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.HttpURLConnection; 007import java.net.URL; 008import java.security.SecureRandom; 009import java.util.HashSet; 010import java.util.List; 011import java.util.Map; 012import java.util.Set; 013import java.util.concurrent.ConcurrentHashMap; 014import java.util.concurrent.ConcurrentMap; 015import java.util.concurrent.LinkedBlockingDeque; 016import java.util.concurrent.ThreadPoolExecutor; 017import java.util.concurrent.TimeUnit; 018import java.util.logging.Level; 019import java.util.logging.Logger; 020 021import org.apache.commons.jcs.access.behavior.ICacheAccess; 022import org.apache.commons.jcs.engine.behavior.ICacheElement; 023import org.openstreetmap.gui.jmapviewer.FeatureAdapter; 024import org.openstreetmap.josm.Main; 025import org.openstreetmap.josm.data.cache.ICachedLoaderListener.LoadResult; 026import org.openstreetmap.josm.data.preferences.IntegerProperty; 027import org.openstreetmap.josm.tools.CheckParameterUtil; 028import org.openstreetmap.josm.tools.HttpClient; 029import org.openstreetmap.josm.tools.Utils; 030 031/** 032 * Generic loader for HTTP based tiles. Uses custom attribute, to check, if entry has expired 033 * according to HTTP headers sent with tile. If so, it tries to verify using Etags 034 * or If-Modified-Since / Last-Modified. 035 * 036 * If the tile is not valid, it will try to download it from remote service and put it 037 * to cache. If remote server will fail it will try to use stale entry. 038 * 039 * This class will keep only one Job running for specified tile. All others will just finish, but 040 * listeners will be gathered and notified, once download job will be finished 041 * 042 * @author Wiktor Niesiobędzki 043 * @param <K> cache entry key type 044 * @param <V> cache value type 045 * @since 8168 046 */ 047public abstract class JCSCachedTileLoaderJob<K, V extends CacheEntry> implements ICachedLoaderJob<K> { 048 private static final Logger LOG = FeatureAdapter.getLogger(JCSCachedTileLoaderJob.class.getCanonicalName()); 049 protected static final long DEFAULT_EXPIRE_TIME = 1000L * 60 * 60 * 24 * 7; // 7 days 050 // Limit for the max-age value send by the server. 051 protected static final long EXPIRE_TIME_SERVER_LIMIT = 1000L * 60 * 60 * 24 * 28; // 4 weeks 052 // Absolute expire time limit. Cached tiles that are older will not be used, 053 // even if the refresh from the server fails. 054 protected static final long ABSOLUTE_EXPIRE_TIME_LIMIT = 1000L * 60 * 60 * 24 * 365; // 1 year 055 056 /** 057 * maximum download threads that will be started 058 */ 059 public static final IntegerProperty THREAD_LIMIT = new IntegerProperty("cache.jcs.max_threads", 10); 060 061 /* 062 * ThreadPoolExecutor starts new threads, until THREAD_LIMIT is reached. Then it puts tasks into LinkedBlockingDeque. 063 * 064 * The queue works FIFO, so one needs to take care about ordering of the entries submitted 065 * 066 * 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 067 * the response, so later it could be used). We could actually cancel what is in LIFOQueue, but this is a tradeoff between simplicity 068 * and performance (we do want to have something to offer to worker threads before tasks will be resubmitted by class consumer) 069 */ 070 071 private static final ThreadPoolExecutor DEFAULT_DOWNLOAD_JOB_DISPATCHER = new ThreadPoolExecutor( 072 1, // we have a small queue, so threads will be quickly started (threads are started only, when queue is full) 073 THREAD_LIMIT.get(), // do not this number of threads 074 30, // keepalive for thread 075 TimeUnit.SECONDS, 076 // make queue of LIFO type - so recently requested tiles will be loaded first (assuming that these are which user is waiting to see) 077 new LinkedBlockingDeque<Runnable>(), 078 Utils.newThreadFactory("JCS-downloader-%d", Thread.NORM_PRIORITY) 079 ); 080 081 082 083 private static final ConcurrentMap<String, Set<ICachedLoaderListener>> inProgress = new ConcurrentHashMap<>(); 084 private static final ConcurrentMap<String, Boolean> useHead = new ConcurrentHashMap<>(); 085 086 protected final long now; // when the job started 087 088 private final ICacheAccess<K, V> cache; 089 private ICacheElement<K, V> cacheElement; 090 protected V cacheData; 091 protected CacheEntryAttributes attributes; 092 093 // HTTP connection parameters 094 private final int connectTimeout; 095 private final int readTimeout; 096 private final Map<String, String> headers; 097 private final ThreadPoolExecutor downloadJobExecutor; 098 private Runnable finishTask; 099 private boolean force; 100 101 /** 102 * @param cache cache instance that we will work on 103 * @param headers HTTP headers to be sent together with request 104 * @param readTimeout when connecting to remote resource 105 * @param connectTimeout when connecting to remote resource 106 * @param downloadJobExecutor that will be executing the jobs 107 */ 108 public JCSCachedTileLoaderJob(ICacheAccess<K, V> cache, 109 int connectTimeout, int readTimeout, 110 Map<String, String> headers, 111 ThreadPoolExecutor downloadJobExecutor) { 112 CheckParameterUtil.ensureParameterNotNull(cache, "cache"); 113 this.cache = cache; 114 this.now = System.currentTimeMillis(); 115 this.connectTimeout = connectTimeout; 116 this.readTimeout = readTimeout; 117 this.headers = headers; 118 this.downloadJobExecutor = downloadJobExecutor; 119 } 120 121 /** 122 * @param cache cache instance that we will work on 123 * @param headers HTTP headers to be sent together with request 124 * @param readTimeout when connecting to remote resource 125 * @param connectTimeout when connecting to remote resource 126 */ 127 public JCSCachedTileLoaderJob(ICacheAccess<K, V> cache, 128 int connectTimeout, int readTimeout, 129 Map<String, String> headers) { 130 this(cache, connectTimeout, readTimeout, 131 headers, DEFAULT_DOWNLOAD_JOB_DISPATCHER); 132 } 133 134 private void ensureCacheElement() { 135 if (cacheElement == null && getCacheKey() != null) { 136 cacheElement = cache.getCacheElement(getCacheKey()); 137 if (cacheElement != null) { 138 attributes = (CacheEntryAttributes) cacheElement.getElementAttributes(); 139 cacheData = cacheElement.getVal(); 140 } 141 } 142 } 143 144 @Override 145 public V get() { 146 ensureCacheElement(); 147 return cacheData; 148 } 149 150 @Override 151 public void submit(ICachedLoaderListener listener, boolean force) throws IOException { 152 this.force = force; 153 boolean first = false; 154 URL url = getUrl(); 155 String deduplicationKey = null; 156 if (url != null) { 157 // url might be null, for example when Bing Attribution is not loaded yet 158 deduplicationKey = url.toString(); 159 } 160 if (deduplicationKey == null) { 161 LOG.log(Level.WARNING, "No url returned for: {0}, skipping", getCacheKey()); 162 throw new IllegalArgumentException("No url returned"); 163 } 164 synchronized (inProgress) { 165 Set<ICachedLoaderListener> newListeners = inProgress.get(deduplicationKey); 166 if (newListeners == null) { 167 newListeners = new HashSet<>(); 168 inProgress.put(deduplicationKey, newListeners); 169 first = true; 170 } 171 newListeners.add(listener); 172 } 173 174 if (first || force) { 175 // submit all jobs to separate thread, so calling thread is not blocked with IO when loading from disk 176 LOG.log(Level.FINE, "JCS - Submitting job for execution for url: {0}", getUrlNoException()); 177 downloadJobExecutor.execute(this); 178 } 179 } 180 181 /** 182 * This method is run when job has finished 183 */ 184 protected void executionFinished() { 185 if (finishTask != null) { 186 finishTask.run(); 187 } 188 } 189 190 /** 191 * 192 * @return checks if object from cache has sufficient data to be returned 193 */ 194 protected boolean isObjectLoadable() { 195 if (cacheData == null) { 196 return false; 197 } 198 byte[] content = cacheData.getContent(); 199 return content != null && content.length > 0; 200 } 201 202 /** 203 * Simple implementation. All errors should be cached as empty. Though some JDK (JDK8 on Windows for example) 204 * doesn't return 4xx error codes, instead they do throw an FileNotFoundException or IOException 205 * 206 * @return true if we should put empty object into cache, regardless of what remote resource has returned 207 */ 208 protected boolean cacheAsEmpty() { 209 return attributes.getResponseCode() < 500; 210 } 211 212 /** 213 * @return key under which discovered server settings will be kept 214 */ 215 protected String getServerKey() { 216 return getUrlNoException().getHost(); 217 } 218 219 @Override 220 public void run() { 221 final Thread currentThread = Thread.currentThread(); 222 final String oldName = currentThread.getName(); 223 currentThread.setName("JCS Downloading: " + getUrlNoException()); 224 LOG.log(Level.FINE, "JCS - starting fetch of url: {0} ", getUrlNoException()); 225 ensureCacheElement(); 226 try { 227 // try to fetch from cache 228 if (!force && cacheElement != null && isCacheElementValid() && isObjectLoadable()) { 229 // we got something in cache, and it's valid, so lets return it 230 LOG.log(Level.FINE, "JCS - Returning object from cache: {0}", getCacheKey()); 231 finishLoading(LoadResult.SUCCESS); 232 return; 233 } 234 235 // try to load object from remote resource 236 if (loadObject()) { 237 finishLoading(LoadResult.SUCCESS); 238 } else { 239 // if loading failed - check if we can return stale entry 240 if (isObjectLoadable()) { 241 // try to get stale entry in cache 242 finishLoading(LoadResult.SUCCESS); 243 LOG.log(Level.FINE, "JCS - found stale object in cache: {0}", getUrlNoException()); 244 } else { 245 // failed completely 246 finishLoading(LoadResult.FAILURE); 247 } 248 } 249 } finally { 250 executionFinished(); 251 currentThread.setName(oldName); 252 } 253 } 254 255 private void finishLoading(LoadResult result) { 256 Set<ICachedLoaderListener> listeners; 257 synchronized (inProgress) { 258 listeners = inProgress.remove(getUrlNoException().toString()); 259 } 260 if (listeners == null) { 261 LOG.log(Level.WARNING, "Listener not found for URL: {0}. Listener not notified!", getUrlNoException()); 262 return; 263 } 264 for (ICachedLoaderListener l: listeners) { 265 l.loadingFinished(cacheData, attributes, result); 266 } 267 } 268 269 protected boolean isCacheElementValid() { 270 long expires = attributes.getExpirationTime(); 271 272 // check by expire date set by server 273 if (expires != 0L) { 274 // put a limit to the expire time (some servers send a value 275 // that is too large) 276 expires = Math.min(expires, attributes.getCreateTime() + EXPIRE_TIME_SERVER_LIMIT); 277 if (now > expires) { 278 LOG.log(Level.FINE, "JCS - Object {0} has expired -> valid to {1}, now is: {2}", 279 new Object[]{getUrlNoException(), Long.toString(expires), Long.toString(now)}); 280 return false; 281 } 282 } else if (attributes.getLastModification() > 0 && 283 now - attributes.getLastModification() > DEFAULT_EXPIRE_TIME) { 284 // check by file modification date 285 LOG.log(Level.FINE, "JCS - Object has expired, maximum file age reached {0}", getUrlNoException()); 286 return false; 287 } else if (now - attributes.getCreateTime() > DEFAULT_EXPIRE_TIME) { 288 LOG.log(Level.FINE, "JCS - Object has expired, maximum time since object creation reached {0}", getUrlNoException()); 289 return false; 290 } 291 return true; 292 } 293 294 /** 295 * @return true if object was successfully downloaded, false, if there was a loading failure 296 */ 297 private boolean loadObject() { 298 if (attributes == null) { 299 attributes = new CacheEntryAttributes(); 300 } 301 try { 302 // if we have object in cache, and host doesn't support If-Modified-Since nor If-None-Match 303 // then just use HEAD request and check returned values 304 if (isObjectLoadable() && 305 Boolean.TRUE.equals(useHead.get(getServerKey())) && 306 isCacheValidUsingHead()) { 307 LOG.log(Level.FINE, "JCS - cache entry verified using HEAD request: {0}", getUrl()); 308 return true; 309 } 310 311 final HttpClient request = getRequest("GET", true); 312 313 if (isObjectLoadable() && 314 (now - attributes.getLastModification()) <= ABSOLUTE_EXPIRE_TIME_LIMIT) { 315 request.setIfModifiedSince(attributes.getLastModification()); 316 } 317 if (isObjectLoadable() && attributes.getEtag() != null) { 318 request.setHeader("If-None-Match", attributes.getEtag()); 319 } 320 321 final HttpClient.Response urlConn = request.connect(); 322 323 if (urlConn.getResponseCode() == 304) { 324 // If isModifiedSince or If-None-Match has been set 325 // and the server answers with a HTTP 304 = "Not Modified" 326 LOG.log(Level.FINE, "JCS - If-Modified-Since/ETag test: local version is up to date: {0}", getUrl()); 327 return true; 328 } else if (isObjectLoadable() // we have an object in cache, but we haven't received 304 response code 329 && ( 330 (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) || 331 attributes.getLastModification() == urlConn.getLastModified()) 332 ) { 333 // we sent ETag or If-Modified-Since, but didn't get 304 response code 334 // for further requests - use HEAD 335 String serverKey = getServerKey(); 336 LOG.log(Level.INFO, "JCS - Host: {0} found not to return 304 codes for If-Modified-Since or If-None-Match headers", 337 serverKey); 338 useHead.put(serverKey, Boolean.TRUE); 339 } 340 341 attributes = parseHeaders(urlConn); 342 343 for (int i = 0; i < 5; ++i) { 344 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_UNAVAILABLE) { 345 Thread.sleep(5000L+new SecureRandom().nextInt(5000)); 346 continue; 347 } 348 349 attributes.setResponseCode(urlConn.getResponseCode()); 350 byte[] raw; 351 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK) { 352 raw = Utils.readBytesFromStream(urlConn.getContent()); 353 } else { 354 raw = new byte[]{}; 355 } 356 357 if (isResponseLoadable(urlConn.getHeaderFields(), urlConn.getResponseCode(), raw)) { 358 // we need to check cacheEmpty, so for cases, when data is returned, but we want to store 359 // as empty (eg. empty tile images) to save some space 360 cacheData = createCacheEntry(raw); 361 cache.put(getCacheKey(), cacheData, attributes); 362 LOG.log(Level.FINE, "JCS - downloaded key: {0}, length: {1}, url: {2}", 363 new Object[] {getCacheKey(), raw.length, getUrl()}); 364 return true; 365 } else if (cacheAsEmpty()) { 366 cacheData = createCacheEntry(new byte[]{}); 367 cache.put(getCacheKey(), cacheData, attributes); 368 LOG.log(Level.FINE, "JCS - Caching empty object {0}", getUrl()); 369 return true; 370 } else { 371 LOG.log(Level.FINE, "JCS - failure during load - reponse is not loadable nor cached as empty"); 372 return false; 373 } 374 } 375 } catch (FileNotFoundException e) { 376 LOG.log(Level.FINE, "JCS - Caching empty object as server returned 404 for: {0}", getUrlNoException()); 377 attributes.setResponseCode(404); 378 attributes.setError(e); 379 boolean doCache = isResponseLoadable(null, 404, null) || cacheAsEmpty(); 380 if (doCache) { 381 cacheData = createCacheEntry(new byte[]{}); 382 cache.put(getCacheKey(), cacheData, attributes); 383 } 384 return doCache; 385 } catch (IOException e) { 386 LOG.log(Level.FINE, "JCS - IOExecption during communication with server for: {0}", getUrlNoException()); 387 if (isObjectLoadable()) { 388 return true; 389 } else { 390 attributes.setError(e); 391 attributes.setResponseCode(599); // set dummy error code, greater than 500 so it will be not cached 392 return false; 393 } 394 395 } catch (InterruptedException e) { 396 attributes.setError(e); 397 LOG.log(Level.WARNING, "JCS - Exception during download {0}", getUrlNoException()); 398 Main.warn(e); 399 } 400 LOG.log(Level.WARNING, "JCS - Silent failure during download: {0}", getUrlNoException()); 401 return false; 402 } 403 404 /** 405 * Check if the object is loadable. This means, if the data will be parsed, and if this response 406 * will finish as successful retrieve. 407 * 408 * This simple implementation doesn't load empty response, nor client (4xx) and server (5xx) errors 409 * 410 * @param headerFields headers sent by server 411 * @param responseCode http status code 412 * @param raw data read from server 413 * @return true if object should be cached and returned to listener 414 */ 415 protected boolean isResponseLoadable(Map<String, List<String>> headerFields, int responseCode, byte[] raw) { 416 if (raw == null || raw.length == 0 || responseCode >= 400) { 417 return false; 418 } 419 return true; 420 } 421 422 protected abstract V createCacheEntry(byte[] content); 423 424 protected CacheEntryAttributes parseHeaders(HttpClient.Response urlConn) { 425 CacheEntryAttributes ret = new CacheEntryAttributes(); 426 427 Long lng = urlConn.getExpiration(); 428 if (lng.equals(0L)) { 429 try { 430 String str = urlConn.getHeaderField("Cache-Control"); 431 if (str != null) { 432 for (String token: str.split(",")) { 433 if (token.startsWith("max-age=")) { 434 lng = Long.parseLong(token.substring(8)) * 1000 + 435 System.currentTimeMillis(); 436 } 437 } 438 } 439 } catch (NumberFormatException e) { 440 // ignore malformed Cache-Control headers 441 Main.trace(e); 442 } 443 } 444 445 ret.setExpirationTime(lng); 446 ret.setLastModification(now); 447 ret.setEtag(urlConn.getHeaderField("ETag")); 448 449 return ret; 450 } 451 452 private HttpClient getRequest(String requestMethod, boolean noCache) throws IOException { 453 final HttpClient urlConn = HttpClient.create(getUrl(), requestMethod); 454 urlConn.setAccept("text/html, image/png, image/jpeg, image/gif, */*"); 455 urlConn.setReadTimeout(readTimeout); // 30 seconds read timeout 456 urlConn.setConnectTimeout(connectTimeout); 457 if (headers != null) { 458 urlConn.setHeaders(headers); 459 } 460 461 if (force || noCache) { 462 urlConn.useCache(false); 463 } 464 return urlConn; 465 } 466 467 private boolean isCacheValidUsingHead() throws IOException { 468 final HttpClient.Response urlConn = getRequest("HEAD", false).connect(); 469 long lastModified = urlConn.getLastModified(); 470 return (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) || 471 (lastModified != 0 && lastModified <= attributes.getLastModification()); 472 } 473 474 /** 475 * TODO: move to JobFactory 476 * cancels all outstanding tasks in the queue. 477 */ 478 public void cancelOutstandingTasks() { 479 for (Runnable r: downloadJobExecutor.getQueue()) { 480 if (downloadJobExecutor.remove(r) && r instanceof JCSCachedTileLoaderJob) { 481 ((JCSCachedTileLoaderJob<?, ?>) r).handleJobCancellation(); 482 } 483 } 484 } 485 486 /** 487 * Sets a job, that will be run, when job will finish execution 488 * @param runnable that will be executed 489 */ 490 public void setFinishedTask(Runnable runnable) { 491 this.finishTask = runnable; 492 493 } 494 495 /** 496 * Marks this job as canceled 497 */ 498 public void handleJobCancellation() { 499 finishLoading(LoadResult.CANCELED); 500 } 501 502 private URL getUrlNoException() { 503 try { 504 return getUrl(); 505 } catch (IOException e) { 506 return null; 507 } 508 } 509}