de.skuzzle.jeve.stores

Interface PerformanceListenerStore

All Superinterfaces:

DefaultListenerStore, ListenerStore

public interface PerformanceListenerStore
extends DefaultListenerStore

Extension to the DefaultListenerStore which offers to enable higher ListenerStore.get(Class) performance. The higher performance is achieved at the cost of lowering the performance of ListenerStore.remove(Class, Listener) and ListenerStore.add(Class, Listener).

Most applications have something like a setup phase in which listeners are registered. After this phase, the listener store is rarely modified anymore, but events will be fired frequently from now on. If this reflects your usage scenario, this ListenerStore implementation can offer higher runtime performance.

After instantiation, this store behaves exactly like the DefaultListenerStore. After the registration phase of your application is finished, you may call optimizeGet() on this store. This will replace all regular Lists which are used to store different listeners with CopyOnWriteArrayLists. This reduces the need to copy the list of retrieved Listeners upon ListenerStore.get(Class). The cost of copying is thereby moved to the ListenerStore.add(Class, Listener) and ListenerStore.remove(Class, Listener) methods.

Since:

3.0.0

Author:

Simon Taddiken

Method Summary

Modifier and Type	Method and Description
static PerformanceListenerStore	create() Creates a new default PerformanceListenerStore.
boolean	isAutoOptimize() Whether auto optimization upon first call to ListenerStore.get(Class) has been enabled in the constructor.
boolean	isOptimized() Whether optimizeGet() has been called on this store.
void	optimizeGet() Interchanges the performance characteristics of ListenerStore.get(Class) with ListenerStore.add(Class, Listener) resp.
static PerformanceListenerStore	withAutoOptimize() Creates a new PerformanceListenerStore with the auto optimize flag set to true.

Methods inherited from interface de.skuzzle.jeve.ListenerStore

add, add, clearAll, clearAll, close, get, isSequential, remove, remove, synchronizedView

Method Detail

create

static PerformanceListenerStore create()

Creates a new default PerformanceListenerStore.

Specified by:

create in interface DefaultListenerStore

Returns:

A new PerformanceListenerStore instance.

withAutoOptimize

static PerformanceListenerStore withAutoOptimize()

Creates a new PerformanceListenerStore with the auto optimize flag set to true. This store will automatically call its optimizeGet() method the first time its ListenerStore.get(Class) method is called.

Returns:

A new PerformanceListenerStore instance.

isAutoOptimize

boolean isAutoOptimize()

Whether auto optimization upon first call to ListenerStore.get(Class) has been enabled in the constructor.

Returns:

Whether auto optimize is enabled.

isOptimized

boolean isOptimized()

Whether optimizeGet() has been called on this store.

Returns:

Whether optimizeGet() has been called on this store.

optimizeGet

void optimizeGet()

Interchanges the performance characteristics of ListenerStore.get(Class) with ListenerStore.add(Class, Listener) resp. ListenerStore.remove(Class, Listener).

This will store all currently registered listeners into CopyOnWriteArrayLists. Thus, after calling this method, the add and remove methods will always copy the internal array of the respective listener list. In return, the ListenerStore.get(Class) method does not need to create a copy of the retrieved listener list to achieve concurrency safety. Therefore, after calling this method

• add and remove perform in O(n).
• clear, clearAll and thus close perform in O(n²).
• get performs in O(1).

Where n is the number of listeners registered for a listener class.

This method may only be called once. Subsequent calls will have no effect. The internal modifications done by this method can not be reverted. Whether this method has already been called can be queried with isOptimized().