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/**
* KeyList
* Copyright 2011 by Michael Peter Christen, mc@yacy.net, Frankfurt a. M., Germany
* First released 18.4.2011 at http://yacy.net
*
* $LastChangedDate: 2011-03-22 10:34:10 +0100 (Di, 22 Mrz 2011) $
* $LastChangedRevision: 7619 $
* $LastChangedBy: orbiter $
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program in the file lgpl21.txt
* If not, see <http://www.gnu.org/licenses/>.
*/
package net.yacy.cora.storage;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.zip.GZIPInputStream;
import net.yacy.cora.document.encoding.UTF8;
/**
* a key list is a file which contains a list of key words; each line one word
* The key list is stored into a java set object and the list can be extended on the fly
* which is done by extending the file with just another line.
* When is key list file is initialized, all lines are read and pushed into a java set
*/
public class KeyList implements Iterable<String> {
private static final Object _obj = new Object();
private final Map<String, Object> keys;
private final RandomAccessFile raf;
public KeyList(final File file) throws IOException {
this.keys = new ConcurrentHashMap<String, Object>();
if (file.exists()) {
InputStream is = new FileInputStream(file);
if (file.getName().endsWith(".gz")) {
is = new GZIPInputStream(is);
}
final BufferedReader reader = new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8));
String l;
try {
while ((l = reader.readLine()) != null) {
if (l.isEmpty() || l.charAt(0) == '#') continue;
l = l.trim().toLowerCase();
this.keys.put(l, _obj);
}
} catch (final IOException e) {
// finish
} finally {
reader.close();
}
}
this.raf = new RandomAccessFile(file, "rw");
}
public void clear() throws IOException {
this.raf.setLength(0);
this.keys.clear();
}
public int size() {
return this.keys.size();
}
public boolean contains(final String key) {
return this.keys.containsKey(key.trim().toLowerCase());
}
public void add(final String key) throws IOException {
if (this.keys.containsKey(key)) return;
synchronized (this.raf) {
if (this.keys.containsKey(key)) return; // check again for those threads who come late (after another has written this)
this.keys.put(key, _obj);
this.raf.seek(this.raf.length());
this.raf.write(UTF8.getBytes(key));
this.raf.writeByte('\n');
}
}
public synchronized void close() throws IOException {
synchronized (this.raf) {
this.raf.close();
}
}
public static void main(final String[] args) {
try {
final KeyList kl = new KeyList(new File("/tmp/test"));
kl.add("eins");
kl.add("zwei");
kl.add("drei");
System.out.println(kl.contains("eins") ? "drin" : "nicht");
} catch (final IOException e) {
e.printStackTrace();
}
}
@Override
public Iterator<String> iterator() {
return this.keys.keySet().iterator();
}
}
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