Package org.jgrapes.io.util

Class ManagedBuffer<T extends Buffer>

java.lang.Object

org.jgrapes.io.util.ManagedBuffer<T>

public class ManagedBuffer<T extends Buffer>
extends Object

A wrapper around a Buffer that maintains a lock count for that buffer.

All methods known from Buffer are provided and delegate to the backing buffer. Managed buffers can be used to maintain pools of buffers. Buffers are locked when retrieved from the pool and can automatically be returned when the last lock is released.

Newly created managed buffer always have a lock count of 1 (you create them for using them, don’t you).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	ManagedBuffer.ByteBufferView	A read-only view of the managed buffer’s content (backing buffer) and a reference to the managed buffer.
class	ManagedBuffer.CharBufferView	A read-only view of the managed buffer’s content (backing buffer) and a reference to the managed buffer.

Field Summary

Fields

Modifier and Type	Field	Description
protected T	backing
static final ManagedBuffer<ByteBuffer>	EMPTY_BYTE_BUFFER
static final ManagedBuffer<CharBuffer>	EMPTY_CHAR_BUFFER
protected T	savedBacking

Constructor Summary

Constructors

Constructor	Description
ManagedBuffer(T buffer, BufferCollector<ManagedBuffer<T>> manager)	Create a new Managed buffer, backed by the given buffer, with a lock count of one.

Method Summary

Modifier and Type	Method	Description
Object	array()
int	arrayOffset()
T	backingBuffer()	Return the backing buffer.
final int	capacity()
final Buffer	clear()
final T	duplicate()	Duplicate the buffer.
int	fillFromChannel(ReadableByteChannel channel)	Convenience method to fill the buffer from the channel.
final Buffer	flip()
boolean	hasArray()
final boolean	hasRemaining()
boolean	isDirect()
boolean	isReadOnly()
final int	limit()
final Buffer	limit(int newLimit)
ManagedBuffer<T>	linkBackingBuffer(ManagedBuffer<T> buffer)	Links this instance’s backing buffer (temporarily) to the given buffer’s backing buffer.
ManagedBuffer<T>	lockBuffer()	Increases the buffer’s lock count.
BufferCollector<?>	manager()	Return the buffer’s manager.
final Buffer	mark()
ManagedBuffer<T>.ByteBufferView	newByteBufferView()	Creates a new ByteBuffer view.
ManagedBuffer<T>.CharBufferView	newCharBufferView()	Creates a new CharBuffer view.
final int	position()
final Buffer	position(int newPosition)
final int	remaining()
ManagedBuffer<T>	replaceBackingBuffer(T buffer)	Replace the backing buffer.
final Buffer	reset()
final Buffer	rewind()
String	toString()
void	unlockBuffer()	Decreases the buffer’s lock count.
static <B extends Buffer> ManagedBuffer<B>	wrap(B buffer)	Convenience method for creating a ManagedBuffer with a BufferCollector.NOOP_COLLECTOR from a NIO buffer.

Methods inherited from class java.lang.Object

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

Field Details

EMPTY_BYTE_BUFFER

public static final ManagedBuffer<ByteBuffer> EMPTY_BYTE_BUFFER

EMPTY_CHAR_BUFFER

public static final ManagedBuffer<CharBuffer> EMPTY_CHAR_BUFFER

backing

protected T extends Buffer backing

savedBacking

protected T extends Buffer savedBacking

Constructor Details

ManagedBuffer

public ManagedBuffer(T buffer,
 BufferCollector<ManagedBuffer<T>> manager)

Create a new Managed buffer, backed by the given buffer, with a lock count of one.

Parameters:

buffer - the backing buffer

manager - used for restoring the buffer when the lock count reaches zero

Method Details

wrap

public static <B extends Buffer> ManagedBuffer<B> wrap(B buffer)

Convenience method for creating a ManagedBuffer with a BufferCollector.NOOP_COLLECTOR from a NIO buffer.

Effectively, this creates an unmanaged buffer that looks like a managed buffer from an existing NIO buffer that does not belong to any pool.

Type Parameters:

B - the buffer type

Parameters:

buffer - the buffer to wrap

Returns:

the managed buffer

backingBuffer

public T backingBuffer()

Return the backing buffer.

Returns:

the buffer

replaceBackingBuffer

public ManagedBuffer<T> replaceBackingBuffer(T buffer)

Replace the backing buffer.

Parameters:

buffer - the new buffer

Returns:

the managed buffer for easy chaining

linkBackingBuffer

public ManagedBuffer<T> linkBackingBuffer(ManagedBuffer<T> buffer)

Links this instance’s backing buffer (temporarily) to the given buffer’s backing buffer.

Locks the given buffer. The buffer is unlocked again and the original backing buffer restored if this method is called with null or this managed buffer is recollected (i.e. no longer used).

This method may be used to “assign” data that is already available in a buffer to this buffer without copying it over.

Parameters:

buffer - the buffer

Returns:

the managed buffer for easy chaining

manager

public BufferCollector<?> manager()

Return the buffer’s manager.

Returns:

the manager

lockBuffer

public ManagedBuffer<T> lockBuffer()

Increases the buffer’s lock count.

Returns:

the managed buffer for easy chaining

unlockBuffer

public void unlockBuffer()
                  throws IllegalStateException

Decreases the buffer’s lock count.

If the lock count reached zero, the buffer collect’s BufferCollector.recollect(B) method is invoked.

Throws:

IllegalStateException - if the buffer is not locked or has been released already

fillFromChannel

public int fillFromChannel(ReadableByteChannel channel)
                    throws IOException

Convenience method to fill the buffer from the channel.

Unlocks the buffer if an IOException occurs. This method may only be invoked for ManagedBuffers backed by a ByteBuffer.

Parameters:

channel - the channel

Returns:

the bytes read

Throws:

IOException - Signals that an I/O exception has occurred.

toString

public String toString()

Overrides:

toString in class Object

array

public Object array()

Returns:

the backing array

See Also:

• Buffer.array()

arrayOffset

public int arrayOffset()

Returns:

the backing array offset

See Also:

• Buffer.arrayOffset()

capacity

public final int capacity()

Returns:

the capacity

See Also:

• Buffer.capacity()

clear

public final Buffer clear()

Returns:

the buffer

See Also:

• Buffer.clear()

duplicate

public final T duplicate()

Duplicate the buffer.

Returns:

the t

flip

public final Buffer flip()

Returns:

the buffer

See Also:

• Buffer.flip()

hasArray

public boolean hasArray()

Returns:

the result

See Also:

• Buffer.hasArray()

hasRemaining

public final boolean hasRemaining()

Returns:

the result

See Also:

• Buffer.hasRemaining()

isDirect

public boolean isDirect()

Returns:

the result

See Also:

• Buffer.isDirect()

isReadOnly

public boolean isReadOnly()

Returns:

the result

See Also:

• Buffer.isReadOnly()

limit

public final int limit()

Returns:

the result

See Also:

• Buffer.limit()

limit

public final Buffer limit(int newLimit)

Parameters:

newLimit - the new limit

Returns:

the result

See Also:

• Buffer.limit(int)

mark

public final Buffer mark()

Returns:

the buffer

See Also:

• Buffer.mark()

position

public final int position()

Returns:

the result

See Also:

• Buffer.position()

position

public final Buffer position(int newPosition)

Parameters:

newPosition - the new position

Returns:

the buffer

See Also:

• Buffer.position(int)

remaining

public final int remaining()

Returns:

the result

See Also:

• Buffer.remaining()

reset

public final Buffer reset()

Returns:

the Buffer

See Also:

• Buffer.reset()

rewind

public final Buffer rewind()

Returns:

the Buffer

See Also:

• Buffer.rewind()

newByteBufferView

public ManagedBuffer<T>.ByteBufferView newByteBufferView()

Creates a new ByteBuffer view.

Returns:

the byte buffer view

newCharBufferView

public ManagedBuffer<T>.CharBufferView newCharBufferView()

Creates a new CharBuffer view.

Returns:

the byte buffer view