IUsageTracker (Atoti Server Java API - 6.0.26)

All Known Implementing Classes:

ConcurrentIdentityUsageTracker
```
public interface IUsageTracker<E>
```
Class tracking usages of objects.
An object must first be registered to the tracker. Afterwards, users can call acquire(Object) to notify their use of the item, and release(Object) to notify they stop using it.
When an object is not used anymore, it shall be removed using deregister(Object).

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`acquire(E item)`	Notifies this tracker that the item starts being used somewhere.
`long`	`count(E item)`	Returns the number of times this item is being used.
`void`	`deregister(E item)`	Deregisters an item from this tracker.
`Collection<E>`	`getTrackedItems()`	Gets the list of all items tracked by this instance.
`boolean`	`isTracking(Object item)`	Tests whether the provided item is tracked by this component.
`void`	`register(E item)`	Registers an item in this tracker.
`long`	`release(E item)`	Notifies this tracker that the item stopped being used.

- Method Detail
  - register
```
void register(E item)
```
    Registers an item in this tracker.
  - deregister
```
void deregister(E item)
```
    Deregisters an item from this tracker.
    
    Throws:
    
    IllegalStateException - if the item is still being used, i.e. its counts is positive.
  - count
```
@Nonnegative
long count(E item)
```
    Returns the number of times this item is being used.
  - acquire
```
void acquire(E item)
```
    Notifies this tracker that the item starts being used somewhere.
  - release
```
long release(E item)
```
    Notifies this tracker that the item stopped being used.
    
    Returns:
    
    the number of times the item is used after this release.
  - getTrackedItems
```
Collection<E> getTrackedItems()
```
    Gets the list of all items tracked by this instance.
  - isTracking
```
boolean isTracking(Object item)
```
    Tests whether the provided item is tracked by this component.