org.apache.jena.tdb.base.file.FileBase 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.channels.FileChannel ;

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

public final class FileBase implements Sync, Closeable
{
    static private Logger log = LoggerFactory.getLogger(FileBase.class) ; 
    // A mixin, which java does not support very well.
    public final String filename ;
    private FileChannel channel ;
    public static boolean DEBUG = false ;
    private final boolean DebugThis  ;
    private static long counter = 0 ;
    private final long id ;

    /** Create an FileBase without managed resources  Use with case. */
    static FileBase createUnmanged(String filename, FileChannel channel) { return new FileBase(filename, channel) ; }
    
    /** Create a Filebase with managed resources */
    static FileBase create(String filename) { return new FileBase(filename) ; }
    static FileBase create(String filename, String mode) { return new FileBase(filename, mode) ; }
    
    private /*public*/ FileBase(String filename)
    {
        this(filename, "rw") ;
    }
    
    private /*public*/ FileBase(String filename, String mode)
    {
        DebugThis = false ;
        id  = (counter++) ;
        
        if ( DebugThis && log.isDebugEnabled() )
            log.debug("open: ["+id+"]"+filename) ;
        this.filename = filename ;
        channel = ChannelManager.acquire(filename, mode) ;
    }
    
    private /*public*/ FileBase(String filename, FileChannel channel)
    {
        DebugThis = false ;
        id  = -1  ;
        this.filename = filename ;
        this.channel = channel ; 
    }

    public final FileChannel channel() { return channel ; }
    
    public long size()
    {
        try {
            return channel.size() ;
        } catch (IOException ex)
        { IO.exception(ex) ; return -1L ; }
    }

    public boolean isClosed()
    {
        return channel == null ;
    }

    
    @Override
    public void close()
    {
        if ( DebugThis )
            log.debug("close: ["+id+"]: "+filename) ;
        ChannelManager.release(channel) ;
        channel = null ;
//        try {
//            channel.close() ;
//            channel = null ;
//        } catch (IOException ex)
//        { throw new FileException("FileBase.close", ex) ; }
    }

    @Override
    public void sync()
    {
        if ( DebugThis ) 
            log.debug("sync: ["+id+"]: "+filename) ;
        try {
            channel.force(false) ;
        } catch (IOException ex)
        { throw new FileException("FileBase.sync", ex) ; }
    }

    public String getFilename() { return filename ; }  
}