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.regex.Matcher; 019 020import org.apache.commons.jcs.access.behavior.ICacheAccess; 021import org.apache.commons.jcs.engine.behavior.ICacheElement; 022import org.openstreetmap.josm.data.cache.ICachedLoaderListener.LoadResult; 023import org.openstreetmap.josm.data.preferences.IntegerProperty; 024import org.openstreetmap.josm.tools.CheckParameterUtil; 025import org.openstreetmap.josm.tools.HttpClient; 026import org.openstreetmap.josm.tools.Logging; 027import org.openstreetmap.josm.tools.Utils; 028 029/** 030 * Generic loader for HTTP based tiles. Uses custom attribute, to check, if entry has expired 031 * according to HTTP headers sent with tile. If so, it tries to verify using Etags 032 * or If-Modified-Since / Last-Modified. 033 * 034 * If the tile is not valid, it will try to download it from remote service and put it 035 * to cache. If remote server will fail it will try to use stale entry. 036 * 037 * This class will keep only one Job running for specified tile. All others will just finish, but 038 * listeners will be gathered and notified, once download job will be finished 039 * 040 * @author Wiktor Niesiobędzki 041 * @param <K> cache entry key type 042 * @param <V> cache value type 043 * @since 8168 044 */ 045public abstract class JCSCachedTileLoaderJob<K, V extends CacheEntry> implements ICachedLoaderJob<K> { 046 protected static final long DEFAULT_EXPIRE_TIME = TimeUnit.DAYS.toMillis(7); 047 // Limit for the max-age value send by the server. 048 protected static final long EXPIRE_TIME_SERVER_LIMIT = TimeUnit.DAYS.toMillis(28); 049 // Absolute expire time limit. Cached tiles that are older will not be used, 050 // even if the refresh from the server fails. 051 protected static final long ABSOLUTE_EXPIRE_TIME_LIMIT = TimeUnit.DAYS.toMillis(365); 052 053 /** 054 * maximum download threads that will be started 055 */ 056 public static final IntegerProperty THREAD_LIMIT = new IntegerProperty("cache.jcs.max_threads", 10); 057 058 /* 059 * ThreadPoolExecutor starts new threads, until THREAD_LIMIT is reached. Then it puts tasks into LinkedBlockingDeque. 060 * 061 * The queue works FIFO, so one needs to take care about ordering of the entries submitted 062 * 063 * 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 064 * the response, so later it could be used). We could actually cancel what is in LIFOQueue, but this is a tradeoff between simplicity 065 * and performance (we do want to have something to offer to worker threads before tasks will be resubmitted by class consumer) 066 */ 067 068 private static final ThreadPoolExecutor DEFAULT_DOWNLOAD_JOB_DISPATCHER = new ThreadPoolExecutor( 069 1, // we have a small queue, so threads will be quickly started (threads are started only, when queue is full) 070 THREAD_LIMIT.get(), // do not this number of threads 071 30, // keepalive for thread 072 TimeUnit.SECONDS, 073 // make queue of LIFO type - so recently requested tiles will be loaded first (assuming that these are which user is waiting to see) 074 new LinkedBlockingDeque<Runnable>(), 075 Utils.newThreadFactory("JCS-downloader-%d", Thread.NORM_PRIORITY) 076 ); 077 078 private static final ConcurrentMap<String, Set<ICachedLoaderListener>> inProgress = new ConcurrentHashMap<>(); 079 private static final ConcurrentMap<String, Boolean> useHead = new ConcurrentHashMap<>(); 080 081 protected final long now; // when the job started 082 083 private final ICacheAccess<K, V> cache; 084 private ICacheElement<K, V> cacheElement; 085 protected V cacheData; 086 protected CacheEntryAttributes attributes; 087 088 // HTTP connection parameters 089 private final int connectTimeout; 090 private final int readTimeout; 091 private final Map<String, String> headers; 092 private final ThreadPoolExecutor downloadJobExecutor; 093 private Runnable finishTask; 094 private boolean force; 095 096 /** 097 * @param cache cache instance that we will work on 098 * @param headers HTTP headers to be sent together with request 099 * @param readTimeout when connecting to remote resource 100 * @param connectTimeout when connecting to remote resource 101 * @param downloadJobExecutor that will be executing the jobs 102 */ 103 public JCSCachedTileLoaderJob(ICacheAccess<K, V> cache, 104 int connectTimeout, int readTimeout, 105 Map<String, String> headers, 106 ThreadPoolExecutor downloadJobExecutor) { 107 CheckParameterUtil.ensureParameterNotNull(cache, "cache"); 108 this.cache = cache; 109 this.now = System.currentTimeMillis(); 110 this.connectTimeout = connectTimeout; 111 this.readTimeout = readTimeout; 112 this.headers = headers; 113 this.downloadJobExecutor = downloadJobExecutor; 114 } 115 116 /** 117 * @param cache cache instance that we will work on 118 * @param headers HTTP headers to be sent together with request 119 * @param readTimeout when connecting to remote resource 120 * @param connectTimeout when connecting to remote resource 121 */ 122 public JCSCachedTileLoaderJob(ICacheAccess<K, V> cache, 123 int connectTimeout, int readTimeout, 124 Map<String, String> headers) { 125 this(cache, connectTimeout, readTimeout, 126 headers, DEFAULT_DOWNLOAD_JOB_DISPATCHER); 127 } 128 129 private void ensureCacheElement() { 130 if (cacheElement == null && getCacheKey() != null) { 131 cacheElement = cache.getCacheElement(getCacheKey()); 132 if (cacheElement != null) { 133 attributes = (CacheEntryAttributes) cacheElement.getElementAttributes(); 134 cacheData = cacheElement.getVal(); 135 } 136 } 137 } 138 139 @Override 140 public V get() { 141 ensureCacheElement(); 142 return cacheData; 143 } 144 145 @Override 146 public void submit(ICachedLoaderListener listener, boolean force) throws IOException { 147 this.force = force; 148 boolean first = false; 149 URL url = getUrl(); 150 String deduplicationKey = null; 151 if (url != null) { 152 // url might be null, for example when Bing Attribution is not loaded yet 153 deduplicationKey = url.toString(); 154 } 155 if (deduplicationKey == null) { 156 Logging.warn("No url returned for: {0}, skipping", getCacheKey()); 157 throw new IllegalArgumentException("No url returned"); 158 } 159 synchronized (inProgress) { 160 Set<ICachedLoaderListener> newListeners = inProgress.get(deduplicationKey); 161 if (newListeners == null) { 162 newListeners = new HashSet<>(); 163 inProgress.put(deduplicationKey, newListeners); 164 first = true; 165 } 166 newListeners.add(listener); 167 } 168 169 if (first || force) { 170 // submit all jobs to separate thread, so calling thread is not blocked with IO when loading from disk 171 Logging.debug("JCS - Submitting job for execution for url: {0}", getUrlNoException()); 172 downloadJobExecutor.execute(this); 173 } 174 } 175 176 /** 177 * This method is run when job has finished 178 */ 179 protected void executionFinished() { 180 if (finishTask != null) { 181 finishTask.run(); 182 } 183 } 184 185 /** 186 * 187 * @return checks if object from cache has sufficient data to be returned 188 */ 189 protected boolean isObjectLoadable() { 190 if (cacheData == null) { 191 return false; 192 } 193 return cacheData.getContent().length > 0; 194 } 195 196 /** 197 * Simple implementation. All errors should be cached as empty. Though some JDK (JDK8 on Windows for example) 198 * doesn't return 4xx error codes, instead they do throw an FileNotFoundException or IOException 199 * 200 * @return true if we should put empty object into cache, regardless of what remote resource has returned 201 */ 202 protected boolean cacheAsEmpty() { 203 return attributes.getResponseCode() < 500; 204 } 205 206 /** 207 * @return key under which discovered server settings will be kept 208 */ 209 protected String getServerKey() { 210 try { 211 return getUrl().getHost(); 212 } catch (IOException e) { 213 Logging.trace(e); 214 return null; 215 } 216 } 217 218 @Override 219 public void run() { 220 final Thread currentThread = Thread.currentThread(); 221 final String oldName = currentThread.getName(); 222 currentThread.setName("JCS Downloading: " + getUrlNoException()); 223 Logging.debug("JCS - starting fetch of url: {0} ", getUrlNoException()); 224 ensureCacheElement(); 225 try { 226 // try to fetch from cache 227 if (!force && cacheElement != null && isCacheElementValid() && isObjectLoadable()) { 228 // we got something in cache, and it's valid, so lets return it 229 Logging.debug("JCS - Returning object from cache: {0}", getCacheKey()); 230 finishLoading(LoadResult.SUCCESS); 231 return; 232 } 233 234 // try to load object from remote resource 235 if (loadObject()) { 236 finishLoading(LoadResult.SUCCESS); 237 } else { 238 // if loading failed - check if we can return stale entry 239 if (isObjectLoadable()) { 240 // try to get stale entry in cache 241 finishLoading(LoadResult.SUCCESS); 242 Logging.debug("JCS - found stale object in cache: {0}", getUrlNoException()); 243 } else { 244 // failed completely 245 finishLoading(LoadResult.FAILURE); 246 } 247 } 248 } finally { 249 executionFinished(); 250 currentThread.setName(oldName); 251 } 252 } 253 254 private void finishLoading(LoadResult result) { 255 Set<ICachedLoaderListener> listeners; 256 synchronized (inProgress) { 257 try { 258 listeners = inProgress.remove(getUrl().toString()); 259 } catch (IOException e) { 260 listeners = null; 261 Logging.trace(e); 262 } 263 } 264 if (listeners == null) { 265 Logging.warn("Listener not found for URL: {0}. Listener not notified!", getUrlNoException()); 266 return; 267 } 268 for (ICachedLoaderListener l: listeners) { 269 l.loadingFinished(cacheData, attributes, result); 270 } 271 } 272 273 protected boolean isCacheElementValid() { 274 long expires = attributes.getExpirationTime(); 275 276 // check by expire date set by server 277 if (expires != 0L) { 278 // put a limit to the expire time (some servers send a value 279 // that is too large) 280 expires = Math.min(expires, attributes.getCreateTime() + EXPIRE_TIME_SERVER_LIMIT); 281 if (now > expires) { 282 Logging.debug("JCS - Object {0} has expired -> valid to {1}, now is: {2}", 283 new Object[]{getUrlNoException(), Long.toString(expires), Long.toString(now)}); 284 return false; 285 } 286 } else if (attributes.getLastModification() > 0 && 287 now - attributes.getLastModification() > DEFAULT_EXPIRE_TIME) { 288 // check by file modification date 289 Logging.debug("JCS - Object has expired, maximum file age reached {0}", getUrlNoException()); 290 return false; 291 } else if (now - attributes.getCreateTime() > DEFAULT_EXPIRE_TIME) { 292 Logging.debug("JCS - Object has expired, maximum time since object creation reached {0}", getUrlNoException()); 293 return false; 294 } 295 return true; 296 } 297 298 /** 299 * @return true if object was successfully downloaded, false, if there was a loading failure 300 */ 301 private boolean loadObject() { 302 if (attributes == null) { 303 attributes = new CacheEntryAttributes(); 304 } 305 try { 306 // if we have object in cache, and host doesn't support If-Modified-Since nor If-None-Match 307 // then just use HEAD request and check returned values 308 if (isObjectLoadable() && 309 Boolean.TRUE.equals(useHead.get(getServerKey())) && 310 isCacheValidUsingHead()) { 311 Logging.debug("JCS - cache entry verified using HEAD request: {0}", getUrl()); 312 return true; 313 } 314 315 Logging.debug("JCS - starting HttpClient GET request for URL: {0}", getUrl()); 316 final HttpClient request = getRequest("GET", true); 317 318 if (isObjectLoadable() && 319 (now - attributes.getLastModification()) <= ABSOLUTE_EXPIRE_TIME_LIMIT) { 320 request.setIfModifiedSince(attributes.getLastModification()); 321 } 322 if (isObjectLoadable() && attributes.getEtag() != null) { 323 request.setHeader("If-None-Match", attributes.getEtag()); 324 } 325 326 final HttpClient.Response urlConn = request.connect(); 327 328 if (urlConn.getResponseCode() == 304) { 329 // If isModifiedSince or If-None-Match has been set 330 // and the server answers with a HTTP 304 = "Not Modified" 331 Logging.debug("JCS - If-Modified-Since/ETag test: local version is up to date: {0}", getUrl()); 332 return true; 333 } else if (isObjectLoadable() // we have an object in cache, but we haven't received 304 response code 334 && ( 335 (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) || 336 attributes.getLastModification() == urlConn.getLastModified()) 337 ) { 338 // we sent ETag or If-Modified-Since, but didn't get 304 response code 339 // for further requests - use HEAD 340 String serverKey = getServerKey(); 341 Logging.info("JCS - Host: {0} found not to return 304 codes for If-Modified-Since or If-None-Match headers", 342 serverKey); 343 useHead.put(serverKey, Boolean.TRUE); 344 } 345 346 attributes = parseHeaders(urlConn); 347 348 for (int i = 0; i < 5; ++i) { 349 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_UNAVAILABLE) { 350 Thread.sleep(5000L+new SecureRandom().nextInt(5000)); 351 continue; 352 } 353 354 attributes.setResponseCode(urlConn.getResponseCode()); 355 byte[] raw; 356 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK) { 357 raw = Utils.readBytesFromStream(urlConn.getContent()); 358 } else { 359 raw = new byte[]{}; 360 try { 361 String data = urlConn.fetchContent(); 362 if (!data.isEmpty()) { 363 Matcher m = HttpClient.getTomcatErrorMatcher(data); 364 if (m.matches()) { 365 attributes.setErrorMessage(m.group(1).replace("'", "''")); 366 } 367 } 368 } catch (IOException e) { 369 Logging.warn(e); 370 } 371 } 372 373 if (isResponseLoadable(urlConn.getHeaderFields(), urlConn.getResponseCode(), raw)) { 374 // we need to check cacheEmpty, so for cases, when data is returned, but we want to store 375 // as empty (eg. empty tile images) to save some space 376 cacheData = createCacheEntry(raw); 377 cache.put(getCacheKey(), cacheData, attributes); 378 Logging.debug("JCS - downloaded key: {0}, length: {1}, url: {2}", 379 new Object[] {getCacheKey(), raw.length, getUrl()}); 380 return true; 381 } else if (cacheAsEmpty()) { 382 cacheData = createCacheEntry(new byte[]{}); 383 cache.put(getCacheKey(), cacheData, attributes); 384 Logging.debug("JCS - Caching empty object {0}", getUrl()); 385 return true; 386 } else { 387 Logging.debug("JCS - failure during load - reponse is not loadable nor cached as empty"); 388 return false; 389 } 390 } 391 } catch (FileNotFoundException e) { 392 Logging.debug("JCS - Caching empty object as server returned 404 for: {0}", getUrlNoException()); 393 attributes.setResponseCode(404); 394 attributes.setError(e); 395 boolean doCache = isResponseLoadable(null, 404, null) || cacheAsEmpty(); 396 if (doCache) { 397 cacheData = createCacheEntry(new byte[]{}); 398 cache.put(getCacheKey(), cacheData, attributes); 399 } 400 return doCache; 401 } catch (IOException e) { 402 Logging.debug("JCS - IOException during communication with server for: {0}", getUrlNoException()); 403 if (isObjectLoadable()) { 404 return true; 405 } else { 406 attributes.setError(e); 407 attributes.setResponseCode(599); // set dummy error code, greater than 500 so it will be not cached 408 return false; 409 } 410 411 } catch (InterruptedException e) { 412 attributes.setError(e); 413 Logging.logWithStackTrace(Logging.LEVEL_WARN, e, "JCS - Exception during download {0}", getUrlNoException()); 414 Thread.currentThread().interrupt(); 415 } 416 Logging.warn("JCS - Silent failure during download: {0}", getUrlNoException()); 417 return false; 418 } 419 420 /** 421 * Check if the object is loadable. This means, if the data will be parsed, and if this response 422 * will finish as successful retrieve. 423 * 424 * This simple implementation doesn't load empty response, nor client (4xx) and server (5xx) errors 425 * 426 * @param headerFields headers sent by server 427 * @param responseCode http status code 428 * @param raw data read from server 429 * @return true if object should be cached and returned to listener 430 */ 431 protected boolean isResponseLoadable(Map<String, List<String>> headerFields, int responseCode, byte[] raw) { 432 return raw != null && raw.length != 0 && responseCode < 400; 433 } 434 435 protected abstract V createCacheEntry(byte[] content); 436 437 protected CacheEntryAttributes parseHeaders(HttpClient.Response urlConn) { 438 CacheEntryAttributes ret = new CacheEntryAttributes(); 439 440 Long lng = urlConn.getExpiration(); 441 if (lng.equals(0L)) { 442 try { 443 String str = urlConn.getHeaderField("Cache-Control"); 444 if (str != null) { 445 for (String token: str.split(",")) { 446 if (token.startsWith("max-age=")) { 447 lng = TimeUnit.SECONDS.toMillis(Long.parseLong(token.substring(8))) + System.currentTimeMillis(); 448 } 449 } 450 } 451 } catch (NumberFormatException e) { 452 // ignore malformed Cache-Control headers 453 Logging.trace(e); 454 } 455 } 456 457 ret.setExpirationTime(lng); 458 ret.setLastModification(now); 459 ret.setEtag(urlConn.getHeaderField("ETag")); 460 461 return ret; 462 } 463 464 private HttpClient getRequest(String requestMethod, boolean noCache) throws IOException { 465 final HttpClient urlConn = HttpClient.create(getUrl(), requestMethod); 466 urlConn.setAccept("text/html, image/png, image/jpeg, image/gif, */*"); 467 urlConn.setReadTimeout(readTimeout); // 30 seconds read timeout 468 urlConn.setConnectTimeout(connectTimeout); 469 if (headers != null) { 470 urlConn.setHeaders(headers); 471 } 472 473 if (force || noCache) { 474 urlConn.useCache(false); 475 } 476 return urlConn; 477 } 478 479 private boolean isCacheValidUsingHead() throws IOException { 480 final HttpClient.Response urlConn = getRequest("HEAD", false).connect(); 481 long lastModified = urlConn.getLastModified(); 482 return (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) || 483 (lastModified != 0 && lastModified <= attributes.getLastModification()); 484 } 485 486 /** 487 * TODO: move to JobFactory 488 * cancels all outstanding tasks in the queue. 489 */ 490 public void cancelOutstandingTasks() { 491 for (Runnable r: downloadJobExecutor.getQueue()) { 492 if (downloadJobExecutor.remove(r) && r instanceof JCSCachedTileLoaderJob) { 493 ((JCSCachedTileLoaderJob<?, ?>) r).handleJobCancellation(); 494 } 495 } 496 } 497 498 /** 499 * Sets a job, that will be run, when job will finish execution 500 * @param runnable that will be executed 501 */ 502 public void setFinishedTask(Runnable runnable) { 503 this.finishTask = runnable; 504 505 } 506 507 /** 508 * Marks this job as canceled 509 */ 510 public void handleJobCancellation() { 511 finishLoading(LoadResult.CANCELED); 512 } 513 514 private URL getUrlNoException() { 515 try { 516 return getUrl(); 517 } catch (IOException e) { 518 return null; 519 } 520 } 521}