samples/topology/src/main/java/org/apache/edgent/samples/topology/TerminateAfterNTuples.java

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to you under the Apache License, Version 2.0 (the
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  http://www.apache.org/licenses/LICENSE-2.0

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package org.apache.edgent.samples.topology;

import java.util.Random;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.edgent.providers.direct.DirectProvider;
import org.apache.edgent.topology.TStream;
import org.apache.edgent.topology.Topology;

/**
 * This application simulates a crash and terminates the JVM after processing
 * a preset number of tuples. This application is used in conjunction with a 
 * monitoring script to demonstrate the restart of a JVM which has terminated
 * because of an Edgent application crash.
 */
public class TerminateAfterNTuples {
    /** The application will terminate the JVM after this tuple count */
    public final static int TERMINATE_COUNT = 15;
    
    public static void main(String[] args) throws Exception {

        DirectProvider tp = new DirectProvider();

        Topology t = tp.newTopology("PeriodicSource");

        // Since this is the Direct provider the graph can access
        // objects created while the topology is being defined
        // (in this case the Random object r).
        Random r = new Random();
        TStream<Double> gaussian = t.poll(() -> r.nextGaussian(), 1, TimeUnit.SECONDS);

        // Program termination
        AtomicInteger count = new AtomicInteger(0);
        gaussian = gaussian.peek(g -> {
            if (count.incrementAndGet() >= TERMINATE_COUNT) {
                System.err.println("The JVM terminates after processing " + 
                        TERMINATE_COUNT + " tuples");
                System.exit(1);
            }
        });

        // Peek at the value on the Stream printing it to System.out
        gaussian = gaussian.peek(g -> System.out.println("R:" + g));

        tp.submit(t);
    }
}