de.intarsys.tools.component

Interface IReferenceCounter

All Known Subinterfaces:

IActivityContext

All Known Implementing Classes:

StandardActivityContext

public interface IReferenceCounter

An object that is aware of its referents.

The object implements a reference counting mechanism that should behave like this:

• the object should keep a counter that increments when acquired and decrements when released
• upon creation the object should be acquired by the constructor or factory method.
• if the client code is not aware if a new object is created (or taken from a registry for example), the object published by the factory method should always be acquired.
• the object should not accept method calls before it is acquired
• when the counter is zero after release, the object should no longer accept any calls

If combined with the INotificationSupport, the object MAY trigger an AttributeChangedEvent upon acquire/release. In this case the ATTR_REFERENCECOUNT should be used to indicate the attribute.

If combined with the INotificationSupport, the object MAY trigger a DestroyedEvent when the reference count reaches 0.

Field Summary

Fields

Modifier and Type	Field and Description
static Attribute	ATTR_REFERENCECOUNT

Method Summary

Methods

Modifier and Type	Method and Description
Object	acquire() Indicate usage of the object.
int	getReferenceCount() The current "usage level".
void	release() Deprecated. use release(handle)
void	release(Object handle) The object is no longer needed.

Field Detail

ATTR_REFERENCECOUNT

static final Attribute ATTR_REFERENCECOUNT

Method Detail

acquire

Object acquire()

Indicate usage of the object. If valid, the reference count should increase and the method returns an opaque handle representing the "usage claim". This handle must be returned upon calling "release".

Returns:

An opaque usage token

getReferenceCount

int getReferenceCount()

The current "usage level". This is the number of unreleased "usage claims" via acquire.

Returns:

The current "usage level".

release

@Deprecated
void release()

Deprecated. use release(handle)

Old style release method

release

void release(Object handle)

The object is no longer needed. The reference count is decreased and the usage marked with the opaque handle is disposed.

Parameters:

handle -