yacy_search_server/source/de/anomic/data/URLLicense.java
2010-04-13 01:16:09 +00:00

86 lines
3.1 KiB
Java

// URLLicense.java
// (C) 2007 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 03.07.2007 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
//
// 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
package de.anomic.data;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import net.yacy.kelondro.data.meta.DigestURI;
public class URLLicense {
// this class defines a license-generation for URLs
// it is used in case of snippet- and preview-Image-fetching to grant also non-authorized users the usage of a image-fetcher servlet
private static final int maxQueue = 500;
private static final long minCheck = 5000;
private final Random random;
private final ConcurrentHashMap<String, DigestURI> permissions;
private final ConcurrentLinkedQueue<String> aging;
private long lastCheck;
private final int keylen;
public URLLicense(final int keylen) {
this.permissions = new ConcurrentHashMap<String, DigestURI>();
this.aging = new ConcurrentLinkedQueue<String>();
this.lastCheck = System.currentTimeMillis();
this.random = new Random(System.currentTimeMillis());
this.keylen = keylen;
}
public String aquireLicense(final DigestURI url) {
// generate license key
StringBuilder stringBuilder = new StringBuilder();
if (url == null) return stringBuilder.toString();
while (stringBuilder.length() < keylen) stringBuilder.append(Integer.toHexString(random.nextInt()));
String license = stringBuilder.substring(0, keylen);
// store reference to url with license key
permissions.put(license, url);
aging.add(license);
if (System.currentTimeMillis() - this.lastCheck > minCheck) {
// check aging
this.lastCheck = System.currentTimeMillis();
String s;
while (aging.size() > maxQueue) {
s = aging.poll();
if (s != null) permissions.remove(s);
}
}
// return the license key
return license;
}
public DigestURI releaseLicense(final String license) {
DigestURI url = null;
url = permissions.remove(license);
return url;
}
}