org.diirt.datasource.sample.PausePv Maven / Gradle / Ivy
/**
* Copyright (C) 2010-18 diirt developers. See COPYRIGHT.TXT
* All rights reserved. Use is subject to license terms. See LICENSE.TXT
*/
package org.diirt.datasource.sample;
import java.util.List;
import org.diirt.datasource.ExpressionLanguage;
import org.diirt.datasource.PVManager;
import static org.diirt.datasource.vtype.ExpressionLanguage.*;
import org.diirt.datasource.PVReader;
import org.diirt.datasource.PVReaderEvent;
import org.diirt.datasource.PVReaderListener;
import org.diirt.datasource.sim.SimulationDataSource;
import java.time.Duration;
import org.diirt.vtype.VNumber;
/**
* Shows the pausing and resuming of pvs.
*
* Pv notifications can be paused and resumed. The connection and caching
* is not halted but delayed. When the pv is resumed, the current cached
* values for pending events are immediately processed.
*
* @author carcassi
*/
public class PausePv {
public static void main(String[] args) throws Exception {
PVManager.setDefaultDataSource(new SimulationDataSource());
System.out.println("Note that events cannot be stopped while they are in-flight.");
System.out.println("Therefore you may see one event arriving after the pause or after the close.");
System.out.println("Starting pv");
PVReader> reader = PVManager.read(ExpressionLanguage.newValuesOf(vNumber("ramp()")))
.readListener(new PVReaderListener>() {
@Override
public void pvChanged(PVReaderEvent> event) {
if (event.isValueChanged()) {
System.out.println("... values are " + event.getPvReader().getValue());
}
}
})
.maxRate(Duration.ofMillis(50));
Thread.sleep(2000);
System.out.println("Pausing for 3 seconds");
reader.setPaused(true);
Thread.sleep(3000);
System.out.println("Unpausing...");
reader.setPaused(false);
Thread.sleep(3000);
System.out.println("Closing...");
reader.close();
PVManager.getDefaultDataSource().close();
System.out.println("Done");
}
}