// Gap.java
// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 30.12.2008 on http:// yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2011-03-08 02:51:51 +0100 (Di, 08. Mär 2011) $
// $LastChangedRevision: 7567 $
// $LastChangedBy: low012 $
//
// 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 net.yacy.kelondro.blob;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;
/**
* this is an extension of a set of {seek, size} pairs
* it is used to denote the position and space of free records
* The class provides methods to dump such a set to a file and read it again
*/
public class Gap extends TreeMap<Long, Integer> {
private static final long serialVersionUID = 1L;
public Gap() {
super();
}
/**
* initialize a kelondroBLOBGap with the content of a dump
* @param file
* @throws IOException
* @throws IOException
*/
public Gap(final File file) throws IOException {
super();
// read the index dump and fill the index
DataInputStream is;
try {
is = new DataInputStream(new BufferedInputStream(new FileInputStream(file), 1024 * 1024));
} catch (OutOfMemoryError e) {
is = new DataInputStream(new FileInputStream(file));
}
long p;
int l;
while (true) {
try {
p = is.readLong();
l = is.readInt();
this.put(Long.valueOf(p), Integer.valueOf(l));
} catch (IOException e) {
break;
}
}
is.close();
is = null;
}
/**
* dump the set to a file
* @param file
* @return
* @throws IOException
*/
public int dump(File file) throws IOException {
File tmp = new File(file.getParentFile(), file.getName() + ".prt");
Iterator<Map.Entry<Long, Integer>> i = this.entrySet().iterator();
DataOutputStream os;
try {
os = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(tmp), 4 * 1024 * 1024));
} catch (OutOfMemoryError e) {
os = new DataOutputStream(new FileOutputStream(tmp));
}
int c = 0;
Map.Entry<Long, Integer> e;
while (i.hasNext()) {
e = i.next();
os.writeLong(e.getKey().longValue());
os.writeInt(e.getValue().intValue());
c++;
}
os.flush();
os.close();
tmp.renameTo(file);
assert file.exists() : file.toString();
assert !tmp.exists() : tmp.toString();
return c;
}
}