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414 lines
17 KiB
414 lines
17 KiB
// plasmaSnippetCache.java
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// -----------------------
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// part of YaCy
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// (C) by Michael Peter Christen; mc@anomic.de
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2005
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// last major change: 07.06.2005
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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// Using this software in any meaning (reading, learning, copying, compiling,
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// running) means that you agree that the Author(s) is (are) not responsible
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// for cost, loss of data or any harm that may be caused directly or indirectly
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// by usage of this softare or this documentation. The usage of this software
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// is on your own risk. The installation and usage (starting/running) of this
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// software may allow other people or application to access your computer and
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// any attached devices and is highly dependent on the configuration of the
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// software which must be done by the user of the software; the author(s) is
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// (are) also not responsible for proper configuration and usage of the
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// software, even if provoked by documentation provided together with
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// the software.
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//
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// Any changes to this file according to the GPL as documented in the file
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// gpl.txt aside this file in the shipment you received can be done to the
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// lines that follows this copyright notice here, but changes must not be
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// done inside the copyright notive above. A re-distribution must contain
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// the intact and unchanged copyright notice.
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// Contributions and changes to the program code must be marked as such.
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package de.anomic.plasma;
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import java.io.IOException;
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import java.net.URL;
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import java.util.Enumeration;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Iterator;
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import java.util.Set;
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import de.anomic.http.httpHeader;
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import de.anomic.kelondro.kelondroMScoreCluster;
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import de.anomic.server.logging.serverLog;
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import de.anomic.yacy.yacySearch;
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import de.anomic.htmlFilter.htmlFilterContentScraper;
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public class plasmaSnippetCache {
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private static final int maxCache = 500;
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public static final int SOURCE_CACHE = 0;
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public static final int SOURCE_FILE = 1;
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public static final int SOURCE_WEB = 2;
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public static final int ERROR_NO_HASH_GIVEN = 11;
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public static final int ERROR_SOURCE_LOADING = 12;
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public static final int ERROR_RESOURCE_LOADING = 13;
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public static final int ERROR_PARSER_FAILED = 14;
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public static final int ERROR_PARSER_NO_LINES = 15;
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public static final int ERROR_NO_MATCH = 16;
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private int snippetsScoreCounter;
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private kelondroMScoreCluster snippetsScore;
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private HashMap snippetsCache;
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private plasmaHTCache cacheManager;
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private plasmaParser parser;
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private serverLog log;
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private String remoteProxyHost;
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private int remoteProxyPort;
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private boolean remoteProxyUse;
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public plasmaSnippetCache(plasmaHTCache cacheManager, plasmaParser parser,
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String remoteProxyHost, int remoteProxyPort, boolean remoteProxyUse,
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serverLog log) {
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this.cacheManager = cacheManager;
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this.parser = parser;
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this.log = log;
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this.remoteProxyHost = remoteProxyHost;
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this.remoteProxyPort = remoteProxyPort;
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this.remoteProxyUse = remoteProxyUse;
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this.snippetsScoreCounter = 0;
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this.snippetsScore = new kelondroMScoreCluster();
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this.snippetsCache = new HashMap();
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}
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public class result {
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public String line;
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public String error;
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public int source;
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public result(String line, int source, String errortext) {
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this.line = line;
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this.source = source;
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this.error = errortext;
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}
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public String toString() {
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return line;
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}
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}
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public boolean existsInCache(URL url, Set queryhashes) {
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String hashes = yacySearch.set2string(queryhashes);
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return retrieveFromCache(hashes, plasmaURL.urlHash(url)) != null;
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}
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public result retrieve(URL url, Set queryhashes, boolean fetchOnline, int snippetMaxLength) {
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// heise = "0OQUNU3JSs05"
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if (queryhashes.size() == 0) {
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//System.out.println("found no queryhashes for URL retrieve " + url);
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return new result(null, ERROR_NO_HASH_GIVEN, "no query hashes given");
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}
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String urlhash = plasmaURL.urlHash(url);
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// try to get snippet from snippetCache
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int source = SOURCE_CACHE;
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String wordhashes = yacySearch.set2string(queryhashes);
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String line = retrieveFromCache(wordhashes, urlhash);
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if (line != null) {
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//System.out.println("found snippet for URL " + url + " in cache: " + line);
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return new result(line, source, null);
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}
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// if the snippet is not in the cache, we can try to get it from the htcache
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byte[] resource = null;
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try {
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resource = cacheManager.loadResource(url);
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if ((fetchOnline) && (resource == null)) {
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loadResourceFromWeb(url, 5000);
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resource = cacheManager.loadResource(url);
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source = SOURCE_WEB;
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}
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} catch (IOException e) {
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return new result(null, ERROR_SOURCE_LOADING, "error loading resource from web: " + e.getMessage());
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}
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if (resource == null) {
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//System.out.println("cannot load document for URL " + url);
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return new result(null, ERROR_RESOURCE_LOADING, "error loading resource from web, cacheManager returned NULL");
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}
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plasmaParserDocument document = parseDocument(url, resource);
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if (document == null) return new result(null, ERROR_PARSER_FAILED, "parser error/failed"); // cannot be parsed
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//System.out.println("loaded document for URL " + url);
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String[] sentences = document.getSentences();
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//System.out.println("----" + url.toString()); for (int l = 0; l < sentences.length; l++) System.out.println(sentences[l]);
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if ((sentences == null) || (sentences.length == 0)) {
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//System.out.println("found no sentences in url " + url);
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return new result(null, ERROR_PARSER_NO_LINES, "parser returned no sentences");
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}
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// we have found a parseable non-empty file: use the lines
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line = computeSnippet(sentences, queryhashes, 8 + 6 * queryhashes.size(), snippetMaxLength);
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//System.out.println("loaded snippet for URL " + url + ": " + line);
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if (line == null) return new result(null, ERROR_NO_MATCH, "no matching snippet found");
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if (line.length() > snippetMaxLength) line = line.substring(0, snippetMaxLength);
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// finally store this snippet in our own cache
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storeToCache(wordhashes, urlhash, line);
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return new result(line, source, null);
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}
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public synchronized void storeToCache(String wordhashes, String urlhash, String snippet) {
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// generate key
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String key = urlhash + wordhashes;
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// do nothing if snippet is known
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if (snippetsCache.containsKey(key)) return;
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// learn new snippet
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snippetsScore.addScore(key, snippetsScoreCounter++);
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snippetsCache.put(key, snippet);
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// care for counter
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if (snippetsScoreCounter == java.lang.Integer.MAX_VALUE) {
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snippetsScoreCounter = 0;
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snippetsScore = new kelondroMScoreCluster();
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snippetsCache = new HashMap();
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}
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// flush cache if cache is full
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while (snippetsCache.size() > maxCache) {
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key = (String) snippetsScore.getMinObject();
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snippetsScore.deleteScore(key);
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snippetsCache.remove(key);
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}
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}
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private String retrieveFromCache(String wordhashes, String urlhash) {
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// generate key
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String key = urlhash + wordhashes;
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return (String) snippetsCache.get(key);
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}
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private String computeSnippet(String[] sentences, Set queryhashes, int minLength, int maxLength) {
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try {
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if ((sentences == null) || (sentences.length == 0)) return null;
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if ((queryhashes == null) || (queryhashes.size() == 0)) return null;
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kelondroMScoreCluster hitTable = new kelondroMScoreCluster();
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Iterator j;
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HashMap hs;
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String hash;
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for (int i = 0; i < sentences.length; i++) {
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//System.out.println("Sentence " + i + ": " + sentences[i]);
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if (sentences[i].length() > minLength) {
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hs = hashSentence(sentences[i]);
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j = queryhashes.iterator();
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while (j.hasNext()) {
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hash = (String) j.next();
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if (hs.containsKey(hash)) {
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//System.out.println("hash " + hash + " appears in line " + i);
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hitTable.incScore(new Integer(i));
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}
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}
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}
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}
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int score = hitTable.getMaxScore(); // best number of hits
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if (score <= 0) return null;
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// we found (a) line(s) that have <score> hits.
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// now find the shortest line of these hits
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int shortLineIndex = -1;
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int shortLineLength = Integer.MAX_VALUE;
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for (int i = 0; i < sentences.length; i++) {
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if ((hitTable.getScore(new Integer(i)) == score) &&
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(sentences[i].length() < shortLineLength)) {
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shortLineIndex = i;
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shortLineLength = sentences[i].length();
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}
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}
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// find a first result
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String result = sentences[shortLineIndex];
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// remove all hashes that appear in the result
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hs = hashSentence(result);
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j = queryhashes.iterator();
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Integer pos;
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Set remaininghashes = new HashSet();
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int p, minpos = result.length(), maxpos = -1;
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while (j.hasNext()) {
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hash = (String) j.next();
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pos = (Integer) hs.get(hash);
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if (pos == null) {
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remaininghashes.add(new String(hash));
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} else {
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p = pos.intValue();
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if (p > maxpos) maxpos = p;
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if (p < minpos) minpos = p;
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}
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}
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// check result size
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maxpos = maxpos + 10;
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if (maxpos > result.length()) maxpos = result.length();
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if (minpos < 0) minpos = 0;
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// we have a result, but is it short enough?
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if (maxpos - minpos + 10 > maxLength) {
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// the string is too long, even if we cut at both ends
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// so cut here in the middle of the string
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int lenb = result.length();
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result = result.substring(0, (minpos + 20 > result.length()) ? result.length() : minpos + 20).trim() +
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" [..] " +
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result.substring((maxpos + 26 > result.length()) ? result.length() : maxpos + 26).trim();
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maxpos = maxpos + lenb - result.length() + 6;
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}
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if (maxpos > maxLength) {
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// the string is too long, even if we cut it at the end
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// so cut it here at both ends at once
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int newlen = maxpos - minpos + 10;
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int around = (maxLength - newlen) / 2;
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result = "[..] " + result.substring(minpos - around, ((maxpos + around) > result.length()) ? result.length() : (maxpos + around)).trim() + " [..]";
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minpos = around;
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maxpos = result.length() - around - 5;
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}
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if (result.length() > maxLength) {
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// trim result, 1st step (cut at right side)
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result = result.substring(0, maxpos).trim() + " [..]";
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}
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if (result.length() > maxLength) {
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// trim result, 2nd step (cut at left side)
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result = "[..] " + result.substring(minpos).trim();
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}
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if (result.length() > maxLength) {
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// trim result, 3rd step (cut in the middle)
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result = result.substring(6, 20).trim() + " [..] " + result.substring(result.length() - 26, result.length() - 6).trim();
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}
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if (queryhashes.size() == 0) return result;
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// the result has not all words in it.
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// find another sentence that represents the missing other words
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// and find recursively more sentences
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maxLength = maxLength - result.length();
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if (maxLength < 20) maxLength = 20;
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String nextSnippet = computeSnippet(sentences, remaininghashes, minLength, maxLength);
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return result + ((nextSnippet == null) ? "" : (" / " + nextSnippet));
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} catch (IndexOutOfBoundsException e) {
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log.logSevere("computeSnippet: error with string generation", e);
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return "";
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}
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}
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private HashMap hashSentence(String sentence) {
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// generates a word-wordPos mapping
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HashMap map = new HashMap();
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Enumeration words = plasmaCondenser.wordTokenizer(sentence, 0);
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int pos = 0;
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String word;
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while (words.hasMoreElements()) {
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word = (String) words.nextElement();
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map.put(plasmaWordIndexEntry.word2hash(word), new Integer(pos));
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pos += word.length() + 1;
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}
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return map;
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}
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public plasmaParserDocument parseDocument(URL url, byte[] resource) {
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if (resource == null) return null;
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httpHeader header = null;
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try {
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header = cacheManager.getCachedResponse(plasmaURL.urlHash(url));
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} catch (IOException e) {}
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if (header == null) {
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String filename = cacheManager.getCachePath(url).getName();
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int p = filename.lastIndexOf('.');
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if ((p < 0) ||
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((p >= 0) && (plasmaParser.supportedFileExtContains(filename.substring(p + 1))))) {
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return parser.parseSource(url, "text/html", resource);
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} else {
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return null;
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}
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} else {
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if (plasmaParser.supportedMimeTypesContains(header.mime())) {
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return parser.parseSource(url, header.mime(), resource);
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} else {
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return null;
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}
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}
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}
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public byte[] getResource(URL url, boolean fetchOnline) {
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// load the url as resource from the web
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try {
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//return httpc.singleGET(url, 5000, null, null, remoteProxyHost, remoteProxyPort);
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byte[] resource = cacheManager.loadResource(url);
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if ((fetchOnline) && (resource == null)) {
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loadResourceFromWeb(url, 5000);
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resource = cacheManager.loadResource(url);
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}
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return resource;
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} catch (IOException e) {
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return null;
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}
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}
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private void loadResourceFromWeb(URL url, int socketTimeout) throws IOException {
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plasmaCrawlWorker.load(
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url,
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"",
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null,
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null,
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0,
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null,
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socketTimeout,
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remoteProxyHost,
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remoteProxyPort,
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remoteProxyUse,
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cacheManager,
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log);
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}
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public void fetch(plasmaSearchResult acc, Set queryhashes, String urlmask, int fetchcount) {
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// fetch snippets
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int i = 0;
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plasmaCrawlLURL.Entry urlentry;
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String urlstring;
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plasmaSnippetCache.result snippet;
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while ((acc.hasMoreElements()) && (i < fetchcount)) {
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urlentry = acc.nextElement();
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if (urlentry.url().getHost().endsWith(".yacyh")) continue;
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urlstring = htmlFilterContentScraper.urlNormalform(urlentry.url());
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if ((urlstring.matches(urlmask)) &&
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(!(existsInCache(urlentry.url(), queryhashes)))) {
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new Fetcher(urlentry.url(), queryhashes).start();
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i++;
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}
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}
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}
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public class Fetcher extends Thread {
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URL url;
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Set queryhashes;
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public Fetcher(URL url, Set queryhashes) {
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if (url.getHost().endsWith(".yacyh")) return;
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this.url = url;
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this.queryhashes = queryhashes;
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}
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public void run() {
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log.logFine("snippetFetcher: try to get URL " + url);
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plasmaSnippetCache.result snippet = retrieve(url, queryhashes, true, 260);
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if (snippet.line == null)
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log.logFine("snippetFetcher: cannot get URL " + url + ". error(" + snippet.source + "): " + snippet.error);
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else
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log.logFine("snippetFetcher: got URL " + url + ", the snippet is '" + snippet.line + "', source=" + snippet.source);
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}
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}
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}
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