source: josm/trunk/src/org/openstreetmap/josm/data/cache/JCSCachedTileLoaderJob.java@ 11397

Last change on this file since 11397 was 11397, checked in by Don-vip, 7 years ago

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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.logging.Level;
19import java.util.logging.Logger;
20
21import org.apache.commons.jcs.access.behavior.ICacheAccess;
22import org.apache.commons.jcs.engine.behavior.ICacheElement;
23import org.openstreetmap.gui.jmapviewer.FeatureAdapter;
24import org.openstreetmap.josm.Main;
25import org.openstreetmap.josm.data.cache.ICachedLoaderListener.LoadResult;
26import org.openstreetmap.josm.data.preferences.IntegerProperty;
27import org.openstreetmap.josm.tools.CheckParameterUtil;
28import org.openstreetmap.josm.tools.HttpClient;
29import org.openstreetmap.josm.tools.Utils;
30
31/**
32 * Generic loader for HTTP based tiles. Uses custom attribute, to check, if entry has expired
33 * according to HTTP headers sent with tile. If so, it tries to verify using Etags
34 * or If-Modified-Since / Last-Modified.
35 *
36 * If the tile is not valid, it will try to download it from remote service and put it
37 * to cache. If remote server will fail it will try to use stale entry.
38 *
39 * This class will keep only one Job running for specified tile. All others will just finish, but
40 * listeners will be gathered and notified, once download job will be finished
41 *
42 * @author Wiktor Niesiobędzki
43 * @param <K> cache entry key type
44 * @param <V> cache value type
45 * @since 8168
46 */
47public abstract class JCSCachedTileLoaderJob<K, V extends CacheEntry> implements ICachedLoaderJob<K> {
48 private static final Logger LOG = FeatureAdapter.getLogger(JCSCachedTileLoaderJob.class.getCanonicalName());
49 protected static final long DEFAULT_EXPIRE_TIME = TimeUnit.DAYS.toMillis(7);
50 // Limit for the max-age value send by the server.
51 protected static final long EXPIRE_TIME_SERVER_LIMIT = TimeUnit.DAYS.toMillis(28);
52 // Absolute expire time limit. Cached tiles that are older will not be used,
53 // even if the refresh from the server fails.
54 protected static final long ABSOLUTE_EXPIRE_TIME_LIMIT = TimeUnit.DAYS.toMillis(365);
55
56 /**
57 * maximum download threads that will be started
58 */
59 public static final IntegerProperty THREAD_LIMIT = new IntegerProperty("cache.jcs.max_threads", 10);
60
61 /*
62 * ThreadPoolExecutor starts new threads, until THREAD_LIMIT is reached. Then it puts tasks into LinkedBlockingDeque.
63 *
64 * The queue works FIFO, so one needs to take care about ordering of the entries submitted
65 *
66 * 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
67 * the response, so later it could be used). We could actually cancel what is in LIFOQueue, but this is a tradeoff between simplicity
68 * and performance (we do want to have something to offer to worker threads before tasks will be resubmitted by class consumer)
69 */
70
71 private static final ThreadPoolExecutor DEFAULT_DOWNLOAD_JOB_DISPATCHER = new ThreadPoolExecutor(
72 1, // we have a small queue, so threads will be quickly started (threads are started only, when queue is full)
73 THREAD_LIMIT.get(), // do not this number of threads
74 30, // keepalive for thread
75 TimeUnit.SECONDS,
76 // make queue of LIFO type - so recently requested tiles will be loaded first (assuming that these are which user is waiting to see)
77 new LinkedBlockingDeque<Runnable>(),
78 Utils.newThreadFactory("JCS-downloader-%d", Thread.NORM_PRIORITY)
79 );
80
81
82
83 private static final ConcurrentMap<String, Set<ICachedLoaderListener>> inProgress = new ConcurrentHashMap<>();
84 private static final ConcurrentMap<String, Boolean> useHead = new ConcurrentHashMap<>();
85
86 protected final long now; // when the job started
87
88 private final ICacheAccess<K, V> cache;
89 private ICacheElement<K, V> cacheElement;
90 protected V cacheData;
91 protected CacheEntryAttributes attributes;
92
93 // HTTP connection parameters
94 private final int connectTimeout;
95 private final int readTimeout;
96 private final Map<String, String> headers;
97 private final ThreadPoolExecutor downloadJobExecutor;
98 private Runnable finishTask;
99 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 return cacheData.getContent().length > 0;
199 }
200
201 /**
202 * Simple implementation. All errors should be cached as empty. Though some JDK (JDK8 on Windows for example)
203 * doesn't return 4xx error codes, instead they do throw an FileNotFoundException or IOException
204 *
205 * @return true if we should put empty object into cache, regardless of what remote resource has returned
206 */
207 protected boolean cacheAsEmpty() {
208 return attributes.getResponseCode() < 500;
209 }
210
211 /**
212 * @return key under which discovered server settings will be kept
213 */
214 protected String getServerKey() {
215 try {
216 return getUrl().getHost();
217 } catch (IOException e) {
218 Main.trace(e);
219 return null;
220 }
221 }
222
223 @Override
224 public void run() {
225 final Thread currentThread = Thread.currentThread();
226 final String oldName = currentThread.getName();
227 currentThread.setName("JCS Downloading: " + getUrlNoException());
228 LOG.log(Level.FINE, "JCS - starting fetch of url: {0} ", getUrlNoException());
229 ensureCacheElement();
230 try {
231 // try to fetch from cache
232 if (!force && cacheElement != null && isCacheElementValid() && isObjectLoadable()) {
233 // we got something in cache, and it's valid, so lets return it
234 LOG.log(Level.FINE, "JCS - Returning object from cache: {0}", getCacheKey());
235 finishLoading(LoadResult.SUCCESS);
236 return;
237 }
238
239 // try to load object from remote resource
240 if (loadObject()) {
241 finishLoading(LoadResult.SUCCESS);
242 } else {
243 // if loading failed - check if we can return stale entry
244 if (isObjectLoadable()) {
245 // try to get stale entry in cache
246 finishLoading(LoadResult.SUCCESS);
247 LOG.log(Level.FINE, "JCS - found stale object in cache: {0}", getUrlNoException());
248 } else {
249 // failed completely
250 finishLoading(LoadResult.FAILURE);
251 }
252 }
253 } finally {
254 executionFinished();
255 currentThread.setName(oldName);
256 }
257 }
258
259 private void finishLoading(LoadResult result) {
260 Set<ICachedLoaderListener> listeners;
261 synchronized (inProgress) {
262 try {
263 listeners = inProgress.remove(getUrl().toString());
264 } catch (IOException e) {
265 listeners = null;
266 Main.trace(e);
267 }
268 }
269 if (listeners == null) {
270 LOG.log(Level.WARNING, "Listener not found for URL: {0}. Listener not notified!", getUrlNoException());
271 return;
272 }
273 for (ICachedLoaderListener l: listeners) {
274 l.loadingFinished(cacheData, attributes, result);
275 }
276 }
277
278 protected boolean isCacheElementValid() {
279 long expires = attributes.getExpirationTime();
280
281 // check by expire date set by server
282 if (expires != 0L) {
283 // put a limit to the expire time (some servers send a value
284 // that is too large)
285 expires = Math.min(expires, attributes.getCreateTime() + EXPIRE_TIME_SERVER_LIMIT);
286 if (now > expires) {
287 LOG.log(Level.FINE, "JCS - Object {0} has expired -> valid to {1}, now is: {2}",
288 new Object[]{getUrlNoException(), Long.toString(expires), Long.toString(now)});
289 return false;
290 }
291 } else if (attributes.getLastModification() > 0 &&
292 now - attributes.getLastModification() > DEFAULT_EXPIRE_TIME) {
293 // check by file modification date
294 LOG.log(Level.FINE, "JCS - Object has expired, maximum file age reached {0}", getUrlNoException());
295 return false;
296 } else if (now - attributes.getCreateTime() > DEFAULT_EXPIRE_TIME) {
297 LOG.log(Level.FINE, "JCS - Object has expired, maximum time since object creation reached {0}", getUrlNoException());
298 return false;
299 }
300 return true;
301 }
302
303 /**
304 * @return true if object was successfully downloaded, false, if there was a loading failure
305 */
306 private boolean loadObject() {
307 if (attributes == null) {
308 attributes = new CacheEntryAttributes();
309 }
310 try {
311 // if we have object in cache, and host doesn't support If-Modified-Since nor If-None-Match
312 // then just use HEAD request and check returned values
313 if (isObjectLoadable() &&
314 Boolean.TRUE.equals(useHead.get(getServerKey())) &&
315 isCacheValidUsingHead()) {
316 LOG.log(Level.FINE, "JCS - cache entry verified using HEAD request: {0}", getUrl());
317 return true;
318 }
319
320 final HttpClient request = getRequest("GET", true);
321
322 if (isObjectLoadable() &&
323 (now - attributes.getLastModification()) <= ABSOLUTE_EXPIRE_TIME_LIMIT) {
324 request.setIfModifiedSince(attributes.getLastModification());
325 }
326 if (isObjectLoadable() && attributes.getEtag() != null) {
327 request.setHeader("If-None-Match", attributes.getEtag());
328 }
329
330 final HttpClient.Response urlConn = request.connect();
331
332 if (urlConn.getResponseCode() == 304) {
333 // If isModifiedSince or If-None-Match has been set
334 // and the server answers with a HTTP 304 = "Not Modified"
335 LOG.log(Level.FINE, "JCS - If-Modified-Since/ETag test: local version is up to date: {0}", getUrl());
336 return true;
337 } else if (isObjectLoadable() // we have an object in cache, but we haven't received 304 response code
338 && (
339 (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) ||
340 attributes.getLastModification() == urlConn.getLastModified())
341 ) {
342 // we sent ETag or If-Modified-Since, but didn't get 304 response code
343 // for further requests - use HEAD
344 String serverKey = getServerKey();
345 LOG.log(Level.INFO, "JCS - Host: {0} found not to return 304 codes for If-Modified-Since or If-None-Match headers",
346 serverKey);
347 useHead.put(serverKey, Boolean.TRUE);
348 }
349
350 attributes = parseHeaders(urlConn);
351
352 for (int i = 0; i < 5; ++i) {
353 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_UNAVAILABLE) {
354 Thread.sleep(5000L+new SecureRandom().nextInt(5000));
355 continue;
356 }
357
358 attributes.setResponseCode(urlConn.getResponseCode());
359 byte[] raw;
360 if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
361 raw = Utils.readBytesFromStream(urlConn.getContent());
362 } else {
363 raw = new byte[]{};
364 }
365
366 if (isResponseLoadable(urlConn.getHeaderFields(), urlConn.getResponseCode(), raw)) {
367 // we need to check cacheEmpty, so for cases, when data is returned, but we want to store
368 // as empty (eg. empty tile images) to save some space
369 cacheData = createCacheEntry(raw);
370 cache.put(getCacheKey(), cacheData, attributes);
371 LOG.log(Level.FINE, "JCS - downloaded key: {0}, length: {1}, url: {2}",
372 new Object[] {getCacheKey(), raw.length, getUrl()});
373 return true;
374 } else if (cacheAsEmpty()) {
375 cacheData = createCacheEntry(new byte[]{});
376 cache.put(getCacheKey(), cacheData, attributes);
377 LOG.log(Level.FINE, "JCS - Caching empty object {0}", getUrl());
378 return true;
379 } else {
380 LOG.log(Level.FINE, "JCS - failure during load - reponse is not loadable nor cached as empty");
381 return false;
382 }
383 }
384 } catch (FileNotFoundException e) {
385 LOG.log(Level.FINE, "JCS - Caching empty object as server returned 404 for: {0}", getUrlNoException());
386 attributes.setResponseCode(404);
387 attributes.setError(e);
388 boolean doCache = isResponseLoadable(null, 404, null) || cacheAsEmpty();
389 if (doCache) {
390 cacheData = createCacheEntry(new byte[]{});
391 cache.put(getCacheKey(), cacheData, attributes);
392 }
393 return doCache;
394 } catch (IOException e) {
395 LOG.log(Level.FINE, "JCS - IOExecption during communication with server for: {0}", getUrlNoException());
396 if (isObjectLoadable()) {
397 return true;
398 } else {
399 attributes.setError(e);
400 attributes.setResponseCode(599); // set dummy error code, greater than 500 so it will be not cached
401 return false;
402 }
403
404 } catch (InterruptedException e) {
405 attributes.setError(e);
406 LOG.log(Level.WARNING, "JCS - Exception during download {0}", getUrlNoException());
407 Main.warn(e);
408 }
409 LOG.log(Level.WARNING, "JCS - Silent failure during download: {0}", getUrlNoException());
410 return false;
411 }
412
413 /**
414 * Check if the object is loadable. This means, if the data will be parsed, and if this response
415 * will finish as successful retrieve.
416 *
417 * This simple implementation doesn't load empty response, nor client (4xx) and server (5xx) errors
418 *
419 * @param headerFields headers sent by server
420 * @param responseCode http status code
421 * @param raw data read from server
422 * @return true if object should be cached and returned to listener
423 */
424 protected boolean isResponseLoadable(Map<String, List<String>> headerFields, int responseCode, byte[] raw) {
425 if (raw == null || raw.length == 0 || responseCode >= 400) {
426 return false;
427 }
428 return true;
429 }
430
431 protected abstract V createCacheEntry(byte[] content);
432
433 protected CacheEntryAttributes parseHeaders(HttpClient.Response urlConn) {
434 CacheEntryAttributes ret = new CacheEntryAttributes();
435
436 Long lng = urlConn.getExpiration();
437 if (lng.equals(0L)) {
438 try {
439 String str = urlConn.getHeaderField("Cache-Control");
440 if (str != null) {
441 for (String token: str.split(",")) {
442 if (token.startsWith("max-age=")) {
443 lng = TimeUnit.SECONDS.toMillis(Long.parseLong(token.substring(8))) + System.currentTimeMillis();
444 }
445 }
446 }
447 } catch (NumberFormatException e) {
448 // ignore malformed Cache-Control headers
449 Main.trace(e);
450 }
451 }
452
453 ret.setExpirationTime(lng);
454 ret.setLastModification(now);
455 ret.setEtag(urlConn.getHeaderField("ETag"));
456
457 return ret;
458 }
459
460 private HttpClient getRequest(String requestMethod, boolean noCache) throws IOException {
461 final HttpClient urlConn = HttpClient.create(getUrl(), requestMethod);
462 urlConn.setAccept("text/html, image/png, image/jpeg, image/gif, */*");
463 urlConn.setReadTimeout(readTimeout); // 30 seconds read timeout
464 urlConn.setConnectTimeout(connectTimeout);
465 if (headers != null) {
466 urlConn.setHeaders(headers);
467 }
468
469 if (force || noCache) {
470 urlConn.useCache(false);
471 }
472 return urlConn;
473 }
474
475 private boolean isCacheValidUsingHead() throws IOException {
476 final HttpClient.Response urlConn = getRequest("HEAD", false).connect();
477 long lastModified = urlConn.getLastModified();
478 return (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) ||
479 (lastModified != 0 && lastModified <= attributes.getLastModification());
480 }
481
482 /**
483 * TODO: move to JobFactory
484 * cancels all outstanding tasks in the queue.
485 */
486 public void cancelOutstandingTasks() {
487 for (Runnable r: downloadJobExecutor.getQueue()) {
488 if (downloadJobExecutor.remove(r) && r instanceof JCSCachedTileLoaderJob) {
489 ((JCSCachedTileLoaderJob<?, ?>) r).handleJobCancellation();
490 }
491 }
492 }
493
494 /**
495 * Sets a job, that will be run, when job will finish execution
496 * @param runnable that will be executed
497 */
498 public void setFinishedTask(Runnable runnable) {
499 this.finishTask = runnable;
500
501 }
502
503 /**
504 * Marks this job as canceled
505 */
506 public void handleJobCancellation() {
507 finishLoading(LoadResult.CANCELED);
508 }
509
510 private URL getUrlNoException() {
511 try {
512 return getUrl();
513 } catch (IOException e) {
514 return null;
515 }
516 }
517}
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