org.rrd4j.core

Class ByteBufferBackend

java.lang.Object

org.rrd4j.core.RrdBackend

org.rrd4j.core.ByteBufferBackend

Direct Known Subclasses:

RrdByteArrayBackend, RrdMemoryBackend, RrdNioBackend

public abstract class ByteBufferBackend
extends RrdBackend

A backend that store and provides access to data using a ByteBuffer, using java internal methods for long, integer and others types.

Field Summary

Fields inherited from class org.rrd4j.core.RrdBackend

BYTEORDER

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ByteBufferBackend(String path)

Method Summary

Modifier and Type	Method and Description
protected void	close() Closes the underlying backend.
protected CharBuffer	getCharBuffer(long offset, int size) Extract a CharBuffer from the backend, used by readString
protected boolean	isDirty()
protected void	read(long offset, byte[] b) Reads a number of bytes from the RRD file on the disk
double	readDouble(long offset) Reads a double value from the underlying storage at the given offset.
double[]	readDouble(long offset, int count) Reads an array of double values from the underlying storage at the given offset.
protected int	readInt(long offset) Reads an integer value from the underlying storage at the given offset.
protected long	readLong(long offset) Reads a long value from the underlying storage at the given offset.
protected short	readShort(long offset) Reads a short value from the underlying storage at the given offset.
protected void	rrdClose() Closes the underlying backend.
protected void	setByteBuffer(ByteBuffer byteBuffer)
protected void	write(long offset, byte[] b) Writes bytes to the underlying RRD file on the disk
protected void	writeDouble(long offset, double value) Writes a double value to the underlying storage at the given offset.
protected void	writeDouble(long offset, double[] values) Writes an array of double values to the underlying storage at the given offset.
protected void	writeDouble(long offset, double value, int count) Writes multiple copies of a double value to the underlying storage at the given offset.
protected void	writeInt(long offset, int value) Writes an integer value to the underlying storage at the given offset.
protected void	writeLong(long offset, long value) Writes a long value to the underlying storage at the given offset.
protected void	writeShort(long offset, short value) Writes a short value to the underlying storage at the given offset.
protected void	writeString(long offset, String value, int length) Writes a string to the underlying storage at the given offset with a fixed length.

Methods inherited from class org.rrd4j.core.RrdBackend

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

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteBufferBackend

protected ByteBufferBackend(String path)

Method Detail

close

protected void close()
              throws IOException

Description copied from class: RrdBackend

Closes the underlying backend. Used internally, should not be called from external code.

Specified by:

close in class RrdBackend

Throws:

IOException - Thrown in case of I/O error

getCharBuffer

protected CharBuffer getCharBuffer(long offset,
                                   int size)
                            throws RrdException

Description copied from class: RrdBackend

Extract a CharBuffer from the backend, used by readString

Overrides:

getCharBuffer in class RrdBackend

Parameters:

offset - the offset in the rrd

size - the size of the buffer, in character

Returns:

a new CharBuffer

Throws:

RrdException

isDirty

protected boolean isDirty()

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.

IllegalArgumentException - if offset is bigger that the possible mapping position (2GiB).

readDouble

public double readDouble(long offset)
                  throws IOException

Description copied from class: RrdBackend

Reads a double value from the underlying storage at the given offset.

Overrides:

readDouble in class RrdBackend

Parameters:

offset - Storage offset.

Returns:

The double value read from storage.

Throws:

IOException - Thrown in case of I/O error.

readDouble

public double[] readDouble(long offset,
                           int count)
                    throws IOException

Description copied from class: RrdBackend

Reads an array of double values from the underlying storage at the given offset.

Overrides:

readDouble in class RrdBackend

Parameters:

offset - Storage offset.

count - Number of double values to read.

Returns:

Array of double values read from storage.

Throws:

IOException - Thrown in case of I/O error.

readInt

protected int readInt(long offset)
               throws IOException

Description copied from class: RrdBackend

Reads an integer value from the underlying storage at the given offset.

Overrides:

readInt in class RrdBackend

Parameters:

offset - Storage offset.

Returns:

The integer value read from storage.

Throws:

IOException - Thrown in case of I/O error.

readLong

protected long readLong(long offset)
                 throws IOException

Description copied from class: RrdBackend

Reads a long value from the underlying storage at the given offset.

Overrides:

readLong in class RrdBackend

Parameters:

offset - Storage offset.

Returns:

The long value read from storage.

Throws:

IOException - Thrown in case of I/O error.

readShort

protected short readShort(long offset)
                   throws IOException

Description copied from class: RrdBackend

Reads a short value from the underlying storage at the given offset.

Overrides:

readShort in class RrdBackend

Parameters:

offset - Storage offset.

Returns:

The short value read from storage.

Throws:

IOException - Thrown in case of I/O error.

rrdClose

protected void rrdClose()
                 throws IOException

Description copied from class: RrdBackend

Closes the underlying backend. Call by RrdDb#close() when it's closed. All subclass must keep calling it.

Overrides:

rrdClose in class RrdBackend

Throws:

IOException - Thrown in case of I/O error

setByteBuffer

protected void setByteBuffer(ByteBuffer byteBuffer)

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 - if any.

IllegalArgumentException - if offset is bigger that the possible mapping position (2GiB).

writeDouble

protected void writeDouble(long offset,
                           double value)
                    throws IOException

Description copied from class: RrdBackend

Writes a double value to the underlying storage at the given offset.

Overrides:

writeDouble in class RrdBackend

Parameters:

offset - Storage offset.

value - Double value to write.

Throws:

IOException - Thrown in case of I/O error.

writeDouble

protected void writeDouble(long offset,
                           double[] values)
                    throws IOException

Description copied from class: RrdBackend

Writes an array of double values to the underlying storage at the given offset.

Overrides:

writeDouble in class RrdBackend

Parameters:

offset - Storage offset.

values - Array of double values to write.

Throws:

IOException - Thrown in case of I/O error.

writeDouble

protected void writeDouble(long offset,
                           double value,
                           int count)
                    throws IOException

Description copied from class: RrdBackend

Writes multiple copies of a double value to the underlying storage at the given offset.

Overrides:

writeDouble in class RrdBackend

Parameters:

offset - Storage offset.

value - Double value to write.

count - Number of times to write the value.

Throws:

IOException - Thrown in case of I/O error.

writeInt

protected void writeInt(long offset,
                        int value)
                 throws IOException

Description copied from class: RrdBackend

Writes an integer value to the underlying storage at the given offset.

Overrides:

writeInt in class RrdBackend

Parameters:

offset - Storage offset.

value - Integer value to write.

Throws:

IOException - Thrown in case of I/O error.

writeLong

protected void writeLong(long offset,
                         long value)
                  throws IOException

Description copied from class: RrdBackend

Writes a long value to the underlying storage at the given offset.

Overrides:

writeLong in class RrdBackend

Parameters:

offset - Storage offset.

value - Long value to write.

Throws:

IOException - Thrown in case of I/O error.

writeShort

protected void writeShort(long offset,
                          short value)
                   throws IOException

Description copied from class: RrdBackend

Writes a short value to the underlying storage at the given offset.

Overrides:

writeShort in class RrdBackend

Parameters:

offset - Storage offset.

value - Short value to write.

Throws:

IOException - Thrown in case of I/O error.

writeString

protected void writeString(long offset,
                           String value,
                           int length)
                    throws IOException

Description copied from class: RrdBackend

Writes a string to the underlying storage at the given offset with a fixed length.

Overrides:

writeString in class RrdBackend

Parameters:

offset - Storage offset.

value - String value to write.

length - Fixed length for the string storage.

Throws:

IOException - Thrown in case of I/O error.