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com.tangosol.io.nio
Class ByteBufferWriteBuffer

java.lang.Object
com.tangosol.io.AbstractWriteBuffer
com.tangosol.io.nio.ByteBufferWriteBuffer

All Implemented Interfaces:

WriteBuffer

public final class ByteBufferWriteBuffer

extends AbstractWriteBuffer

implements WriteBuffer

A WriteBuffer implementation on top of a Java NIO ByteBuffer.

Author:

cp 2006.04.05

Nested Class Summary

class

ByteBufferWriteBuffer.ByteBufferOutput This is a simple implementation of the BufferOutput interface on top of a ByteBuffer.

Nested classes/interfaces inherited from class com.tangosol.io.AbstractWriteBuffer

AbstractWriteBuffer.AbstractBufferOutput

Nested classes/interfaces inherited from interface com.tangosol.io.WriteBuffer

WriteBuffer.BufferOutput

Field Summary

Fields inherited from class com.tangosol.io.AbstractWriteBuffer

CHAR_BUF_MASK, CHAR_BUF_SIZE, m_achBuf, NO_BINARY, NO_BYTES

Constructor Summary

	ByteBufferWriteBuffer(java.nio.ByteBuffer buf) Construct a ByteBufferWriteBuffer on an NIO ByteBuffer.
protected	ByteBufferWriteBuffer(ByteBufferWriteBuffer that) Perform a shallow clone of the supplied ByteBufferWriteBuffer.

Method Summary

java.lang.Object	clone() Create a clone of this WriteBuffer object.
WriteBuffer.BufferOutput	getBufferOutput(int of) Get a BufferOutput object to write data to this buffer starting at a particular offset.
java.nio.ByteBuffer	getByteBuffer() Obtain the ByteBuffer that this WriteBuffer is based on.
int	getCapacity() Determine the number of bytes that the buffer can hold without resizing itself.
ReadBuffer	getReadBuffer() Get a ReadBuffer object that is a snapshot of this WriteBuffer's data.
ReadBuffer	getUnsafeReadBuffer() Get a ReadBuffer object to read data from this buffer.
ByteBufferWriteBuffer	getUnsafeWriteBuffer() Create a "shallow clone" of the ByteBufferWriteBuffer that uses the same underlying memory but through a different (a duplicate) ByteBuffer.
int	length() Determine the length of the data that is in the buffer.
void	retain(int of, int cb) Starting with the byte at offset of, retain cb bytes in this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset of + cb - 1, which is shifted to offset cb - 1.
void	setLength(int cb) Reconfigure the length of the buffer.
Binary	toBinary() Returns a new Binary object that holds the complete contents of this WriteBuffer.
byte[]	toByteArray() Returns a new byte array that holds the complete contents of this WriteBuffer.
void	write(int ofDest, byte b) Store the specified byte at the specified offset within the buffer.
void	write(int ofDest, byte[] abSrc, int ofSrc, int cbSrc) Store the specified number of bytes from the specified location within the passed byte array at the specified offset within this buffer.
void	write(int ofDest, ReadBuffer bufSrc, int ofSrc, int cbSrc) Store the specified portion of the contents of the specified ReadBuffer at the specified offset within this buffer.

Methods inherited from class com.tangosol.io.AbstractWriteBuffer

clear, copyBufferInputPortion, copyBufferInputRemainder, copyStream, getAppendingBufferOutput, getBufferOutput, getMaximumCapacity, getWriteBuffer, getWriteBuffer, releaseBuffers, retain, tmpbuf, tmpbuf, write, write, write, write

Methods inherited from interface com.tangosol.io.WriteBuffer

clear, getAppendingBufferOutput, getBufferOutput, getMaximumCapacity, getWriteBuffer, getWriteBuffer, retain, write, write, write, write

Constructor Detail

ByteBufferWriteBuffer

public ByteBufferWriteBuffer(java.nio.ByteBuffer buf)

Construct a ByteBufferWriteBuffer on an NIO ByteBuffer.

Parameters:

buf - the underlying NIO ByteBuffer

ByteBufferWriteBuffer

protected ByteBufferWriteBuffer(ByteBufferWriteBuffer that)

Perform a shallow clone of the supplied ByteBufferWriteBuffer.

Parameters:

that - the buffer to shallow clone

Method Detail

getByteBuffer

public java.nio.ByteBuffer getByteBuffer()

Obtain the ByteBuffer that this WriteBuffer is based on.

Returns:

the underlying ByteBuffer

write

public void write(int ofDest,
                  byte b)

Store the specified byte at the specified offset within the buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:

 byte[] abSrc = new byte[1];
 abSrc[0] = b;
 write(ofDest, abSrc, 0, abSrc.length);
 

Specified by:

write in interface WriteBuffer

Specified by:

write in class AbstractWriteBuffer

Parameters:

ofDest - the offset within this buffer to store the passed data

b - the byte to store in this buffer

write

public void write(int ofDest,
                  byte[] abSrc,
                  int ofSrc,
                  int cbSrc)

Store the specified number of bytes from the specified location within the passed byte array at the specified offset within this buffer.

As a result of this method, the buffer length as reported by the WriteBuffer.length() method will become Math.max(WriteBuffer.length(), ofDest + cbSrc).

As a result of this method, the buffer capacity as reported by the WriteBuffer.getCapacity() method will not change if the new value returned by WriteBuffer.length() would not exceed the old value returned by WriteBuffer.getCapacity(); otherwise, the capacity will be increased such that WriteBuffer.getCapacity() >= WriteBuffer.length(). Regardless, it is always true that WriteBuffer.getCapacity() >= WriteBuffer.length() and WriteBuffer.getMaximumCapacity() >= WriteBuffer.getCapacity(). If the buffer capacity cannot be increased due to resource constraints, an undesignated Error or RuntimeException will be thrown, such as OutOfMemoryError.

Specified by:

write in interface WriteBuffer

Specified by:

write in class AbstractWriteBuffer

Parameters:

ofDest - the offset within this buffer to store the passed data

abSrc - the array containing the bytes to store in this buffer

ofSrc - the offset within the passed byte array to copy from

cbSrc - the number of bytes to copy from the passed byte array

write

public void write(int ofDest,
                  ReadBuffer bufSrc,
                  int ofSrc,
                  int cbSrc)

Store the specified portion of the contents of the specified ReadBuffer at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:

 byte[] abSrc = bufSrc.toByteArray(ofSrc, cbSrc);
 write(ofDest, abSrc, 0, abSrc.length);
 

Specified by:

write in interface WriteBuffer

Overrides:

write in class AbstractWriteBuffer

Parameters:

ofDest - the offset within this buffer to store the passed data

bufSrc - the array of bytes to store in this buffer

ofSrc - the offset within the passed ReadBuffer to copy from

cbSrc - the number of bytes to copy from the passed ReadBuffer

length

public int length()

Determine the length of the data that is in the buffer. This is the actual number of bytes of data that have been written to the buffer, not the capacity of the buffer.

Specified by:

length in interface WriteBuffer

Specified by:

length in class AbstractWriteBuffer

Returns:

the number of bytes of data represented by this WriteBuffer

setLength

public void setLength(int cb)

Reconfigure the length of the buffer. The length must not be longer than the available capacity.

Parameters:

cb - the new length of the buffer

retain

public void retain(int of,
                   int cb)

Starting with the byte at offset of, retain cb bytes in this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset of + cb - 1, which is shifted to offset cb - 1. After this method, the length of the buffer as indicated by the WriteBuffer.length() method will be equal to cb.

Legal values for the offset of the first byte to retain of are (of >= 0 && of <= WriteBuffer.length()). Legal values for the number of bytes to retain cb are (cb >= 0 && cb <= WriteBuffer.length()), such that (of + cb <= WriteBuffer.length()).

If cb is zero, then this method will have the same effect as clear. If of is zero, then this method will have the effect of truncating the data in the buffer, but no bytes will be shifted within the buffer.

The effect on the capacity of the buffer is implementation-specific; some implementations are expected to retain the same capacity while others are expected to shrink accordingly.

Specified by:

retain in interface WriteBuffer

Specified by:

retain in class AbstractWriteBuffer

Parameters:

of - the offset of the first byte within the WriteBuffer that will be retained

cb - the number of bytes to retain

getCapacity

public int getCapacity()

Determine the number of bytes that the buffer can hold without resizing itself. In other words, a WriteBuffer has getCapacity() - WriteBuffer.length() bytes that can be written to it without overflowing the current underlying buffer allocation. Since the buffer is an abstract concept, the actual mechanism for the underlying buffer is not known, but it could be a Java NIO buffer, or a byte array, etc.

Note that if the maximum size returned by WriteBuffer.getMaximumCapacity() is greater than the current size returned by this method, then the WriteBuffer will automatically resize itself to allocate more space when the amount of data written to it passes the current size.

Specified by:

getCapacity in interface WriteBuffer

Specified by:

getCapacity in class AbstractWriteBuffer

Returns:

the number of bytes of data that this WriteBuffer can hold without resizing its underlying buffer

getBufferOutput

public WriteBuffer.BufferOutput getBufferOutput(int of)

Get a BufferOutput object to write data to this buffer starting at a particular offset.

Note that each call to this method will return a new BufferOutput object, with the possible exception being that a zero-length non-resizing WriteBuffer could always return the same instance (since it is not writable).

This is functionally equivalent to:

 BufferOutput bufout = getBufferOutput();
 bufout.setOffset(of);
 return bufout;
 

Specified by:

getBufferOutput in interface WriteBuffer

Overrides:

getBufferOutput in class AbstractWriteBuffer

Parameters:

of - the offset of the first byte of this buffer that the BufferOutput will write to

Returns:

a BufferOutput that will write to this buffer

getReadBuffer

public ReadBuffer getReadBuffer()

Get a ReadBuffer object that is a snapshot of this WriteBuffer's data.

This method is functionally equivalent to the following code:

 ReadBuffer buf = getUnsafeReadBuffer();
 byte[] ab = buf.toByteArray();
 return new ByteArrayReadBuffer(ab);
 

Specified by:

getReadBuffer in interface WriteBuffer

Overrides:

getReadBuffer in class AbstractWriteBuffer

Returns:

a ReadBuffer that reflects the point-in-time contents of this WriteBuffer

getUnsafeReadBuffer

public ReadBuffer getUnsafeReadBuffer()

Get a ReadBuffer object to read data from this buffer. This method is not guaranteed to return a snapshot of this buffer's data, nor is it guaranteed to return a live view of this buffer, which means that subsequent changes to this WriteBuffer may or may not affect the contents and / or the length of the returned ReadBuffer.

To get a snapshot, use the WriteBuffer.getReadBuffer() method.

Specified by:

getUnsafeReadBuffer in interface WriteBuffer

Specified by:

getUnsafeReadBuffer in class AbstractWriteBuffer

Returns:

a ReadBuffer that reflects the contents of this WriteBuffer but whose behavior is undefined if the WriteBuffer is modified

toByteArray

public byte[] toByteArray()

Returns a new byte array that holds the complete contents of this WriteBuffer.

This method is functionally equivalent to the following code:

 return getUnsafeReadBuffer().toByteArray();
 

Specified by:

toByteArray in interface WriteBuffer

Overrides:

toByteArray in class AbstractWriteBuffer

Returns:

the contents of this WriteBuffer as a byte[]

toBinary

public Binary toBinary()

Returns a new Binary object that holds the complete contents of this WriteBuffer.

This method is functionally equivalent to the following code:

 return getUnsafeReadBuffer().toBinary();
 

Specified by:

toBinary in interface WriteBuffer

Overrides:

toBinary in class AbstractWriteBuffer

Returns:

the contents of this WriteBuffer as a Binary object

clone

public java.lang.Object clone()

Create a clone of this WriteBuffer object. Changes to the clone will not affect the original, and vice-versa.

Specified by:

clone in interface WriteBuffer

Overrides:

clone in class AbstractWriteBuffer

Returns:

a WriteBuffer object with the same contents as this WriteBuffer object

getUnsafeWriteBuffer

public ByteBufferWriteBuffer getUnsafeWriteBuffer()

Create a "shallow clone" of the ByteBufferWriteBuffer that uses the same underlying memory but through a different (a duplicate) ByteBuffer. This method is primarily intended to allow multiple threads to be able to write to the same block of NIO memory, by creating shallow clones of the ByteBufferWriteBuffer, one for each thread, since the ByteBuffer itself is not thread safe.

Returns:

a ByteBufferWriteBuffer that shares the same underlying memory, but does not share the same NIO ByteBuffer

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