source: josm/trunk/src/org/openstreetmap/josm/data/cache/JCSCachedTileLoaderJob.java@ 13608

Last change on this file since 13608 was 13358, checked in by Don-vip, 6 years ago

fix #15830 - Support (and autodetect) WMS 1.3.0
  • Property svn:eol-style set to native
File size: 21.3 KB
Line 
1// License: GPL. For details, see LICENSE file.
2package org.openstreetmap.josm.data.cache;
3
4import java.io.FileNotFoundException;
5import java.io.IOException;
6import java.net.HttpURLConnection;
7import java.net.URL;
8import java.security.SecureRandom;
9import java.util.HashSet;
10import java.util.List;
11import java.util.Map;
12import java.util.Set;
13import java.util.concurrent.ConcurrentHashMap;
14import java.util.concurrent.ConcurrentMap;
15import java.util.concurrent.LinkedBlockingDeque;
16import java.util.concurrent.ThreadPoolExecutor;
17import java.util.concurrent.TimeUnit;
18import java.util.regex.Matcher;
19
20import org.apache.commons.jcs.access.behavior.ICacheAccess;
21import org.apache.commons.jcs.engine.behavior.ICacheElement;
22import org.openstreetmap.josm.data.cache.ICachedLoaderListener.LoadResult;
23import org.openstreetmap.josm.data.preferences.IntegerProperty;
24import org.openstreetmap.josm.tools.CheckParameterUtil;
25import org.openstreetmap.josm.tools.HttpClient;
26import org.openstreetmap.josm.tools.Logging;
27import org.openstreetmap.josm.tools.Utils;
28
29/**
30 * Generic loader for HTTP based tiles. Uses custom attribute, to check, if entry has expired
31 * according to HTTP headers sent with tile. If so, it tries to verify using Etags
32 * or If-Modified-Since / Last-Modified.
33 *
34 * If the tile is not valid, it will try to download it from remote service and put it
35 * to cache. If remote server will fail it will try to use stale entry.
36 *
37 * This class will keep only one Job running for specified tile. All others will just finish, but
38 * listeners will be gathered and notified, once download job will be finished
39 *
40 * @author Wiktor Niesiobędzki
41 * @param <K> cache entry key type
42 * @param <V> cache value type
43 * @since 8168
44 */
45public abstract class JCSCachedTileLoaderJob<K, V extends CacheEntry> implements ICachedLoaderJob<K> {
46 protected static final long DEFAULT_EXPIRE_TIME = TimeUnit.DAYS.toMillis(7);
47 // Limit for the max-age value send by the server.
48 protected static final long EXPIRE_TIME_SERVER_LIMIT = TimeUnit.DAYS.toMillis(28);
49 // Absolute expire time limit. Cached tiles that are older will not be used,
50 // even if the refresh from the server fails.
51 protected static final long ABSOLUTE_EXPIRE_TIME_LIMIT = TimeUnit.DAYS.toMillis(365);
52
53 /**
54 * maximum download threads that will be started
55 */
56 public static final IntegerProperty THREAD_LIMIT = new IntegerProperty("cache.jcs.max_threads", 10);
57
58 /*
59 * ThreadPoolExecutor starts new threads, until THREAD_LIMIT is reached. Then it puts tasks into LinkedBlockingDeque.
60 *
61 * The queue works FIFO, so one needs to take care about ordering of the entries submitted
62 *
63 * 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
64 * the response, so later it could be used). We could actually cancel what is in LIFOQueue, but this is a tradeoff between simplicity
65 * and performance (we do want to have something to offer to worker threads before tasks will be resubmitted by class consumer)
66 */
67
68 private static final ThreadPoolExecutor DEFAULT_DOWNLOAD_JOB_DISPATCHER = new ThreadPoolExecutor(
69 1, // we have a small queue, so threads will be quickly started (threads are started only, when queue is full)
70 THREAD_LIMIT.get(), // do not this number of threads
71 30, // keepalive for thread
72 TimeUnit.SECONDS,
73 // make queue of LIFO type - so recently requested tiles will be loaded first (assuming that these are which user is waiting to see)
74 new LinkedBlockingDeque<Runnable>(),
75 Utils.newThreadFactory("JCS-downloader-%d", Thread.NORM_PRIORITY)
76 );
77
78 private static final ConcurrentMap<String, Set<ICachedLoaderListener>> inProgress = new ConcurrentHashMap<>();
79 private static final ConcurrentMap<String, Boolean> useHead = new ConcurrentHashMap<>();
80
81 protected final long now; // when the job started
82
83 private final ICacheAccess<K, V> cache;
84 private ICacheElement<K, V> cacheElement;
85 protected V cacheData;
86 protected CacheEntryAttributes attributes;
87
88 // HTTP connection parameters
89 private final int connectTimeout;
90 private final int readTimeout;
91 private final Map<String, String> headers;
92 private final ThreadPoolExecutor downloadJobExecutor;
93 private Runnable finishTask;
94 private boolean force;
95
96 /**
97 * @param cache cache instance that we will work on
98 * @param headers HTTP headers to be sent together with request
99 * @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}
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