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ActiveMQ example source code file (DataFile.java)

This example ActiveMQ source code file (DataFile.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

comparable, datafile, datafile, file, file, integer, io, ioexception, ioexception, linkednode, override, randomaccessfile, randomaccessfile, string

The ActiveMQ DataFile.java source code

/**
 * 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.activemq.kaha.impl.async;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

import org.apache.activemq.util.IOHelper;
import org.apache.activemq.util.LinkedNode;

/**
 * DataFile
 * 
 * 
 */
public class DataFile extends LinkedNode implements Comparable<DataFile> {

    protected final File file;
    protected final Integer dataFileId;
    protected final int preferedSize;

    protected int length;
    protected int referenceCount;

    DataFile(File file, int number, int preferedSize) {
        this.file = file;
        this.preferedSize = preferedSize;
        this.dataFileId = Integer.valueOf(number);
        length = (int)(file.exists() ? file.length() : 0);
    }
    
    File getFile() {
        return file;
    }

    public Integer getDataFileId() {
        return dataFileId;
    }

    public synchronized int getLength() {
        return length;
    }

    public void setLength(int length) {
        this.length = length;
    }

    public synchronized void incrementLength(int size) {
        length += size;
    }

    public synchronized int increment() {
        return ++referenceCount;
    }

    public synchronized int decrement() {
        return --referenceCount;
    }
    
    public synchronized int getReferenceCount(){
    	return referenceCount;
    }

    public synchronized boolean isUnused() {
        return referenceCount <= 0;
    }

    public synchronized String toString() {
        String result = file.getName() + " number = " + dataFileId + " , length = " + length + " refCount = " + referenceCount;
        return result;
    }

    public synchronized RandomAccessFile openRandomAccessFile(boolean appender) throws IOException {
        RandomAccessFile rc = new RandomAccessFile(file, "rw");
        // When we start to write files size them up so that the OS has a chance
        // to allocate the file contiguously.
        if (appender) {
            if (length < preferedSize) {
                try {
                    // this can throw if we run out of disk space
                    rc.setLength(preferedSize);
                } catch (IOException ioe) {            
                    try {
                        rc.close();
                    } catch(Exception ignored) {
                    }
                    throw ioe;
                }
            }
        }
        return rc;
    }

    public synchronized void closeRandomAccessFile(RandomAccessFile file) throws IOException {
        // On close set the file size to the real size.
        if (length != file.length()) {
            file.setLength(getLength());
        }
        file.close();
    }

    public synchronized boolean delete() throws IOException {
        return file.delete();
    }
    
    public synchronized void move(File targetDirectory) throws IOException{
        IOHelper.moveFile(file,targetDirectory);
    }

    public int compareTo(DataFile df) {
        return dataFileId - df.dataFileId;
    }

    @Override
    public boolean equals(Object o) {
        boolean result = false;
        if (o instanceof DataFile) {
            result = compareTo((DataFile)o) == 0;
        }
        return result;
    }

    @Override
    public int hashCode() {
        return dataFileId;
    }
}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ DataFile.java source code file:

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