org.rrd4j.core

Class RrdNioBackend

java.lang.Object

org.rrd4j.core.RrdBackend

org.rrd4j.core.ByteBufferBackend

org.rrd4j.core.RrdNioBackend

All Implemented Interfaces:

RrdFileBackend

public class RrdNioBackend
extends ByteBufferBackend
implements RrdFileBackend

Backend which is used to store RRD data to ordinary disk files using java.nio.* package. This is the default backend engine.

This version buffers all stat files in a single temporary buffer file sequentially, keeping track of each file's offset and length, then flushes all to the mapped file in batch.

Field Summary

Fields inherited from class org.rrd4j.core.RrdBackend

BYTEORDER

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
void	bufferStatFile(ByteBuffer data, long targetFileOffset) Buffers one stat file's data into the single temp buffer file sequentially.
void	close() Closes the underlying RRD file.
void	flushBufferedStatFiles() Flushes all buffered stat files sequentially from the temp buffer file into their designated positions in the mapped RRD file in one batch operation.
String	getCanonicalPath() Returns canonical path to the file on the disk.
long	getLength() Returns the number of RRD bytes in the underlying storage.
protected void	setLength(long newLength) Sets the number of bytes in the underlying RRD storage.
protected void	sync() Override sync to disable unbuffered flush.

Methods inherited from class org.rrd4j.core.ByteBufferBackend

getCharBuffer, isDirty, read, readDouble, readDouble, readInt, readLong, readShort, rrdClose, setByteBuffer, write, writeDouble, writeDouble, writeDouble, writeInt, writeLong, writeShort, writeString

Methods inherited from class org.rrd4j.core.RrdBackend

done, getFactory, getPath, getUri, isCachingAllowed, isInstanceCreated, readAll, readString, writeString

Methods inherited from class java.lang.Object

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

Constructor Detail

RrdNioBackend

protected RrdNioBackend(String path,
                        boolean readOnly,
                        RrdSyncThreadPool threadPool,
                        int syncPeriod)
                 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 read-only mode. False otherwise

threadPool - Sync thread pool; can be null

syncPeriod - Sync period in seconds

Throws:

IOException - On I/O error

Method Detail

bufferStatFile

public void bufferStatFile(ByteBuffer data,
                           long targetFileOffset)
                    throws IOException

Buffers one stat file's data into the single temp buffer file sequentially. This method appends the data to the temp file and records the offset and length, including the target offset in the mapped file where this stat file belongs.

Parameters:

data - ByteBuffer containing the stat file's bytes to buffer

targetFileOffset - Position in the mapped RRD file to write this stat file to on flush

Throws:

IOException - If writing to temp file fails

close

public void close()
           throws IOException

Closes the underlying RRD file. Also closes and deletes the temporary buffer file used for buffering.

Overrides:

close in class ByteBufferBackend

Throws:

IOException - On I/O error

flushBufferedStatFiles

public void flushBufferedStatFiles()

Flushes all buffered stat files sequentially from the temp buffer file into their designated positions in the mapped RRD file in one batch operation. After flushing, the temp buffer file and index are cleared for the next batch.

getCanonicalPath

public String getCanonicalPath()

Description copied from interface: RrdFileBackend

Returns canonical path to the file on the disk.

Specified by:

getCanonicalPath in interface RrdFileBackend

Returns:

Canonical file path

getLength

public long getLength()
               throws IOException

Description copied from class: RrdBackend

Returns the number of RRD bytes in the underlying storage.

Specified by:

getLength in class RrdBackend

Returns:

Number of RRD bytes in the storage.

Throws:

IOException - Thrown in case of I/O error.

setLength

protected void setLength(long newLength)
                  throws IOException

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

Specified by:

setLength in class RrdBackend

Parameters:

newLength - Length of the underlying RRD storage in bytes.

Throws:

IllegalArgumentException - if the length is bigger than the possible mapping position (2GiB).

IOException - Thrown in case of I/O error.

sync

protected void sync()

Override sync to disable unbuffered flush.