Package db

Class DBBuffer

java.lang.Object

db.DBBuffer

public class DBBuffer
extends java.lang.Object

DBBuffer facilitates synchronized access to a ChainedBuffer.

Method Summary

Modifier and Type	Method	Description
void	append(DBBuffer buffer)	Append the contents of the specified dbBuf onto the end of this buffer.
void	delete()	Delete and release all underlying DataBuffers.
void	fill(int startOffset, int endOffset, byte fillByte)	Fill the buffer over the specified range with a byte value.
void	fill(java.io.InputStream in)	Fill buffer with data provided by InputStream.
void	get(int offset, byte[] data)	Get the byte data located at the specified offset.
void	get(int offset, byte[] data, 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	getByte(int offset)	Get the 8-bit byte value located at the specified offset.
int	getId()	Get the first buffer ID associated with this chained buffer.
int	length()	Returns the length;
void	put(int offset, byte[] bytes)	Put the bytes provided into the buffer at the specified offset.
void	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.
void	putByte(int offset, byte b)	Put the 8-bit byte value into the buffer at the specified offset.
void	setSize(int size, boolean preserveData)	Set the new size for this DBBuffer object.
DBBuffer	split(int offset)	Split this DBBuffer object into two separate DBBuffers.

Methods inherited from class java.lang.Object

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

Method Detail

split

public DBBuffer split(int offset)
               throws java.io.IOException

Split this DBBuffer object into two separate DBBuffers. This DBBuffer remains valid but its new size is equal offset. The newly created DBBuffer is returned.

Parameters:

offset - the split point. The byte at this offset becomes the first byte within the new buffer.

Returns:

the new DBBuffer object.

Throws:

java.lang.ArrayIndexOutOfBoundsException - if offset is invalid.

java.io.IOException - thrown if an IO error occurs

setSize

public void setSize(int size,
                    boolean preserveData)
             throws java.io.IOException

Set the new size for this DBBuffer object.

Parameters:

size - new size

preserveData - if true, existing data is preserved at the original offsets. If false, no additional effort will be expended to preserve data.

Throws:

java.io.IOException - thrown if an IO error occurs.

length

public int length()

Returns the length;

Returns:

getId

public int getId()

Get the first buffer ID associated with this chained buffer. This DBBuffer may be reinstatiated using the returned buffer ID provided subsequent changes are not made.

Returns:

buffer ID

fill

public void fill(int startOffset,
                 int endOffset,
                 byte fillByte)
          throws java.io.IOException

Fill the buffer over the specified range with a byte value.

Parameters:

startOffset - starting offset, inclusive

endOffset - ending offset, exclusive

fillByte - byte value

Throws:

java.io.IOException

append

public void append(DBBuffer buffer)
            throws java.io.IOException

Append the contents of the specified dbBuf onto the end of this buffer. The size of this buffer increases by the size of dbBuf. When the operation is complete, dbBuf object is no longer valid and must not be used.

Parameters:

buffer - the buffer to be appended to this buffer.

Throws:

java.io.IOException - thrown if an IO error occurs

getByte

public byte getByte(int offset)
             throws java.io.IOException

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

Parameters:

offset - byte offset from start of buffer.

Returns:

the byte value at the specified offset.

Throws:

java.lang.ArrayIndexOutOfBoundsException - is thrown if an invalid offset is specified.

java.io.IOException - is thrown if an error occurs while accessing the underlying storage.

get

public void get(int offset,
                byte[] data,
                int dataOffset,
                int length)
         throws java.io.IOException

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

Parameters:

offset - byte offset from the start of the buffer.

data - 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.

java.io.IOException - is thrown if an error occurs while accessing the underlying storage.

fill

public void fill(java.io.InputStream in)
          throws java.io.IOException

Fill buffer with data provided by InputStream. If stream is exhausted, the remainder of the buffer will be filled with 0's.

Parameters:

in - data source

Throws:

java.io.IOException - thrown if IO error occurs.

put

public void put(int offset,
                byte[] bytes,
                int dataOffset,
                int length)
         throws java.io.IOException

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.

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.

Throws:

java.lang.ArrayIndexOutOfBoundsException - if an invalid offset is provided or the end of buffer was encountered while storing the data.

java.io.IOException - is thrown if an error occurs while accessing the underlying storage.

put

public void put(int offset,
                byte[] bytes)
         throws java.io.IOException

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.

Parameters:

offset - byte offset from start of buffer.

bytes - the byte data to be stored.

Throws:

java.lang.ArrayIndexOutOfBoundsException - if an invalid offset is provided or the end of buffer was encountered while storing the data.

java.io.IOException - is thrown if an error occurs while accessing the underlying storage.

putByte

public void putByte(int offset,
                    byte b)
             throws java.io.IOException

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

Parameters:

offset - byte offset from start of buffer.

b - the byte value to be stored.

Throws:

java.lang.ArrayIndexOutOfBoundsException - if an invalid offset is provided.

java.io.IOException - is thrown if an error occurs while accessing the underlying storage.

get

public void get(int offset,
                byte[] data)
         throws java.io.IOException

Get the byte data located at the specified offset.

Parameters:

offset - byte offset from start of buffer.

Throws:

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

java.io.IOException - is thrown if an error occurs while accessing the underlying storage.

delete

public void delete()
            throws java.io.IOException

Delete and release all underlying DataBuffers.

Throws:

java.io.IOException