Package org.jrobin.core

Class RrdNioBackend

java.lang.Object

org.jrobin.core.RrdBackend

org.jrobin.core.RrdFileBackend

org.jrobin.core.RrdNioBackend

public class RrdNioBackend
extends RrdFileBackend

JRobin backend which is used to store RRD data to ordinary disk files by using fast java.nio.* package. This is the default backend engine since JRobin 1.4.0.

Field Summary

Fields inherited from class org.jrobin.core.RrdFileBackend

file

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	RrdNioBackend(String path, boolean readOnly, int syncPeriod)	Creates RrdFileBackend object for the given file path, backed by java.nio.* classes.
protected	RrdNioBackend(String path, boolean readOnly, SyncManager syncManager)	Creates RrdFileBackend object for the given file path, backed by java.nio.* classes.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the underlying RRD file.
protected void	finalize()
protected void	read(long offset, byte[] b)	Reads a number of bytes from the RRD file on the disk
protected void	setLength(long newLength)	Sets length of the underlying RRD file.
protected void	sync()	This method forces all data cached in memory but not yet stored in the file, to be stored in it.
protected void	write(long offset, byte[] b)	Writes bytes to the underlying RRD file on the disk

Methods inherited from class org.jrobin.core.RrdFileBackend

getCanonicalPath, getCanonicalPath, getLength

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, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RrdNioBackend

protected RrdNioBackend(String path,
                        boolean readOnly,
                        int syncPeriod)
                 throws IOException

Creates RrdFileBackend object for the given file path, backed by java.nio.* classes. This constructor will create a SyncManager for each instance, which is very inefficient. It is recommended that you instead use the RrdNioBackend(String, boolean, SyncManager) constructor instead.

Parameters:

path - Path to a JRB file.

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

syncPeriod - How often (in seconds) to sync MMAP'd RRD data to disk

Throws:

IOException - Thrown in case of I/O error

RrdNioBackend

protected RrdNioBackend(String path,
                        boolean readOnly,
                        SyncManager syncManager)
                 throws IOException

Creates RrdFileBackend object for the given file path, backed by java.nio.* classes.

Parameters:

path - Path to a file

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

syncManager - An object for managing synchronization of NIO-backed RRDs, generally owned by the backend factory. If null, MMAP'd data will only be synchronized to disk upon unmap. Note that if the file is opened read-only, the SyncManager is ignored. unmapFile()

Throws:

IOException - Thrown in case of I/O error

Method Detail

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

setLength

protected void setLength(long newLength)
                  throws IOException

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

Overrides:

setLength in class RrdFileBackend

Parameters:

newLength - Length of the RRD file

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

Overrides:

write in class RrdFileBackend

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

Overrides:

read in class RrdFileBackend

Parameters:

offset - Starting file offset

b - Buffer which receives bytes read from the file.

Throws:

IOException - Thrown in case of I/O error.

close

public void close()
           throws IOException

Closes the underlying RRD file.

Overrides:

close in class RrdFileBackend

Throws:

IOException - Thrown in case of I/O error

sync

protected void sync()

This method forces all data cached in memory but not yet stored in the file, to be stored in it.