jrun.jms.core.gc
Class GarbageCollectionService

jrunx.kernel.ServiceAdapter
  |
  +--jrun.jms.core.util.JMSServiceAdapter
        |
        +--jrun.jms.core.gc.GarbageCollectionService

All Implemented Interfaces:

GarbageCollectionServiceMBean, JMSService, JMSServiceAdapterMBean, javax.naming.Referenceable, SchedulableEventListener, java.io.Serializable, Service, ServiceMBean

public class GarbageCollectionService

extends JMSServiceAdapter

implements GarbageCollectionServiceMBean, SchedulableEventListener

The garbage collection service is responsible for managing all transient garbage collection for OpenJMS, which includes messages, destinations, endpoints etc. It does not deal with persistent data, which is handled through the database service. Other services or managers can register themselves with GarbageCollectionService if they implement the GarbageCollectable interface.

Gargabe collection will be initiated when the amount of free memory falls below a low water mark, which is calculated as a percentage of total memory. By default garbage collection will run when free memory falls below 20% of total memory, this can be changed through the configuration file.

The service will check the memory usage every 30 seconds by default. but this can also be modified through the configuration file.

In addition the garbage collection service can also be configured to execute at regular intervals regardless the amount of residual free memory. This option can be employed to ease the burden of performing wholesale garbage collection when memory falls below the low water mark threshold. The default value for this is 300 seconds. Setting this value to 0 will disable this capability.

This service makes use of the EventManager to register events for garabage collection.

Version:

$Revision: 1.4 $ $Date: 2001/10/11 21:17:32 $

Author:

Jim Alateras

See Also:

Serialized Form

Field Summary

static java.lang.String

OBJECT_NAME The name of the service

Fields inherited from class jrunx.kernel.ServiceAdapter

DEFAULT_DEACTIVATED, DEFAULT_DOMAIN, DOMAIN_NAME_SEPARATOR, DOMAIN_NAME_SUFFIX, domainName, jndiBindable, LOGGER_CACHE_TIME, SCHEDULER_SERVICE, SECURITY_MANAGER, server, status, TRANSACTION_MANAGER

Fields inherited from interface jrunx.kernel.Service

INITIALIZED, STARTED, STARTING, STOPPED, STOPPING, UNINITIALIZED

Constructor Summary

GarbageCollectionService()
Create an instance of a garbage collection service.

Method Summary

boolean	belowLowWaterThreshold() Check whether the low water threshold has been reached.
void	init() Not every service needs to init, implement it out of convenience.
static GarbageCollectionService	instance() Return the singleton instance of the GarbageCollectionService
void	onSchedulableEvent(java.lang.Object Handle, int type) This method is called whenever a schedulableEvent gets fired.
void	register(GarbageCollectable entry) Register an entity that wishes to participate in the garbage collection process.
void	run()
void	start() Every service other than mere data collections should start
void	stop() Every service other than mere data collections should stop
void	unregister(GarbageCollectable entry) Unregister the specified entry from the list of garbge collectable entities

Methods inherited from class jrun.jms.core.util.JMSServiceAdapter

getMetaData, restart, resume, setMetaData, suspend

Methods inherited from class jrunx.kernel.ServiceAdapter

bind, destroy, findObjectInstance, findObjectInstance, findObjectInstance, getBindToJNDI, getDeactivated, getDomainName, getDomainSearchPath, getJRunService, getLogger, getName, getParentService, getReference, getResourceManager, getServerName, getServerProperties, getStatus, invokeMethod, isInPartition, isPartition, lookup, postDeregister, postRegister, preDeregister, preRegister, requestServer, scheduleRunnable, setBindToJNDI, setDeactivated, setDomainName, setName, setParentService, toString, unbind, unscheduleRunnable, updateStatus

Methods inherited from interface jrunx.kernel.ServiceMBean

bind, getBindToJNDI, getDeactivated, getDomainName, getJRunService, getLogger, getName, getParentService, getServerName, requestServer, setBindToJNDI, setDeactivated, setDomainName, setName, setParentService, unbind

Methods inherited from interface jrunx.kernel.Service

destroy, getStatus, updateStatus

Field Detail

OBJECT_NAME

public static final java.lang.String OBJECT_NAME

The name of the service

Constructor Detail

GarbageCollectionService

public GarbageCollectionService()
                         throws GarbageCollectionServiceException

Create an instance of a garbage collection service. It uses the configuration manager to extract the service parameters.

It will throw a GarbageCollectionServiceException, if it cannot construct the service

Throws:

GarbageCollectionServiceException -

Method Detail

instance

public static GarbageCollectionService instance()
                                         throws GarbageCollectionServiceException

Return the singleton instance of the GarbageCollectionService

Returns:

GarbageCollectionService

Throws:

GarbageCollectionServiceException -

init

public void init()
          throws java.lang.Exception

Description copied from class: ServiceAdapter

Not every service needs to init, implement it out of convenience.

Specified by:

init in interface Service

Overrides:

init in class ServiceAdapter

belowLowWaterThreshold

public boolean belowLowWaterThreshold()

Check whether the low water threshold has been reached.

Returns:

boolean - true if it has; false otherwise

register

public void register(GarbageCollectable entry)

Register an entity that wishes to participate in the garbage collection process. This entity will be added to the list of other registered entities and will be called when GC is triggered.

Parameters:

entry - - entry to add to list

unregister

public void unregister(GarbageCollectable entry)

Unregister the specified entry from the list of garbge collectable entities

Parameters:

entry - - entry to remove

run

public void run()

start

public void start()
           throws java.lang.Exception

Description copied from class: ServiceAdapter

Every service other than mere data collections should start

Specified by:

start in interface Service

Overrides:

start in class ServiceAdapter

stop

public void stop()
          throws java.lang.Exception

Description copied from class: ServiceAdapter

Every service other than mere data collections should stop

Specified by:

stop in interface Service

Overrides:

stop in class ServiceAdapter

onSchedulableEvent

public void onSchedulableEvent(java.lang.Object Handle,
                               int type)

Description copied from interface: SchedulableEventListener

This method is called whenever a schedulableEvent gets fired. It passes the object associated with event.

Specified by:

onSchedulableEvent in interface SchedulableEventListener