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com.tangosol.io.nio
Class DirectBufferManager

java.lang.Object
com.tangosol.util.Base
com.tangosol.io.nio.AbstractBufferManager
com.tangosol.io.nio.DirectBufferManager

All Implemented Interfaces:

ByteBufferManager

public class DirectBufferManager

extends AbstractBufferManager

Manages a growable direct ByteBuffer.

Since:

Coherence 2.2

Author:

cp 2002.09.16

See Also:

ByteBuffer

Field Summary

static int	CLEANUP_FINALIZERS Use Runtime.runFinalization() to trigger finalization (default).
static int	CLEANUP_GC Use Runtime.gc() to trigger finalization.
static int	CLEANUP_NONE Do not perform any buffer cleanup.
protected static boolean	MODE_DEBUG Set to true to use on-heap storage, false to use off-heap.
protected static long	s_cbUncollected Total amount of memory that have not been collected yet.

Constructor Summary

DirectBufferManager(int cbInitial, int cbMaximum)
Construct a DirectBufferManager that supports a buffer of a certain initial and maximum size.

Method Summary

protected void	allocateBuffer() Allocate a new buffer, copying old data if there is any.
protected void	cleanupBuffers() Determines if and how to induce the JVM to run finalizers.
static int	getAllocations() Return the total number of buffers allocated by the DirectBufferManager.
static int	getCleanupMethod() Return the method used for buffers cleanup when the threshold is met.
static float	getCleanupThreshold() Return the value used to calculate the size threshold for the uncollected buffers that triggers a cleanup operation.
static long	getTotalAllocationTime() Return the total time spent allocating buffers, copying the previous content and cleaning up uncollected buffers.
protected static void	setCleanupMethod(int nCleanupMethod) Set the method to be used for buffers cleanup when the threshold is met.
protected static void	setCleanupThreshold(float flCleanupThreshold) Determines how often, to run the cleanupBuffers() method.

Methods inherited from class com.tangosol.io.nio.AbstractBufferManager

calibrate, getBuffer, getCapacity, getGrowthThreshold, getMaxCapacity, getMaxIncrement, getMinCapacity, getShrinkageThreshold, grow, setBuffer, setCapacity, setGrowthThreshold, setMaxCapacity, setMinCapacity, setShrinkageThreshold, shrink

Field Detail

CLEANUP_NONE

public static final int CLEANUP_NONE

Do not perform any buffer cleanup.

See Also:

Constant Field Values

CLEANUP_FINALIZERS

public static final int CLEANUP_FINALIZERS

Use Runtime.runFinalization() to trigger finalization (default).

See Also:

Constant Field Values

CLEANUP_GC

public static final int CLEANUP_GC

Use Runtime.gc() to trigger finalization.

See Also:

Constant Field Values

MODE_DEBUG

protected static final boolean MODE_DEBUG

Set to true to use on-heap storage, false to use off-heap.

See Also:

Constant Field Values

s_cbUncollected

protected static volatile long s_cbUncollected

Total amount of memory that have not been collected yet.

Constructor Detail

DirectBufferManager

public DirectBufferManager(int cbInitial,
                           int cbMaximum)

Construct a DirectBufferManager that supports a buffer of a certain initial and maximum size.

Parameters:

cbInitial - the initial size

cbMaximum - the maximum size

Method Detail

allocateBuffer

protected void allocateBuffer()

Allocate a new buffer, copying old data if there is any.

Specified by:

allocateBuffer in class AbstractBufferManager

See Also:

ByteBuffer.allocateDirect()

cleanupBuffers

protected void cleanupBuffers()

Determines if and how to induce the JVM to run finalizers. This allows to somewhat mitigate the cleanup threshold frequency, induce the GC. In a 64-bit VMs this issue is probably reduced to a minimum.

getTotalAllocationTime

public static long getTotalAllocationTime()

Return the total time spent allocating buffers, copying the previous content and cleaning up uncollected buffers.

Returns:

the number of milliseconds spent in allocating, copying and cleaning up uncollected buffers

getAllocations

public static int getAllocations()

Return the total number of buffers allocated by the DirectBufferManager.

Returns:

the total number of allocations

getCleanupMethod

public static int getCleanupMethod()

Return the method used for buffers cleanup when the threshold is met.

The possible return values are:

CLEANUP_FINALIZERS - use Runtime.runFinalization() (default);

CLEANUP_GC - use Runtime.gc();

CLEANUP_NONE - do not perform any cleanup.

Returns:

one of the CLEANUP_* constants representing the cleanup method

setCleanupMethod

protected static void setCleanupMethod(int nCleanupMethod)

Set the method to be used for buffers cleanup when the threshold is met.

Parameters:

nCleanupMethod - a value representing the cleanup method; valid values are the CLEANUP_* constants

Throws:

java.lang.IllegalArgumentException - if passed value is not a valid CLEANUP_* constant

getCleanupThreshold

public static float getCleanupThreshold()

Return the value used to calculate the size threshold for the uncollected buffers that triggers a cleanup operation. Cleanup is performed when the total size of uncollected memory has grown over the product of this value and the maximum Java heap size.

Returns:

a value between 0.0 and 1.0 used to calculate the cleanup frequency

setCleanupThreshold

protected static void setCleanupThreshold(float flCleanupThreshold)

Determines how often, to run the cleanupBuffers() method. Cleanup is performed when the uncollected memory has grown over the product of this value and the maximum Java heap size.

Parameters:

flCleanupThreshold - a value between 0.0 and 1.0 used to calculate the cleanup frequency

Throws:

java.lang.IllegalArgumentException - if the passed value is not valid

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