001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.activemq.kaha.impl.async;
018    
019    import java.io.File;
020    import java.io.IOException;
021    import java.io.RandomAccessFile;
022    
023    /**
024     * Allows you to open a data file in read only mode.  Useful when working with 
025     * archived data files.
026     */
027    public class ReadOnlyDataFile extends DataFile {
028    
029        ReadOnlyDataFile(File file, int number, int preferedSize) {
030            super(file, number, preferedSize);
031        }
032        
033        
034        public RandomAccessFile openRandomAccessFile(boolean appender) throws IOException {
035            RandomAccessFile rc = new RandomAccessFile(file, "r");
036            // When we start to write files size them up so that the OS has a chance
037            // to allocate the file contigously.
038            if (appender) {
039                if (length < preferedSize) {
040                    rc.setLength(preferedSize);
041                }
042            }
043            return rc;
044        }
045    
046        public void closeRandomAccessFile(RandomAccessFile file) throws IOException {
047            file.close();
048        }
049    
050        public synchronized boolean delete() throws IOException {
051            throw new RuntimeException("Not valid on a read only file.");
052        }
053        
054        public synchronized void move(File targetDirectory) throws IOException{
055            throw new RuntimeException("Not valid on a read only file.");
056        }
057    
058    }