Class MemByteHolder

java.lang.Object

org.apache.derby.impl.store.raw.data.MemByteHolder

All Implemented Interfaces:

ByteHolder

public class MemByteHolder
extends Object
implements ByteHolder

A ByteHolder that stores all its bytes in memory.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) int	bufSize
(package private) Vector<byte[]>	bufV
(package private) byte[]	curBuf
(package private) int	curBufDataBytes
(package private) int	curBufPos
(package private) int	curBufVEleAt
(package private) int	lastBufDataBytes
(package private) int	lastBufVEleAt
(package private) boolean	writing

Constructor Summary

Constructors

Constructor	Description
MemByteHolder(int bufSize)	Create a new MemByteHolder.

Method Summary

Modifier and Type	Method	Description
int	available()	Return the number of bytes that can be read from this ByteHolder without blocking on an IO.
void	clear()	Clear the bytes from the ByteHolder and place it in writing mode.
ByteHolder	cloneEmpty()	Return a byte holder matching existing type and size of current ByteHolder, but don't bother to fill the bytes.
private String	dumpBuf(int bufVEleAt)	Create a string representation of an internal buffer of bytes.
protected boolean	getNextBuffer_r()	Get the next buffer for reading bytes.
protected void	getNextBuffer_w()	Get the next buffer for writing bytes.
protected void	getNextBuffer_w_Sanity()	Do sanity checking when getting the next write buffer
protected void	initBuffer_w()	Initialize a buffer for writing
int	numBytesSaved()	Return the number of bytes that have been saved to this byte holder.
int	read()	Read a byte from this ByteHolder.
int	read(byte[] b, int off, int len)	Read up to 'len' bytes from this ByteHolder and store them in an array at offset 'off'.
int	read(byte[] b, int off, OutputStream out, int len)
int	read(OutputStream out, int len)	Read from the ByteHolder.
int	shiftToFront()	shift the remaining unread bytes to the beginning of the byte holder
long	skip(long count)	Skip over the specified number of bytes in a ByteHolder.
void	startReading()	Place a ByteHolder in reading mode.
String	toString()	Produce a string describing the state of this ByteHolder.
void	write(byte[] data, int offset, int len)	Write len bytes of data starting at 'offset' to this ByteHolder.
void	write(int b)	Write a byte to this ByteHolder.
long	write(InputStream is, long count)	Write up to count bytes from an input stream to this ByteHolder.
boolean	writingMode()	Return true if this is in writing mode.

Methods inherited from class Object

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

Field Details

bufSize

int bufSize

writing

boolean writing

bufV

Vector<byte[]> bufV

curBufVEleAt

int curBufVEleAt

curBuf

byte[] curBuf

curBufPos

int curBufPos

curBufDataBytes

int curBufDataBytes

lastBufVEleAt

int lastBufVEleAt

lastBufDataBytes

int lastBufDataBytes

Constructor Details

MemByteHolder

public MemByteHolder(int bufSize)

Create a new MemByteHolder. Store bytes as a list of buffers of size 'bufSize'.

Method Details

write

public void write(int b)
           throws IOException

Description copied from interface: ByteHolder

Write a byte to this ByteHolder.

The ByteHolder must be in writing mode to call this.

Specified by:

write in interface ByteHolder

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.write(int)

write

public void write(byte[] data,
 int offset,
 int len)
           throws IOException

Description copied from interface: ByteHolder

Write len bytes of data starting at 'offset' to this ByteHolder.

The ByteHolder must be in writing mode to call this.

Specified by:

write in interface ByteHolder

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.write(int)

write

public long write(InputStream is,
 long count)
           throws IOException

Description copied from interface: ByteHolder

Write up to count bytes from an input stream to this ByteHolder. This may write fewer bytes if it encounters an end of file on the input stream.

Specified by:

write in interface ByteHolder

Returns:

the number of bytes written.

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.write(int)

clear

public void clear()
           throws IOException

Description copied from interface: ByteHolder

Clear the bytes from the ByteHolder and place it in writing mode. This may not free the memory the ByteHolder uses to store data.

Specified by:

clear in interface ByteHolder

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.clear()

startReading

public void startReading()
                  throws IOException

Description copied from interface: ByteHolder

Place a ByteHolder in reading mode. After this call, reads scan bytes sequentially in the order they were written to the ByteHolder starting from the first byte. When the ByteHolder is already in readmode this simply arranges for reads to start at the beginning of the sequence of saved bytes.

Specified by:

startReading in interface ByteHolder

Throws:

IOException

See Also:

• ByteHolder.startReading()

read

public int read()
         throws IOException

Description copied from interface: ByteHolder

Read a byte from this ByteHolder.

The ByteHolder must be in reading mode to call this.

Specified by:

read in interface ByteHolder

Returns:

The byte or -1 if there are no bytes available.

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.read()

read

public int read(byte[] b,
 int off,
 int len)
         throws IOException

Description copied from interface: ByteHolder

Read up to 'len' bytes from this ByteHolder and store them in an array at offset 'off'.

The ByteHolder must be in reading mode to call this.

Specified by:

read in interface ByteHolder

Returns:

the number of bytes read or -1 if the this ByteHolder has no more bytes.

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.read()

read

public int read(OutputStream out,
 int len)
         throws IOException

Description copied from interface: ByteHolder

Read from the ByteHolder.

Read up to 'len' bytes from this ByteHolder and write them to the OutputStream

The ByteHolder must be in reading mode to call this.

Specified by:

read in interface ByteHolder

Returns:

the number of bytes read or -1 if the this ByteHolder has no more bytes.

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.read()

read

public int read(byte[] b,
 int off,
 OutputStream out,
 int len)
         throws IOException

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.read()

shiftToFront

public int shiftToFront()
                 throws IOException

Description copied from interface: ByteHolder

shift the remaining unread bytes to the beginning of the byte holder

Specified by:

shiftToFront in interface ByteHolder

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.shiftToFront()

available

public int available()

Description copied from interface: ByteHolder

Return the number of bytes that can be read from this ByteHolder without blocking on an IO.

Specified by:

available in interface ByteHolder

See Also:

• ByteHolder.available()

numBytesSaved

public int numBytesSaved()

Return the number of bytes that have been saved to this byte holder. This result is different from available() as it is unaffected by the current read position on the ByteHolder.

Specified by:

numBytesSaved in interface ByteHolder

See Also:

• ByteHolder.numBytesSaved()

skip

public long skip(long count)
          throws IOException

Description copied from interface: ByteHolder

Skip over the specified number of bytes in a ByteHolder.

Specified by:

skip in interface ByteHolder

Throws:

IOException - Thrown on error

See Also:

• ByteHolder.skip(long)

writingMode

public boolean writingMode()

Description copied from interface: ByteHolder

Return true if this is in writing mode.

Specified by:

writingMode in interface ByteHolder

See Also:

• ByteHolder.writingMode()

cloneEmpty

public ByteHolder cloneEmpty()

Description copied from interface: ByteHolder

Return a byte holder matching existing type and size of current ByteHolder, but don't bother to fill the bytes. Normal usage is expected to reset the holding stream to the beginning, so the copy of current state would be wasted.

Specified by:

cloneEmpty in interface ByteHolder

Returns:

An empty ByteHolder.

See Also:

• ByteHolder.cloneEmpty()

getNextBuffer_w

protected void getNextBuffer_w()
                        throws IOException

Get the next buffer for writing bytes.

Throws:

IOException - Thrown on error

getNextBuffer_w_Sanity

protected void getNextBuffer_w_Sanity()

Do sanity checking when getting the next write buffer

initBuffer_w

protected void initBuffer_w()

Initialize a buffer for writing

getNextBuffer_r

protected boolean getNextBuffer_r()
                           throws IOException

Get the next buffer for reading bytes.

Returns:

true if the user has read all the bytes in this ByteHolder.

Throws:

IOException - Thrown on error

dumpBuf

private String dumpBuf(int bufVEleAt)

Create a string representation of an internal buffer of bytes. This is useful during debugging.

toString

public String toString()

Produce a string describing the state of this ByteHolder. This is mainly for debugging.

Overrides:

toString in class Object