org.jrobin.core
Class RrdFileBackend

java.lang.Object
  org.jrobin.core.RrdBackend
      org.jrobin.core.RrdFileBackend

Direct Known Subclasses:

RrdNioBackend, RrdSafeFileBackend

public class RrdFileBackend
extends RrdBackend

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).

Field Summary

protected RandomAccessFile	file radnom access file handle
protected boolean	readOnly read/write file status

Constructor Summary

protected

RrdFileBackend(String path, boolean readOnly) Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Method Summary

void	close() Closes the underlying RRD file.
String	getCanonicalPath() Returns canonical path to the file on the disk.
static String	getCanonicalPath(String path) Returns canonical path to the file on the disk.
long	getLength() Returns RRD file length.
protected void	read(long offset, byte[] b) Reads a number of bytes from the RRD file on the disk
protected void	setLength(long length) Sets length of the underlying RRD file.
protected void	write(long offset, byte[] b) Writes bytes to the underlying RRD file on the disk

Methods inherited from class org.jrobin.core.RrdBackend

getPath, isCachingAllowed, readAll

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

readOnly

protected boolean readOnly

read/write file status

file

protected RandomAccessFile file

radnom access file handle

Constructor Detail

RrdFileBackend

protected RrdFileBackend(String path,
                         boolean readOnly)
                  throws IOException

Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Parameters:

path - Path to a file

readOnly - True, if file should be open in a read-only mode. False otherwise

Throws:

IOException - Thrown in case of I/O error

Method Detail

close

public void close()
           throws IOException

Closes the underlying RRD file.

Overrides:

close in class RrdBackend

Throws:

IOException - Thrown in case of I/O error

getCanonicalPath

public static String getCanonicalPath(String path)
                               throws IOException

Returns canonical path to the file on the disk.

Parameters:

path - File path

Returns:

Canonical file path

Throws:

IOException - Thrown in case of I/O error

getCanonicalPath

public String getCanonicalPath()
                        throws IOException

Returns canonical path to the file on the disk.

Returns:

Canonical file path

Throws:

IOException - Thrown in case of I/O error

write

protected void write(long offset,
                     byte[] b)
              throws IOException

Writes bytes to the underlying RRD file on the disk

Specified by:

write in class RrdBackend

Parameters:

offset - Starting file offset

b - Bytes to be written.

Throws:

IOException - Thrown in case of I/O error

read

protected void read(long offset,
                    byte[] b)
             throws IOException

Reads a number of bytes from the RRD file on the disk

Specified by:

read in class RrdBackend

Parameters:

offset - Starting file offset

b - Buffer which receives bytes read from the file.

Throws:

IOException - Thrown in case of I/O error.

getLength

public long getLength()
               throws IOException

Returns RRD file length.

Specified by:

getLength in class RrdBackend

Returns:

File length.

Throws:

IOException - Thrown in case of I/O error.

setLength

protected void setLength(long length)
                  throws IOException

Sets length of the underlying RRD file. This method is called only once, immediately after a new RRD file gets created.

Specified by:

setLength in class RrdBackend

Parameters:

length - Length of the RRD file

Throws:

IOException - Thrown in case of I/O error.