timertest.java

来自「JGRoups源码」· Java 代码 · 共 200 行

// $Id: TimerTest.java,v 1.5 2005/12/23 18:36:28 belaban Exp $
package org.jgroups.tests;


import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jgroups.stack.Interval;
import org.jgroups.util.Util;

import java.util.HashMap;
import java.util.Timer;
import java.util.TimerTask;


/**
 * Test cases for Timer. May fail sometimes, for example if there is GC during the run. Therefore, if run
 * standalone, the likelyhood of GC is smaller than when run with the entire testsuite 
 *
 * @author Bela Ban
 */
public class TimerTest extends TestCase {
    Timer win=null;
    final int NUM_MSGS=1000;
    long[] xmit_timeouts={1000, 2000, 4000, 8000};
    double PERCENTAGE_OFF=0.3; // how much can expected xmit_timeout and real timeout differ to still be okay ?
    HashMap msgs=new HashMap(); // keys=seqnos (Long), values=Entries


    class MyTask extends TimerTask {
        Entry entry;

        MyTask(Entry entry) {
            this.entry=entry;
        }

        public void run() {
            entry.retransmit();
        }

    }


    class Entry {
        long start_time=0;  // time message was added
        long first_xmit=0;  // time between start_time and first_xmit should be ca. 1000ms
        long second_xmit=0; // time between first_xmit and second_xmit should be ca. 2000ms
        long third_xmit=0;  // time between third_xmit and second_xmit should be ca. 4000ms
        long fourth_xmit=0; // time between third_xmit and second_xmit should be ca. 8000ms
        Interval interval=new Interval(xmit_timeouts);
        long seqno=0;

        Entry(long seqno) {
            this.seqno=seqno;
            start_time=System.currentTimeMillis();
        }


        public void retransmit() {
            if(first_xmit == 0)
                first_xmit=System.currentTimeMillis();
            else
                if(second_xmit == 0)
                    second_xmit=System.currentTimeMillis();
                else
                    if(third_xmit == 0)
                        third_xmit=System.currentTimeMillis();
                    else
                        if(fourth_xmit == 0)
                            fourth_xmit=System.currentTimeMillis();

            win.schedule(new MyTask(this), interval.next());
        }


        public long next() {
            return interval.next();
        }


        /**
         * Entry is correct if xmit timeouts are not more than 30% off the mark
         */
        boolean isCorrect() {
            long t;
            long expected;
            long diff, delta;
            boolean off=false;

            t=first_xmit - start_time;
            expected=xmit_timeouts[0];
            diff=Math.abs(expected - t);
            delta=(long)(expected * PERCENTAGE_OFF);
            if(diff >= delta) off=true;

            t=second_xmit - first_xmit;
            expected=xmit_timeouts[1];
            diff=Math.abs(expected - t);
            delta=(long)(expected * PERCENTAGE_OFF);
            if(diff >= delta) off=true;

            t=third_xmit - second_xmit;
            expected=xmit_timeouts[2];
            diff=Math.abs(expected - t);
            delta=(long)(expected * PERCENTAGE_OFF);
            if(diff >= delta) off=true;

            t=fourth_xmit - third_xmit;
            expected=xmit_timeouts[3];
            diff=Math.abs(expected - t);
            delta=(long)(expected * PERCENTAGE_OFF);
            if(diff >= delta) off=true;

            if(off) {
                System.err.println("#" + seqno + ": " + this + ": (" + "entry is more than " +
                        PERCENTAGE_OFF + " percentage off ");
                return false;
            }
            return true;
        }


        public String toString() {
            StringBuffer sb=new StringBuffer();
            sb.append(first_xmit - start_time).append(", ").append(second_xmit - first_xmit).append(", ");
            sb.append(third_xmit - second_xmit).append(", ").append(fourth_xmit - third_xmit);
            return sb.toString();
        }
    }


    public TimerTest(String name) {
        super(name);
    }


    /**
     * Tests whether retransmits are called at correct times for 1000 messages. A retransmit should not be
     * more than 30% earlier or later than the scheduled retransmission time
     */
    public void testRetransmits() {
        Entry entry;
        MyTask task;
        int num_non_correct_entries=0;

        win=new Timer();

        // 1. Add NUM_MSGS messages:
        System.out.println("-- adding " + NUM_MSGS + " messages:");
        for(long i=0; i < NUM_MSGS; i++) {
            entry=new Entry(i);
            task=new MyTask(entry);
            msgs.put(new Long(i), entry);
            win.schedule(task, entry.next());
        }
        System.out.println("-- done");

        // 2. Wait for at least 4 xmits/msg: total of 1000 + 2000 + 4000 + 8000ms = 15000ms; wait for 20000ms
        System.out.println("-- waiting for 20 secs for all retransmits");
        Util.sleep(20000);

        // 3. Check whether all Entries have correct retransmission times
        for(long i=0; i < NUM_MSGS; i++) {
            entry=(Entry)msgs.get(new Long(i));
            if(!entry.isCorrect()) {
                num_non_correct_entries++;
            }
        }

        if(num_non_correct_entries > 0)
            System.err.println("Number of incorrect retransmission timeouts: " + num_non_correct_entries);
        else {
            for(long i=0; i < NUM_MSGS; i++) {
                entry=(Entry)msgs.get(new Long(i));
                if(entry != null)
                    System.out.println(i + ": " + entry);
            }
        }
        assertTrue(num_non_correct_entries == 0);
        try {
            win.cancel();
        }
        catch(Exception ex) {
            System.err.println(ex);
        }
    }


    public static Test suite() {
        TestSuite suite;
        suite=new TestSuite(TimerTest.class);
        return (suite);
    }

    public static void main(String[] args) {
        String[] name={TimerTest.class.getName()};
        junit.textui.TestRunner.main(name);
    }
}