org.jrobin.core

Class RrdFileBackend

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 RandomAccessFilefile
radnom access file handle
protected booleanreadOnly
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
voidclose()
Closes the underlying RRD file.
static StringgetCanonicalPath(String path)
Returns canonical path to the file on the disk.
StringgetCanonicalPath()
Returns canonical path to the file on the disk.
longgetLength()
Returns RRD file length.
protected voidread(long offset, byte[] b)
Reads a number of bytes from the RRD file on the disk
protected voidsetLength(long length)
Sets length of the underlying RRD file.
protected voidwrite(long offset, byte[] b)
Writes bytes to the underlying RRD file on the disk

Field Detail

file

protected RandomAccessFile file
radnom access file handle

readOnly

protected boolean readOnly
read/write file status

Constructor Detail

RrdFileBackend

protected RrdFileBackend(String path, boolean readOnly)
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()
Closes the underlying RRD file.

Throws: IOException Thrown in case of I/O error

getCanonicalPath

public static String getCanonicalPath(String path)
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()
Returns canonical path to the file on the disk.

Returns: Canonical file path

Throws: IOException Thrown in case of I/O error

getLength

public long getLength()
Returns RRD file length.

Returns: File length.

Throws: IOException Thrown in case of I/O error.

read

protected void read(long offset, byte[] b)
Reads a number of bytes from the RRD file on the disk

Parameters: offset Starting file offset b Buffer which receives bytes read from the file.

Throws: IOException Thrown in case of I/O error.

setLength

protected void setLength(long length)
Sets length of the underlying RRD file. This method is called only once, immediately after a new RRD file gets created.

Parameters: length Length of the RRD file

Throws: IOException Thrown in case of I/O error.

write

protected void write(long offset, byte[] b)
Writes bytes to the underlying RRD file on the disk

Parameters: offset Starting file offset b Bytes to be written.

Throws: IOException Thrown in case of I/O error