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/*******************************************************************************
* Copyright (c) 2001-2005 Sasa Markovic and Ciaran Treanor.
* Copyright (c) 2011 The OpenNMS Group, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*******************************************************************************/
package org.jrobin.core;
import java.io.IOException;
import java.io.RandomAccessFile;
/**
* JRobin backend which is used to store RRD data to ordinary files on the disk. This was the
* default factory before 1.4.0 version.
*
* This backend is based on the RandomAccessFile class (java.io.* package).
*/
public class RrdFileBackend extends RrdBackend {
/**
* radnom access file handle
*/
protected RandomAccessFile file;
/**
* Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.
*
* @param path Path to a file
* @param readOnly True, if file should be open in a read-only mode. False otherwise
* @throws IOException Thrown in case of I/O error
*/
protected RrdFileBackend(final String path, final boolean readOnly) throws IOException {
super(path, readOnly);
this.file = new RandomAccessFile(path, readOnly ? "r" : "rw");
}
/**
* Closes the underlying RRD file.
*
* @throws IOException Thrown in case of I/O error
*/
public void close() throws IOException {
file.close();
}
/**
* Returns canonical path to the file on the disk.
*
* @param path File path
* @return Canonical file path
* @throws IOException Thrown in case of I/O error
*/
public static String getCanonicalPath(String path) throws IOException {
return Util.getCanonicalPath(path);
}
/**
* Returns canonical path to the file on the disk.
*
* @return Canonical file path
* @throws IOException Thrown in case of I/O error
*/
public String getCanonicalPath() throws IOException {
return RrdFileBackend.getCanonicalPath(getPath());
}
/**
* Writes bytes to the underlying RRD file on the disk
*
* @param offset Starting file offset
* @param b Bytes to be written.
* @throws IOException Thrown in case of I/O error
*/
protected void write(long offset, byte[] b) throws IOException {
file.seek(offset);
file.write(b);
}
/**
* Reads a number of bytes from the RRD file on the disk
*
* @param offset Starting file offset
* @param b Buffer which receives bytes read from the file.
* @throws IOException Thrown in case of I/O error.
*/
protected void read(long offset, byte[] b) throws IOException {
file.seek(offset);
if (file.read(b) != b.length) {
throw new IOException("Not enough bytes available in file " + getPath());
}
}
/**
* Returns RRD file length.
*
* @return File length.
* @throws IOException Thrown in case of I/O error.
*/
public long getLength() throws IOException {
return file.length();
}
/**
* Sets length of the underlying RRD file. This method is called only once, immediately
* after a new RRD file gets created.
*
* @param length Length of the RRD file
* @throws IOException Thrown in case of I/O error.
*/
protected void setLength(long length) throws IOException {
file.setLength(length);
}
}