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232 lines
8.5 KiB
232 lines
8.5 KiB
// httpCache.java
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// -----------------------
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// part of YaCy
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2004
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//
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// $LastChangedDate$
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// $LastChangedRevision$
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// $LastChangedBy$
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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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Class documentation:
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This class has two purposes:
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1. provide a object that carries path and header information
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that shall be used as objects within a scheduler's stack
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2. static methods for a cache control and cache aging
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the class shall also be used to do a cache-cleaning and index creation
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*/
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package de.anomic.http.client;
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import java.io.ByteArrayInputStream;
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import java.io.File;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.HashMap;
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import java.util.Map;
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import de.anomic.http.metadata.ResponseHeader;
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import de.anomic.kelondro.blob.ArrayStack;
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import de.anomic.kelondro.blob.Compressor;
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import de.anomic.kelondro.blob.Heap;
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import de.anomic.kelondro.blob.MapView;
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import de.anomic.kelondro.order.Base64Order;
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import de.anomic.yacy.yacySeedDB;
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import de.anomic.yacy.yacyURL;
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import de.anomic.yacy.logging.Log;
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public final class Cache {
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private static final String RESPONSE_HEADER_DB_NAME = "responseHeader.heap";
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private static final String FILE_DB_NAME = "file.array";
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private static MapView responseHeaderDB = null;
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private static Compressor fileDB = null;
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private static ArrayStack fileDBunbuffered = null;
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private static long maxCacheSize = 0l;
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private static File cachePath = null;
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private static String prefix;
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public static final Log log = new Log("HTCACHE");
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public static void init(final File htCachePath, String peerSalt, final long CacheSizeMax) {
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cachePath = htCachePath;
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maxCacheSize = CacheSizeMax;
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prefix = peerSalt;
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// set/make cache path
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if (!htCachePath.exists()) {
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htCachePath.mkdirs();
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}
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// open the response header database
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final File dbfile = new File(cachePath, RESPONSE_HEADER_DB_NAME);
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Heap blob = null;
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try {
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blob = new Heap(dbfile, yacySeedDB.commonHashLength, Base64Order.enhancedCoder, 1024 * 1024);
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} catch (final IOException e) {
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e.printStackTrace();
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}
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responseHeaderDB = new MapView(blob, 500, '_');
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try {
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fileDBunbuffered = new ArrayStack(new File(cachePath, FILE_DB_NAME), prefix, 12, Base64Order.enhancedCoder, 1024 * 1024 * 2);
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fileDBunbuffered.setMaxSize(maxCacheSize);
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fileDB = new Compressor(fileDBunbuffered, 2 * 1024 * 1024);
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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/**
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* This method changes the HTCache size.<br>
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* @param the new cache size in bytes
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*/
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public static void setCacheSize(final long newCacheSize) {
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maxCacheSize = newCacheSize;
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fileDBunbuffered.setMaxSize(maxCacheSize);
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}
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/**
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* close the databases
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*/
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public static void close() {
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responseHeaderDB.close();
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fileDB.close(true);
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}
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public static void store(yacyURL url, final ResponseHeader responseHeader, byte[] file) {
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if (responseHeader != null && file != null) try {
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// store the response header into the header database
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final HashMap<String, String> hm = new HashMap<String, String>();
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hm.putAll(responseHeader);
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hm.put("@@URL", url.toNormalform(true, false));
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responseHeaderDB.put(url.hash(), hm);
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fileDB.put(url.hash().getBytes("UTF-8"), file);
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if (log.isFine()) log.logFine("stored in cache: " + url.toNormalform(true, false));
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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/**
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* check if the responseHeaderDB and the fileDB has an entry for the given url
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* @param url the url of the resource
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* @return true if the content of the url is in the cache, false othervise
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*/
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public static boolean has(final yacyURL url) {
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try {
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return responseHeaderDB.has(url.hash()) && fileDB.has(url.hash().getBytes());
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} catch (IOException e) {
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e.printStackTrace();
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return false;
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}
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}
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/**
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* Returns an object containing metadata about a cached resource
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* @param url the {@link URL} of the resource
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* @return an {@link IResourceInfo info object}
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* @throws <b>IllegalAccessException</b> if the {@link SecurityManager} doesn't allow instantiation
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* of the info object with the given protocol
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* @throws <b>UnsupportedProtocolException</b> if the protocol is not supported and therefore the
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* info object couldn't be created
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*/
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public static ResponseHeader getResponseHeader(final yacyURL url) {
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// loading data from database
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Map<String, String> hdb;
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try {
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hdb = responseHeaderDB.get(url.hash());
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} catch (final IOException e) {
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return null;
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}
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if (hdb == null) return null;
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return new ResponseHeader(null, hdb);
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}
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/**
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* Returns the content of a cached resource as {@link InputStream}
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* @param url the requested resource
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* @return the resource content as {@link InputStream}. In no data
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* is available or the cached file is not readable, <code>null</code>
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* is returned.
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*/
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public static InputStream getContentStream(final yacyURL url) {
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// load the url as resource from the cache
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byte[] b = getContent(url);
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if (b == null) return null;
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return new ByteArrayInputStream(b);
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}
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/**
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* Returns the content of a cached resource as byte[]
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* @param url the requested resource
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* @return the resource content as byte[]. In no data
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* is available or the cached file is not readable, <code>null</code>
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* is returned.
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*/
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public static byte[] getContent(final yacyURL url) {
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// load the url as resource from the cache
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try {
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return fileDB.get(url.hash().getBytes("UTF-8"));
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} catch (IOException e) {
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e.printStackTrace();
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return null;
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}
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}
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/**
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* requesting the content length of a resource is discouraged since it may
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* be performed by loading of the resource from the cache and then measuring the
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* size after decompression of the content. This may use a lot of CPU resources
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* and maybe cause also high IO. Please omit usage of this method as much as possible.
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* @param url
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* @return the size of the cached content
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*/
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public static long getResourceContentLength(final yacyURL url) {
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// first try to get the length from the response header,
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// this is less costly than loading the content from its gzipped cache
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ResponseHeader responseHeader = getResponseHeader(url);
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if (responseHeader != null) {
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long length = responseHeader.getContentLength();
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if (length > 0) return length;
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}
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// load the url as resource from the cache (possibly decompress it),
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// and get the length from the content array size
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try {
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return fileDB.length(url.hash().getBytes("UTF-8"));
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} catch (IOException e) {
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e.printStackTrace();
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return -1;
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}
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}
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/**
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* removed response header and cached content from the database
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* @param url
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* @throws IOException
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*/
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public static void delete(yacyURL url) throws IOException {
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responseHeaderDB.remove(url.hash());
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fileDB.remove(url.hash().getBytes("UTF-8"));
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}
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}
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