org.lsst.ccs.services

Class AgentPeriodicTaskService

java.lang.Object

org.lsst.ccs.services.AgentPeriodicTaskService

All Implemented Interfaces:

AlertHandler, ClearAlertHandler, HasLifecycle, ServiceLifecycle, AgentService

public final class AgentPeriodicTaskService
extends Object
implements ServiceLifecycle, HasLifecycle, ClearAlertHandler, AgentService

A service to schedule periodic tasks. This service is responsible to manage the Agent's periodic tasks: - allow components to schedule periodic tasks - starts all the scheduled tasks once the Agent has started - stops the tasks upon shutdown It also provides utility methods to set/get the period of a task.

Author:

The LSST CCS Team

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	AgentPeriodicTaskService.AgentPeriodicTaskExecutionHandler

Nested classes/interfaces inherited from interface org.lsst.ccs.framework.ClearAlertHandler

ClearAlertHandler.ClearAlertCode

Constructor Summary

Constructors

Constructor and Description
AgentPeriodicTaskService()

Method Summary

Modifier and Type	Method and Description
void	build() First lifecycle hook.
ClearAlertHandler.ClearAlertCode	canClearAlert(Alert alert, AlertState state) Callback to clear an Alert instance.
Scheduler	createScheduler(String name, int nThreads) Create a scheduler by name and the default number of threads.
List<String>	getAgentPeriodicTaskNames() Get the list of names of the scheduled tasks.
String	getAgentServiceName() Get the name of this service.
Duration	getPeriodicTaskPeriod(String taskName) Get the period of a PeriodicTaks.
void	init() Called from the enclosing Subsystem at initialization phase.
void	preBuild()
void	preInit()
void	scheduleAgentPeriodicTask(AgentPeriodicTask task) Schedule a PeriodicTask.
void	scheduleAgentPeriodicTask(AgentPeriodicTask task, String schedulerName)
void	setPeriodicTaskPeriod(String taskName, Duration period) Change the period of a PeriodicTask.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.lsst.ccs.ServiceLifecycle

afterInit, afterStart, preShutdown, preStart

Methods inherited from interface org.lsst.ccs.framework.HasLifecycle

postBuild, postInit, postShutdown, postStart, shutdown, start

Methods inherited from interface org.lsst.ccs.services.AgentService

startForAgent

Constructor Detail

AgentPeriodicTaskService

public AgentPeriodicTaskService()

Method Detail

getAgentServiceName

public String getAgentServiceName()

Description copied from interface: AgentService

Get the name of this service. This name will be used to add the given service to the lookup tree.

Specified by:

getAgentServiceName in interface AgentService

Returns:

the AgentService name.

preBuild

public void preBuild()

Specified by:

preBuild in interface ServiceLifecycle

build

public void build()

Description copied from interface: HasLifecycle

First lifecycle hook. Modification of the component tree is allowed at this stage. After this stage the tree of component cannot be modified anymore. This is where agent periodic tasks should be scheduled.

Specified by:

build in interface HasLifecycle

preInit

public void preInit()

Specified by:

preInit in interface ServiceLifecycle

init

public void init()

Description copied from interface: HasLifecycle

Called from the enclosing Subsystem at initialization phase.

This method is called before the children components of this object have their init method called.

At the time it is called, connection to the messaging layer is not yet done, so there should be no attempt to send messages in the body of this method. Configuration for message listening can nevertheless be done here, such as adding MessageListener objects.

It is unnecessary to call super.init()

Specified by:

init in interface HasLifecycle

createScheduler

public Scheduler createScheduler(String name,
                                 int nThreads)

Create a scheduler by name and the default number of threads. This scheduler can be then used to schedule periodic tasks. The number of threads allocated for this scheduler can be changed via a configuration parameter.

Parameters:

name -

nThreads -

scheduleAgentPeriodicTask

public void scheduleAgentPeriodicTask(AgentPeriodicTask task)

Schedule a PeriodicTask. Any CCS component can schedule an AgentPeriodicTask for execution. This method is available only using the init period of . Any invocation of this method at a later stage will result in a RuntimeException.

Parameters:

task - The PeriodicTask to schedule

scheduleAgentPeriodicTask

public void scheduleAgentPeriodicTask(AgentPeriodicTask task,
                                      String schedulerName)

getPeriodicTaskPeriod

public Duration getPeriodicTaskPeriod(String taskName)

Get the period of a PeriodicTaks.

Parameters:

taskName - The name of the task

Returns:

The periodic task period in milliseconds.

setPeriodicTaskPeriod

public void setPeriodicTaskPeriod(String taskName,
                                  Duration period)

Change the period of a PeriodicTask. If the Subsystem configuration Environment has been initialized and the Subsystem is not in INITAIL_SAFE configuration we use the configuration environment to change the period. Otherwise we simply change the AgentPeriodicTask directly.

Parameters:

taskName - The name of the task

period - The period Duration

getAgentPeriodicTaskNames

@Command(name="getAgentPeriodicTaskNames",
         description="Get the list of the names of the scheduled tasks",
         type=QUERY,
         category=SYSTEM)
public List<String> getAgentPeriodicTaskNames()

Get the list of names of the scheduled tasks.

Returns:

the Enumeration of task names.

canClearAlert

public ClearAlertHandler.ClearAlertCode canClearAlert(Alert alert,
                                                      AlertState state)

Description copied from interface: ClearAlertHandler

Callback to clear an Alert instance. Return a ClearAlertCode for the provided Alert.

Specified by:

canClearAlert in interface ClearAlertHandler

Parameters:

alert - The Alert instance to clear.

state - The AlertState for the provided Alert.

Returns:

A ClearAlertCode to indicate which action is to be taken by the framework.