Class RetainableByteBuffer.DynamicCapacity

java.lang.Object

org.eclipse.jetty.io.Retainable.Wrapper

org.eclipse.jetty.io.RetainableByteBuffer.Abstract

org.eclipse.jetty.io.RetainableByteBuffer.DynamicCapacity

All Implemented Interfaces:

Retainable, RetainableByteBuffer, RetainableByteBuffer.Mutable

Enclosing interface:

RetainableByteBuffer

public static class RetainableByteBuffer.DynamicCapacity
extends RetainableByteBuffer.Abstract
implements RetainableByteBuffer.Mutable

An RetainableByteBuffer.Mutable RetainableByteBuffer that can grow its capacity, backed by a chain of ByteBuffer, which may grow either by aggregation and/or retention. When retaining, a chain of zero copy buffers are kept. When aggregating, this class avoid repetitive copies of the same data during growth by aggregating to a chain of buffers, which are only copied to a single buffer if required. If the minRetainSize is {code 0}, then appending to this buffer will always retain and accumulate. If the minRetainSize is Integer.MAX_VALUE, then appending to this buffer will always aggregate.

Nested Class Summary

Nested classes/interfaces inherited from interface Retainable

Retainable.ReferenceCounter, Retainable.Wrapper

Nested classes/interfaces inherited from interface RetainableByteBuffer

RetainableByteBuffer.Abstract, RetainableByteBuffer.DynamicCapacity, RetainableByteBuffer.EmptyRetainableByteBuffer, RetainableByteBuffer.FixedCapacity, RetainableByteBuffer.Mutable, RetainableByteBuffer.NonRetainableByteBuffer, RetainableByteBuffer.Pooled, RetainableByteBuffer.Wrapper

Field Summary

Fields inherited from interface Retainable

NON_RETAINABLE

Fields inherited from interface RetainableByteBuffer

EMPTY

Constructor Summary

Constructors

Constructor	Description
DynamicCapacity()	A buffer with no size limit and default aggregation and retention settings.
DynamicCapacity(ByteBufferPool pool)
DynamicCapacity(ByteBufferPool.Sized sizedPool)
DynamicCapacity(ByteBufferPool.Sized sizedPool, long maxSize)
DynamicCapacity(ByteBufferPool.Sized sizedPool, long maxSize, int minRetainSize)
DynamicCapacity(ByteBufferPool pool, boolean direct, long maxSize)
DynamicCapacity(ByteBufferPool pool, boolean direct, long maxSize, int aggregationSize)
DynamicCapacity(ByteBufferPool pool, boolean direct, long maxSize, int aggregationSize, int minRetainSize)

Method Summary

Modifier and Type	Method	Description
RetainableByteBuffer.Mutable	add(ByteBuffer bytes)	Add the passed ByteBuffer to this buffer, growing this buffer if necessary and possible.
RetainableByteBuffer.Mutable	add(RetainableByteBuffer bytes)	Add the passed RetainableByteBuffer to this buffer, growing this buffer if necessary and possible.
protected void	addExtraStringInfo(StringBuilder builder)
protected void	addValueMarker(StringBuilder builder, boolean beginning)
protected void	addValueString(StringBuilder builder)
boolean	append(ByteBuffer bytes)	Copies the contents of the given byte buffer to the end of this buffer, growing this buffer if necessary and possible.
boolean	append(RetainableByteBuffer retainableBytes)	Retain or copy the contents of the given retainable byte buffer to the end of this buffer, growing this buffer if necessary and possible.
boolean	appendTo(ByteBuffer to)	Appends and consumes the contents of this buffer to the passed buffer, limited by the capacity of the target buffer.
boolean	appendTo(RetainableByteBuffer to)	Appends and consumes the contents of this buffer to the passed buffer, limited by the capacity of the target buffer.
RetainableByteBuffer.Mutable	asMutable()	Access this buffer via the RetainableByteBuffer.Mutable API.
int	capacity()
void	clear()
RetainableByteBuffer	copy()	Creates a deep copy of this RetainableByteBuffer that is entirely independent
byte	get()	Consumes and returns a byte from this RetainableByteBuffer
int	get(byte[] bytes, int offset, int length)	Consumes and copies the bytes from this RetainableByteBuffer to the given byte array.
byte	get(long index)	Returns a byte from this RetainableByteBuffer at a specific index
int	getAggregationSize()
ByteBuffer	getByteBuffer()	Get the wrapped, not null, ByteBuffer.
long	getMaxSize()
int	getMinRetainSize()
boolean	hasRemaining()
boolean	isDirect()
boolean	isFull()
boolean	isMutable()	Check if the underlying implementation is mutable.
void	limit(long limit)	Limit this buffer's contents to the size.
long	maxSize()
RetainableByteBuffer.Mutable	put(byte b)	Put a byte to the buffer, growing this buffer if necessary and possible.
RetainableByteBuffer.Mutable	put(byte[] bytes, int offset, int length)	Put a byte array to the buffer, growing this buffer if necessary and possible.
RetainableByteBuffer.Mutable	put(long index, byte b)	Put a byte to the buffer at a given index.
RetainableByteBuffer.Mutable	putInt(int i)	Put an int to the buffer, growing this buffer if necessary and possible.
RetainableByteBuffer.Mutable	putLong(long l)	Put a long to the buffer, growing this buffer if necessary and possible.
RetainableByteBuffer.Mutable	putShort(short s)	Put a short to the buffer, growing this buffer if necessary and possible.
void	putTo(ByteBuffer toInfillMode)	Consumes and puts the contents of this retainable byte buffer at the end of the given byte buffer.
boolean	release()	Releases this resource, potentially decrementing a reference count (if any).
int	remaining()
long	size()
long	skip(long length)	Skips, advancing the ByteBuffer position, the given number of bytes.
RetainableByteBuffer.Mutable	slice()	Get a slice of the buffer.
RetainableByteBuffer.Mutable	slice(long length)	Get a partial slice of the buffer.
long	space()
RetainableByteBuffer	take(long length)	Take the contents of this buffer, from the head, leaving remaining bytes in this buffer.
byte[]	takeByteArray()	Take the contents of this buffer, leaving it clear and independent.
RetainableByteBuffer	takeFrom(long skip)	Take the contents of this buffer, from the tail, leaving remaining bytes in this buffer.
void	writeTo(Content.Sink sink, boolean last, Callback callback)	Asynchronously writes and consumes the contents of this retainable byte buffer into the given sink.

Methods inherited from class RetainableByteBuffer.Abstract

addStringInfo, toDetailString, toString

Methods inherited from class Retainable.Wrapper

canRetain, getRetained, getWrapped, isRetained, retain

Methods inherited from class Object

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

Methods inherited from interface Retainable

canRetain, getRetained, isRetained, retain

Methods inherited from interface RetainableByteBuffer

isEmpty, take, toDetailString, writeTo

Methods inherited from interface RetainableByteBuffer.Mutable

put

Constructor Details

DynamicCapacity

public DynamicCapacity()

A buffer with no size limit and default aggregation and retention settings.

DynamicCapacity

public DynamicCapacity(ByteBufferPool.Sized sizedPool)

Parameters:

sizedPool - The pool from which to allocate buffers, with ByteBufferPool.Sized.isDirect() configured and ByteBufferPool.Sized.getSize() used for the size of aggregation buffers.

DynamicCapacity

public DynamicCapacity(ByteBufferPool.Sized sizedPool,
 long maxSize)

Parameters:

sizedPool - The pool from which to allocate buffers, with ByteBufferPool.Sized.isDirect() configured and ByteBufferPool.Sized.getSize() used for the size of aggregation buffers.

maxSize - The maximum length of the accumulated buffers or -1 for 2GB limit

DynamicCapacity

public DynamicCapacity(ByteBufferPool.Sized sizedPool,
 long maxSize,
 int minRetainSize)

Parameters:

sizedPool - The pool from which to allocate buffers, with ByteBufferPool.Sized.isDirect() configured and ByteBufferPool.Sized.getSize() used for the size of aggregation buffers.

maxSize - The maximum length of the accumulated buffers or -1 for 2GB limit

minRetainSize - The minimal size of a RetainableByteBuffer before it will be retained; or 0 to always retain; or -1 for a heuristic;

DynamicCapacity

public DynamicCapacity(ByteBufferPool pool)

Parameters:

pool - The pool from which to allocate buffers

DynamicCapacity

public DynamicCapacity(ByteBufferPool pool,
 boolean direct,
 long maxSize)

Parameters:

pool - The pool from which to allocate buffers

direct - true if direct buffers should be used

maxSize - The maximum length of the accumulated buffers or -1 for 2GB limit

DynamicCapacity

public DynamicCapacity(ByteBufferPool pool,
 boolean direct,
 long maxSize,
 int aggregationSize)

Parameters:

pool - The pool from which to allocate buffers

direct - true if direct buffers should be used

maxSize - The maximum length of the accumulated buffers or -1 for 2GB limit

aggregationSize - The default size of aggregation buffers; or 0 for no aggregation growth; or -1 for a default size. If the aggregationSize is 0 and the maxSize is less that Integer.MAX_VALUE, then a single aggregation buffer may be allocated and the class will behave similarly to RetainableByteBuffer.FixedCapacity.

DynamicCapacity

public DynamicCapacity(ByteBufferPool pool,
 boolean direct,
 long maxSize,
 int aggregationSize,
 int minRetainSize)

Parameters:

pool - The pool from which to allocate buffers

direct - true if direct buffers should be used

maxSize - The maximum length of the accumulated buffers or -1 for 2GB limit

aggregationSize - The default size of aggregation buffers; or 0 for no aggregation growth; or -1 for a default size. If the aggregationSize is 0 and the maxSize is less that Integer.MAX_VALUE, then a single aggregation buffer may be allocated and the class will behave similarly to RetainableByteBuffer.FixedCapacity.

minRetainSize - The minimal size of a RetainableByteBuffer before it will be retained; or 0 to always retain; or -1 for a heuristic;

Method Details

getMaxSize

public long getMaxSize()

getAggregationSize

public int getAggregationSize()

getMinRetainSize

public int getMinRetainSize()

isMutable

public boolean isMutable()

Description copied from interface: RetainableByteBuffer

Check if the underlying implementation is mutable. Note that the immutable RetainableByteBuffer API may be backed by a mutable ByteBuffer or the RetainableByteBuffer.Mutable API may be backed by an immutable ByteBuffer.

Specified by:

isMutable in interface RetainableByteBuffer

Returns:

whether this buffers implementation is mutable

See Also:

• RetainableByteBuffer.asMutable()

asMutable

public RetainableByteBuffer.Mutable asMutable()

Description copied from interface: RetainableByteBuffer

Access this buffer via the RetainableByteBuffer.Mutable API. Note that the RetainableByteBuffer.Mutable API may be backed by an immutable ByteBuffer.

Specified by:

asMutable in interface RetainableByteBuffer

Returns:

An RetainableByteBuffer.Mutable representation of this buffer with same data and pointers.

See Also:

• RetainableByteBuffer.isMutable()

getByteBuffer

public ByteBuffer getByteBuffer()
                         throws BufferOverflowException

Description copied from interface: RetainableByteBuffer

Get the wrapped, not null, ByteBuffer.

If the implementation contains multiple buffers, they are coalesced to a single buffer before being returned. If the content is too large for a single ByteBuffer, then the content should be access with RetainableByteBuffer.writeTo(Content.Sink, boolean).

Specified by:

getByteBuffer in interface RetainableByteBuffer

Returns:

the wrapped, not null, ByteBuffer

Throws:

BufferOverflowException - if the contents is too large for a single ByteBuffer

take

public RetainableByteBuffer take(long length)

Description copied from interface: RetainableByteBuffer

Take the contents of this buffer, from the head, leaving remaining bytes in this buffer. This is similar to RetainableByteBuffer.slice(long) followed by a RetainableByteBuffer.skip(long), but avoids shared data.

Specified by:

take in interface RetainableByteBuffer

Parameters:

length - The number of bytes to take

Returns:

A buffer with the contents of this buffer after limiting bytes, avoiding copies if possible, but with no shared internal buffers.

takeFrom

public RetainableByteBuffer takeFrom(long skip)

Description copied from interface: RetainableByteBuffer

Take the contents of this buffer, from the tail, leaving remaining bytes in this buffer.

Specified by:

takeFrom in interface RetainableByteBuffer

Parameters:

skip - The number of bytes to skip before taking the tail.

Returns:

A buffer with the contents of this buffer after skipping bytes, avoiding copies if possible, but with no shared internal buffers.

takeByteArray

public byte[] takeByteArray()

Description copied from interface: RetainableByteBuffer

Take the contents of this buffer, leaving it clear and independent.

Specified by:

takeByteArray in interface RetainableByteBuffer

Returns:

A possibly newly allocated array with the contents of this buffer, avoiding copies if possible.

get

public byte get()
         throws BufferUnderflowException

Description copied from interface: RetainableByteBuffer

Consumes and returns a byte from this RetainableByteBuffer

Specified by:

get in interface RetainableByteBuffer

Returns:

the byte

Throws:

BufferUnderflowException - if the buffer is empty.

See Also:

• RetainableByteBuffer.get(byte[], int, int)
• RetainableByteBuffer.get(long)

get

public byte get(long index)
         throws IndexOutOfBoundsException

Description copied from interface: RetainableByteBuffer

Returns a byte from this RetainableByteBuffer at a specific index

Specified by:

get in interface RetainableByteBuffer

Parameters:

index - The index relative to the current start of unconsumed data in the buffer.

Returns:

the byte

Throws:

IndexOutOfBoundsException - if the index is too large.

get

public int get(byte[] bytes,
 int offset,
 int length)

Description copied from interface: RetainableByteBuffer

Consumes and copies the bytes from this RetainableByteBuffer to the given byte array.

Specified by:

get in interface RetainableByteBuffer

Parameters:

bytes - the byte array to copy the bytes into

offset - the offset within the byte array

length - the maximum number of bytes to copy

Returns:

the number of bytes actually copied

isDirect

public boolean isDirect()

Specified by:

isDirect in interface RetainableByteBuffer

Returns:

whether the ByteBuffer is direct

hasRemaining

public boolean hasRemaining()

Specified by:

hasRemaining in interface RetainableByteBuffer

Returns:

whether the ByteBuffer has remaining bytes

skip

public long skip(long length)

Description copied from interface: RetainableByteBuffer

Skips, advancing the ByteBuffer position, the given number of bytes.

Specified by:

skip in interface RetainableByteBuffer

Parameters:

length - the maximum number of bytes to skip

Returns:

the number of bytes actually skipped

limit

public void limit(long limit)

Description copied from interface: RetainableByteBuffer

Limit this buffer's contents to the size.

Specified by:

limit in interface RetainableByteBuffer

Parameters:

limit - the new size of the buffer

slice

public RetainableByteBuffer.Mutable slice()

Description copied from interface: RetainableByteBuffer

Get a slice of the buffer.

Specified by:

slice in interface RetainableByteBuffer

Returns:

A sliced RetainableByteBuffer sharing this buffers data and reference count, but with independent position. The buffer is retained by this call.

See Also:

• RetainableByteBuffer.slice(long)

slice

public RetainableByteBuffer.Mutable slice(long length)

Description copied from interface: RetainableByteBuffer

Get a partial slice of the buffer. This is equivalent to RetainableByteBuffer.slice().RetainableByteBuffer.limit(long), but may be implemented more efficiently.

Specified by:

slice in interface RetainableByteBuffer

Parameters:

length - The number of bytes to slice, which may beyond the limit and less than the capacity, in which case it will ensure some spare capacity in the slice.

Returns:

A sliced RetainableByteBuffer sharing the first length bytes of this buffers data and reference count, but with independent position. The buffer is retained by this call.

space

public long space()

Specified by:

space in interface RetainableByteBuffer

Returns:

the number of bytes that can be added, appended or put into this buffer, assuming it is mutable.

isFull

public boolean isFull()

Specified by:

isFull in interface RetainableByteBuffer

Returns:

true if no more bytes can be added, appended or put to this buffer, assuming it is mutable.

copy

public RetainableByteBuffer copy()

Description copied from interface: RetainableByteBuffer

Creates a deep copy of this RetainableByteBuffer that is entirely independent

Specified by:

copy in interface RetainableByteBuffer

Returns:

A copy of this RetainableByteBuffer

remaining

public int remaining()

Specified by:

remaining in interface RetainableByteBuffer

Returns:

Integer.MAX_VALUE if the length of this Accumulator is greater than Integer.MAX_VALUE

See Also:

• RetainableByteBuffer.size()

size

public long size()

Specified by:

size in interface RetainableByteBuffer

Returns:

the number of remaining bytes in the ByteBuffer

See Also:

• RetainableByteBuffer.remaining()

capacity

public int capacity()

Specified by:

capacity in interface RetainableByteBuffer

Returns:

Integer.MAX_VALUE if the maxLength of this Accumulator is greater than Integer.MAX_VALUE.

See Also:

• RetainableByteBuffer.maxSize()

maxSize

public long maxSize()

Specified by:

maxSize in interface RetainableByteBuffer

Returns:

the maximum size in bytes.

See Also:

• RetainableByteBuffer.size()

release

public boolean release()

Description copied from interface: Retainable

Releases this resource, potentially decrementing a reference count (if any).

Specified by:

release in interface Retainable

Overrides:

release in class Retainable.Wrapper

Returns:

true when the reference count goes to zero or if there was no reference count, false otherwise.

clear

public void clear()

Specified by:

clear in interface RetainableByteBuffer

See Also:

• BufferUtil.clear(ByteBuffer)

append

public boolean append(ByteBuffer bytes)

Description copied from interface: RetainableByteBuffer.Mutable

Copies the contents of the given byte buffer to the end of this buffer, growing this buffer if necessary and possible.

Specified by:

append in interface RetainableByteBuffer.Mutable

Parameters:

bytes - the byte buffer to copy from, which is consumed.

Returns:

true if all bytes of the given buffer were copied, false otherwise.

See Also:

• RetainableByteBuffer.Mutable.add(ByteBuffer)

append

public boolean append(RetainableByteBuffer retainableBytes)

Description copied from interface: RetainableByteBuffer.Mutable

Retain or copy the contents of the given retainable byte buffer to the end of this buffer, growing this buffer if necessary and possible. The implementation will heuristically decide to retain or copy the contents Unlike the similar RetainableByteBuffer.Mutable.add(RetainableByteBuffer), implementations of this method must Retainable.retain() the passed buffer if they keep a reference to it.

Specified by:

append in interface RetainableByteBuffer.Mutable

Parameters:

retainableBytes - the retainable byte buffer to copy from, which is consumed.

Returns:

true if all bytes of the given buffer were copied, false otherwise.

See Also:

• RetainableByteBuffer.Mutable.add(RetainableByteBuffer)

add

public RetainableByteBuffer.Mutable add(ByteBuffer bytes)
                                 throws ReadOnlyBufferException,
BufferOverflowException

Description copied from interface: RetainableByteBuffer.Mutable

Add the passed ByteBuffer to this buffer, growing this buffer if necessary and possible. The source ByteBuffer is passed by reference and the caller gives up "ownership", so implementations of this method may choose to avoid copies by keeping a reference to the buffer.

Specified by:

add in interface RetainableByteBuffer.Mutable

Parameters:

bytes - the byte buffer to add, which is passed by reference and is not necessarily consumed by the add.

Returns:

this buffer.

Throws:

ReadOnlyBufferException - if this buffer is read only.

BufferOverflowException - if this buffer cannot fit the byte

See Also:

• RetainableByteBuffer.Mutable.append(ByteBuffer)

add

public RetainableByteBuffer.Mutable add(RetainableByteBuffer bytes)
                                 throws ReadOnlyBufferException,
BufferOverflowException

Description copied from interface: RetainableByteBuffer.Mutable

Add the passed RetainableByteBuffer to this buffer, growing this buffer if necessary and possible. The source RetainableByteBuffer is passed by reference and the caller gives up ownership, so implementations of this method may avoid copies by keeping a reference to the buffer. Unlike the similar RetainableByteBuffer.Mutable.append(RetainableByteBuffer) and contrary to the general rules of Retainable, implementations of this method need not call Retainable.retain() if keeping a reference, but they must ultimately call Retainable.release() the passed buffer. Callers should use add rather than RetainableByteBuffer.Mutable.append(RetainableByteBuffer) if they already have an obligation to release the buffer and wish to delegate that obligation to this buffer.

Specified by:

add in interface RetainableByteBuffer.Mutable

Parameters:

bytes - the byte buffer to add, which is passed by reference and is not necessarily consumed by the add.

Returns:

this buffer.

Throws:

ReadOnlyBufferException - if this buffer is read only.

BufferOverflowException - if this buffer cannot fit the byte

put

public RetainableByteBuffer.Mutable put(byte b)

Description copied from interface: RetainableByteBuffer.Mutable

Put a byte to the buffer, growing this buffer if necessary and possible.

Specified by:

put in interface RetainableByteBuffer.Mutable

Parameters:

b - the byte to put

Returns:

this buffer.

put

public RetainableByteBuffer.Mutable put(long index,
 byte b)

Description copied from interface: RetainableByteBuffer.Mutable

Put a byte to the buffer at a given index.

Specified by:

put in interface RetainableByteBuffer.Mutable

Parameters:

index - The index relative to the current start of unconsumed data in the buffer.

b - the byte to put

Returns:

this buffer.

putShort

public RetainableByteBuffer.Mutable putShort(short s)

Description copied from interface: RetainableByteBuffer.Mutable

Put a short to the buffer, growing this buffer if necessary and possible.

Specified by:

putShort in interface RetainableByteBuffer.Mutable

Parameters:

s - the short to put

Returns:

this buffer.

putInt

public RetainableByteBuffer.Mutable putInt(int i)

Description copied from interface: RetainableByteBuffer.Mutable

Put an int to the buffer, growing this buffer if necessary and possible.

Specified by:

putInt in interface RetainableByteBuffer.Mutable

Parameters:

i - the int to put

Returns:

this buffer.

putLong

public RetainableByteBuffer.Mutable putLong(long l)

Description copied from interface: RetainableByteBuffer.Mutable

Put a long to the buffer, growing this buffer if necessary and possible.

Specified by:

putLong in interface RetainableByteBuffer.Mutable

Parameters:

l - the long to put

Returns:

this buffer.

put

public RetainableByteBuffer.Mutable put(byte[] bytes,
 int offset,
 int length)

Description copied from interface: RetainableByteBuffer.Mutable

Put a byte array to the buffer, growing this buffer if necessary and possible.

Specified by:

put in interface RetainableByteBuffer.Mutable

Parameters:

bytes - the byte array to put

offset - the offset into the array

length - the length in bytes to put

Returns:

this buffer.

appendTo

public boolean appendTo(ByteBuffer to)

Description copied from interface: RetainableByteBuffer

Appends and consumes the contents of this buffer to the passed buffer, limited by the capacity of the target buffer.

Specified by:

appendTo in interface RetainableByteBuffer

Parameters:

to - The buffer to append bytes to, whose limit will be updated.

Returns:

true if all bytes in this buffer are able to be appended.

See Also:

• RetainableByteBuffer.putTo(ByteBuffer)

appendTo

public boolean appendTo(RetainableByteBuffer to)

Description copied from interface: RetainableByteBuffer

Appends and consumes the contents of this buffer to the passed buffer, limited by the capacity of the target buffer.

Specified by:

appendTo in interface RetainableByteBuffer

Parameters:

to - The buffer to append bytes to, whose limit will be updated.

Returns:

true if all bytes in this buffer are able to be appended.

See Also:

• RetainableByteBuffer.putTo(ByteBuffer)

putTo

public void putTo(ByteBuffer toInfillMode)

Description copied from interface: RetainableByteBuffer

Consumes and puts the contents of this retainable byte buffer at the end of the given byte buffer.

Specified by:

putTo in interface RetainableByteBuffer

Parameters:

toInfillMode - the destination buffer, whose position is updated.

See Also:

• ByteBuffer.put(ByteBuffer)

writeTo

public void writeTo(Content.Sink sink,
 boolean last,
 Callback callback)

Description copied from interface: RetainableByteBuffer

Asynchronously writes and consumes the contents of this retainable byte buffer into the given sink.

Specified by:

writeTo in interface RetainableByteBuffer

Parameters:

sink - the destination sink.

last - true if this is the last write.

callback - the callback to call upon the write completion.

See Also:

• Content.Sink.write(boolean, ByteBuffer, Callback)

addExtraStringInfo

protected void addExtraStringInfo(StringBuilder builder)

Overrides:

addExtraStringInfo in class RetainableByteBuffer.Abstract

addValueString

protected void addValueString(StringBuilder builder)

Overrides:

addValueString in class RetainableByteBuffer.Abstract

addValueMarker

protected void addValueMarker(StringBuilder builder,
 boolean beginning)

Overrides:

addValueMarker in class RetainableByteBuffer.Abstract