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yacy_search_server/source/de/anomic/index/indexCell.java

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// indexRAMRI.java
// (C) 2005, 2006 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 2005 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2009-01-02 12:38:20 +0100 (Fr, 02 Jan 2009) $
// $LastChangedRevision: 5432 $
// $LastChangedBy: orbiter $
//
// 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.index;
import java.io.File;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
import de.anomic.kelondro.index.Row;
import de.anomic.kelondro.order.CloneableIterator;
import de.anomic.kelondro.order.kelondroMergeIterator;
import de.anomic.kelondro.order.kelondroOrder;
/*
* an index cell is a part of the horizontal index in the new segment-oriented index
* data structure of YaCy. If there is no filter in front of a cell, it might also be
* the organization for a complete segment index. Each cell consists of a number of BLOB files, that
* must be merged to represent a single index. In fact these index files are only merged on demand
* if there are too many of them. An index merge can be done with a stream read and stream write operation.
* in normal operation, there are only a number of read-only BLOB files and a single RAM cache that is
* kept in the RAM as long as a given limit of entries is reached. Then the cache is flushed and becomes
* another BLOB file in the index array.
*/
public final class indexCell implements indexRI {
// class variables
private indexContainerBLOBArray array;
private indexContainerRAMHeap ram;
private int maxRamEntries;
@SuppressWarnings("unchecked")
public indexCell(
final File cellPath,
final Row payloadrow,
final int maxRamEntries
) throws IOException {
this.array = new indexContainerBLOBArray(cellPath, payloadrow);
this.ram = new indexContainerRAMHeap(payloadrow);
this.maxRamEntries = maxRamEntries;
}
private void cacheDump() throws IOException {
// dump the ram
File dumpFile = this.array.newContainerBLOBFile();
this.ram.dump(dumpFile);
// get a fresh ram cache
this.ram = new indexContainerRAMHeap(this.array.rowdef());
// add the dumped indexContainerBLOB to the array
this.array.mountBLOBContainer(dumpFile);
}
/**
* add entries to the cell: this adds the new entries always to the RAM part, never to BLOBs
* @throws IOException
*/
public synchronized void addEntries(indexContainer newEntries) throws IOException {
this.ram.add(newEntries);
if (this.ram.size() > this.maxRamEntries) cacheDump();
}
/**
* clear the RAM and BLOB part, deletes everything in the cell
*/
public synchronized void clear() throws IOException {
this.ram.clear();
this.array.clear();
}
/**
* when a cell is closed, the current RAM is dumped to a file which will be opened as
* BLOB file the next time a cell is opened. A name for the dump is automatically generated
* and is composed of the current date and the cell salt
*/
public synchronized void close() {
// dump the ram
try {
this.ram.dump(this.array.newContainerBLOBFile());
} catch (IOException e) {
e.printStackTrace();
}
// close all
this.ram.close();
this.array.close();
}
/**
* deleting a container affects the containers in RAM and all the BLOB files
* the deleted containers are merged and returned as result of the method
*/
public indexContainer deleteContainer(String wordHash) throws IOException {
indexContainer c0 = this.ram.delete(wordHash);
indexContainer c1 = this.array.get(wordHash);
if (c1 == null) {
if (c0 == null) return null;
return c0;
}
this.array.delete(wordHash);
if (c0 == null) return c1;
return c1.merge(c0);
}
/**
* all containers in the BLOBs and the RAM are merged and returned
*/
public indexContainer getContainer(String wordHash, Set<String> urlselection) throws IOException {
indexContainer c0 = this.ram.get(wordHash);
indexContainer c1 = this.array.get(wordHash);
if (c1 == null) {
if (c0 == null) return null;
return c0;
}
if (c0 == null) return c1;
return c1.merge(c0);
}
/**
* checks if there is any container for this wordHash, either in RAM or any BLOB
*/
public boolean hasContainer(String wordHash) {
if (this.ram.has(wordHash)) return true;
return this.array.has(wordHash);
}
public int minMem() {
return 10 * 1024 * 1024;
}
/**
* remove url references from a selected word hash. this deletes also in the BLOB
* files, which means that there exists new gap entries after the deletion
* The gaps are never merged in place, but can be eliminated when BLOBs are merged into
* new BLOBs. This returns the sum of all url references that have been removed
* @throws IOException
* @throws IOException
*/
public int removeEntries(String wordHash, Set<String> urlHashes) throws IOException {
int reduced = this.array.replace(wordHash, new RemoveRewriter(urlHashes));
return reduced / this.array.rowdef().objectsize;
}
public boolean removeEntry(String wordHash, String urlHash) throws IOException {
int reduced = this.array.replace(wordHash, new RemoveRewriter(urlHash));
return reduced > 0;
}
public int size() {
return this.ram.size() + this.array.size();
}
public CloneableIterator<indexContainer> wordContainers(String startWordHash, boolean rot) throws IOException {
return wordContainers(startWordHash, rot, false);
}
public synchronized CloneableIterator<indexContainer> wordContainers(final String startWordHash, boolean rot, final boolean ramOnly) throws IOException {
final kelondroOrder<indexContainer> containerOrder = new indexContainerOrder(this.ram.rowdef().getOrdering().clone());
containerOrder.rotate(new indexContainer(startWordHash, this.ram.rowdef(), 0));
if (ramOnly) {
return this.ram.wordContainers(startWordHash, false);
}
return new kelondroMergeIterator<indexContainer>(
this.ram.wordContainers(startWordHash, false),
this.array.wordContainers(startWordHash, false),
containerOrder,
indexContainer.containerMergeMethod,
true);
}
public class RemoveRewriter implements indexContainerBLOBArray.ContainerRewriter {
Set<String> urlHashes;
public RemoveRewriter(Set<String> urlHashes) {
this.urlHashes = urlHashes;
}
public RemoveRewriter(String urlHash) {
this.urlHashes = new HashSet<String>();
this.urlHashes.add(urlHash);
}
public indexContainer rewrite(indexContainer container) {
container.removeEntries(urlHashes);
return container;
}
}
}