jdk.management.resource

Class SimpleMeter

java.lang.Object

jdk.management.resource.SimpleMeter

All Implemented Interfaces:

ResourceMeter, ResourceRequest

Direct Known Subclasses:

NotifyingMeter

public class SimpleMeter
extends Object
implements ResourceMeter, ResourceRequest

A SimpleMeter counts resource requests and releases and allocates from an optional parent. The amount is validated before requesting allocation from the parent. Subclasses can override the validation to include bounds checking, notification, callbacks, etc.

Since:

8u40

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SimpleMeter(ResourceType type, ResourceRequest parent) Constructor for subclasses.

Method Summary

Modifier and Type	Method and Description
static SimpleMeter	create(ResourceType type) Returns a new SimpleMeter with the ResourceType.
static SimpleMeter	create(ResourceType type, ResourceRequest parent) Returns a new SimpleMeter with the ResourceType and allocating from a parent.
boolean	equals(Object obj) Indicates whether some other object is the same object as this one.
long	getAllocated() Returns the cumulative total of allocations from the ResourceMeter.
ResourceRequest	getParent() Returns the parent ResourceRequest.
ResourceType	getType() Returns the ResourceType.
long	getValue() Returns the current net value of the ResourceMeter.
int	hashCode() Returns the hashcode from for this object.
long	request(long amount, ResourceId id) Returns the validated and allocated amount and adjusts the meter.
String	toString() Returns a string representation of the meter.
protected long	validate(long previous, long amount, ResourceId id) Validate the amount returning the validated amount.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SimpleMeter

protected SimpleMeter(ResourceType type,
                      ResourceRequest parent)

Constructor for subclasses.

Parameters:

type - the ResourceType for the meter

parent - a ResourceRequest used as the parent to allocate from; may be null

Method Detail

create

public static SimpleMeter create(ResourceType type)

Returns a new SimpleMeter with the ResourceType.

Parameters:

type - the ResourceType

Returns:

a new SimpleMeter

create

public static SimpleMeter create(ResourceType type,
                                 ResourceRequest parent)

Returns a new SimpleMeter with the ResourceType and allocating from a parent.

Parameters:

type - the ResourceType

parent - the parent ResourceMeter; may be null

Returns:

a new SimpleMeter

getValue

public final long getValue()

Description copied from interface: ResourceMeter

Returns the current net value of the ResourceMeter. The net value is the difference between the cumulative amounts allocated minus all amounts released.

Specified by:

getValue in interface ResourceMeter

Returns:

the current net value of the meter

getAllocated

public final long getAllocated()

Description copied from interface: ResourceMeter

Returns the cumulative total of allocations from the ResourceMeter.

Specified by:

getAllocated in interface ResourceMeter

Returns:

the total allocated from the meter

getType

public final ResourceType getType()

Description copied from interface: ResourceMeter

Returns the ResourceType.

Specified by:

getType in interface ResourceMeter

Returns:

the ResourceType

getParent

public final ResourceRequest getParent()

Returns the parent ResourceRequest.

Returns:

Returns the parent ResourceRequest; may be null

request

public final long request(long amount,
                          ResourceId id)

Returns the validated and allocated amount and adjusts the meter. For allocation, amount greater than zero, the amount is applied to the meter before validation so it is immediately visible. If the validation or allocation from the parent is for a different amount the delta is restored to the meter. For releasing a resource, amount less than zero, the amount is applied after validation to avoid premature release of the resource.

Specified by:

request in interface ResourceRequest

Parameters:

amount - the amount to allocate; if zero nothing is done

id - the ResourceId for the resource instance; may be null

Returns:

the allocated amount, zero, positive or negative

validate

protected long validate(long previous,
                        long amount,
                        ResourceId id)
                 throws ResourceRequestDeniedException

Validate the amount returning the validated amount. Override to apply bounds checks and callbacks.

For allocation, positive amounts, the amount is applied to the meter before validation so it is immediately visible. For releasing a resource, negative amounts, the amount is applied after validation to avoid premature release of the resource. If the amount returned is different than requested the meter will be corrected with the difference.

Parameters:

previous - the meter value before the current request

amount - an amount, positive to allocate, negative to release

id - the ResourceId for the resource instance; may be null

Returns:

the validated amount, zero or throw an exception to deny; return a value with the same sign as the amount

Throws:

ResourceRequestDeniedException - if the amount cannot be satisfied

toString

public String toString()

Returns a string representation of the meter.

Overrides:

toString in class Object

Returns:

a string representation of the meter

hashCode

public final int hashCode()

Returns the hashcode from for this object.

Overrides:

hashCode in class Object

Returns:

a hashcode for this object

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

equals

public final boolean equals(Object obj)

Indicates whether some other object is the same object as this one.

Overrides:

equals in class Object

Parameters:

obj - the reference object with which to compare

Returns:

true if this object is the same as the obj argument; false otherwise

See Also:

Object.hashCode(), HashMap