org.jrobin.core

Class RrdJRobin14FileBackend

java.lang.Object

org.jrobin.core.RrdBackend

org.jrobin.core.RrdJRobin14FileBackend

public class RrdJRobin14FileBackend
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).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RrdJRobin14FileBackend.LockMode

Field Summary

Fields

Modifier and Type	Field and Description
protected RandomAccessFile	m_file random access file handle
protected FileLock	m_fileLock file lock
protected RrdJRobin14FileBackend.LockMode	m_lockMode locking mode

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RrdJRobin14FileBackend(String path, boolean readOnly, RrdJRobin14FileBackend.LockMode lockMode) Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the underlying RRD file.
String	getCanonicalPath() 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, isInstanceCreated, isReadOnly, readAll, readDouble, readDouble, readInt, readLong, readString, writeDouble, writeDouble, writeDouble, writeInt, writeLong, writeString

Methods inherited from class java.lang.Object

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

Field Detail

m_lockMode

protected RrdJRobin14FileBackend.LockMode m_lockMode

locking mode

m_file

protected RandomAccessFile m_file

random access file handle

m_fileLock

protected FileLock m_fileLock

file lock

Constructor Detail

RrdJRobin14FileBackend

protected RrdJRobin14FileBackend(String path,
                                 boolean readOnly,
                                 RrdJRobin14FileBackend.LockMode lockMode)
                          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

lockMode - Locking mode: Exception if locked, Wait if locked, or no locks.

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 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.