source: josm/trunk/src/org/openstreetmap/josm/data/cache/JCSCachedTileLoaderJob.java @ 11535

Last change on this file since 11535 was 11535, checked in by Don-vip, 2 years ago

sonar - squid:S2142 - "InterruptedException" should not be ignored

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File size: 21.1 KB
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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            Thread.currentThread().interrupt();
409        }
410        LOG.log(Level.WARNING, "JCS - Silent failure during download: {0}", getUrlNoException());
411        return false;
412    }
413
414    /**
415     * Check if the object is loadable. This means, if the data will be parsed, and if this response
416     * will finish as successful retrieve.
417     *
418     * This simple implementation doesn't load empty response, nor client (4xx) and server (5xx) errors
419     *
420     * @param headerFields headers sent by server
421     * @param responseCode http status code
422     * @param raw data read from server
423     * @return true if object should be cached and returned to listener
424     */
425    protected boolean isResponseLoadable(Map<String, List<String>> headerFields, int responseCode, byte[] raw) {
426        if (raw == null || raw.length == 0 || responseCode >= 400) {
427            return false;
428        }
429        return true;
430    }
431
432    protected abstract V createCacheEntry(byte[] content);
433
434    protected CacheEntryAttributes parseHeaders(HttpClient.Response urlConn) {
435        CacheEntryAttributes ret = new CacheEntryAttributes();
436
437        Long lng = urlConn.getExpiration();
438        if (lng.equals(0L)) {
439            try {
440                String str = urlConn.getHeaderField("Cache-Control");
441                if (str != null) {
442                    for (String token: str.split(",")) {
443                        if (token.startsWith("max-age=")) {
444                            lng = TimeUnit.SECONDS.toMillis(Long.parseLong(token.substring(8))) + System.currentTimeMillis();
445                        }
446                    }
447                }
448            } catch (NumberFormatException e) {
449                // ignore malformed Cache-Control headers
450                Main.trace(e);
451            }
452        }
453
454        ret.setExpirationTime(lng);
455        ret.setLastModification(now);
456        ret.setEtag(urlConn.getHeaderField("ETag"));
457
458        return ret;
459    }
460
461    private HttpClient getRequest(String requestMethod, boolean noCache) throws IOException {
462        final HttpClient urlConn = HttpClient.create(getUrl(), requestMethod);
463        urlConn.setAccept("text/html, image/png, image/jpeg, image/gif, */*");
464        urlConn.setReadTimeout(readTimeout); // 30 seconds read timeout
465        urlConn.setConnectTimeout(connectTimeout);
466        if (headers != null) {
467            urlConn.setHeaders(headers);
468        }
469
470        if (force || noCache) {
471            urlConn.useCache(false);
472        }
473        return urlConn;
474    }
475
476    private boolean isCacheValidUsingHead() throws IOException {
477        final HttpClient.Response urlConn = getRequest("HEAD", false).connect();
478        long lastModified = urlConn.getLastModified();
479        return (attributes.getEtag() != null && attributes.getEtag().equals(urlConn.getHeaderField("ETag"))) ||
480                (lastModified != 0 && lastModified <= attributes.getLastModification());
481    }
482
483    /**
484     * TODO: move to JobFactory
485     * cancels all outstanding tasks in the queue.
486     */
487    public void cancelOutstandingTasks() {
488        for (Runnable r: downloadJobExecutor.getQueue()) {
489            if (downloadJobExecutor.remove(r) && r instanceof JCSCachedTileLoaderJob) {
490                ((JCSCachedTileLoaderJob<?, ?>) r).handleJobCancellation();
491            }
492        }
493    }
494
495    /**
496     * Sets a job, that will be run, when job will finish execution
497     * @param runnable that will be executed
498     */
499    public void setFinishedTask(Runnable runnable) {
500        this.finishTask = runnable;
501
502    }
503
504    /**
505     * Marks this job as canceled
506     */
507    public void handleJobCancellation() {
508        finishLoading(LoadResult.CANCELED);
509    }
510
511    private URL getUrlNoException() {
512        try {
513            return getUrl();
514        } catch (IOException e) {
515            return null;
516        }
517    }
518}
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