org.lsst.ccs

Class PersistencyService

java.lang.Object

org.lsst.ccs.PersistencyService

All Implemented Interfaces:

HasLifecycle, ServiceLifecycle

public final class PersistencyService
extends Object
implements ServiceLifecycle, HasLifecycle

This objects is responsible for keeping track of fields annotated with Persist and to write them into a local file at subsystem shutdown or at regular time intervals.

Author:

LSST CCS Team

Method Summary

Modifier and Type	Method and Description
boolean	isLocalPersistenceFilePresent() Tells whether a local persistence file exists on the local filesystem for that agent.
boolean	load() Reads the persisted data local file and applies the contained value to the Persist annotated fields.
boolean	persistNow() Persists the annotated fields values in a local file.
void	preInit()
void	preStart() Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#start() has been called.
void	setAutomatic(boolean loadAtStartup, boolean persistAtShutdown) Customize the behavior of the local persistence service.
void	shutdown() Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#shutdown() has been called.

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, preBuild, preShutdown

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

build, init, postBuild, postInit, postShutdown, postStart, start

Method Detail

preInit

public void preInit()

Specified by:

preInit in interface ServiceLifecycle

preStart

public void preStart()

Description copied from interface: ServiceLifecycle

Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#start() has been called.

The preceding lifecycle step is HasLifecycle.postInit()

The following lifecycle step is HasLifecycle.start() At the time it is called :

• the PhaseState is INITIALIZING
• connection with the messaging layer is effective, the enclosing subsystem has started StatusHeartBeat publication

Specified by:

preStart in interface ServiceLifecycle

shutdown

public void shutdown()

Description copied from interface: HasLifecycle

Called from the enclosing Subsystem when org.lsst.ccs.Subsystem#shutdown() has been called. At the time it is called :

• PhaseState is CLOSING.
• HardwareController.checkStopped() has been called

It should be overridden to free non hardware related resources.

Specified by:

shutdown in interface HasLifecycle

setAutomatic

public void setAutomatic(boolean loadAtStartup,
                         boolean persistAtShutdown)

Customize the behavior of the local persistence service. This method can only when the Agent is initializing, otherwise it throws an exception.

Parameters:

loadAtStartup - true if the persistence file should be loaded automatically at startup

persistAtShutdown - true if the persistence file should be written autmatically at shutdown

persistNow

@Command(description="writes persistent data in local file")
public boolean persistNow()

Persists the annotated fields values in a local file. REVIEW : how do we make sure that modifications made to the fields are visible ? Does it matter ?

Returns:

true if the persistence was successful, false otherwise.

load

@Command(description="loads persistent data from local file")
public boolean load()

Reads the persisted data local file and applies the contained value to the Persist annotated fields. Inconsistent data are silently ignored

Returns:

true if the local persistent file has been set correctly, false otherwise.

isLocalPersistenceFilePresent

@Command(description="returns true if a local persistence file is present, false otherwise.")
public boolean isLocalPersistenceFilePresent()

Tells whether a local persistence file exists on the local filesystem for that agent.

Returns:

true if such a file exists, false otherwise.