com.gemstone.gemfire.internal.shared

Class ByteBufferReference

java.lang.Object

com.gemstone.gemfire.internal.shared.ByteBufferReference

public abstract class ByteBufferReference
extends java.lang.Object

Base class for explicit reference counted ByteBuffers.

Constructor Summary

Constructors

Constructor and Description
ByteBufferReference()

Method Summary

Modifier and Type	Method and Description
abstract java.nio.ByteBuffer	getBuffer() Return the data as a ByteBuffer.
abstract java.nio.ByteBuffer	getBufferRetain() Return the data as a ByteBuffer after applying a retain().
abstract ByteBufferReference	getValueRetain(FetchRequest fetchRequest) Get a compressed/decompressed/original version of the underlying value after a retain()
abstract boolean	needsRelease() Returns true if explicit calls to release() are required for this object to be eagerly released else they can be skipped (e.g.
abstract int	referenceCount() Get the current reference count for this object.
abstract void	release() An optional explicit release of the underlying data.
abstract boolean	retain() Explicitly mark the buffer to be retained so it is not released until a corresponding release() has been invoked.
abstract int	size() Size of the underlying data.

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteBufferReference

public ByteBufferReference()

Method Detail

referenceCount

public abstract int referenceCount()

Get the current reference count for this object.

retain

public abstract boolean retain()

Explicitly mark the buffer to be retained so it is not released until a corresponding release() has been invoked.

Returns:

True if the retain was on a valid buffer else false if the underlying data has already been released (and will lead to empty writes).

getBufferRetain

public abstract java.nio.ByteBuffer getBufferRetain()

Return the data as a ByteBuffer after applying a retain(). Callers should preferably invoke release() explicitly for eager release of the buffer (if it is direct).

getBuffer

public abstract java.nio.ByteBuffer getBuffer()

Return the data as a ByteBuffer. Should be invoked only after a retain() or getValueRetain(com.gemstone.gemfire.internal.shared.FetchRequest) call.

getValueRetain

public abstract ByteBufferReference getValueRetain(FetchRequest fetchRequest)

Get a compressed/decompressed/original version of the underlying value after a retain()

Parameters:

fetchRequest - one of the FetchRequest values

Returns:

possibly transformed data as per @FetchRequest

release

public abstract void release()

An optional explicit release of the underlying data. The buffer may no longer be usable after this call and return empty data.

NOTE: Implementations should never require this call to be invoked (along with retain() and not lead to memory leaks if skipped. Typically this means using NIO DirectByteBuffers for data which will release automatically in the GC cycles when no references remain.

needsRelease

public abstract boolean needsRelease()

Returns true if explicit calls to release() are required for this object to be eagerly released else they can be skipped (e.g. heap buffers)

size

public abstract int size()

Size of the underlying data. If there are some callers who are doing explicit retain/release calls, then callers of this should also use the same consistently to ensure data does not get released prematurely.