/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package lupos.datastructures.patriciatrie.disk;
import java.io.IOException;
import lupos.datastructures.patriciatrie.TrieSet;
import lupos.datastructures.patriciatrie.disk.nodemanager.NodeManager;
import lupos.datastructures.patriciatrie.node.Node;
/**
* This class implements the disk based behavior for a trie for a set of strings.
*/
public class DBTrieSet extends TrieSet {
/** This encoding will be used when Strings are serialized */
public static final String OUTPUT_ENCODING = "UTF-8";
/** NodeManager responsible for all the nodes of this trie */
private NodeManager nodeManager;
/**
* Creates a new trie
*
* @param fileName
* Base filename for the trie
* @param bufferSize
* Amount of nodes that are simultaneously kept in memory
* @param pageSize
* The size of a page to be stored on disk
* @throws IOException
*/
public DBTrieSet(final String fileName, final int bufferSize, final int pageSize) throws IOException {
super();
this.nodeManager = new NodeManager(this, fileName, bufferSize, pageSize);
if (this.nodeManager.isEmpty(1)) {
this.setRootNode(null);
}
else {
this.setRootNode((Node) this.nodeManager.loadDBNode(1, DBNode.deserializer));
}
}
/**
* Creates a new trie with the default buffer size
*
* @param fileName
* Base filename for the trie
* @throws IOException
*/
public DBTrieSet(final String fileName) throws IOException {
this(fileName, NodeManager.NODES_TO_BUFFER, NodeManager.DEFAULT_PAGESIZE);
}
/**
* Saves all unsaved changes to disk and closes the underlying node manager.
* After this method has been called, the trie should not be accessed
* anymore.
*/
@Override
public void release() {
if (this.getRootNode() != null) {
this.nodeManager.saveDBNode((IDBNode) this.getRootNode());
}
this.nodeManager.writeBufferToDisk();
try {
this.nodeManager.close();
} catch (IOException e) {
e.printStackTrace();
}
super.release();
}
@Override
protected Node createNodeInstance() {
return new DBNode(this.nodeManager, -1);
}
@Override
protected Node createRootNodeInstance() {
return new DBNode(this.nodeManager, 1);
}
@Override
protected void changeRootNode(final Node rootNode_local) {
this.setRootNode(rootNode_local);
((DBNode) this.getRootNode()).setNodeIndex(1);
this.nodeManager.saveDBNode((IDBNode) this.getRootNode());
}
}