com.tangosol.io
Class MultiBufferWriteBuffer

java.lang.Object
  com.tangosol.io.AbstractWriteBuffer
      com.tangosol.io.MultiBufferWriteBuffer

All Implemented Interfaces:

WriteBuffer

public class MultiBufferWriteBuffer
extends AbstractWriteBuffer

The MultiBufferWriteBuffer is used to present a single WriteBuffer that collects together a sequence of underlying WriteBuffer objects, and which grows by allocating additional WriteBuffer objects as necessary.

Author:

cp 2006.04.10

Nested Class Summary

class

MultiBufferWriteBuffer.MultiBufferOutput The MultiBufferOutput implementation extends the AbstractBufferOutput to provide "pass through" operations to the underlying buffer if the operation is guaranteed to fit in the underlying buffer; otherwise, it vitualizes the operation onto the MultiBufferWriteBuffer itself so that the over-run of one underlying WriteBuffer will end up being written to the next underlying WriteBuffer.

static interface

MultiBufferWriteBuffer.WriteBufferPool A WriteBufferPool is used to dynamically allocate WriteBuffer objects as the MultiBufferWriteBuffer requires them.

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

MultiBufferWriteBuffer(MultiBufferWriteBuffer.WriteBufferPool bufferpool)
Construct a MultiBufferWriteBuffer that will use the passed WriteBufferPool to allocate WriteBuffer objects from.

Method Summary

protected WriteBuffer	advance() Once the current buffer is full, allocate a new one and make it the current buffer.
protected WriteBuffer	advanceTo(int of) Increase the MultiBufferWriteBuffer length so that the next byte to write is at the specified offset.
Object	clone() Create a clone of this WriteBuffer object.
WriteBuffer	getBuffer(int iBuffer) Obtain the specified buffer.
int	getBufferCount() Determine the number of WriteBuffer objects allocated by this MultiBufferWriteBuffer from the WriteBufferPool.
protected int	getBufferIndexByOffset(int of) Determine which underlying WriteBuffer contains the specified offset.
int	getBufferOffset(int iBuffer) Determine the offset of the specified buffer.
WriteBuffer.BufferOutput	getBufferOutput(int of) Get a BufferOutput object to write data to this buffer starting at a particular offset.
MultiBufferWriteBuffer.WriteBufferPool	getBufferPool() Obtain the factory used to create WriteBuffer objects.
int	getCapacity() Determine the number of bytes that the buffer can hold without resizing itself.
protected WriteBuffer	getCurrentBuffer() Obtain the current buffer.
protected int	getCurrentBufferAbsoluteOffset() Determine the offset of the first byte of the current buffer.
protected int	getCurrentBufferRemaining() Determine the maximum number of bytes that can still be written to the current underlying WriteBuffer.
int	getMaximumCapacity() Determine the maximum number of bytes that the buffer can hold.
ReadBuffer	getUnsafeReadBuffer() Get a ReadBuffer object to read data from this buffer.
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	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, copyStream, getAppendingBufferOutput, getBufferOutput, getReadBuffer, getWriteBuffer, getWriteBuffer, retain, tmpbuf, tmpbuf, toBinary, toByteArray, write, write, write, write

Constructor Detail

MultiBufferWriteBuffer

public MultiBufferWriteBuffer(MultiBufferWriteBuffer.WriteBufferPool bufferpool)

Construct a MultiBufferWriteBuffer that will use the passed WriteBufferPool to allocate WriteBuffer objects from.

Parameters:

bufferpool - a MultiBufferWriteBuffer.WriteBufferPool from which the MultiBufferWriteBuffer will allocate WriteBuffer objects

Method Detail

getBufferPool

public MultiBufferWriteBuffer.WriteBufferPool getBufferPool()

Obtain the factory used to create WriteBuffer objects.

Returns:

the WriteBufferPool used by this MultiBufferWriteBuffer

getBufferCount

public int getBufferCount()

Determine the number of WriteBuffer objects allocated by this MultiBufferWriteBuffer from the WriteBufferPool.

Returns:

the count of WriteBuffer objects allocated

getBufferOffset

public int getBufferOffset(int iBuffer)

Determine the offset of the specified buffer. The offset of a buffer is the absolute offset of the first byte stored in the buffer.

Parameters:

iBuffer - an index 0 <= iBuffer < getBufferCount()

Returns:

the absolute offset of the first byte of the specified WriteBuffer

getBuffer

public WriteBuffer getBuffer(int iBuffer)

Obtain the specified buffer.

Parameters:

iBuffer - an index 0 <= iBuffer < getBufferCount()

Returns:

the specified WriteBuffer

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 AbstractWriteBuffer.length() method will become Math.max(AbstractWriteBuffer.length(), ofDest + cbSrc).

As a result of this method, the buffer capacity as reported by the AbstractWriteBuffer.getCapacity() method will not change if the new value returned by AbstractWriteBuffer.length() would not exceed the old value returned by AbstractWriteBuffer.getCapacity(); otherwise, the capacity will be increased such that AbstractWriteBuffer.getCapacity() >= AbstractWriteBuffer.length(). Regardless, it is always true that AbstractWriteBuffer.getCapacity() >= AbstractWriteBuffer.length() and AbstractWriteBuffer.getMaximumCapacity() >= AbstractWriteBuffer.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

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 AbstractWriteBuffer.length() method will be equal to cb.

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

getMaximumCapacity

public int getMaximumCapacity()

Determine the maximum number of bytes that the buffer can hold. If the maximum size is greater than the current size, then the buffer is expected to resize itself as necessary up to the maximum size in order to contain the data given to it.

Specified by:

getMaximumCapacity in interface WriteBuffer

Overrides:

getMaximumCapacity in class AbstractWriteBuffer

Returns:

the maximum number of bytes of data that the WriteBuffer can hold

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 AbstractWriteBuffer.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

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

clone

public 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

getBufferIndexByOffset

protected int getBufferIndexByOffset(int of)

Determine which underlying WriteBuffer contains the specified offset.

Parameters:

of - an offset into the MultiBufferWriteBuffer, 0 <= of <= length()

Returns:

the index of the WriteBuffer containing the specified offset

advance

protected WriteBuffer advance()

Once the current buffer is full, allocate a new one and make it the current buffer.

Returns:

the new WriteBuffer object

advanceTo

protected WriteBuffer advanceTo(int of)

Increase the MultiBufferWriteBuffer length so that the next byte to write is at the specified offset.

Parameters:

of - the offset to advance to

Returns:

the underlying WriteBuffer containing space for the next byte to write

getCurrentBuffer

protected WriteBuffer getCurrentBuffer()

Obtain the current buffer.

Returns:

the current underlying WriteBuffer

getCurrentBufferAbsoluteOffset

protected int getCurrentBufferAbsoluteOffset()

Determine the offset of the first byte of the current buffer.

Returns:

the offset of the first byte written to the current underlying WriteBuffer

getCurrentBufferRemaining

protected int getCurrentBufferRemaining()

Determine the maximum number of bytes that can still be written to the current underlying WriteBuffer.

Returns:

the number of bytes of capacity that remain on the current underlying WriteBuffer object