Package db.buffers

Class DataBuffer

java.lang.Object

db.buffers.DataBuffer

All Implemented Interfaces:

Buffer, java.io.Externalizable, java.io.Serializable

public class DataBuffer
extends java.lang.Object
implements Buffer, java.io.Externalizable

DataBuffer provides an accessible binary buffer for use with a BufferMgr and BufferFile.

See Also:

Serialized Form

Field Summary

Fields

Change	Modifier and Type	Field	Description
	static java.lang.String	COMPRESSED_SERIAL_OUTPUT_PROPERTY
NEW	protected byte[]	data
	static long	serialVersionUID

Constructor Summary

Constructors

Change	Modifier	Constructor	Description
		DataBuffer()	Constructor for de-serialization
	protected	DataBuffer(byte[] data)	Construct a data buffer.
	protected	DataBuffer(int bufsize)	Construct a data buffer.

Method Summary

Change	Modifier and Type	Method	Description
	void	clear()	Sets all the values in the buffer to 0;
	void	copy(int offset, DataBuffer buf, int bufOffset, int length)	Copy data from another buffer into this buffer.
	static void	enableCompressedSerializationOutput(boolean enable)
	void	get(int offset, byte[] bytes)	Get the byte data located at the specified offset and store into the bytes array provided.
	void	get(int offset, byte[] bytes, int dataOffset, int length)	Get the byte data located at the specified offset and store into the data array at the specified data offset.
	byte[]	get(int offset, int length)	Get the byte data located at the specified offset.
	byte	getByte(int offset)	Get the 8-bit byte value located at the specified offset.
NEW	protected byte[]	getData()	Get the storage array associated with this buffer.
	int	getId()	Get the ID associated with this buffer.
	int	getInt(int offset)	Get the 32-bit integer value located at the specified offset.
	long	getLong(int offset)	Get the 64-bit long value located at the specified offset.
	short	getShort(int offset)	Get the 16-bit short value located at the specified offset.
	boolean	isDirty()	Return true if this buffer contains modified data.
	boolean	isEmpty()	Return true if this buffer is empty/unused.
	int	length()	Get the length of the buffer in bytes.
	void	move(int src, int dest, int length)	Move the data within this buffer.
	int	put(int offset, byte[] bytes)	Put the bytes provided into the buffer at the specified offset.
	int	put(int offset, byte[] bytes, int dataOffset, int length)	Put a specified number of bytes from the array provided into the buffer at the specified offset.
	int	putByte(int offset, byte b)	Put the 8-bit byte value into the buffer at the specified offset.
	int	putInt(int offset, int v)	Put the 32-bit integer value into the buffer at the specified offset.
	int	putLong(int offset, long v)	Put the 64-bit long value into the buffer at the specified offset.
	int	putShort(int offset, short v)	Put the 16-bit short value into the buffer at the specified offset.
	void	readExternal(java.io.ObjectInput in)
	protected void	setData(byte[] data)	Get the storage array associated with this buffer.
NEW	protected void	setDirty(boolean state)	Set the dirty flag.
NEW	protected void	setEmpty(boolean state)	Set the empty flag.
NEW	protected void	setId(int id)	Set the ID associated with this buffer.
	static boolean	usingCompressedSerializationOutput()
	void	writeExternal(java.io.ObjectOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

public static final long serialVersionUID

See Also:

Constant Field Values

COMPRESSED_SERIAL_OUTPUT_PROPERTY

public static final java.lang.String COMPRESSED_SERIAL_OUTPUT_PROPERTY

See Also:

Constant Field Values

data NEW

protected byte[] data

Constructor Detail

DataBuffer

public DataBuffer()

Constructor for de-serialization

DataBuffer

protected DataBuffer(int bufsize)

Construct a data buffer. A new binary buffer is created.

Parameters:

bufsize - buffer size

DataBuffer

protected DataBuffer(byte[] data)

Construct a data buffer.

Parameters:

data - binary storage array for this buffer.

Method Detail

enableCompressedSerializationOutput

public static void enableCompressedSerializationOutput(boolean enable)

usingCompressedSerializationOutput

public static boolean usingCompressedSerializationOutput()

getData NEW

protected byte[] getData()

Get the storage array associated with this buffer.

Returns:

byte storage array.

setData NEW

protected void setData(byte[] data)

Get the storage array associated with this buffer.

getId

public int getId()

Get the ID associated with this buffer.

Specified by:

getId in interface Buffer

Returns:

buffer ID.

setId NEW

protected void setId(int id)

Set the ID associated with this buffer.

Parameters:

id - buffer ID

isDirty

public boolean isDirty()

Return true if this buffer contains modified data. When this buffer is released to the BufferMgr, the data is consumed and this flag reset to false.

setDirty NEW

protected void setDirty(boolean state)

Set the dirty flag.

Parameters:

state - flag state.

isEmpty

public boolean isEmpty()

Return true if this buffer is empty/unused. Writing to empty buffer does not change the state of this flag.

setEmpty NEW

protected void setEmpty(boolean state)

Set the empty flag.

Parameters:

state - flag state

length

public int length()

Description copied from interface: Buffer

Get the length of the buffer in bytes. The length reflects the number of bytes which have been allocated to the buffer.

Specified by:

length in interface Buffer

Returns:

length of allocated buffer.

get

public void get(int offset,
                byte[] bytes,
                int dataOffset,
                int length)
         throws java.lang.ArrayIndexOutOfBoundsException

Description copied from interface: Buffer

Get the byte data located at the specified offset and store into the data array at the specified data offset.

Specified by:

get in interface Buffer

Parameters:

offset - byte offset from the start of the buffer.

bytes - byte array to store the data.

dataOffset - offset into the data buffer

length - amount of data to read

Throws:

java.lang.ArrayIndexOutOfBoundsException - if an invalid offset, dataOffset, or length is specified.

get

public void get(int offset,
                byte[] bytes)

Description copied from interface: Buffer

Get the byte data located at the specified offset and store into the bytes array provided.

Specified by:

get in interface Buffer

Parameters:

offset - byte offset from start of buffer.

bytes - byte array to store data

get

public byte[] get(int offset,
                  int length)
           throws java.lang.ArrayIndexOutOfBoundsException

Description copied from interface: Buffer

Get the byte data located at the specified offset.

Specified by:

get in interface Buffer

Parameters:

offset - byte offset from start of buffer.

Returns:

the byte array.

Throws:

java.lang.ArrayIndexOutOfBoundsException - is thrown if an invalid offset is specified or the end of the buffer was encountered while reading the data.

getByte

public byte getByte(int offset)

Description copied from interface: Buffer

Get the 8-bit byte value located at the specified offset.

Specified by:

getByte in interface Buffer

Parameters:

offset - byte offset from start of buffer.

Returns:

the byte value at the specified offset.

getInt

public int getInt(int offset)

Description copied from interface: Buffer

Get the 32-bit integer value located at the specified offset.

Specified by:

getInt in interface Buffer

Parameters:

offset - byte offset from start of buffer.

Returns:

the integer value at the specified offset.

getShort

public short getShort(int offset)

Description copied from interface: Buffer

Get the 16-bit short value located at the specified offset.

Specified by:

getShort in interface Buffer

Parameters:

offset - byte offset from start of buffer.

Returns:

the short value at the specified offset.

getLong

public long getLong(int offset)

Description copied from interface: Buffer

Get the 64-bit long value located at the specified offset.

Specified by:

getLong in interface Buffer

Parameters:

offset - byte offset from start of buffer.

Returns:

the long value at the specified offset.

put

public int put(int offset,
               byte[] bytes,
               int dataOffset,
               int length)

Description copied from interface: Buffer

Put a specified number of bytes from the array provided into the buffer at the specified offset. The number of bytes stored is specified by the length specified.

Specified by:

put in interface Buffer

Parameters:

offset - byte offset from start of buffer.

bytes - the byte data to be stored.

dataOffset - the starting offset into the data.

length - the number of bytes to be stored.

Returns:

the next available offset into the buffer, or -1 if the buffer is full.

put

public int put(int offset,
               byte[] bytes)

Description copied from interface: Buffer

Put the bytes provided into the buffer at the specified offset. The number of bytes stored is determined by the length of the bytes array.

Specified by:

put in interface Buffer

Parameters:

offset - byte offset from start of buffer.

bytes - the byte data to be stored.

Returns:

the next available offset into the buffer, or -1 if the buffer is full.

putByte

public int putByte(int offset,
                   byte b)

Description copied from interface: Buffer

Put the 8-bit byte value into the buffer at the specified offset.

Specified by:

putByte in interface Buffer

Parameters:

offset - byte offset from start of buffer.

b - the byte value to be stored.

Returns:

the next available offset into the buffer, or -1 if the buffer is full.

putInt

public int putInt(int offset,
                  int v)

Description copied from interface: Buffer

Put the 32-bit integer value into the buffer at the specified offset.

Specified by:

putInt in interface Buffer

Parameters:

offset - byte offset from start of buffer.

v - the integer value to be stored.

Returns:

the next available offset into the buffer, or -1 if the buffer is full.

putShort

public int putShort(int offset,
                    short v)

Description copied from interface: Buffer

Put the 16-bit short value into the buffer at the specified offset.

Specified by:

putShort in interface Buffer

Parameters:

offset - byte offset from start of buffer.

v - the short value to be stored.

Returns:

the next available offset into the buffer, or -1 if the buffer is full.

putLong

public int putLong(int offset,
                   long v)

Description copied from interface: Buffer

Put the 64-bit long value into the buffer at the specified offset.

Specified by:

putLong in interface Buffer

Parameters:

offset - byte offset from start of buffer.

v - the long value to be stored.

Returns:

the next available offset into the buffer, or -1 if the buffer is full.

clear

public void clear()

Sets all the values in the buffer to 0;

move

public void move(int src,
                 int dest,
                 int length)

Move the data within this buffer.

Parameters:

src - source offset within this buffer

dest - destination offset within this buffer

length - length of data to be moved

Throws:

java.lang.ArrayIndexOutOfBoundsException - is thrown if parameters result in data access beyond the buffer size.

copy

public void copy(int offset,
                 DataBuffer buf,
                 int bufOffset,
                 int length)

Copy data from another buffer into this buffer.

Parameters:

offset - offset within this buffer.

buf - source buffer

bufOffset - source buffer offset

length - amount of data to copy.

Throws:

java.lang.ArrayIndexOutOfBoundsException - is thrown if parameters result in data access beyond the buffer size.

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

java.lang.ClassNotFoundException