Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.impl.io.vfmem.BlockedByteArray

Field Summary

Modifier and Type	Field and Description
private static final int	_16K Constant for 16 KB.
private static final int	_32K Constant for 32 KB.
private static final int	_4K Constant for 4 KB.
private static final int	_8K Constant for 8 KB.
private int	allocatedBlocks The number of allocated blocks.
private byte[][]	blocks References to blocks of data.
private int	blockSize The size of a block of data (the allocation unit).
private static final int	DEFAULT_BLOCKSIZE The default block size.
private static final int	INITIAL_BLOCK_HOLDER_SIZE The default number of slots for holding a block of data.
private long	length The number of bytes stored in the blocked byte array.
private static final int	MIN_HOLDER_GROWTH Minimum number of holder slots to grow with when the block holder array has to grow to be able to reference all the data arrays.

Constructor Summary

Access	Constructor and Description
public	BlockedByteArray() Creates a new blocked byte array with the default number of slots to hold byte arrays (blocks).

Method Summary

Modifier and Type	Method and Description
private void	checkBlockSize(int the requested number of bytes to be written len) Tries to optimize the block size by setting it equal to the the page size used by the database.
pack-priv synchronized BlockedByteArrayInputStream	Returns: An `InputStream`-object. getInputStream() Returns an input stream serving the data in the blocked byte array.
pack-priv synchronized BlockedByteArrayOutputStream	Returns: An `OutputStream`-object. getOutputStream(long initial position of the output stream pos) Returns an output stream writing data into the blocked byte array.
private void	increaseCapacity(long the index that must fit into the array lastIndex) Increases the capacity of this blocked byte array by allocating more blocks.
public synchronized long	Returns: Bytes allocated. length() Returns the number of bytes allocated.
public synchronized int	Returns: A single byte. read(long position to read from pos) Returns the byte at the given position.
public synchronized int	Returns: The number of bytes read. read(long the position to start reading at pos, byte[] the destination buffer buf, int offset into the destination buffer offset, int the number of bytes to read len) Reads up to `len` bytes.
pack-priv synchronized void	release() Releases this array.
public synchronized void	setLength(final long the new length of the allocated data in bytes newLength) Changes the allocated length of the data.
public synchronized int	Returns: `1`, which is the number of bytes written. writeByte(long the position to write the byte at pos, byte the byte to write b) Writes the given byte into the blocked byte array.
public synchronized int	Returns: The number of bytes written. writeBytes(final long the position to start writing at pos, final byte[] the source buffer buf, int the offset into the source buffer offset, final int the number of bytes to write len) Writes the given bytes into the blocked byte array.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

_16K	back to summary
private static final int _16K Constant for 16 KB.

_32K	back to summary
private static final int _32K Constant for 32 KB.

_4K	back to summary
private static final int _4K Constant for 4 KB.

_8K	back to summary
private static final int _8K Constant for 8 KB.

allocatedBlocks	back to summary
private int allocatedBlocks The number of allocated blocks.

blocks	back to summary
private byte[][] blocks References to blocks of data.

blockSize	back to summary
private int blockSize The size of a block of data (the allocation unit).

DEFAULT_BLOCKSIZE	back to summary
private static final int DEFAULT_BLOCKSIZE The default block size.

INITIAL_BLOCK_HOLDER_SIZE	back to summary
private static final int INITIAL_BLOCK_HOLDER_SIZE The default number of slots for holding a block of data.

length	back to summary
private long length The number of bytes stored in the blocked byte array.

MIN_HOLDER_GROWTH	back to summary
private static final int MIN_HOLDER_GROWTH Minimum number of holder slots to grow with when the block holder array has to grow to be able to reference all the data arrays.

Constructor Detail

BlockedByteArray back to summary

BlockedByteArray	back to summary
public BlockedByteArray() Creates a new blocked byte array with the default number of slots to hold byte arrays (blocks). No blocks are pre-allocated. See Also `INITIAL_BLOCK_HOLDER_SIZE`

public BlockedByteArray()

Creates a new blocked byte array with the default number of slots to hold byte arrays (blocks).

No blocks are pre-allocated.

See Also: INITIAL_BLOCK_HOLDER_SIZE

Method Detail

checkBlockSize	back to summary
private void checkBlockSize(int len) Tries to optimize the block size by setting it equal to the the page size used by the database. Since we don't have a way of knowing which page size will be used, wait to set the block size until the first write request and see how many bytes are written then. Parameters len:int the requested number of bytes to be written

checkBlockSize

back to summary

private void checkBlockSize(int len)

Tries to optimize the block size by setting it equal to the the page size used by the database.

Since we don't have a way of knowing which page size will be used, wait to set the block size until the first write request and see how many bytes are written then.

Parameters

len:int: the requested number of bytes to be written

getInputStream back to summary

getInputStream	back to summary
pack-priv synchronized BlockedByteArrayInputStream getInputStream() Returns an input stream serving the data in the blocked byte array. Returns:BlockedByteArrayInputStream An `InputStream`-object.

pack-priv synchronized BlockedByteArrayInputStream getInputStream()

Returns an input stream serving the data in the blocked byte array.

Returns:BlockedByteArrayInputStream: An InputStream-object.

getOutputStream back to summary

getOutputStream	back to summary
pack-priv synchronized BlockedByteArrayOutputStream getOutputStream(long pos) Returns an output stream writing data into the blocked byte array. Parameters pos:long initial position of the output stream Returns:BlockedByteArrayOutputStream An `OutputStream`-object.

pack-priv synchronized BlockedByteArrayOutputStream getOutputStream(long pos)

Returns an output stream writing data into the blocked byte array.

Parameters

pos:long: initial position of the output stream

Returns:BlockedByteArrayOutputStream

An OutputStream-object.

increaseCapacity	back to summary
private void increaseCapacity(long lastIndex) Increases the capacity of this blocked byte array by allocating more blocks. Parameters lastIndex:long the index that must fit into the array

increaseCapacity

back to summary

private void increaseCapacity(long lastIndex)

Increases the capacity of this blocked byte array by allocating more blocks.

Parameters

lastIndex:long: the index that must fit into the array

length	back to summary
public synchronized long length() Returns the number of bytes allocated. Returns:long Bytes allocated.

length

back to summary

public synchronized long length()

Returns the number of bytes allocated.

Returns:long: Bytes allocated.

read	back to summary
public synchronized int read(long pos) Returns the byte at the given position. Parameters pos:long position to read from Returns:int A single byte.

read

back to summary

public synchronized int read(long pos)

Returns the byte at the given position.

Parameters

pos:long: position to read from

Returns:int

A single byte.

read back to summary

read	back to summary
public synchronized int read(long pos, byte[] buf, int offset, int len) Reads up to `len` bytes. Parameters pos:long the position to start reading at buf:byte[] the destination buffer offset:int offset into the destination buffer len:int the number of bytes to read Returns:int The number of bytes read.

public synchronized int read(long pos, byte[] buf, int offset, int len)

Reads up to len bytes.

Parameters

pos:long: the position to start reading at
buf:byte[]: the destination buffer
offset:int: offset into the destination buffer
len:int: the number of bytes to read

Returns:int

The number of bytes read.

release	back to summary
pack-priv synchronized void release() Releases this array.

setLength	back to summary
public synchronized void setLength(final long newLength) Changes the allocated length of the data. If the new length is larger than the current length, the blocked byte array will be extended with new blocks. If the new length is smaller, existing (allocated) blocks will be removed if possible. Parameters newLength:long the new length of the allocated data in bytes

setLength

back to summary

public synchronized void setLength(final long newLength)

Changes the allocated length of the data.

If the new length is larger than the current length, the blocked byte array will be extended with new blocks. If the new length is smaller, existing (allocated) blocks will be removed if possible.

Parameters

newLength:long: the new length of the allocated data in bytes

writeByte back to summary

writeByte	back to summary
public synchronized int writeByte(long pos, byte b) Writes the given byte into the blocked byte array. Parameters pos:long the position to write the byte at b:byte the byte to write Returns:int `1`, which is the number of bytes written.

public synchronized int writeByte(long pos, byte b)

Writes the given byte into the blocked byte array.

Parameters

pos:long: the position to write the byte at
b:byte: the byte to write

Returns:int

1, which is the number of bytes written.

writeBytes	back to summary
public synchronized int writeBytes(final long pos, final byte[] buf, int offset, final int len) Writes the given bytes into the blocked byte array. Parameters pos:long the position to start writing at buf:byte[] the source buffer offset:int the offset into the source buffer len:int the number of bytes to write Returns:int The number of bytes written.

writeBytes

back to summary

public synchronized int writeBytes(final long pos, final byte[] buf, int offset, final int len)

Writes the given bytes into the blocked byte array.

Parameters

pos:long: the position to start writing at
buf:byte[]: the source buffer
offset:int: the offset into the source buffer
len:int: the number of bytes to write

Returns:int

The number of bytes written.

public Class BlockedByteArray

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail