org.csstudio.utility.pv.epics

Class RefCountedMonitor

java.lang.Object

org.csstudio.utility.pv.epics.RefCountedMonitor

All Implemented Interfaces:

gov.aps.jca.event.MonitorListener, EventListener

public class RefCountedMonitor
extends Object
implements gov.aps.jca.event.MonitorListener

RefCountedMonitor is a monitor reference, which uses a single channel access monitor subscription for many different listeners. This object should be created for the first requested subscription for specific channel and of specific type. Or later creation should reference the same cached object. When all channels unsubscribe this reference should be disposed of as well.

Author:

Jaka Bobnar

Constructor Summary

Constructors

Constructor and Description
RefCountedMonitor(gov.aps.jca.Channel channel, gov.aps.jca.dbr.DBRType type, int mask, String name) Creates a new reference monitor for the given channel of the given type.

Method Summary

Modifier and Type	Method and Description
void	addMonitorListener(gov.aps.jca.event.MonitorListener listener) Adds a listener to this monitor.
int	decRefs() Decrement reference count.
void	dispose() Dispose of this reference.
String	getName()
void	incRefs() Increment reference count.
void	monitorChanged(gov.aps.jca.event.MonitorEvent ev)
void	removeMonitorListener(gov.aps.jca.event.MonitorListener listener) Removes the listener from this reference.

Methods inherited from class java.lang.Object

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

Constructor Detail

RefCountedMonitor

public RefCountedMonitor(gov.aps.jca.Channel channel,
                         gov.aps.jca.dbr.DBRType type,
                         int mask,
                         String name)
                  throws gov.aps.jca.CAException

Creates a new reference monitor for the given channel of the given type.

Parameters:

channel - the channel to subscribe to

type - the data type for the subscription

mask - the monitor mask

name - the name of this reference used for caching

Throws:

IllegalStateException - if creation of subscription failed

gov.aps.jca.CAException - if creation of subscription failed

Method Detail

addMonitorListener

public void addMonitorListener(gov.aps.jca.event.MonitorListener listener)

Adds a listener to this monitor. If this reference already received a value from the CA, the value is forwarded to the listener.

Parameters:

listener - the listener to add

removeMonitorListener

public void removeMonitorListener(gov.aps.jca.event.MonitorListener listener)

Removes the listener from this reference.

Parameters:

listener - the listener to remove

dispose

public void dispose()
             throws gov.aps.jca.CAException

Dispose of this reference.

Throws:

gov.aps.jca.CAException - if the monitor is still referenced by a PV

incRefs

public void incRefs()

Increment reference count.

decRefs

public int decRefs()

Decrement reference count.

Returns:

Remaining references.

monitorChanged

public void monitorChanged(gov.aps.jca.event.MonitorEvent ev)

Specified by:

monitorChanged in interface gov.aps.jca.event.MonitorListener

getName

public String getName()

Returns:

the name of this channel