.util.concurrent.LinkedBlockingDeque; 015import java.util.concurrent.ThreadPoolExecutor; 016import java.util.concurrent.TimeUnit; 017import java.util.logging.Level; 018import java.util.logging.Logger; 019 020import org.apache.commons.jcs.access.behavior.ICacheAccess; 021import org.apache.commons.jcs.engine.behavior.ICacheElement; 022import org.openstreetmap.gui.jmapviewer.FeatureAdapter; 023import org.openstreetmap.josm.Main; 024import org.openstreetmap.josm.data.cache.ICachedLoaderListener.LoadResult; 025import org.openstreetmap.josm.data.preferences.IntegerProperty; 026import org.openstreetmap.josm.tools.HttpClient; 027import org.openstreetmap.josm.tools.Utils; 028 029import sun.net.www.protocol.http.HttpURLConnection; 030 031/** 032 * @author Wiktor Niesiobędzki 033 * 034 * @param <K> cache entry key type 035 * @param <V> cache value type 036 * 037 * Generic loader for HTTP based tiles. Uses custom attribute, to check, if entry has expired 038 * according to HTTP headers sent with tile. If so, it tries to verify using Etags 039 * or If-Modified-Since / Last-Modified. 040 * 041 * If the tile is not valid, it will try to download it from remote service and put it 042 * to cache. If remote server will fail it will try to use stale entry. 043 * 044 * This class will keep only one Job running for specified tile. All others will just finish, but 045 * listeners will be gathered and notified, once download job will be finished 046 * 047 * @since 8168 048 */ 049public abstract class JCSCachedTileLoaderJob<K, V extends CacheEntry> implements ICachedLoaderJob<K> { 050 private static final Logger log = FeatureAdapter.getLogger(JCSCachedTileLoaderJob.class.getCanonicalName()); 051 protected static final long DEFAULT_EXPIRE_TIME = 1000L * 60 * 60 * 24 * 7; // 7 days 052 // Limit for the max-age value send by the server. 053 protected static final long EXPIRE_TIME_SERVER_LIMIT = 1000L * 60 * 60 * 24 * 28; // 4 weeks 054 // Absolute expire time limit. Cached tiles that are older will not be used, 055 // even if the refresh from the server fails. 056 protected static final long ABSOLUTE_EXPIRE_TIME_LIMIT = 1000L * 60 * 60 * 24 * 365; // 1 year 057 058 /** 059 * maximum download threads that will be started 060 */ 061 public static final IntegerProperty THREAD_LIMIT = new IntegerProperty("cache.jcs.max_threads", 10); 062 063 /* 064 * ThreadPoolExecutor starts new threads, until THREAD_LIMIT is reached. Then it puts tasks into LinkedBlockingDeque. 065 * 066 * The queue works FIFO, so one needs to take care about ordering of the entries submitted 067 * 068 * There is no point in canceling tasks, that are already taken by worker threads (if we made so much effort, we can at least cache 069 * the response, so later it could be used). We could actually cancel what is in LIFOQueue, but this is a tradeoff between simplicity 070 * and performance (we do want to have something to offer to worker threads before tasks will be resubmitted by class consumer) 071 */ 072 073 private static final ThreadPoolExecutor DEFAULT_DOWNLOAD_JOB_DISPATCHER = new ThreadPoolExecutor( 074 1, // we have a small queue, so threads will be quickly started (threads are started only, when queue is full) 075 THREAD_LIMIT.get(), // do not this number of threads 076 30, // keepalive for thread 077 TimeUnit.SECONDS, 078 // make queue of LIFO type - so recently requested tiles will be loaded first (assuming that these are which user is waiting to see) 079 new LinkedBlockingDeque<Runnable>(), 080 Utils.newThreadFactory("JCS-downloader-%d", Thread.NORM_PRIORITY) 081 ); 082 083 084 085 private static final ConcurrentMap<String, Set<ICachedLoaderListener>> inProgress = new ConcurrentHashMap<>(); 086 private static final ConcurrentMap<String, Boolean> useHead = new ConcurrentHashMap<>(); 087 088 protected final long now; // when the job started 089 090 private final ICacheAccess<K, V> cache; 091 private ICacheElement<K, V> cacheElement; 092 protected V cacheData; 093 protected CacheEntryAttributes attributes; 094 095 // HTTP connection parameters 096 private final int connectTimeout; 097 private final int readTimeout; 098 private final Map<String, String> headers; 099 private final ThreadPoolExecutor downloadJobExecutor; 100 private Runnable finishTask; 101 private boolean force; 102 103 /** 104 * @param cache cache instance that we will work on 105 * @param headers HTTP headers to be sent together with request 106 * @param readTimeout when connecting to remote resource 107 * @param connectTimeout when connecting to remote resource 108 * @param downloadJobExecutor that will be executing the jobs 109 */ 110 public JCSCachedTileLoaderJob(ICacheAccess<K, V> cache, 111 int connectTimeout, int readTimeout, 112 Map<String, String> headers, 113 ThreadPoolExecutor downloadJobExecutor) { 114 115 this.cache = cache; 116 this.now = System.currentTimeMillis(); 117 this.connectTimeout = connectTimeout; 118 this.readTimeout = readTimeout; 119 this.headers = headers; 120 this.downloadJobExecutor = downloadJobExecutor; 121 } 122 123 /** 124 * @param cache cache instance that we will work on 125 * @param headers HTTP headers to be sent together with request 126 * @param readTimeout when connecting to remote resource 127 * @param connectTimeout when connecting to remote resource 128 */ 129 public JCSCachedTileLoaderJob(ICacheAccess<K, V> cache, 130 int connectTimeout, int readTimeout, 131 Map<String, String> headers) { 132 this(cache, connectTimeout, readTimeout, 133 headers, DEFAULT_DOWNLOAD_JOB_DISPATCHER); 134 } 135 136 private void ensureCacheElement() { 137 if (cacheElement == null && getCacheKey() != null) { 138 cacheElement = cache.getCacheElement(getCacheKey()); 139 if (cacheElement != null) { 140 attributes = (CacheEntryAttributes) cacheElement.getElementAttributes(); 141 cacheData = cacheElement.getVal(); 142 } 143 } 144 } 145 146 @Override 147 public V get() { 148 ensureCacheElement(); 149 return cacheData; 150 } 151 152 @Override 153 public void submit(ICachedLoaderListener listener, boolean force) throws IOException { 154 this.force = force; 155 boolean first = false; 156 URL url = getUrl(); 157 String deduplicationKey = null; 158 if (url != null) { 159 // url might be null, for example when Bing Attribution is not loaded yet 160 deduplicationKey = url.toString(); 161 } 162 if (deduplicationKey == null) { 163 log.log(Level.WARNING, "No url returned for: {0}, skipping", getCacheKey()); 164 throw new IllegalArgumentException("No url returned"); 165 } 166 synchronized (inProgress) { 167 Set<ICachedLoaderListener> newListeners = inProgress.get(deduplicationKey); 168 if (newListeners == null) { 169 newListeners = new HashSet<>(); 170 inProgress.put(deduplicationKey, newListeners); 171 first = true; 172 } 173 newListeners.add(listener); 174 } 175 176 if (first || force) { 177 // submit all jobs to separate thread, so calling thread is not blocked with IO when loading from disk 178 log.log(Level.FINE, "JCS - Submitting job for execution for url: {0}", getUrlNoException()); 179 downloadJobExecutor.execute(this); 180 } 181 } 182 183 /** 184 * This method is run when job has finished 185 */ 186 protected void executionFinished() { 187 if (finishTask != null) { 188 finishTask.run(); 189 } 190 } 191 192 /** 193 * 194 * @return checks if object from cache has sufficient data to be returned 195 */ 196 protected boolean isObjectLoadable() { 197 if (cacheData == null) { 198 return false; 199 } 200 byte[] content = cacheData.getContent(); 201 return content != null && content.length > 0; 202 } 203 204 /** 205 * Simple implementation. All errors should be cached as empty. Though some JDK (JDK8 on Windows for example) 206 * doesn't return 4xx error codes, instead they do throw an FileNotFoundException or IOException 207 * 208 * @return true if we should put empty object into cache, regardless of what remote resource has returned 209 */ 210 protected boolean cacheAsEmpty() { 211 return attributes.getResponseCode() < 500; 212 } 213 214 /** 215 * @return key under which discovered server settings will be kept 216 */ 217 protected String getServerKey() { 218 return getUrlNoException().getHost(); 219 } 220 221 @Override 222 public void run() { 223 final Thread currentThread = Thread.currentThread(); 224 final String oldName = currentThread.getName(); 225 currentThread.setName("JCS Downloading: " + getUrlNoException()); 226 log.log(Level.FINE, "JCS - starting fetch of url: {0} ", getUrlNoException()); 227 ensureCacheElement(); 228 try { 229 // try to fetch from cache 230 if (!force && cacheElement != null && isCacheElementValid() && isObjectLoadable()) { 231 // we got something in cache, and it's valid, so lets return it 232 log.log(Level.FINE, "JCS - Returning object from cache: {0}", getCacheKey()); 233 finishLoading(LoadResult.SUCCESS); 234 return; 235 } 236 237 // try to load object from remote resource 238 if (loadObject()) { 239 finishLoading(LoadResult.SUCCESS); 240 } else { 241 // if loading failed - check if we can return stale entry 242 if (isObjectLoadable()) { 243 // try to get stale entry in cache 244 finishLoading(LoadResult.SUCCESS); 245 log.log(Level.FINE, "JCS - found stale object in cache: {0}", getUrlNoException()); 246 } else { 247 // failed completely 248 finishLoading(LoadResult.FAILURE); 249 } 250 } 251 } finally { 252 executionFinished(); 253 currentThread.setName(oldName); 254 } 255 } 256 257 private void finishLoading(LoadResult result) { 258 Set<ICachedLoaderListener> listeners; 259 synchronized (inProgress) { 260 listeners = inProgress.remove(getUrlNoException().toString()); 261 } 262 if (listeners == null) { 263 log.log(Level.WARNING, "Listener not found for URL: {0}. Listener not notified!", getUrlNoException()); 264 return; 265 } 266 for (ICachedLoaderListener l: listeners) { 267 l.loadingFinished(cacheData, attributes, result); 268 } 269 } 270 271 protected boolean isCacheElementValid() { 272 long expires = attributes.getExpirationTime(); 273 274 // check by expire date set by server 275 if (expires != 0L) { 276 // put a limit to the expire time (some servers send a value 277 // that is too large) 278 expires = Math.min(expires, attributes.getCreateTime() + EXPIRE_TIME_SERVER_LIMIT); 279 if (now > expires) { 280 log.log(Level.FINE, "JCS - Object {0} has expired -> valid to {1}, now is: {2}", 281 new Object[]{getUrlNoException(), Long.toString(expires), Long.toString(now)}); 282 return false; 283 } 284 } else if (attributes.getLastModification() > 0 && 285 now - attributes.getLastModification() > DEFAULT_EXPIRE_TIME) { 286 // check by file modification date 287 log.log(Level.FINE, "JCS - Object has expired, maximum file age reached {0}", getUrlNoException()); 288 return false; 289 } else if (now - attributes.getCreateTime() > DEFAULT_EXPIRE_TIME) { 290 log.log(Level.FINE, "JCS - Object has expired, maximum time since object creation reached {0}", getUrlNoException()); 291 return false; 292 } 293 return true; 294 } 295 296 /** 297 * @return true if object was successfully downloaded, false, if there was a loading failure 298 */ 299 private boolean loadObject() { 300 if (attributes == null) { 301 attributes = new CacheEntryAttributes(); 302 } 303 try { 304 // if we have object in cache, and host doesn't support If-Modified-Since nor If-None-Match 305 // then just use HEAD request and check returned values 306 if (isObjectLoadable() && 307 Boolean.TRUE.equals(useHead.get(getServerKey())) && 308 isCacheValidUsingHead()) { 309 log.log(Level.FINE, "JCS - cache entry verified using HEAD request: {0}", getUrl()); 310 return true; 311 } 312 313 final HttpClient request = getRequest("GET", true); 314 315 if (isObjectLoadable() && 316 (now - attributes.getLastModification()) <= ABSOLUTE_EXPIRE_TIME_LIMIT) { 317 request.setIfModifiedSince(attributes.getLastModification()); 318 } 319 if (isObjectLoadable() && attributes.getEtag() != null) { 320 request.setHeader("If-None-Match", attributes.getEtag()); 321 } 322 323 final HttpClient.Response urlConn = request.connect(); 324 325 if (urlConn.getResponseCode() == 304) { 326 // If isModifiedSince or If-None-Match has been set 327 // and the server answers with a HTTP 304 = "Not Modified" 328 log.log(Level.FINE, "JCS - If-Modified-Since/ETag test: local version is up to date: {0}", getUrl()); 329 return true; 330 } else if (isObjectLoadable() // we have an object in cache, but we haven't received 304 response code 331 && ( 332 (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) || 333 attributes.getLastModification() == urlConn.getLastModified()) 334 ) { 335 // we sent ETag or If-Modified-Since, but didn't get 304 response code 336 // for further requests - use HEAD 337 String serverKey = getServerKey(); 338 log.log(Level.INFO, "JCS - Host: {0} found not to return 304 codes for If-Modified-Since or If-None-Match headers", 339 serverKey); 340 useHead.put(serverKey, Boolean.TRUE); 341 } 342 343 attributes = parseHeaders(urlConn); 344 345 for (int i = 0; i < 5; ++i) { 346 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_UNAVAILABLE) { 347 Thread.sleep(5000L+new SecureRandom().nextInt(5000)); 348 continue; 349 } 350 351 attributes.setResponseCode(urlConn.getResponseCode()); 352 byte[] raw; 353 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK) { 354 raw = Utils.readBytesFromStream(urlConn.getContent()); 355 } else { 356 raw = new byte[]{}; 357 } 358 359 if (isResponseLoadable(urlConn.getHeaderFields(), urlConn.getResponseCode(), raw)) { 360 // we need to check cacheEmpty, so for cases, when data is returned, but we want to store 361 // as empty (eg. empty tile images) to save some space 362 cacheData = createCacheEntry(raw); 363 cache.put(getCacheKey(), cacheData, attributes); 364 log.log(Level.FINE, "JCS - downloaded key: {0}, length: {1}, url: {2}", 365 new Object[] {getCacheKey(), raw.length, getUrl()}); 366 return true; 367 } else if (cacheAsEmpty()) { 368 cacheData = createCacheEntry(new byte[]{}); 369 cache.put(getCacheKey(), cacheData, attributes); 370 log.log(Level.FINE, "JCS - Caching empty object {0}", getUrl()); 371 return true; 372 } else { 373 log.log(Level.FINE, "JCS - failure during load - reponse is not loadable nor cached as empty"); 374 return false; 375 } 376 } 377 } catch (FileNotFoundException e) { 378 log.log(Level.FINE, "JCS - Caching empty object as server returned 404 for: {0}", getUrlNoException()); 379 attributes.setResponseCode(404); 380 attributes.setError(e); 381 boolean doCache = isResponseLoadable(null, 404, null) || cacheAsEmpty(); 382 if (doCache) { 383 cacheData = createCacheEntry(new byte[]{}); 384 cache.put(getCacheKey(), cacheData, attributes); 385 } 386 return doCache; 387 } catch (IOException e) { 388 log.log(Level.FINE, "JCS - IOExecption during communication with server for: {0}", getUrlNoException()); 389 attributes.setError(e); 390 attributes.setResponseCode(499); // set dummy error code 391 boolean doCache = isResponseLoadable(null, 499, null) || cacheAsEmpty(); //generic 499 error code returned 392 if (doCache) { 393 cacheData = createCacheEntry(new byte[]{}); 394 cache.put(getCacheKey(), createCacheEntry(new byte[]{}), attributes); 395 } 396 return doCache; 397 } catch (InterruptedException e) { 398 attributes.setError(e); 399 log.log(Level.WARNING, "JCS - Exception during download {0}", getUrlNoException()); 400 Main.warn(e); 401 } 402 log.log(Level.WARNING, "JCS - Silent failure during download: {0}", getUrlNoException()); 403 return false; 404 } 405 406 /** 407 * Check if the object is loadable. This means, if the data will be parsed, and if this response 408 * will finish as successful retrieve. 409 * 410 * This simple implementation doesn't load empty response, nor client (4xx) and server (5xx) errors 411 * 412 * @param headerFields headers sent by server 413 * @param responseCode http status code 414 * @param raw data read from server 415 * @return true if object should be cached and returned to listener 416 */ 417 protected boolean isResponseLoadable(Map<String, List<String>> headerFields, int responseCode, byte[] raw) { 418 if (raw == null || raw.length == 0 || responseCode >= 400) { 419 return false; 420 } 421 return true; 422 } 423 424 protected abstract V createCacheEntry(byte[] content); 425 426 protected CacheEntryAttributes parseHeaders(HttpClient.Response urlConn) { 427 CacheEntryAttributes ret = new CacheEntryAttributes(); 428 429 Long lng = urlConn.getExpiration(); 430 if (lng.equals(0L)) { 431 try { 432 String str = urlConn.getHeaderField("Cache-Control"); 433 if (str != null) { 434 for (String token: str.split(",")) { 435 if (token.startsWith("max-age=")) { 436 lng = Long.parseLong(token.substring(8)) * 1000 + 437 System.currentTimeMillis(); 438 } 439 } 440 } 441 } catch (NumberFormatException e) { 442 // ignore malformed Cache-Control headers 443 if (Main.isTraceEnabled()) { 444 Main.trace(e.getMessage()); 445 } 446 } 447 } 448 449 ret.setExpirationTime(lng); 450 ret.setLastModification(now); 451 ret.setEtag(urlConn.getHeaderField("ETag")); 452 453 return ret; 454 } 455 456 private HttpClient getRequest(String requestMethod, boolean noCache) throws IOException { 457 final HttpClient urlConn = HttpClient.create(getUrl(), requestMethod); 458 urlConn.setAccept("text/html, image/png, image/jpeg, image/gif, */*"); 459 urlConn.setReadTimeout(readTimeout); // 30 seconds read timeout 460 urlConn.setConnectTimeout(connectTimeout); 461 if (headers != null) { 462 urlConn.setHeaders(headers); 463 } 464 465 if (force || noCache) { 466 urlConn.useCache(false); 467 } 468 return urlConn; 469 } 470 471 private boolean isCacheValidUsingHead() throws IOException { 472 final HttpClient.Response urlConn = getRequest("HEAD", false).connect(); 473 long lastModified = urlConn.getLastModified(); 474 return (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) || 475 (lastModified != 0 && lastModified <= attributes.getLastModification()); 476 } 477 478 /** 479 * TODO: move to JobFactory 480 * cancels all outstanding tasks in the queue. 481 */ 482 public void cancelOutstandingTasks() { 483 for (Runnable r: downloadJobExecutor.getQueue()) { 484 if (downloadJobExecutor.remove(r) && r instanceof JCSCachedTileLoaderJob) { 485 ((JCSCachedTileLoaderJob<?, ?>) r).handleJobCancellation(); 486 } 487 } 488 } 489 490 /** 491 * Sets a job, that will be run, when job will finish execution 492 * @param runnable that will be executed 493 */ 494 public void setFinishedTask(Runnable runnable) { 495 this.finishTask = runnable; 496 497 } 498 499 /** 500 * Marks this job as canceled 501 */ 502 public void handleJobCancellation() { 503 finishLoading(LoadResult.CANCELED); 504 } 505 506 private URL getUrlNoException() { 507 try { 508 return getUrl(); 509 } catch (IOException e) { 510 return null; 511 } 512 } 513}