com.cosylab.epics.caj.CAJMonitor Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of jca Show documentation

JCA is an EPICS Channel Access library for Java. For more information concerning EPICS or Channel Access please refer to the <a href="http://www.aps.anl.gov/epics">EPICS Web pages</a> or read the <a href="http://www.aps.anl.gov/epics/base/R3-14/8-docs/CAref.html">Channel Access manual (3.14)</a>. <p>This module also includes CAJ, A 100% pure Java implementation of the EPICS Channel Access library.</p>

There is a newer version: 2.4.2

Show newest version

/*
 * Copyright (c) 2004 by Cosylab
 *
 * The full license specifying the redistribution, modification, usage and other
 * rights and obligations is included with the distribution of this project in
 * the file "LICENSE-CAJ". If the license is not included visit Cosylab web site,
 * .
 *
 * THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND, NOT EVEN THE
 * IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, ASSUMES
 * _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE RESULTING FROM THE USE, MODIFICATION,
 * OR REDISTRIBUTION OF THIS SOFTWARE.
 */

package com.cosylab.epics.caj;

import java.io.IOException;
import java.util.ArrayList;

import com.cosylab.epics.caj.impl.Transport;
import com.cosylab.epics.caj.impl.requests.EventAddRequest;
import com.cosylab.epics.caj.impl.requests.EventCancelRequest;

import gov.aps.jca.CAException;
import gov.aps.jca.Channel;
import gov.aps.jca.Context;
import gov.aps.jca.Monitor;
import gov.aps.jca.dbr.DBRType;
import gov.aps.jca.event.MonitorEvent;
import gov.aps.jca.event.MonitorListener;

/**
 * Implementation of CAJ JCA Monitor. 
 * @author Matej Sekoranja
 * @version $id$
 */
public class CAJMonitor extends Monitor implements MonitorListener {

	/**
	 * Context.
	 */
	protected CAJContext context;

	/**
	 * Monitored value type.
	 */
	protected DBRType type;

	/**
	 * Number of elements (size of array) of monitored value type.
	 */
	protected int count;
	
	/**
	 * Monitored channel.
	 */
	protected CAJChannel channel;
	
	/**
	 * Event add request.
	 */
	protected EventAddRequest eventAddRequest = null;
	
	/**
	 * Monitor mask.
	 */
	protected int mask;

	/**
	 * Monitor listeners.
	 */
	protected ArrayList listeners = new ArrayList();
	
	/**
	 * Subscription ID.
	 */
	protected int subsid;

	/**
	 * Cleared flag.
	 */
	protected volatile boolean cleared = false;
	
	/**
	 * Constructor.
	 * @param context CAJContext
	 * @param type DBRType
	 * @param count count
	 * @param channel CAJChannel
	 * @param listener MonitorListener
	 * @param mask mask
	 * @throws CAException JCA Exception
	 */
	public CAJMonitor(CAJContext context, DBRType type, int count,
					  CAJChannel channel, MonitorListener listener, int mask) throws CAException
	{
		this.context = context;
		this.type = type;
		this.count = count;
		this.channel = channel;
		this.mask = mask;

		// register listener if non-null
		if (listener != null)
			addMonitorListener(listener);

		internalConnect();
		
		// register to the channel
		channel.registerMonitor(this);		
	}

	/**
	 * Subscribe monitor.
	 */
	private void internalConnect() throws CAException {
		
		try {
			eventAddRequest = new EventAddRequest(channel, this, channel.getTransport(), channel.getServerChannelID(), type.getValue(), count, mask);
			eventAddRequest.submit();
			subsid = eventAddRequest.getIOID();
		} catch (IOException ioex) {
			throw new CAException("Failed to create monitor.", ioex);
		}

	}

	/**
	 * @see gov.aps.jca.Monitor#clear()
	 */
	public synchronized void clear() throws CAException {
	    
	    if (cleared)
	        return;
	    cleared = true;
		
		Transport t = channel.getTransport();
		if (t != null)
		{
			try {
				new EventCancelRequest(t, channel.getServerChannelID(), subsid, type.getValue(), count).submit();
			} catch (IOException ioex) {
				// OK if transport/channel is closed
				// throw new CAException("Failed to clear monitor.", ioex);
			}
		}
		
	    // Cancel the EventAddRequest, unregistering it.
		// This prevents resubscriptions.
	    eventAddRequest.cancel();

	    // unregister from the channel
		channel.unregisterMonitor(this);		
	}

	/**
	 * @see gov.aps.jca.Monitor#getContext()
	 */
	public Context getContext() {
		return context;
	}

	/**
	 * @see gov.aps.jca.Monitor#getChannel()
	 */
	public Channel getChannel() {
		return channel;
	}

	/**
	 * @see gov.aps.jca.Monitor#getType()
	 */
	public DBRType getType() {
		return type;
	}

	/**
	 * @see gov.aps.jca.Monitor#getCount()
	 */
	public int getCount() {
		return count;
	}

	/**
	 * @see gov.aps.jca.Monitor#getMask()
	 */
	public int getMask() {
		return mask;
	}

	/**
	 * @see gov.aps.jca.Monitor#getMonitorListener()
	 */
	public MonitorListener getMonitorListener() {
		synchronized (listeners)
		{
			if (listeners.size() == 0)
				return null;
			else
				return (MonitorListener)listeners.get(0);
		}
	}

	/**
	 * @see gov.aps.jca.Monitor#addMonitorListener(gov.aps.jca.event.MonitorListener)
	 */
	public void addMonitorListener(MonitorListener l) {
		
		if (l == null)
			throw new IllegalArgumentException("l == null");
		
		synchronized (listeners)
		{
			if (!listeners.contains(l))
				listeners.add(l);
		}
	}

	/**
	 * @see gov.aps.jca.Monitor#removeMonitorListener(gov.aps.jca.event.MonitorListener)
	 */
	public void removeMonitorListener(MonitorListener l) {

		if (l == null)
			throw new IllegalArgumentException("l == null");

		synchronized (listeners)
		{
			listeners.remove(l);
		}
	}

	/**
	 * @see gov.aps.jca.Monitor#getMonitorListeners()
	 */
	public MonitorListener[] getMonitorListeners() {
		synchronized (listeners)
		{
			MonitorListener[] l = new MonitorListener[listeners.size()];
			return (MonitorListener[])listeners.toArray(l);
		}
	}

	/**
	 * @see gov.aps.jca.event.MonitorListener#monitorChanged(gov.aps.jca.event.MonitorEvent)
	 */
	public void monitorChanged(MonitorEvent ev) {
		context.getEventDispatcher().dispatch(ev, listeners);
	}

	/**
	 * Get this monitor subscription ID.
	 * @return monitor subscription ID
	 */
	public int getSID() {
		return subsid;
	}

	/**
	 * Get cleared flag.
	 * @return cleared flag.
	 */
    public boolean isCleared() {
        return cleared;
    }
}