// plasmaHTCache.java // ----------------------- // part of YaCy // (C) by Michael Peter Christen; mc@anomic.de // first published on http://www.anomic.de // Frankfurt, Germany, 2004 // // $LastChangedDate$ // $LastChangedRevision$ // $LastChangedBy$ // // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 2 of the License, or // (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA // // Using this software in any meaning (reading, learning, copying, compiling, // running) means that you agree that the Author(s) is (are) not responsible // for cost, loss of data or any harm that may be caused directly or indirectly // by usage of this softare or this documentation. The usage of this software // is on your own risk. The installation and usage (starting/running) of this // software may allow other people or application to access your computer and // any attached devices and is highly dependent on the configuration of the // software which must be done by the user of the software; the author(s) is // (are) also not responsible for proper configuration and usage of the // software, even if provoked by documentation provided together with // the software. // // Any changes to this file according to the GPL as documented in the file // gpl.txt aside this file in the shipment you received can be done to the // lines that follows this copyright notice here, but changes must not be // done inside the copyright notive above. A re-distribution must contain // the intact and unchanged copyright notice. // Contributions and changes to the program code must be marked as such. /* Class documentation: This class has two purposes: 1. provide a object that carries path and header information that shall be used as objects within a scheduler's stack 2. static methods for a cache control and cache aging the class shall also be used to do a cache-cleaning and index creation */ package de.anomic.plasma; import java.io.File; import java.io.FileNotFoundException; import java.util.HashSet; import java.io.IOException; import java.net.MalformedURLException; import java.net.URL; import java.util.Date; import java.util.Iterator; import java.util.LinkedList; import java.util.Map; import java.util.TreeMap; import de.anomic.htmlFilter.htmlFilterContentScraper; import de.anomic.http.httpHeader; import de.anomic.http.httpc; import de.anomic.kelondro.kelondroDyn; import de.anomic.kelondro.kelondroMScoreCluster; import de.anomic.kelondro.kelondroMap; import de.anomic.server.serverFileUtils; import de.anomic.server.serverInstantThread; import de.anomic.server.logging.serverLog; import de.anomic.server.serverDate; import de.anomic.tools.enumerateFiles; public final class plasmaHTCache { private static final int stackLimit = 150; // if we exceed that limit, we do not check idle public static final long oneday = 1000 * 60 * 60 * 24; // milliseconds of a day private kelondroMap responseHeaderDB = null; private final LinkedList cacheStack; private final TreeMap cacheAge; // a - relation public long currCacheSize; public long maxCacheSize; public final File cachePath; public final serverLog log; public static final HashSet filesInUse = new HashSet(); // can we delete this file public plasmaHTCache(File htCachePath, long maxCacheSize, int bufferkb) { // this.switchboard = switchboard; this.log = new serverLog("HTCACHE"); this.cachePath = htCachePath; this.maxCacheSize = maxCacheSize; // set/make cache path if (!(htCachePath.exists())) { htCachePath.mkdirs(); } if (!(htCachePath.isDirectory())) { // if the cache does not exists or is a file and not a directory, panic this.log.logSevere("the cache path " + htCachePath.toString() + " is not a directory or does not exists and cannot be created"); System.exit(0); } // open the response header database File dbfile = new File(this.cachePath, "responseHeader.db"); try { if (dbfile.exists()) this.responseHeaderDB = new kelondroMap(new kelondroDyn(dbfile, bufferkb * 0x400)); else this.responseHeaderDB = new kelondroMap(new kelondroDyn(dbfile, bufferkb * 0x400, plasmaURL.urlHashLength, 150)); } catch (IOException e) { this.log.logSevere("the request header database could not be opened: " + e.getMessage()); System.exit(0); } // init stack this.cacheStack = new LinkedList(); // init cache age and size management this.cacheAge = new TreeMap(); this.currCacheSize = 0; this.maxCacheSize = maxCacheSize; // start the cache startup thread // this will collect information about the current cache size and elements serverInstantThread.oneTimeJob(this, "cacheScan", this.log, 5000); } public int size() { synchronized (this.cacheStack) { return this.cacheStack.size(); } } public int dbSize() { return this.responseHeaderDB.size(); } public int[] dbCacheChunkSize() { return this.responseHeaderDB.cacheChunkSize(); } public int[] dbCacheFillStatus() { return this.responseHeaderDB.cacheFillStatus(); } public void push(Entry entry) { synchronized (this.cacheStack) { this.cacheStack.add(entry); } } public Entry pop() { synchronized (this.cacheStack) { if (this.cacheStack.size() > 0) return (Entry) this.cacheStack.removeFirst(); return null; } } public void storeHeader(String urlHash, httpHeader responseHeader) throws IOException { this.responseHeaderDB.set(urlHash, responseHeader); } /** * This method changes the HTCache size.
* @param new cache size in bytes */ public final void setCacheSize(long newCacheSize) { this.maxCacheSize = newCacheSize; } /** * This method returns the free HTCache size.
* @return the cache size in bytes */ public long getFreeSize() { return (this.currCacheSize >= this.maxCacheSize) ? 0 : this.maxCacheSize - this.currCacheSize; } public boolean writeFile(URL url, byte[] array) { if (array == null) return false; File file = getCachePath(url); try { deleteFile(file); file.getParentFile().mkdirs(); serverFileUtils.write(array, file); } catch (FileNotFoundException e) { // this is the case of a "(Not a directory)" error, which should be prohibited // by the shallStoreCache() property. However, sometimes the error still occurs // In this case do nothing. this.log.logSevere("File storage failed (not a directory): " + e.getMessage()); return false; } catch (IOException e) { this.log.logSevere("File storage failed (IO error): " + e.getMessage()); return false; } writeFileAnnouncement(file); return true; } public void writeFileAnnouncement(File file) { synchronized (this.cacheAge) { if (file.exists()) { this.currCacheSize += file.length(); this.cacheAge.put(ageString(file.lastModified(), file), file); cleanup(); } } } public boolean deleteFile(URL url) { return deleteURLfromCache(url, "FROM"); } private boolean deleteURLfromCache (URL url, String msg) { if (deleteFileandDirs(getCachePath(url), msg)) { try { // As the file is gone, the entry in responseHeader.db is not needed anymore this.log.logFinest("Trying to remove responseHeader from URL: " + url.toString()); this.responseHeaderDB.remove(plasmaURL.urlHash(url)); } catch (IOException e) { this.log.logInfo("IOExeption removing response header from DB: " + e.getMessage(), e); } return true; } return false; } private boolean deleteFile(File obj) { if (obj.exists() && !filesInUse.contains(obj)) { long size = obj.length(); if (obj.delete()) { this.currCacheSize -= size; return true; } } return false; } private boolean deleteFileandDirs (File obj, String msg) { if (deleteFile(obj)) { this.log.logInfo("DELETED " + msg + " CACHE : " + obj.toString()); obj = obj.getParentFile(); // If the has been emptied, remove it // Loop as long as we produce empty driectoriers, but stop at HTCACHE while ((!(obj.equals(this.cachePath))) && (obj.isDirectory()) && (obj.list().length == 0)) { if (obj.delete()) this.log.logInfo("DELETED EMPTY DIRECTORY : " + obj.toString()); obj = obj.getParentFile(); } return true; } return false; } private void cleanupDoIt(long newCacheSize) { if (this.cacheAge.size() == 0) return; File obj; Iterator iter = this.cacheAge.keySet().iterator(); while (iter.hasNext() && (this.currCacheSize >= newCacheSize)) { Object key = iter.next(); obj = (File) this.cacheAge.get(key); if (obj != null) { if (filesInUse.contains(obj)) continue; this.log.logFinest("Trying to delete old file: " + obj.toString()); if (deleteFileandDirs (obj, "OLD")) { try { // As the file is gone, the entry in responseHeader.db is not needed anymore this.log.logFinest("Trying to remove responseHeader for URL: " + getURL(this.cachePath ,obj).toString()); this.responseHeaderDB.remove(plasmaURL.urlHash(getURL(this.cachePath ,obj))); } catch (IOException e) { this.log.logInfo("IOExeption removing response header from DB: " + e.getMessage(), e); } } } } } private void cleanup() { // clean up cache to have 4% (enough) space for next entries if ((this.currCacheSize >= this.maxCacheSize) && (this.cacheAge.size() > 0)) { if (this.maxCacheSize > 0) cleanupDoIt(this.maxCacheSize - ((this.maxCacheSize / 100) * 4)); } } public void close() throws IOException { this.responseHeaderDB.close(); } private String ageString(long date, File f) { StringBuffer sb = new StringBuffer(32); String s = Long.toHexString(date); for (int i = s.length(); i < 16; i++) sb.append('0'); sb.append(s); s = Integer.toHexString(f.hashCode()); for (int i = s.length(); i < 8; i++) sb.append('0'); sb.append(s); return sb.toString(); } public void cacheScan() { //log.logSystem("STARTING CACHE SCANNING"); kelondroMScoreCluster doms = new kelondroMScoreCluster(); int c = 0; enumerateFiles ef = new enumerateFiles(this.cachePath, true, false, true, true); File f; while (ef.hasMoreElements()) { c++; f = (File) ef.nextElement(); long d = f.lastModified(); //System.out.println("Cache: " + dom(f)); doms.incScore(dom(f)); this.currCacheSize += f.length(); this.cacheAge.put(ageString(d, f), f); } //System.out.println("%" + (String) cacheAge.firstKey() + "=" + cacheAge.get(cacheAge.firstKey())); long ageHours = 0; try { ageHours = (System.currentTimeMillis() - Long.parseLong(((String) this.cacheAge.firstKey()).substring(0, 16), 16)) / 3600000; } catch (NumberFormatException e) { //e.printStackTrace(); } this.log.logConfig("CACHE SCANNED, CONTAINS " + c + " FILES = " + this.currCacheSize/1048576 + "MB, OLDEST IS " + ((ageHours < 24) ? (ageHours + " HOURS") : ((ageHours / 24) + " DAYS")) + " OLD"); cleanup(); // start to prefetch ip's from dns String dom; long start = System.currentTimeMillis(); String ip, result = ""; c = 0; while ((doms.size() > 0) && (c < 50) && ((System.currentTimeMillis() - start) < 60000)) { dom = (String) doms.getMaxObject(); ip = httpc.dnsResolve(dom); if (ip == null) continue; result += ", " + dom + "=" + ip; this.log.logConfig("PRE-FILLED " + dom + "=" + ip); c++; doms.deleteScore(dom); // wait a short while to prevent that this looks like a DoS try {Thread.sleep(100);} catch (InterruptedException e) {} } if (result.length() > 2) this.log.logConfig("PRE-FILLED DNS CACHE, FETCHED " + c + " ADDRESSES: " + result.substring(2)); } private String dom(File f) { String s = f.toString().substring(this.cachePath.toString().length() + 1); int p = s.indexOf("/"); if (p < 0) p = s.indexOf("\\"); if (p < 0) return null; return s.substring(0, p); } public httpHeader getCachedResponse(String urlHash) throws IOException { Map hdb = this.responseHeaderDB.get(urlHash); if (hdb == null) return null; return new httpHeader(null, hdb); } public boolean full() { return (this.cacheStack.size() > stackLimit); } public boolean empty() { return (this.cacheStack.size() == 0); } public static boolean isPicture(httpHeader response) { Object ct = response.get(httpHeader.CONTENT_TYPE); if (ct == null) return false; return ((String)ct).toUpperCase().startsWith("IMAGE"); } public static boolean isText(httpHeader response) { // Object ct = response.get(httpHeader.CONTENT_TYPE); // if (ct == null) return false; // String t = ((String)ct).toLowerCase(); // return ((t.startsWith("text")) || (t.equals("application/xhtml+xml"))); return plasmaParser.supportedMimeTypesContains(response.mime()); } public static boolean noIndexingURL(String urlString) { if (urlString == null) return false; urlString = urlString.toLowerCase(); // return ( // (urlString.endsWith(".gz")) || // (urlString.endsWith(".msi")) || // (urlString.endsWith(".doc")) || // (urlString.endsWith(".zip")) || // (urlString.endsWith(".tgz")) || // (urlString.endsWith(".rar")) || // (urlString.endsWith(".pdf")) || // (urlString.endsWith(".ppt")) || // (urlString.endsWith(".xls")) || // (urlString.endsWith(".log")) || // (urlString.endsWith(".java")) || // (urlString.endsWith(".c")) || // (urlString.endsWith(".p")) // ); int idx = urlString.indexOf("?"); if (idx > 0) urlString = urlString.substring(0,idx); idx = urlString.lastIndexOf("."); if (idx > 0) urlString = urlString.substring(idx+1); return plasmaParser.mediaExtContains(urlString); } /** * this method creates from a given host and path a cache path * from a given host (which may also be an IPv4 - number, but not IPv6 or * a domain; all without leading 'http://') and a path (which must start * with a leading '/', and may also end in an '/') a path to a file * in the file system with root as given in cachePath is constructed * it will also be ensured, that the complete path exists; if necessary * that path will be generated * @return URL */ public File getCachePath(URL url) { // this.log.logFinest("plasmaHTCache: getCachePath: IN=" + url.toString()); String remotePath = url.getPath(); if (!(remotePath.startsWith("/"))) remotePath = "/" + remotePath; if (remotePath.endsWith("/")) remotePath = remotePath + "ndx"; if (remotePath.indexOf('#') > 0) remotePath.substring(0, remotePath.indexOf('#')); remotePath = remotePath.replace('?', '_'); remotePath = remotePath.replace('&', '_'); // yes this is not reversible, but that is not needed remotePath = remotePath.replace(':', '_'); // yes this is not reversible, but that is not needed int port = url.getPort(); if (port < 0) port = 80; // this.log.logFinest("plasmaHTCache: getCachePath: OUT=" + url.getHost() + ((port == 80) ? "" : ("+" + port)) + remotePath); return new File(this.cachePath, url.getHost() + ((port == 80) ? "" : ("+" + port)) + remotePath); } /** * this is the reverse function to getCachePath: it constructs the url as string * from a given storage path */ public static URL getURL(File cachePath, File f) { // this.log.logFinest("plasmaHTCache: getURL: IN: Path=[" + cachePath + "]"); // this.log.logFinest("plasmaHTCache: getURL: IN: File=[" + f + "]"); String s = f.toString().replace('\\', '/'); String c = cachePath.toString().replace('\\', '/'); int p = s.lastIndexOf(c); if (p >= 0) { s = s.substring(p + c.length()); while (s.startsWith("/")) s = s.substring(1); if ((p = s.indexOf("+")) >= 0) { s = s.substring(0, p) + ":" + s.substring(p + 1); /* } else { p = s.indexOf("/"); if (p < 0) s = s + ":80/"; else s = s.substring(0, p) + ":80" + s.substring(p);*/ } if (s.endsWith("ndx")) { s = s.substring(0, s.length() - 3); } // this.log.logFinest("plasmaHTCache: getURL: OUT=" + s); try { /* URL url = null; url = new URL("http://" + s); this.log.logFinest("plasmaHTCache: getURL: URL=" + url.toString()); return url;//new URL("http://" + s); */ return new URL("http://" + s); } catch (Exception e) { return null; } } return null; } public byte[] loadResource(URL url) { // load the url as resource from the cache File f = getCachePath(url); if (f.exists()) try { return serverFileUtils.read(f); } catch (IOException e) { return null; } return null; } public static boolean isPOST(String urlString) { return ((urlString.indexOf("?") >= 0) || (urlString.indexOf("&") >= 0)); } public static boolean isCGI(String urlString) { // Borg-0300 String ls = urlString.toLowerCase(); return ((ls.indexOf(".cgi") >= 0) || (ls.indexOf(".exe") >= 0) || (ls.indexOf(";jsessionid=") >= 0) || (ls.indexOf("sessionid/") >= 0) || (ls.indexOf("phpsessid=") >= 0)); } public Entry newEntry(Date initDate, int depth, URL url, String name, httpHeader requestHeader, String responseStatus, httpHeader responseHeader, String initiator, plasmaCrawlProfile.entry profile) { return new Entry(initDate, depth, url, name, requestHeader, responseStatus, responseHeader, initiator, profile); } public final class Entry { // the class objects public Date initDate; // the date when the request happened; will be used as a key public int depth; // the depth of prefetching public httpHeader requestHeader; // we carry also the header to prevent too many file system access public String responseStatus; public httpHeader responseHeader; // we carry also the header to prevent too many file system access public File cacheFile; // the cache file public byte[] cacheArray; // or the cache as byte-array public URL url; public String name; // the name of the link, read as anchor from an -tag public String nomalizedURLHash; public String nomalizedURLString; public int status; // cache load/hit/stale etc status public Date lastModified; public char doctype; public String language; public plasmaCrawlProfile.entry profile; private String initiator; public Entry(Date initDate, int depth, URL url, String name, httpHeader requestHeader, String responseStatus, httpHeader responseHeader, String initiator, plasmaCrawlProfile.entry profile) { // normalize url serverLog.logFine("PLASMA", "Entry: URL=" + url.toString()); this.nomalizedURLString = htmlFilterContentScraper.urlNormalform(url); try { this.url = new URL(this.nomalizedURLString); } catch (MalformedURLException e) { System.out.println("internal error at httpdProxyCache.Entry: " + e); System.exit(-1); } this.name = name; this.cacheFile = getCachePath(this.url); this.nomalizedURLHash = plasmaURL.urlHash(this.nomalizedURLString); // assigned: this.initDate = initDate; this.depth = depth; this.requestHeader = requestHeader; this.responseStatus = responseStatus; this.responseHeader = responseHeader; this.profile = profile; this.initiator = (initiator == null) ? null : ((initiator.length() == 0) ? null: initiator); // calculated: if (responseHeader == null) { try { throw new RuntimeException("RESPONSE HEADER = NULL"); } catch (Exception e) { System.out.println("RESPONSE HEADER = NULL in " + url); e.printStackTrace(); System.exit(0); } this.lastModified = new Date(serverDate.correctedUTCTime()); } else { this.lastModified = responseHeader.lastModified(); if (this.lastModified == null) this.lastModified = new Date(serverDate.correctedUTCTime()); // does not exist in header } this.doctype = plasmaWordIndexEntry.docType(responseHeader.mime()); if (this.doctype == plasmaWordIndexEntry.DT_UNKNOWN) this.doctype = plasmaWordIndexEntry.docType(url); this.language = plasmaWordIndexEntry.language(url); // to be defined later: this.cacheArray = null; } public String name() { return this.name; } public String initiator() { return this.initiator; } public boolean proxy() { return initiator() == null; } public long size() { if (this.cacheArray == null) return 0; return this.cacheArray.length; } public URL referrerURL() { if (this.requestHeader == null) return null; try { return new URL((String) this.requestHeader.get(httpHeader.REFERER, "")); } catch (Exception e) { return null; } } /* public boolean update() { return ((status == CACHE_FILL) || (status == CACHE_STALE_RELOAD_GOOD)); } */ // the following three methods for cache read/write granting shall be as loose as possible // but also as strict as necessary to enable caching of most items public String shallStoreCacheForProxy() { // returns NULL if the answer is TRUE // in case of FALSE, the reason as String is returned // check profile if (!(this.profile.storeHTCache())) return "storage_not_wanted"; // decide upon header information if a specific file should be stored to the cache or not // if the storage was requested by prefetching, the request map is null // check status code if (!((this.responseStatus.startsWith("200")) || (this.responseStatus.startsWith("203")))) return "bad_status_" + this.responseStatus.substring(0,3); // check storage location // sometimes a file name is equal to a path name in the same directory; // or sometimes a file name is equal a directory name created earlier; // we cannot match that here in the cache file path and therefore omit writing into the cache if ((this.cacheFile.getParentFile().isFile()) || (this.cacheFile.isDirectory())) return "path_ambiguous"; if (this.cacheFile.toString().indexOf("..") >= 0) return "path_dangerous"; // -CGI access in request // CGI access makes the page very individual, and therefore not usable in caches if ((isPOST(this.nomalizedURLString)) && (!(this.profile.crawlingQ()))) return "dynamic_post"; if (isCGI(this.nomalizedURLString)) return "dynamic_cgi"; // -authorization cases in request // authorization makes pages very individual, and therefore we cannot use the // content in the cache if ((this.requestHeader != null) && (this.requestHeader.containsKey(httpHeader.AUTHORIZATION))) return "personalized"; // -ranges in request and response // we do not cache partial content if ((this.requestHeader != null) && (this.requestHeader.containsKey(httpHeader.RANGE))) return "partial"; if ((this.responseHeader != null) && (this.responseHeader.containsKey(httpHeader.CONTENT_RANGE))) return "partial"; // -if-modified-since in request // we do not care about if-modified-since, because this case only occurres if the // cache file does not exist, and we need as much info as possible for the indexing // -cookies in request // we do not care about cookies, because that would prevent loading more pages // from one domain once a request resulted in a client-side stored cookie // -set-cookie in response // we do not care about cookies in responses, because that info comes along // any/many pages from a server and does not express the validity of the page // in modes of life-time/expiration or individuality // -pragma in response // if we have a pragma non-cache, we don't cache. usually if this is wanted from // the server, it makes sense if ((this.responseHeader.containsKey(httpHeader.PRAGMA)) && (((String) this.responseHeader.get(httpHeader.PRAGMA)).toUpperCase().equals("NO-CACHE"))) return "controlled_no_cache"; // -expires in response // we do not care about expires, because at the time this is called the data is // obvious valid and that header info is used in the indexing later on // -cache-control in response // the cache-control has many value options. String cacheControl = (String) this.responseHeader.get(httpHeader.CACHE_CONTROL); if (cacheControl != null) { cacheControl = cacheControl.trim().toUpperCase(); if (cacheControl.startsWith("MAX-AGE=")) { // we need also the load date Date date = this.responseHeader.date(); if (date == null) return "stale_no_date_given_in_response"; try { long ttl = 1000 * Long.parseLong(cacheControl.substring(8)); // milliseconds to live if (serverDate.correctedUTCTime() - date.getTime() > ttl) { //System.out.println("***not indexed because cache-control"); return "stale_expired"; } } catch (Exception e) { return "stale_error_" + e.getMessage() + ")"; } } } return null; } public boolean shallUseCacheForProxy() { // decide upon header information if a specific file should be taken from the cache or not //System.out.println("SHALL READ CACHE: requestHeader = " + requestHeader.toString() + ", responseHeader = " + responseHeader.toString()); // -CGI access in request // CGI access makes the page very individual, and therefore not usable in caches if (isPOST(this.nomalizedURLString)) return false; if (isCGI(this.nomalizedURLString)) return false; // -authorization cases in request if (this.requestHeader.containsKey(httpHeader.AUTHORIZATION)) return false; // -ranges in request // we do not cache partial content if ((this.requestHeader != null) && (this.requestHeader.containsKey(httpHeader.RANGE))) return false; //Date d1, d2; // -if-modified-since in request // The entity has to be transferred only if it has // been modified since the date given by the If-Modified-Since header. if (this.requestHeader.containsKey(httpHeader.IF_MODIFIED_SINCE)) { // checking this makes only sense if the cached response contains // a Last-Modified field. If the field does not exist, we go the safe way if (!(this.responseHeader.containsKey(httpHeader.LAST_MODIFIED))) return false; // parse date Date d1, d2; d2 = this.responseHeader.lastModified(); if (d2 == null) d2 = new Date(serverDate.correctedUTCTime()); d1 = this.requestHeader.ifModifiedSince(); if (d1 == null) d1 = new Date(serverDate.correctedUTCTime()); // finally, we shall treat the cache as stale if the modification time is after the if-.. time if (d2.after(d1)) return false; } boolean isNotPicture = !isPicture(this.responseHeader); // -cookies in request // unfortunately, we should reload in case of a cookie // but we think that pictures can still be considered as fresh if ((this.requestHeader.containsKey(httpHeader.COOKIE)) && (isNotPicture)) return false; // -set-cookie in cached response // this is a similar case as for COOKIE. if ((this.responseHeader.containsKey(httpHeader.SET_COOKIE)) && (isNotPicture)) return false; // too strong if ((this.responseHeader.containsKey(httpHeader.SET_COOKIE2)) && (isNotPicture)) return false; // too strong // -pragma in cached response // logically, we would not need to care about no-cache pragmas in cached response headers, // because they cannot exist since they are not written to the cache. // So this IF should always fail.. if ((this.responseHeader.containsKey(httpHeader.PRAGMA)) && (((String) this.responseHeader.get(httpHeader.PRAGMA)).toUpperCase().equals("NO-CACHE"))) return false; // calculate often needed values for freshness attributes Date date = this.responseHeader.date(); Date expires = this.responseHeader.expires(); Date lastModified = this.responseHeader.lastModified(); String cacheControl = (String) this.responseHeader.get(httpHeader.CACHE_CONTROL); // see for documentation also: // http://www.web-caching.com/cacheability.html // http://vancouver-webpages.com/CacheNow/ // look for freshnes information // if we don't have any freshnes indication, we treat the file as stale. // no handle for freshness control: if ((expires == null) && (cacheControl == null) && (lastModified == null)) return false; // -expires in cached response // the expires value gives us a very easy hint when the cache is stale if (expires != null) { //System.out.println("EXPIRES-TEST: expires=" + expires + ", NOW=" + serverDate.correctedGMTDate() + ", url=" + url); if (expires.before(new Date(serverDate.correctedUTCTime()))) return false; } // -lastModified in cached response // we can apply a TTL (Time To Live) heuristic here. We call the time delta between the last read // of the file and the last modified date as the age of the file. If we consider the file as // middel-aged then, the maximum TTL would be cache-creation plus age. // This would be a TTL factor of 100% we want no more than 10% TTL, so that a 10 month old cache // file may only be treated as fresh for one more month, not more. if (lastModified != null) { if (date == null) date = new Date(serverDate.correctedUTCTime()); long age = date.getTime() - lastModified.getTime(); if (age < 0) return false; // TTL (Time-To-Live) is age/10 = (d2.getTime() - d1.getTime()) / 10 // the actual living-time is serverDate.correctedGMTDate().getTime() - d2.getTime() // therefore the cache is stale, if serverDate.correctedGMTDate().getTime() - d2.getTime() > age/10 if (serverDate.correctedUTCTime() - date.getTime() > age / 10) return false; } // -cache-control in cached response // the cache-control has many value options. if (cacheControl != null) { cacheControl = cacheControl.trim().toUpperCase(); if (cacheControl.startsWith("PUBLIC")) { // ok, do nothing } else if ((cacheControl.startsWith("PRIVATE")) || (cacheControl.startsWith("NO-CACHE")) || (cacheControl.startsWith("NO-STORE"))) { // easy case return false; } else if (cacheControl.startsWith("MAX-AGE=")) { // we need also the load date if (date == null) return false; try { long ttl = 1000 * Long.parseLong(cacheControl.substring(8)); // milliseconds to live if (serverDate.correctedUTCTime() - date.getTime() > ttl) { return false; } } catch (Exception e) { return false; } } } return true; } } /* public static void main(String[] args) { //String[] s = TimeZone.getAvailableIDs(); //for (int i = 0; i < s.length; i++) System.out.println("ZONE=" + s[i]); Calendar c = GregorianCalendar.getInstance(); int zoneOffset = c.get(Calendar.ZONE_OFFSET)/(60*60*1000); int DSTOffset = c.get(Calendar.DST_OFFSET)/(60*60*1000); System.out.println("This Offset = " + (zoneOffset + DSTOffset)); for (int i = 0; i < 12; i++) { c = new GregorianCalendar(TimeZone.getTimeZone("Etc/GMT-" + i)); //c.setTimeZone(TimeZone.getTimeZone("Etc/GMT+0")); System.out.println("Zone offset: "+ c.get(Calendar.ZONE_OFFSET)/(60*60*1000)); System.out.println(c.get(GregorianCalendar.HOUR) + ", " + c.getTime() + ", " + c.getTimeInMillis()); } } **/ }