// plasmaHTCache.java // ----------------------- // part of YaCy // (C) by Michael Peter Christen; mc@anomic.de // first published on http://www.anomic.de // Frankfurt, Germany, 2004 // last major change: 12.02.2004 // // 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.io.IOException; import java.net.MalformedURLException; import java.net.URL; import java.util.Date; import java.util.LinkedList; 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.serverLog; 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 private static final long idleDelay = 2000; // 2 seconds no hits until we think that we idle private static final long oneday = 1000 * 60 * 60 * 24; // milliseconds of a day private final plasmaSwitchboard switchboard; private kelondroMap responseHeaderDB = null; private final LinkedList cacheStack; private final TreeMap cacheAge; // a - relation public long currCacheSize; public long maxCacheSize; private long lastAcc; private final File cachePath; public static serverLog log; public static final int CACHE_UNFILLED = 0; // default case without assignment public static final int CACHE_FILL = 1; // this means: update == true public static final int CACHE_HIT = 2; // the best case: reading from Cache public static final int CACHE_STALE_NO_RELOAD = 3; // this shall be treated as a rare case that should not appear public static final int CACHE_STALE_RELOAD_GOOD = 4; // this means: update == true public static final int CACHE_STALE_RELOAD_BAD = 5; // this updates only the responseHeader, not the content public static final int CACHE_PASSING = 6; // does not touch cache, just passing public plasmaHTCache(plasmaSwitchboard switchboard, int bufferkb) { this.switchboard = switchboard; int loglevel = Integer.parseInt(switchboard.getConfig("plasmaLoglevel", "2")); this.log = new serverLog("HTCACHE", loglevel); // set cache path cachePath = new File(switchboard.getRootPath(),switchboard.getConfig("proxyCache","HTCACHE")); if (!(cachePath.exists())) { // make the cache path cachePath.mkdir(); } if (!(cachePath.isDirectory())) { // if the cache does not exists or is a file and not a directory, panic System.out.println("the cache path " + cachePath.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(cachePath, "responseHeader.db"); try { if (dbfile.exists()) responseHeaderDB = new kelondroMap(new kelondroDyn(dbfile, bufferkb * 0x400)); else responseHeaderDB = new kelondroMap(new kelondroDyn(dbfile, bufferkb * 0x400, plasmaCrawlLURL.urlHashLength, 150)); } catch (IOException e) { System.out.println("the request header database could not be opened: " + e.getMessage()); System.exit(0); } // init stack cacheStack = new LinkedList(); // init idle check lastAcc = System.currentTimeMillis(); // init cache age and size management cacheAge = new TreeMap(); currCacheSize = 0; maxCacheSize = Long.parseLong(switchboard.getConfig("proxyCacheSize", "2")); // this is megabyte maxCacheSize = maxCacheSize * 1024 * 1024; // now it's the number of bytes // start the cache startup thread // this will collect information about the current cache size and elements serverInstantThread.oneTimeJob(this, "cacheScan", log, 5000); } public void close() throws IOException { responseHeaderDB.close(); } private String ageString(long date, File f) { String s = Integer.toHexString(f.hashCode()); while (s.length() < 8) s = "0" + s; s = Long.toHexString(date) + s; while (s.length() < 24) s = "0" + s; return s; } public void cacheScan() { //log.logSystem("STARTING CACHE SCANNING"); kelondroMScoreCluster doms = new kelondroMScoreCluster(); int c = 0; enumerateFiles ef = new enumerateFiles(cachePath, true, false, 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)); currCacheSize += f.length(); cacheAge.put(ageString(d, f), f); } //System.out.println("%" + (String) cacheAge.firstKey() + "=" + cacheAge.get(cacheAge.firstKey())); long ageHours = (System.currentTimeMillis() - Long.parseLong(((String) cacheAge.firstKey()).substring(0, 16), 16)) / 3600000; log.logSystem("CACHE SCANNED, CONTAINS " + c + " FILES = " + currCacheSize/1048576 + "MB, OLDEST IS " + ((ageHours < 24) ? (ageHours + " HOURS") : ((ageHours / 24) + " DAYS")) + " OLD"); // 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) break; result += ", " + dom + "=" + ip; log.logSystem("PRE-FILLED " + dom + "=" + ip); c++; doms.deleteScore(dom); // wait a short while to prevent that this looks like a DoS try {Thread.currentThread().sleep(100);} catch (InterruptedException e) {} } if (result.length() > 2) log.logSystem("PRE-FILLED DNS CACHE, FETCHED " + c + " ADDRESSES: " + result.substring(2)); } private String dom(File f) { String s = f.toString().substring(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 { httpHeader header = new httpHeader(null, responseHeaderDB.get(urlHash)); //System.out.println("DEBUG: getCachedResponse hash=" + urlHash + ", header=" + header.toString()); return header; } public boolean idle() { return (System.currentTimeMillis() > (idleDelay + lastAcc)); } public boolean full() { return (cacheStack.size() > stackLimit); } public boolean empty() { return (cacheStack.size() == 0); } synchronized public void stackProcess(Entry entry) throws IOException { lastAcc = System.currentTimeMillis(); if (full()) process(entry); else cacheStack.add(entry); } synchronized public void stackProcess(Entry entry, byte[] cacheArray) throws IOException { lastAcc = System.currentTimeMillis(); entry.cacheArray = cacheArray; if (full()) process(entry); else cacheStack.add(entry); } public int size() { return cacheStack.size(); } synchronized public void process(Entry entry) throws IOException { if (entry == null) return; // store response header if ((entry.status == CACHE_FILL) || (entry.status == CACHE_STALE_RELOAD_GOOD) || (entry.status == CACHE_STALE_RELOAD_BAD)) { responseHeaderDB.set(entry.nomalizedURLHash, entry.responseHeader); } // work off unwritten files and undone parsing String storeError = null; if (((entry.status == CACHE_FILL) || (entry.status == CACHE_STALE_RELOAD_GOOD)) && ((storeError = entry.shallStoreCache()) == null)) { // write file if not written yet if (entry.cacheArray != null) try { if (entry.cacheFile.exists()) { currCacheSize -= entry.cacheFile.length(); entry.cacheFile.delete(); } entry.cacheFile.getParentFile().mkdirs(); log.logInfo("WRITE FILE (" + entry.cacheArray.length + " bytes) " + entry.cacheFile); serverFileUtils.write(entry.cacheArray, entry.cacheFile); log.logDebug("AFTER WRITE cacheArray = " + entry.cacheFile + ": " + ((entry.cacheArray == null) ? "empty" : "full")); //entry.cacheArray = null; } 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. log.logError("File storage failed: " + e.getMessage()); } // update statistics currCacheSize += entry.cacheFile.length(); cacheAge.put(ageString(entry.cacheFile.lastModified(), entry.cacheFile), entry.cacheFile); // enqueue in switchboard switchboard.enQueue(entry); } else if (entry.status == CACHE_PASSING) { // even if the file should not be stored in the cache, it can be used to be indexed if (storeError != null) log.logDebug("NOT STORED " + entry.cacheFile + ":" + storeError); // enqueue in switchboard switchboard.enQueue(entry); } // write log switch (entry.status) { case CACHE_UNFILLED: log.logInfo("CACHE UNFILLED: " + entry.cacheFile); break; case CACHE_FILL: log.logInfo("CACHE FILL: " + entry.cacheFile + ((entry.cacheArray == null) ? "" : " (cacheArray is filled)") + ((entry.scraper == null) ? "" : " (scraper is filled)")); break; case CACHE_HIT: log.logInfo("CACHE HIT: " + entry.cacheFile); break; case CACHE_STALE_NO_RELOAD: log.logInfo("CACHE STALE, NO RELOAD: " + entry.cacheFile); break; case CACHE_STALE_RELOAD_GOOD: log.logInfo("CACHE STALE, NECESSARY RELOAD: " + entry.cacheFile); break; case CACHE_STALE_RELOAD_BAD: log.logInfo("CACHE STALE, SUPERFLUOUS RELOAD: " + entry.cacheFile); break; case CACHE_PASSING: log.logInfo("PASSING: " + entry.cacheFile); break; default: log.logInfo("CACHE STATE UNKNOWN: " + entry.cacheFile); break; } } public boolean job() { if (empty()) return false; try { File f; int workoff; workoff = 1 + cacheStack.size() / 10; // we want to work off always 10 % to prevent that we collaps while ((workoff-- > 0) && (!(empty()))) { process((Entry) cacheStack.removeFirst()); } // loop until we are not idle or nothing more to do while ((!empty()) && (idle())) { // work off stack and store entries to file system process((Entry) cacheStack.removeFirst()); // clean up cache to have enough space for next entries while (currCacheSize > maxCacheSize) { f = (File) cacheAge.remove(cacheAge.firstKey()); if (f.exists()) { currCacheSize -= f.length(); f.delete(); log.logInfo("DELETED OLD CACHE : " + f.toString()); } } } } catch (IOException e) { System.out.println("The proxy cache manager has died because of an IO-problem: " + e.getMessage()); e.printStackTrace(System.out); System.exit(-1); } return true; } 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 public File getCachePath(URL url) { // 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 //System.out.println("DEBUG: getCachedPath=" + 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 int port = url.getPort(); if (port < 0) port = 80; return new File(this.cachePath, url.getHost() + ((port == 80) ? "" : ("+" + port)) + remotePath); } public static URL getURL(File cachePath, File f) { // this is the reverse function to getCachePath: it constructs the url as string // from a given storage path String s = f.toString().replace('\\', '/'); String c = cachePath.toString().replace('\\', '/'); //System.out.println("DEBUG: getURL for c=" + c + ", s=" + s); 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); //System.out.println("DEBUG: getURL url=" + s); try { return new URL("http://" + s); } catch (Exception e) { return null; } } return null; } public static boolean isPOST(String urlString) { return ((urlString.indexOf("?") >= 0) || (urlString.indexOf("&") >= 0)); } public static boolean isCGI(String urlString) { return ((urlString.toLowerCase().indexOf(".cgi") >= 0) || (urlString.toLowerCase().indexOf(".exe") >= 0)); } public Entry newEntry(Date initDate, int depth, URL url, httpHeader requestHeader, String responseStatus, httpHeader responseHeader, String initiator, plasmaCrawlProfile.entry profile) { //System.out.println("NEW ENTRY: " + url.toString()); // DEBUG return new Entry(initDate, depth, url, 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 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 htmlFilterContentScraper scraper; public Entry(Date initDate, int depth, URL url, httpHeader requestHeader, String responseStatus, httpHeader responseHeader, String initiator, plasmaCrawlProfile.entry profile) { // normalize url this.nomalizedURLString = htmlFilterContentScraper.urlNormalform(url); try { this.url = new URL(nomalizedURLString); } catch (MalformedURLException e) { System.out.println("internal error at httpdProxyCache.Entry: " + e); System.exit(-1); } this.cacheFile = getCachePath(this.url); this.nomalizedURLHash = plasmaCrawlLURL.urlHash(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); } lastModified = new Date(); } else { lastModified = responseHeader.lastModified(); if (lastModified == null) lastModified = new Date(); // does not exist in header } this.doctype = plasmaWordIndexEntry.docType(nomalizedURLString); this.language = plasmaWordIndexEntry.language(url); // to be defined later: this.cacheArray = null; this.status = CACHE_UNFILLED; this.scraper = null; } public String initiator() { return initiator; } public boolean proxy() { return initiator() == null; } public long size() { if (cacheArray == null) return 0; else return cacheArray.length; } public URL referrerURL() { if (requestHeader == null) return null; try { return new URL((String) 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 shallStoreCache() { // returns NULL if the answer is TRUE // in case of FALSE, the reason as String is returned // check profile if (!(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 (!((responseStatus.startsWith("200")) || (responseStatus.startsWith("203")))) return "bad_status_" + 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 ((cacheFile.getParentFile().isFile()) || (cacheFile.isDirectory())) return "path_ambiguous"; if (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(nomalizedURLString)) && (!(profile.crawlingQ()))) return "dynamic_post"; if (isCGI(nomalizedURLString)) return "dynamic_cgi"; // -authorization cases in request // authorization makes pages very individual, and therefore we cannot use the // content in the cache if ((requestHeader != null) && (requestHeader.containsKey(httpHeader.AUTHORIZATION))) return "personalized"; // -ranges in request and response // we do not cache partial content if ((requestHeader != null) && (requestHeader.containsKey(httpHeader.RANGE))) return "partial"; if ((responseHeader != null) && (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 ((responseHeader.containsKey(httpHeader.PRAGMA)) && (((String) 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) 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 = 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 ((new Date()).getTime() - 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 shallUseCache() { // 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(nomalizedURLString)) return false; if (isCGI(nomalizedURLString)) return false; // -authorization cases in request if (requestHeader.containsKey(httpHeader.AUTHORIZATION)) return false; // -ranges in request // we do not cache partial content if ((requestHeader != null) && (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 (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 (!(responseHeader.containsKey(httpHeader.LAST_MODIFIED))) return false; // parse date Date d1, d2; d2 = responseHeader.lastModified(); if (d2 == null) d2 = new Date(); d1 = requestHeader.ifModifiedSince(); if (d1 == null) d1 = new Date(); // 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(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 ((requestHeader.containsKey(httpHeader.COOKIE)) && (isNotPicture)) return false; // -set-cookie in cached response // this is a similar case as for COOKIE. if ((responseHeader.containsKey(httpHeader.SET_COOKIE)) && (isNotPicture)) return false; // too strong if ((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 ((responseHeader.containsKey(httpHeader.PRAGMA)) && (((String) responseHeader.get(httpHeader.PRAGMA)).toUpperCase().equals("NO-CACHE"))) return false; // calculate often needed values for freshness attributes Date date = responseHeader.date(); Date expires = responseHeader.expires(); Date lastModified = responseHeader.lastModified(); String cacheControl = (String) 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) { Date yesterday = new Date((new Date()).getTime() - oneday); if (expires.before(yesterday)) 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(); 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 new Date().getTime() - d2.getTime() // therefore the cache is stale, if Date().getTime() - d2.getTime() > age/10 if ((new Date()).getTime() - 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 ((new Date()).getTime() - date.getTime() > ttl) { return false; } } catch (Exception e) { return false; } } } return true; } public String shallIndexCacheForProxy() { // decide upon header information if a specific file should be indexed // this method returns null if the answer is 'YES'! // if the answer is 'NO' (do not index), it returns a string with the reason // to reject the crawling demand in clear text // check profile if (!(profile.localIndexing())) return "Indexing_Not_Allowed"; // -CGI access in request // CGI access makes the page very individual, and therefore not usable in caches if ((isPOST(nomalizedURLString)) && (!(profile.crawlingQ()))) return "Dynamic_(POST)"; if ((isCGI(nomalizedURLString)) && (!(profile.crawlingQ()))) return "Dynamic_(CGI)"; // -authorization cases in request // we checked that in shallStoreCache // -ranges in request // we checked that in shallStoreCache // a picture cannot be indexed if (isPicture(responseHeader)) return "Media_Content_(Picture)"; if (!(isText(responseHeader))) return "Media_Content_(not_text)"; if (noIndexingURL(nomalizedURLString)) return "Media_Content_(forbidden)"; // -if-modified-since in request // if the page is fresh at the very moment we can index it if ((requestHeader != null) && (requestHeader.containsKey(httpHeader.IF_MODIFIED_SINCE)) && (responseHeader.containsKey(httpHeader.LAST_MODIFIED))) { // parse date Date d1, d2; d2 = responseHeader.lastModified(); if (d2 == null) d2 = new Date(); d1 = requestHeader.ifModifiedSince(); if (d1 == null) d1 = new Date(); // finally, we shall treat the cache as stale if the modification time is after the if-.. time if (d2.after(d1)) { //System.out.println("***not indexed because if-modified-since"); return "Stale_(Last-Modified>Modified-Since)"; } } // -cookies in request // unfortunately, we cannot index pages which have been requested with a cookie // because the returned content may be special for the client if ((requestHeader != null) && (requestHeader.containsKey(httpHeader.COOKIE))) { //System.out.println("***not indexed because cookie"); return "Dynamic_(Requested_With_Cookie)"; } // -set-cookie in response // the set-cookie from the server does not indicate that the content is special // thus we do not care about it here for indexing // -pragma in cached response if ((responseHeader.containsKey(httpHeader.PRAGMA)) && (((String) responseHeader.get(httpHeader.PRAGMA)).toUpperCase().equals("NO-CACHE"))) return "Denied_(pragma_no_cache)"; // see for documentation also: // http://www.web-caching.com/cacheability.html // calculate often needed values for freshness attributes Date date = responseHeader.date(); Date expires = responseHeader.expires(); Date lastModified = responseHeader.lastModified(); String cacheControl = (String) responseHeader.get(httpHeader.CACHE_CONTROL); // look for freshnes information // -expires in cached response // the expires value gives us a very easy hint when the cache is stale // sometimes, the expires date is set to the past to prevent that a page is cached // we use that information to see if we should index it if (expires != null) { Date yesterday = new Date((new Date()).getTime() - oneday); if (expires.before(yesterday)) return "Stale_(Expired)"; } // -lastModified in cached response // this information is too weak to use it to prevent indexing // even if we can apply a TTL heuristic for cache usage // -cache-control in cached response // the cache-control has many value options. if (cacheControl != null) { cacheControl = cacheControl.trim().toUpperCase(); /* we have the following cases for cache-control: "public" -- can be indexed "private", "no-cache", "no-store" -- cannot be indexed "max-age=" -- stale/fresh dependent on date */ if (cacheControl.startsWith("PUBLIC")) { // ok, do nothing } else if ((cacheControl.startsWith("PRIVATE")) || (cacheControl.startsWith("NO-CACHE")) || (cacheControl.startsWith("NO-STORE"))) { // easy case return "Stale_(denied_by_cache-control=" + cacheControl+ ")"; } else if (cacheControl.startsWith("MAX-AGE=")) { // we need also the load date if (date == null) return "Stale_(no_date_given_in_response)"; try { long ttl = 1000 * Long.parseLong(cacheControl.substring(8)); // milliseconds to live if ((new Date()).getTime() - date.getTime() > ttl) { //System.out.println("***not indexed because cache-control"); return "Stale_(expired_by_cache-control)"; } } catch (Exception e) { return "Error_(" + e.getMessage() + ")"; } } } return null; } public String shallIndexCacheForCrawler() { // decide upon header information if a specific file should be indexed // this method returns null if the answer is 'YES'! // if the answer is 'NO' (do not index), it returns a string with the reason // to reject the crawling demand in clear text // check profile if (!(profile.localIndexing())) return "Indexing_Not_Allowed"; // -CGI access in request // CGI access makes the page very individual, and therefore not usable in caches if ((isPOST(nomalizedURLString)) && (!(profile.crawlingQ()))) return "Dynamic_(POST)"; if ((isCGI(nomalizedURLString)) && (!(profile.crawlingQ()))) return "Dynamic_(CGI)"; // -authorization cases in request // we checked that in shallStoreCache // -ranges in request // we checked that in shallStoreCache // a picture cannot be indexed if (isPicture(responseHeader)) return "Media_Content_(Picture)"; if (!(isText(responseHeader))) return "Media_Content_(not_text)"; if (noIndexingURL(nomalizedURLString)) return "Media_Content_(forbidden)"; // -if-modified-since in request // if the page is fresh at the very moment we can index it // -> this does not apply for the crawler // -cookies in request // unfortunately, we cannot index pages which have been requested with a cookie // because the returned content may be special for the client // -> this does not apply for a crawler // -set-cookie in response // the set-cookie from the server does not indicate that the content is special // thus we do not care about it here for indexing // -> this does not apply for a crawler // -pragma in cached response // -> in the crawler we ignore this // look for freshnes information // -expires in cached response // the expires value gives us a very easy hint when the cache is stale // sometimes, the expires date is set to the past to prevent that a page is cached // we use that information to see if we should index it // -> this does not apply for a crawler // -lastModified in cached response // this information is too weak to use it to prevent indexing // even if we can apply a TTL heuristic for cache usage // -cache-control in cached response // the cache-control has many value options. // -> in the crawler we ignore this return null; } } }