org.apache.jena.tdb.base.file.PlainFilePersistent Maven / Gradle / Ivy

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TDB is a storage subsystem for Jena and ARQ, it is a native triple store providing persistent storage of triples/quads.

There is a newer version: 4.10.0

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.tdb.base.file;

import java.io.IOException ;
import java.nio.ByteBuffer ;
import java.nio.channels.FileChannel ;

import org.apache.jena.atlas.io.IO ;
import org.slf4j.Logger ;
import org.slf4j.LoggerFactory ;

/** Single, unsegmented file with ByteBuffer */
public class PlainFilePersistent extends PlainFile
{
    private static Logger log = LoggerFactory.getLogger(PlainFilePersistent.class) ;
    
    private FileBase file ;

    // Plain file over mmapped ByteBuffer 
    PlainFilePersistent(Location loc, String filename)
    {
        this(loc.getPath(filename, "dat")) ;
    }
    
    PlainFilePersistent(String filename)
    {
        file = FileBase.create(filename) ;
        //long filesize = file.out.length() ;
        //if ( channel.size() == 0 ) {}
        byteBuffer = allocateBuffer(filesize) ;
    }
    
    @Override
    public void sync()
    { 
        file.sync() ; 
    }
    
    @Override
    public void close()
    {
        file.close() ;
    }

    @Override
    protected ByteBuffer allocateBuffer(long size)
    {
        try { return file.channel().map(FileChannel.MapMode.READ_WRITE, 0, size) ; }
        catch (IOException ex)  { IO.exception(ex) ; return null ; }
    }
}