org.jboss.gravia.runtime

Class ModuleTracker<T>

java.lang.Object

org.jboss.gravia.runtime.ModuleTracker<T>

Type Parameters:

T - The type of the tracked object.

All Implemented Interfaces:

ModuleTrackerCustomizer<T>

public class ModuleTracker<T>
extends Object
implements ModuleTrackerCustomizer<T>

The ModuleTracker class simplifies tracking modules much like the ServiceTracker simplifies tracking services.

A ModuleTracker is constructed with state criteria and a ModuleTrackerCustomizer object. A ModuleTracker can use the ModuleTrackerCustomizer to select which modules are tracked and to create a customized object to be tracked with the module. The ModuleTracker can then be opened to begin tracking all modules whose state matches the specified state criteria.

The getModules method can be called to get the Module objects of the modules being tracked. The getObject method can be called to get the customized object for a tracked module.

The ModuleTracker class is thread-safe. It does not call a ModuleTrackerCustomizer while holding any locks. ModuleTrackerCustomizer implementations must also be thread-safe.

Thread Safety: Thread Safe

Field Summary

Fields

Modifier and Type	Field and Description
protected ModuleContext	context The Module Context used by this ModuleTracker.

Constructor Summary

Constructors

Constructor and Description
ModuleTracker(ModuleContext context, ModuleTrackerCustomizer<T> customizer, Module.State... states) Create a ModuleTracker for modules whose state is present in the specified state mask.

Method Summary

Methods

Modifier and Type	Method and Description
T	addingModule(Module module, ModuleEvent event) Default implementation of the ModuleTrackerCustomizer.addingModule method.
void	close() Close this ModuleTracker.
Module[]	getModules() Return an array of Modules for all modules being tracked by this ModuleTracker.
T	getObject(Module module) Returns the customized object for the specified Module if the specified module is being tracked by this ModuleTracker.
Map<Module,T>	getTracked() Return a Map with the Modules and customized objects for all modules being tracked by this ModuleTracker.
int	getTrackingCount() Returns the tracking count for this ModuleTracker.
boolean	isEmpty() Return if this ModuleTracker is empty.
void	modifiedModule(Module module, ModuleEvent event, T object) Default implementation of the ModuleTrackerCustomizer.modifiedModule method.
void	open() Open this ModuleTracker and begin tracking modules.
void	remove(Module module) Remove a module from this ModuleTracker.
void	removedModule(Module module, ModuleEvent event, T object) Default implementation of the ModuleTrackerCustomizer.removedModule method.
int	size() Return the number of modules being tracked by this ModuleTracker.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

context

protected final ModuleContext context

The Module Context used by this ModuleTracker.

Constructor Detail

ModuleTracker

public ModuleTracker(ModuleContext context,
             ModuleTrackerCustomizer<T> customizer,
             Module.State... states)

Create a ModuleTracker for modules whose state is present in the specified state mask.

Modules whose state is present on the specified state mask will be tracked by this ModuleTracker.

Parameters:

context - The ModuleContext against which the tracking is done.

states - The list of the module states to be tracked.

customizer - The customizer object to call when modules are added, modified, or removed in this ModuleTracker. If customizer is null, then this ModuleTracker will be used as the ModuleTrackerCustomizer and this ModuleTracker will call the ModuleTrackerCustomizer methods on itself.

See Also:

Module.getState()

Method Detail

open

public void open()

Open this ModuleTracker and begin tracking modules.

Module which match the state criteria specified when this ModuleTracker was created are now tracked by this ModuleTracker.

Throws:

IllegalStateException - If the ModuleContext with which this ModuleTracker was created is no longer valid.

SecurityException - If the caller and this class do not have the appropriate AdminPermission[context module,LISTENER], and the Java Runtime Environment supports permissions.

close

public void close()

Close this ModuleTracker.

This method should be called when this ModuleTracker should end the tracking of modules.

This implementation calls getModules() to get the list of tracked modules to remove.

addingModule

public T addingModule(Module module,
             ModuleEvent event)

Default implementation of the ModuleTrackerCustomizer.addingModule method.

This method is only called when this ModuleTracker has been constructed with a null ModuleTrackerCustomizer argument.

This implementation simply returns the specified Module.

This method can be overridden in a subclass to customize the object to be tracked for the module being added.

Specified by:

addingModule in interface ModuleTrackerCustomizer<T>

Parameters:

module - The Module being added to this ModuleTracker object.

event - The module event which caused this customizer method to be called or null if there is no module event associated with the call to this method.

Returns:

The specified module.

See Also:

ModuleTrackerCustomizer.addingModule(Module, ModuleEvent)

modifiedModule

public void modifiedModule(Module module,
                  ModuleEvent event,
                  T object)

Default implementation of the ModuleTrackerCustomizer.modifiedModule method.

This method is only called when this ModuleTracker has been constructed with a null ModuleTrackerCustomizer argument.

This implementation does nothing.

Specified by:

modifiedModule in interface ModuleTrackerCustomizer<T>

Parameters:

module - The Module whose state has been modified.

event - The module event which caused this customizer method to be called or null if there is no module event associated with the call to this method.

object - The customized object for the specified Module.

See Also:

ModuleTrackerCustomizer.modifiedModule(Module, ModuleEvent, Object)

removedModule

public void removedModule(Module module,
                 ModuleEvent event,
                 T object)

Default implementation of the ModuleTrackerCustomizer.removedModule method.

This method is only called when this ModuleTracker has been constructed with a null ModuleTrackerCustomizer argument.

This implementation does nothing.

Specified by:

removedModule in interface ModuleTrackerCustomizer<T>

Parameters:

module - The Module being removed.

event - The module event which caused this customizer method to be called or null if there is no module event associated with the call to this method.

object - The customized object for the specified module.

See Also:

ModuleTrackerCustomizer.removedModule(Module, ModuleEvent, Object)

getModules

public Module[] getModules()

Return an array of Modules for all modules being tracked by this ModuleTracker.

Returns:

An array of Modules or null if no modules are being tracked.

getObject

public T getObject(Module module)

Returns the customized object for the specified Module if the specified module is being tracked by this ModuleTracker.

Parameters:

module - The Module being tracked.

Returns:

The customized object for the specified Module or null if the specified Module is not being tracked.

remove

public void remove(Module module)

Remove a module from this ModuleTracker. The specified module will be removed from this ModuleTracker . If the specified module was being tracked then the ModuleTrackerCustomizer.removedModule method will be called for that module.

Parameters:

module - The Module to be removed.

size

public int size()

Return the number of modules being tracked by this ModuleTracker.

Returns:

The number of modules being tracked.

getTrackingCount

public int getTrackingCount()

Returns the tracking count for this ModuleTracker. The tracking count is initialized to 0 when this ModuleTracker is opened. Every time a module is added, modified or removed from this ModuleTracker the tracking count is incremented.

The tracking count can be used to determine if this ModuleTracker has added, modified or removed a module by comparing a tracking count value previously collected with the current tracking count value. If the value has not changed, then no module has been added, modified or removed from this ModuleTracker since the previous tracking count was collected.

Returns:

The tracking count for this ModuleTracker or -1 if this ModuleTracker is not open.

getTracked

public Map<Module,T> getTracked()

Return a Map with the Modules and customized objects for all modules being tracked by this ModuleTracker.

Returns:

A Map with the Modules and customized objects for all services being tracked by this ModuleTracker. If no modules are being tracked, then the returned map is empty.

isEmpty

public boolean isEmpty()

Return if this ModuleTracker is empty.

Returns:

true if this ModuleTracker is not tracking any modules.