fr.esrf.TangoApi.events
Class EventQueue

java.lang.Object
  fr.esrf.TangoApi.events.EventQueue

public class EventQueue
extends java.lang.Object

This class manage a vector of EventData to implement an event queue mechanism..


Usage example:

/**
* This class check the event queue mechanism.
* @author verdier
* /

import fr.esrf.Tango.DevFailed;
import fr.esrf.TangoDs.TangoConst;
import fr.esrf.TangoDs.Except;
import fr.esrf.TangoApi.DeviceProxy;
import fr.esrf.TangoApi.CallBack;
import fr.esrf.TangoApi.DeviceAttribute;
import fr.esrf.TangoApi.events.EventData;
import java.util.Date;

public class QueueTest extends DeviceProxy
{

//===============================================================
/**
* Constructor
* @param devname The device name.
* @param attname The attribute name.
* /
//===============================================================
public QueueTest(String devname, String attname) throws DevFailed
{
super(devname);
subscribe_event(attname, TangoConst.CHANGE_EVENT, 0, new String[] {}, true);

}
//===============================================================
/**
* Event management.
* Wait a bit to have enough events, get them and push them to callback
* /
//===============================================================
public void manageEvents()
{
// nb events to wait.
int nb = 10;
while(get_event_queue_size() < nb)
{
try { Thread.sleep(1000); }
catch(Exception e) {}

}

// Get all change events and display them
EventData[] events = get_events(TangoConst.CHANGE_EVENT);
for (EventData event : events)
{
System.out.print("Event at " + new Date(event.date) + ": ");
if (event.err)
Except.print_exception(event.errors);

else
{
DeviceAttribute value = event.attr_value;
if (value.hasFailed())
Except.print_exception(value.getErrStack());

else
try
{
if (value.getType()==TangoConst.Tango_DEV_DOUBLE)
System.out.println(value.extractDouble());

}
catch(DevFailed e)
{
Except.print_exception(e);

}

}

}

}
//===============================================================
/**
* main method.
* /
//===============================================================
public static void main (String[] args)
{
String devname = "my/device/test";
String attribute = "value";
try
{
QueueTest client = new QueueTest(devname, attribute);
client.manageEvents();

}
catch(DevFailed e)
{
Except.print_exception(e);

}

}
//===============================================================

}

Author:

pascal_verdier

Constructor Summary

EventQueue()
Creates a new instance of EventQueue for infinite EventData number

EventQueue(int max_size)
Creates a new instance of EventQueue for several EventData

Method Summary

EventData[]	getEvents() returns all EventData in queue.
EventData[]	getEvents(int event_type) returns all events in queue for specified type.
long	getLastEventDate() Returns the date of the last inserted and not yet extracted event.
EventData	getNextEvent() Returns the first event in queue.
EventData	getNextEvent(int event_type) Returns the first event in queue for specified type.
void	insert_event(EventData event) Insert an event in queue.
boolean	is_empty() returns true if no EventData in queue.
int	size() returns the number of EventData in queue for specified type.
int	size(int event_type) returns the number of EventData in queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

EventQueue

public EventQueue()

Creates a new instance of EventQueue for infinite EventData number

EventQueue

public EventQueue(int max_size)

Creates a new instance of EventQueue for several EventData

Parameters:

max_size - maximum size of the event queue.

Method Detail

is_empty

public boolean is_empty()

returns true if no EventData in queue.

size

public int size(int event_type)

returns the number of EventData in queue.

Parameters:

event_type - Specified event type.

size

public int size()

returns the number of EventData in queue for specified type.

insert_event

public void insert_event(EventData event)

Insert an event in queue.

Parameters:

event - Event to be inserted.

getNextEvent

public EventData getNextEvent()
                       throws DevFailed

Returns the first event in queue.

Throws:

DevFailed

getNextEvent

public EventData getNextEvent(int event_type)
                       throws DevFailed

Returns the first event in queue for specified type.

Parameters:

event_type - Specified event type.

Throws:

DevFailed

getEvents

public EventData[] getEvents()

returns all EventData in queue.

getEvents

public EventData[] getEvents(int event_type)

returns all events in queue for specified type.

Parameters:

event_type - Specified event type.

getLastEventDate

public long getLastEventDate()
                      throws DevFailed

Returns the date of the last inserted and not yet extracted event.

Throws:

DevFailed