yacy_search_server/source/de/anomic/data/URLLicense.java
Michael Peter Christen 2fc8ecee36 ConcurrentLinkedQueue has a VERY long return time on the .size() method.
See
http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/ConcurrentLinkedQueue.html

and the following test programm:

public class QueueLengthTimeTest {


    public static long countTest(Queue<Integer> q, int c) {
        long t = System.currentTimeMillis();
        for (int i = 0; i < c; i++) {
            q.add(q.size());
        }
        return System.currentTimeMillis() - t;
    }

    public static void main(String[] args) {
        int c = 1;
        for (int i = 0; i < 100; i++) {
            Runtime.getRuntime().gc();
            long t1 = countTest(new ArrayBlockingQueue<Integer>(c), c);
            Runtime.getRuntime().gc();
            long t2 = countTest(new LinkedBlockingQueue<Integer>(), c);
            Runtime.getRuntime().gc();
            long t3 = countTest(new ConcurrentLinkedQueue<Integer>(),
c);

            System.out.println("count = " + c + ": ArrayBlockingQueue =
" + t1 + ", LinkedBlockingQueue = " + t2 + ", ConcurrentLinkedQueue = "
+ t3);
            c = c * 2;
        }
    }
}
2012-02-27 00:42:32 +01:00

87 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.Queue;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.LinkedBlockingQueue;
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 Queue<String> aging;
private long lastCheck;
private final int keylen;
public URLLicense(final int keylen) {
this.permissions = new ConcurrentHashMap<String, DigestURI>();
this.aging = new LinkedBlockingQueue<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(this.keylen * 2);
if (url == null) return stringBuilder.toString();
while (stringBuilder.length() < this.keylen) stringBuilder.append(Integer.toHexString(this.random.nextInt()));
String license = stringBuilder.substring(0, this.keylen);
// store reference to url with license key
this.permissions.put(license, url);
this.aging.add(license);
if (System.currentTimeMillis() - this.lastCheck > minCheck) {
// check aging
this.lastCheck = System.currentTimeMillis();
String s;
while (this.aging.size() > maxQueue) {
s = this.aging.poll();
if (s != null) this.permissions.remove(s);
}
}
// return the license key
return license;
}
public DigestURI releaseLicense(final String license) {
DigestURI url = null;
url = this.permissions.remove(license);
return url;
}
}